Model Engine Maker
Supporting => Tooling & Machines => Topic started by: ttrikalin on June 18, 2013, 11:22:48 PM
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Your Graces,
there are threads that are captivating, engaging and informative. Threads that take us on adventures, spur the imagination, forge bonds across countries and timezones. Threads that unravel in fast, steady and fulfilling pace; knowledge laden, each post more valuable than the next. Threads we long to follow, to read again, to brief our spouses about.
This is not one of those threads.
This thread is about the sorry state of affairs I have found my self in, still continuing on a journey that started three winters and a baby ago. In 2010, I parted with a thousand odd dollars to acquire a South Bend 10K that had never seen a day of production work, yet was blessed with two decades' worth of caressing touches by high school teens.
Unencumbered by the thought process (I hear this is what my car mechanic's uncle's brother says), I embarked on a reconditioning. I must be reconditioning with hitherto unseen skill and care, as I have been at it for several calendar years and am not even half way done.
The modest motivation of regular reporting might help me progress, and why not, finish this summer. So here we go...
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This is the bed, fresh off the grinder, and shimmed and leveled within Connelly's specs: The deviation from the horizon is 0.001" over the length of the bed (the saddle is just sitting there, not scraped in yet).
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0864_zpsa7757f60.jpg)
This is the cross-slide, after several cycles of spotting and scraping. The upper surface
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0851_zpse82167e3.jpg)
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0855_zps76cfb7c6.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0855_zps76cfb7c6.jpg.html)
and the lower surface (sliding/bearing ways):
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0852_zpse9baee30.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0852_zpse9baee30.jpg.html)
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It seems to me that the cross-slide's bearing surface needs a round or two to carry better...
upper and lower surfaces of the cross-slide are within Connelly's specs with respect to parallelism. A tenths indicator registers under one tenth over the length of the ways... but my indicator is one I restored my self and needs repeated measurements to trust, and I am measuring on a chinese tombstone (to borrow from nick mueller)...
I still have to scrape the guiding way of the dovetail and the flat gib...
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Hey Tom!
My condolences!
If I can help...let me know.
Dave
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Who ground it for you?
Dave
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What are you using for a master?.....and do you need to borrow any?
Dave
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This is not one of those threads.
:lolb: :lolb:
Oh man. That was a great post. I really enjoyed that.
I can't contribute to the subject...I know next to nothing about it...but know that I'm supporting you.
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Who ground it for you?
The same bloke who ground yours. The other Dave at Forest City Grinding, IL. I am happy with his work... Dave is a gent. He shipped the bed back to me before I even put the check in the mail...
I trust the guy and I would recommend him...
tom
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Nice to know there are still folks out there like that, not that common these days.
Bill
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Tom
Ill help you any way I can Tom...you know that.
The bearing on the flat way is coming along nice. A few more cycles.
I find classical Boston suites me when the points count goes up.
Dave
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Glad to see that there is one who actually does a recondition. And not just a paint strip, some putty and a layer of lacquer.
You'll need a lot of patience (if that's your first). Spotting looks promising, but the way needs something like 5 more passes.
Nick
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Glad to see that there is one who actually does a recondition. And not just a paint strip, some putty and a layer of lacquer.
You'll need a lot of patience (if that's your first). Spotting looks promising, but the way needs something like 5 more passes.
Nick
As am I. I knew you have been thinking about it...and I guess I can't say I didn't know you started....but I did caution you! :ROFL:
The pain goes away eventually.....
But you've gotten farther than I did in the same time...so keep at it!....Mine has been two years yesterday! :censored:.but the scraping is done, and its assembly and debug at this point....life does throw up distractions doesn't it!
Best of luck with it Tom....and again glad to help if you need it.
Dave
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I joined this Forum to learn new things and this is certainly stuff I had not thought about before. Keep up the good work!
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Hi, great project and looks like it'll be a nice piece of kit when back together. I've never understood scraping - how do you get the blue on on to highlight the high spots? Or are those the bits that have been done? How do you go about scraping? Just scrape a bit off and check for fit again?
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Hi, great project and looks like it'll be a nice piece of kit when back together. I've never understood scraping - how do you get the blue on on to highlight the high spots? Or are those the bits that have been done? How do you go about scraping? Just scrape a bit off and check for fit again?
It's a bit more complicated than that Nick...and like lots of things, there are various ways to approach the problem. One of the best references on this side of the pond is Connelly's book "Machine Tool Reconditioning"...though it doesn't talk much about the actual technique. Some of Nick Mueller's (OUR Nick ) video's would be well to search out on Youtube as a picture is worth a thousand words and clearly Nick knows what he's doing! :NotWorthy:
I learned from some scraping hands ...for some of my education...while at Heald Machine ( Cincinnati Milacron) and Moore Tool....though I am mostly self taught, and scraping is one of those things you can't really learn unless you do it. I'm an Engineer by training...not a scraper.....but I get by. I can assure you there are a lot of different ways to put on the marking media...and types of marking media...and types of scraper tools...and techniques for using those tools.....and for making do with the tools you have!....which you have to do sometimes. Sounds like Tom will be demonstrating....and I'm looking forward to whatever he would like to present....
Dave
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It's one of the things I'm sure my grandad could have told me something about but never got chance, I know he had some funny shaped "engineers scrapers" but I never questioned it any further. Cheers, Will have to do a bit of research, find it fascinating that people can make a large area of metal flat by hand!
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I learned from some scraping hands
Yes, the best you can do, is get a beginner's course from say Forrest Addy. He does offer them in the USA. Look at PracticalMachinist, he offers classes there.
Don't take a class that lasts for a week, you will break down at day two. I even can't imagine how his pupils survive a 3 day class that lasts 8 hours a day. As a beginner, you can't scrape 8 hours. 4 hours and you are fed up!
Learn the basics, and you can build a lot on that continuing at home.
Or find someone who can show it to you. A few evenings with 2…3 hours will put you on the right track. The rest is "just" learning to understand what is happening, judging from the blue and the way you apply the blue. The time-consuming part in the learning curve is reading the blue and understanding its language.
And don't forget, metrology will be a hefty investment!
Nick
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And don't forget, metrology will be a hefty investment!
Yes sir it is!......even a cheap precision level is not cheap!
and indicators
and squares
and possibly straight edges...
labor put into making masters....sometimes for one use!
ect
Dave
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What are you using for a master?.....and do you need to borrow any?
Ah, I have made a 45 degree prism which I have been scraping for a master. It is not ready yet. Although it carries spots over the whole surface, they are not uniform, and less than 20 per square inch. However, it passes the 3 papers test...
For those who have not read about said test... it tests for straightness:
1. rest the to-be-tested master on the surface plate sandwitching three pieces of cigarette paper, one at each end, and one at the middle
2. draw each piece of paper sequentially as if to remove them-- If the master is straight, you should feel the same resistance
Connelly says (and I believe him, having done it sometimes) that this is more sensitive than you would think. It is rather easy to sense a difference in resistance.
Thanks, Dave for the offer, but for now let's see how my own master turns out... I will take pictures tomorrow night...
take care,
tom in MA
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And don't forget, metrology will be a hefty investment!
So true. I have lousy instruments...
1. a small chinese tombstone 9"x12", supposedly 0.000050" tolerance (over what distance? the ... certificate did not clarify)
2. another chinese tombstone 12"x18", 0.000100" tolerance (over over some distance)
3. an old Starrett Last Word indicator, 0.001" resolution
4. a no name indicator, 0.0005" resolution
5. a Federal 0.0001" DTI, which was sticky and I restored (should post a story about the restoration thereof)
I do not plan to buy better surface plates... but I will buy a tenths indicator... I will fabricate hardware for indicator setups for measuring...
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Have at it buddy!....
Dave
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Hey Nick,
I just saw this vid of yours.....Damn man...I need to change my pants now! :lolb:
https://www.youtube.com/watch?v=Y8NqeD73ZZ4
Dave
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Nick
I have a couple of mills made in China that were spotted the same as in your video. Took hours to correct them.
Dave
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OK, today I got 2 hours in the shop and decided to continue a tad on the lathe... So I did six rounds on the lower bearing ways of the cross slide, and got to this
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0876_zps6d2464af.jpg)
Marking is done with minimal dye on the tombstone... and when its day you can "mark" without dye at all, by giving the ways a wipe with ethanol, let them dry, and the touch the part on the tombstone. I recall reading about this in Connelly... I was surprised to see that in daylight, it really works...
After the baby goes to bed I may have some time to check parallelism with the upper surface... It was within 0.0002" over the length of the ways last time in any direction, and I would not expect it to have worsened much if at all by now...
Dave, Nick or others who know what they do... Some questions...
1. Connelly, I gather, wants me to attain 15-20 points per square inch, because these ways will be the template for the mating (upper side) ways on the saddle... I would say I may have gotten near the lower point (I do not show my 1 inch window in the photo... for reference, the narrow surface is a bit over half an inch...)
2. Would you say that the bearing is homogeneous? It appears that the points are not entirely evenly scattered, but this is a matter of opinion(*). I am tempted to call this bearing quality OK, but I fear this is optimistic.
tom
(*) I could measure the distribution by digitizing locations of points and doing a Kolmogorov-Smirnov test against what I would get from a uniform distribution in each direction ... but let's see what you think first...
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And this is the lower surface of the swivel compound base, marked using the upper surface of the cross slide as a template:
(http://i810.photobucket.com/albums/zz22/ttrikalin/2013-06-17190700_zps30c8547b.jpg)
As a reminder, the latter has been scraped enough to attain good marking:
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0855_zps76cfb7c6.jpg)
1. In terms of bearing quality, I call the above two surfaces done.
2. I still have to check again for alignment... and because alignment and bearing quality are achieved at the same time, take point (1) above with a grain of salt.
The alignment tests have not been completed... especially for the whole assembly of cross slide, swivel base and swivel compound. Connelly gives a tolerance for the assembly of 0.0035" per 10" of travel. It seems to me that I can do much better, and I will try... but he knows what he's talking about and I may find this much more difficult than meets the eye.
Still hanging in there,
tom
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OK, today I got 2 hours in the shop and decided to continue a tad on the lathe... So I did six rounds on the lower bearing ways of the cross slide, and got to this
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0876_zps6d2464af.jpg)
Marking is done with minimal dye on the tombstone... and when its day you can "mark" without dye at all, by giving the ways a wipe with ethanol, let them dry, and the touch the part on the tombstone. I recall reading about this in Connelly... I was surprised to see that in daylight, it really works...
After the baby goes to bed I may have some time to check parallelism with the upper surface... It was within 0.0002" over the length of the ways last time in any direction, and I would not expect it to have worsened much if at all by now...
Dave, Nick or others who know what they do... Some questions...
1. Connelly, I gather, wants me to attain 15-20 points per square inch, because these ways will be the template for the mating (upper side) ways on the saddle... I would say I may have gotten near the lower point (I do not show my 1 inch window in the photo... for reference, the narrow surface is a bit over half an inch...)
2. Would you say that the bearing is homogeneous? It appears that the points are not entirely evenly scattered, but this is a matter of opinion(*). I am tempted to call this bearing quality OK, but I fear this is optimistic.
tom
(*) I could measure the distribution by digitizing locations of points and doing a Kolmogorov-Smirnov test against what I would get from a uniform distribution in each direction ... but let's see what you think first...
First of all, stone that thing and mark it up again...I see some burrs...or spots so small they might as well be burrs
Look at the mark up again, and compare it to the photo....I suspect it will get better distribution.
I'd do like the following for a cycle and see what's going on. If the pattern changes drastically, and I suspect it will, I would say your being too aggressive for the condition of the bearing. Shorten your stroke and lighten your cut..
(http://i164.photobucket.com/albums/u27/mcandrew1894/Family/MarkupforTom_zps538b864b.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Family/MarkupforTom_zps538b864b.jpg.html)
It would appear your using a fairly small radius blade as the marking show very hard bearing. You may want to use a blade with a bit larger radius
Cross your cuts at about a 30 degree angle...even on the bottom of the compound.....see the streaks in the blue on the top of the cross slide that you used for a master?....those streaks appear as little silver arcs...that is either dirt, chips, or burrs...make sure you stone the part before you mark it up...if it's dirt you will feel it instantly...it even sounds wrong during the mark up!
The best think to clean the part with?...the meaty palm of your hand....works very well...though you will have blue hands for a while....
I would leave the area marked "ignore for 1 cycle" ..just like it is....see if it hardens up...it's a bit low as you don't have bulls eye's in the middle of the marking....let them go for a cycle or two and see if they mark up with a bulls eye.
I would also to the area's marked "hard bearing" 1 cycle only....and see how the whole pattern changes...I suspect your touching on those area's only.....really
Your blue appears thin...but it's telling you where things are at.....leave that as it is a for a couple of cycles....just so we can see what's going on.
Dave
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This is closer to what your after...not so much the number of points,..no I haven't counted.... but the points themselves....they are pretty much all the same size and evenly distributed.
(http://i164.photobucket.com/albums/u27/mcandrew1894/tooling/P7130057.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/tooling/P7130057.jpg.html)
That will give you the repeatability you desire. and wear the longest. The answer is to cut evenly...same pressure, and stroke length.
And you want bit better than 15-20 for a part your going to used as a master....I would anyway...but it takes a while.
Dave
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Hi, I have been watching your scraping work, and Dave´s too in his SB9 rebuild tread, both are great and I been learning a lot, soon I hope to start scrapping myself on my chinese tombstone.
I have a question about the stone you guys use for clearing the burrs, I have seen this stone mentioned in some videos I have been watching, its a tin flat black stone...
This stone, its need to of some special kind? or grit?, here the only stone I could get is these ultra cheap 6x2" gray kitchen knife sharpening stone :Lol:
I'm following your work with enthusiasm!
Saludos
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Mostly agree with what Dave wrote.
Sharp eye re the burrs! :ThumbsUp:
personally, I don't want to see any blue spots that at the border of the surface. They bear a high risk of being overseen. And sometimes, they are incredibly hard to spot. So yes, stone them down.
A word about stoning:
Do not stone too much. You are scraping, not stoning. Just a few passes until you hear/feel that the burrs are gone.
Scraper radius:
This work looks small, so the radius of the tool gets smaller too. You ware working in small areas and everything scales down. 60 mm radius is what I would use here (and I use it most of the time for finishing).
Coverage/number of spots:
In the upper guide, the area in the left 1/3 looks good to me (with some spots left for improvement).
But I have to say, that the spots per square inch method is crap. Not the fact that you want to have a certain number of spots, but the fact that there is no repeatable way to measure them. Just make a thicker layer of blue, and the coverage shoots up. If the layer is thick enough, you have 100% :)
A better way is to observe how the spots develop. As long as they do get more, there is work left to be done. If they stay the same and you have to split them to increase their count, you can call it good.
The picture doesn't look like you are in the splitting phase, a few more passes to be done. Maybe you should be a bit more aggressive. My guess is, that you do work too cautious.
Hope that helps a bit.
Nick
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Your probably right Nick...Most people scrape too cautious. The radius seems too small to me at least on the piece....but I agree with your assessment that a 60mm radius is about right for the job.
I also agree with your comments about the stone....easy does it.
I suppose much depends on how heavy the blue really is....I'm sure Tom will show us shortly. And as I don't usually use blue, perhaps I'm reading it differently so I defer to you on that.
:cheers:
Dave
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And hey Tom....what are you using for a camera?....head on shots of spotting is hard to do... :ThumbsUp:
Dave
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@Tom:
Except for the burrs, I do not see severe obvious errors. So, you should not be too disappointed by the critics. You are on the right track, and you are very close to a good result.
Also, the pattern of you scraping passes looks good to me. The more random it gets, be better it is. If you look at in which direction you scraped on a spot and the direction is random (half one direction, other half the other direction) you know that you are good or almost good. If all high spots have the same scraping direction, there is work left to be done.
I know how annoying scraping can be. :cussing:
Nick
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No critics here. Keep gong Tom!
Dave
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No critics here. Keep gong Tom!
Dave
@Tom:
Except for the burrs, I do not see severe obvious errors. So, you should not be too disappointed by the critics. You are on the right track, and you are very close to a good result.
Also, the pattern of you scraping passes looks good to me. The more random it gets, be better it is. If you look at in which direction you scraped on a spot and the direction is random (half one direction, other half the other direction) you know that you are good or almost good. If all high spots have the same scraping direction, there is work left to be done.
I know how annoying scraping can be. :cussing:
Nick
Gents,
I am very much in debt for the pointers, and I assure you, I have not taken the feedback the wrong way.
Your comments are already helping me break out of chasing my tail with the reading of the marking...
I did not reply this am, as I printed the comments and went down to the garage to have a go at it, and take photos... and now these are coming in installments in the next posts...
So what follows is:
1. a standardization of the amount of blue I put on the tombstone
2. the evolution of the markings after 2, 7 and 9 cycles
3. high magnification of the markings at 9 cycles
4. the planning to resurrect a dead-on-arrival VFD -- the suboptimal way ;)
here we go...
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Point 1. On the standardization of marking and reading.
What Nick described in the quotation below I have seen in practice. In fact, after a while, weaker characters like me might be tempted to thicken the dye on the tombstone, and pat ourselves on the back on work well done...
[...] But I have to say, that the spots per square inch method is crap. Not the fact that you want to have a certain number of spots, but the fact that there is no repeatable way to measure them. Just make a thicker layer of blue, and the coverage shoots up. If the layer is thick enough, you have 100% :)
A better way is to observe how the spots develop. As long as they do get more, there is work left to be done. If they stay the same and you have to split them to increase their count, you can call it good. [...]
So I cleaned the tombstone well, with plenty of 90% alcohol... I use the hi-spot blue (and nitrile gloves -- anastasia does not let me in the apartment otherwise. :( )
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0878_zps1363bb21.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0878_zps1363bb21.jpg.html)
I usually put the blue by eye, by smearing a decidedly smaller quantity than Mike Moore did in his video (to be expected -- he was demonstrating rough scraping :facepalm: ).
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0879_zpsaba168b0.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0879_zpsaba168b0.jpg.html)
But for today, I wiped that off, and decided to try something more repeatable... sort of... I do not have a precision scale, so a by-eye volumetric approach should do...
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0883_zps116ad63c.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0883_zps116ad63c.jpg.html)
A dolop, a bit more than 3 mm in diameter:
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0884_zps03383b3a.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0884_zps03383b3a.jpg.html)
This ended up being a tad thick, so I removed some by swiping most of it off from 1/4 of the 9" by 12" tombstone, and re-distributed it...
I renewed the blue in cycle 6 -- and this may account for apparent differences in the photos that will follow...
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The "calibrated eyeball dolop" is how I do it too Tom...works for me
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Point 2. On the evolution of marks and the need to deburr (always deburr)...
[...] I have a question about the stone you guys use for clearing the burrs, I have seen this stone mentioned in some videos I have been watching, its a tin flat black stone...
[...]
So this is the stone I use... I was supposedly a slip stone, of the soft arkansas variety, which I got online for a few bucks (too expensive still -- but I have this as a hobby so I do not really ponder the pennies...)
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0880_zps86c69955.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0880_zps86c69955.jpg.html)
Dave was right -- :embarassed: I was not paying attention to stoning. I was also using the stone pretty loaded. So I cleaned the stone, and listened to its sounds after each scraping pass. There is a distinct cutting sound that I think corresponds to the raised burrs being knocked down (cut?) by the stone. After a couple of easy passes the sound and the resistance vanish, and the stone slips smoothly over the surface.
Next post is my understanding of how the burr is raised while scraping... also based on connelly's descriptions and stuff I may have read here or elsewhere.... so please correct me...
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Point 2, continued.. .On the nature of burrs...
So this is my understanding about the nature of burrs, based on observation, and on what I've read in Connelly's book, and what I've read on this forum... Please correct me if this is off....
When we cut with the scraper, there is a lip of metal that is left behind, at the end of the stroke. The schematic tries to show this... it is not accurate of course in that it is not to scale, and that the deepest point of the cut is drawn near the lip (burr). The deepest point of the cut should be closer to the midway of the stroke, and the blade should start coming up before the end of the stroke. Well, I probably scrape the wrong way (i.e., as I drew...) So in some twisted sense, my drawing is accurate!
(http://i810.photobucket.com/albums/zz22/ttrikalin/Burrs_zps1e0efbab.jpg) (http://s810.photobucket.com/user/ttrikalin/media/Burrs_zps1e0efbab.jpg.html)
So when we stone the work, we knock down the lip raised by the blade... I think...
(http://i810.photobucket.com/albums/zz22/ttrikalin/Burrs_2_zpsc99fa680.jpg) (http://s810.photobucket.com/user/ttrikalin/media/Burrs_2_zpsc99fa680.jpg.html)
tom
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Point 2, continued.. .On the nature of burrs...
So this is my understanding about the nature of burrs, based on observation, and on what I've read in Connelly's book, and what I've read on this forum... Please correct me if this is off....
When we cut with the scraper, there is a lip of metal that is left behind, at the end of the stroke. The schematic tries to show this... it is not accurate of course in that it is not to scale, and that the deepest point of the cut is drawn near the lip (burr). The deepest point of the cut should be closer to the midway of the stroke, and the blade should start coming up before the end of the stroke. Well, I probably scrape the wrong way (i.e., as I drew...) So in some twisted sense, my drawing is accurate!
(http://i810.photobucket.com/albums/zz22/ttrikalin/Burrs_zps1e0efbab.jpg) (http://s810.photobucket.com/user/ttrikalin/media/Burrs_zps1e0efbab.jpg.html)
So when we stone the work, we knock down the lip raised by the blade... I think...
(http://i810.photobucket.com/albums/zz22/ttrikalin/Burrs_2_zpsc99fa680.jpg) (http://s810.photobucket.com/user/ttrikalin/media/Burrs_2_zpsc99fa680.jpg.html)
tom
Yes...that is pretty accurate...at least from my perspective...your should lighten the stroke just before you finish so it doesn't leave as much of a burr....but for the life of me I don't know how to teach anyone that.....I leave some burrs...but not too bad...but I do stone my work. Your stone looks much nicer than mine...but is similar...I dress it on 150 grit sandpaper every once in a LONG while...but otherwise I just use it.
When you mark up the part, if there is a burr on it , or dirt, or chips...the moment you move it on the "tombstone"...you will feel it, and you will hear it...it sounds very different...and you will see swirls in the marking medium.....
Dave
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I should get a photo of the work after a pass, before and after the stoning... and with tangential light... till then... Take a sneak peak through the microscope... I know the picture is crappy, but I am holding the camera to the eye piece... Magnification is (I think x20) -- I do not recall the setting.
The red ellipse shows a stoned burr (from a previous cycle) on a spotted surface. The stroke is light, and the radius is small, so the width of the cut is small (~2mm), and the cut is shallow. THe red arrows show the direction of some cuts that have been overlapped by other cuts... The upper one, pointing to the ellipse is the cut that generated the aforementioned burr. The other arrow shows another cut, in a different direction...
(http://i810.photobucket.com/albums/zz22/ttrikalin/Burr_microscope_zps1514babf.jpg) (http://s810.photobucket.com/user/ttrikalin/media/Burr_microscope_zps1514babf.jpg.html)
more later, baby woke up...
t
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Tom, your method of finding out the thickness of the blue won't work that well.
Make a very thin layer and pick up all the blue with your work. Means: Spot, wipe off from work, spot, ... until the work no longer picks up blue. Part of the blue still will be sitting in the many pores of the surface plate. These pores are a desirable property.
You will find out, that it takes much more blue on a fresh plate than it takes on one that you have been using after cleaning.
Nick
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Tom, your method of finding out the thickness of the blue won't work that well.
Make a very thin layer and pick up all the blue with your work. Means: Spot, wipe off from work, spot, ... until the work no longer picks up blue. Part of the blue still will be sitting in the many pores of the surface plate. These pores are a desirable property.
You will find out, that it takes much more blue on a fresh plate than it takes on one that you have been using after cleaning.
I hear ya... The standardization is simply for meself... I scrape for 2 hours every two weeks, and by the time I start getting the hang of it I stop... So this thread is a reminder for me too...
btw -- I tried spotting with a banana, as shown in the video you posted, but it didn't work too well for me... When I ate the banana I also ate some Dykem blue, and now my tongue is blue :P
-
and now my tongue is blue
I want a video of it! :LittleDevil:
Nick
-
2. Evolution of the markings...
It seems to me that I am chasing my tail... but I am not sure... I am sure I am not consistent in my scraping force -- I have only a few hours' experience, and scattered...
This is where we left off yesterday...
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0876_zps6d2464af.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0876_zps6d2464af.jpg.html)
I wiped it off, stoned it, marked again, and after two passes:
(http://i810.photobucket.com/albums/zz22/ttrikalin/0fb312d4-017f-456b-aabd-5ff849c55126_zpsb4bd5f8d.jpg) (http://s810.photobucket.com/user/ttrikalin/media/0fb312d4-017f-456b-aabd-5ff849c55126_zpsb4bd5f8d.jpg.html)
and after three passes ...
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0885_zpsf3fa9592.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0885_zpsf3fa9592.jpg.html)
After 7 passes... (blue was added in this spotting).
(http://i810.photobucket.com/albums/zz22/ttrikalin/d9fef209-a4b8-41fa-a442-04558320a777_zps1b87dbe0.jpg) (http://s810.photobucket.com/user/ttrikalin/media/d9fef209-a4b8-41fa-a442-04558320a777_zps1b87dbe0.jpg.html)
and after 9 passes...
(http://i810.photobucket.com/albums/zz22/ttrikalin/c9edc755-e045-4e6f-b232-bfe0ffea554e_zps830083b7.jpg) (http://s810.photobucket.com/user/ttrikalin/media/c9edc755-e045-4e6f-b232-bfe0ffea554e_zps830083b7.jpg.html)
In the next post, I will mark which areas I see as "good" and which need more work...
t
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The only conclusion I can draw from the pictures is, that you are scraping too hard.
That makes you an exception!
Do only scrape the spots with an eye (better just the eyes, not the whole blue spot) and only something around 3 strokes. Light strokes.
Take a picture of two consecutive passes.
Nick
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So this is some topography for cycle 9. I am sure I have deburred this before spotting, and that I have not spotted clumsily (i.e., i let the weight of the part be the only downward force (well, if I pushed down it would be very lightly), and I moved less than an inch in 2 directions...
(http://i810.photobucket.com/albums/zz22/ttrikalin/round9Areas_zps8c0b1f0c.jpg) (http://s810.photobucket.com/user/ttrikalin/media/round9Areas_zps8c0b1f0c.jpg.html)
Were I to order the 6 areas in some sense of "optimality" (not defined, but bear with me):
1. areas A2 and B1 are better
2. Next is B3
3. Next is B2 and A1 and A3
Though if you ask me what the difference is between tier 2 and 3 is , I'd say that it is small (to my untrained eye).
I then decided to do some high magnification photos...
-
The only conclusion I can draw from the pictures is, that you are scraping too hard.
That makes you an exception!
[...]
:praise2:
Thanks, this matches what Dave said also...
PS.
I will tell Anastasia
"I was told that I scrape too hard, and that most people scrape too lightly"
or perhaps
"I was told I am an exception in that I am hard in my scraping"
which is almost
"I was told I am an exceptional guy, hard as nails, and tough as O1 steel"
And to dress it up a bit
"I was told I am an exceptional guy, hard, and tough, but with a sensitive streak".
That will do it.
-
[...]
And to dress it up a bit
"I was told I am an exceptional guy, hard, and tough, but with a sensitive streak".
That will do it.
Anastasia said about my scraping prowess.
"#%^@&$ (@ &&$& @"
or perhaps
"%$#* pay more attention, and then clean the %*^#V up before coming upstairs"
which is almost
"you are delightfully carefree and adorably clumsy"
-
Now some photos of area A2 in high magnification ... We focus on the circle...
(http://i810.photobucket.com/albums/zz22/ttrikalin/e5352861-5899-46f5-93a3-5ead71380944_zps1dcc3860.jpg) (http://s810.photobucket.com/user/ttrikalin/media/e5352861-5899-46f5-93a3-5ead71380944_zps1dcc3860.jpg.html)
zooming in
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0910_zpsaf2a342f.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0910_zpsaf2a342f.jpg.html)
zooming in (a nearby point)
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0911_zps91ca3f97.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0911_zps91ca3f97.jpg.html)
and zooming more
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0914_zps4476bc69.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0914_zps4476bc69.jpg.html)
It had never occurred to me to look under the microscope... the actual image is clear and beautiful, even with the butchery I do...
t
-
And this is the setup...
I scrape on my welding table...
My brother came to visit last year from greece... he is a mechanical engineer (he works in Luxembourg now)... and when he came he taught me how to arc weld (well, he tried...)
I think the table came out pretty good...
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0906_zps85c23753.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0906_zps85c23753.jpg.html)
And a general view...
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0897_zpsd577ea12.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0897_zpsd577ea12.jpg.html)
Next I will post on the VFD... perhaps in a separate thread... though it is for the SB repair in some sense... so perhaps here...
t
-
[...]
And to dress it up a bit
"I was told I am an exceptional guy, hard, and tough, but with a sensitive streak".
That will do it.
Anastasia said about my scraping prowess.
"#%^@&$ (@ &&$& @"
or perhaps
"%$#* pay more attention, and then clean the %*^#V up before coming upstairs"
which is almost
"you are delightfully carefree and adorably clumsy"
:lolb:...Ya gotta love that girl.....
From what I see Tom....I agree...your bearing is coming along...but you have a problem developing...or IT maybe there ALREADY...it's high in the middle.
I would take two easy passes...in just sections A2 and B2.....you want to lighten that up a bit and get the part to sit down on the outboard ends more...otherwise you MAY have a rocker part
A way to tell that is to put the part on a clean plate and tap it with your fingers....like a doctor thumps your abdomen during a check up...if you hear it go "clink clink".....its a rocking horse...
better to take out the center a bit and get the ends to sit down...and the mark up will settle down too........THEN
Put away the muscle building program and go easy....and scrape Straight Down....work ALL the high points and nothing but the high points....and the center will come back...but this time in a very stable manner with good progression of bearing.
Dave
ON EDIT
Just do area A2.....a couple of cycles only!....and check the mark up....
AND GENTLY
-
and now my tongue is blue
I want a video of it! :LittleDevil:
Nick
So do I!
-
OK, now that the baby is asleep and I've had some time to kick back, switch gears and move to point 4...
1. a standardization of the amount of blue I put on the tombstone
2. the evolution of the markings after 2, 7 and 9 cycles
3. high magnification of the markings at 9 cycles
4. the planning to resurrect a dead-on-arrival VFD -- the suboptimal way ;)
A VFD is short for a variable frequency drive, and is the gizmo that powers the motor of the lathe... So in some sense this small digression is not really related to the reconditioning of the lathe... In fact it is not related to the actual VFD that powers the lathe...
So here the story goes... This is the VFD... The part of the picture that's in focus...
(http://i810.photobucket.com/albums/zz22/ttrikalin/da0996c6-7abb-4080-9001-82d9771d8bee_zps5155f770.jpg) (http://s810.photobucket.com/user/ttrikalin/media/da0996c6-7abb-4080-9001-82d9771d8bee_zps5155f770.jpg.html)
My VFD is a very nice gizmo. It takes the 1 phase 115V output I have at home and spits out a 220V 3 phase, which me motor needs to turn...
I have a VFD from TB Woods (they are no longer making them). I got it online... The first came dead on arrival, and the vendor immediately replaced it with another one. He told me I could keep the first one, he did not want it back. Nice guy.
I decided to diagnose the old one... and if I can fix it, I would have two...
-
I really like mine....Thanks Again Don!
Dave
-
VFDs take the input AC, convert it to DC in a CONVERTER MODULE and charge big capacitors, that store large charge. Then the capacitor gives juice to the INVERTER MODULE. The latter has power semiconductors -- IGBTs (https://en.wikipedia.org/wiki/Insulated-gate_bipolar_transistor (https://en.wikipedia.org/wiki/Insulated-gate_bipolar_transistor)) which, under microcontroller control (with pulse width modulation) can output the stored energy into pretty much whatever waveform you want (well, whatever the gal or guy who programmed the controller wanted).
I had the VFD in storage for a year, so there was surely no charge in the capacitors... (I did use care)... This is the thingie's guts ...
I was planning on checking the inverter module first. It is a bunch of diodes, and it is easy to check.
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0868_zpsdea2c10a.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0868_zpsdea2c10a.jpg.html)
The VFD does all the business in one BIG CHIP... IXYS MUBW 15-06 A7... This chip has the converter, a temp sensor, a chopper brake (more later), and the inverter modules... all in one... Googling the datasheet I got the schematic... and was able to identify the pins on the board... You can see them numbered with black pen...
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0866_zps812300ea.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0866_zps812300ea.jpg.html)
The schematic is here...
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_0869_zpsc9306366.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_0869_zpsc9306366.jpg.html)
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I simple checked the diodes with the multimeter... 4 diodes in the converter module are open (shot)... These are D11 through D14... The other diodes (e.g. D15, D16, and so on) have a small voltage drop in the conducting direction (.38V, as per datasheet) and do not conduct in the other direction, as they are supposed to do...
So now I simply plan to tap into the main board with a mini PCB of my own that has diodes of the correct specification in the place of the shot ones... I was able to find diodes that match the specs of the ones in the chip... this is important... as the input has to be balanced...
-
I think this will work in the end... The silly thing is that the parts cost me ~$20 at Mouser.com... and a replacement chip from IXYS is no more than $50, (it comes from the depths of China)...
So in all, I am banging me head to provide a suboptimal solution to a solved problem... :facepalm:
t
-
I think this will work in the end... The silly thing is that the parts cost me ~$20 at Mouser.com... and a replacement chip from IXYS is no more than $50, (it comes from the depths of China)...
So in all, I am banging me head to provide a suboptimal solution to a solved problem... :facepalm:
t
Oh ...and don't forget the scraping part..... :lolb:
At least you have company!
:cheers:
Dave
-
and that I have not spotted clumsily (i.e., i let the weight of the part be the only downward force (well, if I pushed down it would be very lightly), and I moved less than an inch in 2 directions...
Oh-oh! Who told you this!?
To properly develop the spotting pattern, the part hast to be moved. The finer the scraping, the more it has to be moved. You need to give the blue a chance to be wiped away from the peaks and to build the bull's eye.
So place the part (that's how I do it) on the plate where no blue is, move it into the blue area and move it there in circles (so say figure 8, I don't do it so).
Diameter of the circle maybe 10 cm (not really that important). Maybe something around 5 turns.
No jerky moves, but smooth and gently. Grap the part so, that you don't tilt it. That means a bit below the center of gravity. That part is quite flat, so don't worry about that. Push it down a bit.
Steamer already mentioned the rocking test.
Sometimes, it is hard to hear wether it rocks, so here is a better way:
Lay the part down, put a DI on top of one corner and try to rock it diagonally (over two opposing corners). Repeat at a second corner, but not one diagonal to the first one :)
Nick
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You have got a extremely steep high point here:
(Red circle) and the other ones marked are also quite "forceful".
The one with the red circle really has to be scraped down. Twice as many strokes as the other ones.
If you rub the work more (as described above), you will polish the high spots. Then, the points standing out more will appear to be black. They have a black spot in the center. You won't find many of these (in theory only three) and you really have to hammer these down.
By the color gradient (speed of change of color), you can guesstimate the slope of the point. A high gradient means that the mountain has a steep angle. So scraping them means that you have to scrape just at the peak and not a bit on the sides. Envision the Matterhorn surrounded by smooth hills (that are at almost the same height).
The spots in the black circle are friendly. Those are the hills you want to get.
Nick
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and that I have not spotted clumsily (i.e., i let the weight of the part be the only downward force (well, if I pushed down it would be very lightly), and I moved less than an inch in 2 directions...
Oh-oh! Who told you this!?
To properly develop the spotting pattern, the part hast to be moved. The finer the scraping, the more it has to be moved. You need to give the blue a chance to be wiped away from the peaks and to build the bull's eye.
So place the part (that's how I do it) on the plate where no blue is, move it into the blue area and move it there in circles (so say figure 8, I don't do it so).
Diameter of the circle maybe 10 cm (not really that important). Maybe something around 5 turns.
No jerky moves, but smooth and gently. Grap the part so, that you don't tilt it. That means a bit below the center of gravity. That part is quite flat, so don't worry about that. Push it down a bit.
Steamer already mentioned the rocking test.
Sometimes, it is hard to hear wether it rocks, so here is a better way:
Lay the part down, put a DI on top of one corner and try to rock it diagonally (over two opposing corners). Repeat at a second corner, but not one diagonal to the first one :)
Nick
Wot Nick Said!....... :ThumbsUp:
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and that I have not spotted clumsily (i.e., i let the weight of the part be the only downward force (well, if I pushed down it would be very lightly), and I moved less than an inch in 2 directions...
Oh-oh! Who told you this!?
Wot Nick Said!....... :ThumbsUp:
I wanna say I read it but its a lie. I somehow formed this idea, and never gave me the opportunity to stand corrected -- until now. Duh.
You see why I do this thread? I am already learning that I've been chasing me tail...
OK I'll write more... and please pay attention and correct me!
thanks, sirs!
-
Now, it would be interesting (at least for you) how different the spotting is with both methods. Without scraping in between.
Nick
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Is it wrong that I am finding this quite fascinating?! :ThumbsUp:
I still don't understand though so am going to go back through the whole thing!
Nick
-
Now, it would be interesting (at least for you) how different the spotting is with both methods. Without scraping in between.
Nick
YES!......you find all kinds of sins when you do this...and it teaches to ask "The part" lots of questions!.....The part will lie to you if your not careful!......
The problem is assumptions. Don't have any assumptions and the part will not lie to you!
Dave
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Try this one.....mark up the part....and note the marking.
NOW
Rotate the part 180 degrees and note the marking.....does it look the same?...
It might....it might not.... and it depends.
Dave
-
I'm at the final check in alignment phase....and I'm checking the cross slide squareness to the axis of the spindle.....I'll be doing the straight edge in the 4 jaw test...and hopefully, I won't need to adjust the saddle....I'll post here Tom...very briefly....how I'm doing it on my SB....as a reference...but it's in Connelly.
Dave
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Just a little scraping question. Can y'all scrape two pieces to the point that they will "wring" together like Gage blocks?
Eric
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Just a little scraping question. Can y'all scrape two pieces to the point that they will "wring" together like Gage blocks?
Somewhere in the net, I have seen a picture of a scraped surface mirroring a newspaper. It looked like a mirror, but it was scraped. :o
I wouldn't try that. I think Forrest Addy made something like this. Or at least coming close to a mirror finish.
If that wrings together? Don't know!
Nick
-
I believe it's possible but IMHO you need 3 pieces. Just using 2 will feed off each others error and so on and on and on..................
Best Regards
Bob
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Nick,
Moore tool scrapes the ways of the jig grinders to .0000020"/24"....Then.....they lap them!....This becomes the ways for Roller bearing slides.
They are not mirror ....but they are pretty damn close!
NO I can't do that...but Eddie could! :NotWorthy: :NotWorthy:
Dave
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If you ever have a chance to get your hands on the book "Foundations of Mechanical Accuracy" or something like that; it is a big hardbound book published by Moore and has lots of pictures and theory about how and why they do what they do. When the guys are scraping, the machines are insulated with blankets so the body heat of the scraper doesn't warm the casting as he is working,
We used to have a copy in the Metrology lab at work but I'm not sure is is still there.
Dave
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Thanks Dave!....I used to work there......
"Eddie"...who has been there over 30 years as a scraper....knew Dick Moore.
Dave
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Wow I did not know;
We used to have a Moore CMM (I'm not sure if that is what it was called) with all the tooling years ago in the lab and there was also a Jig grinder in the tool shop; beautiful machines :praise2:.
Sadly do the evolution of the company they're gone now.
Dave
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Nope....still there...though not making NEW jig grinders....they are rebuilding machines in Bridgeport. I worked at their division in New Hampshire on Diamond Turning Lathes, but we had lots of stuff made in Bridgeport.......They still do contract manufacturing....but for special, tight tolerance stuff....
Dave
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Hi Dave
I meant the evolution of "my" company; we don't have any of the Moore tools left on our site. We don't manufacture anything in the US any more and that is the reason why for the most part.
Dave
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YUP!.....Not much of the machine tool industry left in this country......I hear ya!
Dave
-
Sadly, the classic Bridgeport Series 1 mill's castings are now done offshore and they have changed much of the design (i.e. 60 degree table dovetails instead of the 50 degree used since 1939. This is to match all of the Asian copies)
So, parts interchangeability is pretty much gone. I read on another forum that a brand new BP, had a few undrilled oil passages for the table. When Hardinge was informed of this (with pictures) they suggested that the owner drill them himself.
Sad. I'm glad to have my 1969 Series 1 and can get parts from many sources.
-
Yup, we gave up our machine industry, our steel industry, our textile industry, our auto industry, and then sent all our techno support industry abroad also. Government didn't let GM fail, however, Detroit just went bankrupt. I love my country, it's the Government I fear. Just ask a native American or a Viet Nam vet. Shut up Eric. Hey my gear cutters came in so check in on my build update first of the week 8)
Eric
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I worked for a number of years for Cincinnati Milacron, Heald Machine Division in Worcester Ma.
We were at the Westec machine tool show...( late 80's early 90's) and we were tooling around the show looking at our competitors. Over in the corner was a grind house with one of their "NEW" grinders. We looked at it and scratched our heads...looked JUST LIKE a Heald 271A universal grinder...except ...instead of saying Heald...it had Chinese writing cast into the side. So we wandered over and got some brochures...got a couple more beers...and went on our way...we didn't really take them very seriously at the time....while we were driving back...we read the brochures...on the back of the last page at the bottom it stated..."For spare parts, contact Heald Machine." :rant: :hellno:.......I believe we let loose the lawyers on them...but it didn't do much. ::)
And the beat goes on......
Dave
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Got the 3 jaw mounted to the Southbend, and set up for the final check on the spindle...I mounted a good parallel in the 3 jaw, and trammed it in with the cross slide...once it reads zero zero
(http://i164.photobucket.com/albums/u27/mcandrew1894/Southbend%209A/2013-07-20_16-31-44_814_zps201cf598.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Southbend%209A/2013-07-20_16-31-44_814_zps201cf598.jpg.html)
(http://i164.photobucket.com/albums/u27/mcandrew1894/Southbend%209A/2013-07-20_16-31-39_582_zpseef1b0c5.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Southbend%209A/2013-07-20_16-31-39_582_zpseef1b0c5.jpg.html)
(http://i164.photobucket.com/albums/u27/mcandrew1894/Southbend%209A/2013-07-20_16-30-14_131_zpsb159b9ed.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Southbend%209A/2013-07-20_16-30-14_131_zpsb159b9ed.jpg.html)
(http://i164.photobucket.com/albums/u27/mcandrew1894/Southbend%209A/2013-07-20_16-30-08_191_zps6adb8cd3.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Southbend%209A/2013-07-20_16-30-08_191_zps6adb8cd3.jpg.html)
Rotate the chuck with the parallel 180 degrees and check the reading at the far side...the error shown is twice the actual error.
(http://i164.photobucket.com/albums/u27/mcandrew1894/Southbend%209A/2013-07-20_16-36-54_345_zps7d61c27d.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Southbend%209A/2013-07-20_16-36-54_345_zps7d61c27d.jpg.html)
or the actual error is about .0007" plus...which tells me that lathe will turn concave..not convex...which is a good thing.
It' is a bit more than is stated in Connelly...but the spindle skew is affected by belt tension...so I';m going to leave it be and call it good!
Dave
-
Nice test, nice clock.
Mosey
-
Nice Article by Whitworth.....on scraping.
http://books.google.com/books?id=AlgJAAAAIAAJ&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Dave
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And another nice book....
http://books.google.com/books?vid=OCLC16227267&id=djQDAAAAQAAJ&pg=PA1&lpg=PA1&dq=the+whitworth+measuring+machine#v=onepage&q=the%20whitworth%20measuring%20machine&f=false
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Ah, time to post some update on the adventure thus far. I have told you that the lathe bed came back from the grinder; I trust the person who did it, not only because he has been a gentleman about all aspects of our interaction, but because he does lathe bed grinding for a living for many years; grinding the 3.5 feet long bed of the little SoB is really an easy job.
While setting the bed up on the bench, I came to realize how flimsy these beds are... I document in the next posts right after my am diaper change... this first one is to revive the thread so that I can find it again...
tom
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The little SoB is a bench lathe. I did not appreciate how much the bed twists and conforms to the bench before actually getting serious about leveling the bed.
Here, by leveling, I mean ensuring the ways are straight and without a `wind', i.e., a twist along the longitudinal direction. As has been discussed many many times, the easiest reference is the horizon, from which I can measure deviations with my Chinese precision level. The level is graduated at 0.0005" at 10".
For a precision lathe, Connelly submits a longitudinal tolerance of 0.001"/12" along the length of the bed, for both front and rear inverted V ways; and the transverse tolerance is 0.001"/12" measured along the length of the ways.
This is how you measure longitudinal tolerance:
(http://i810.photobucket.com/albums/zz22/ttrikalin/lathe_bed/IMG_1283_zpse10dfcf1.jpg)
and this is how you measure the transverse tolerance:
(http://i810.photobucket.com/albums/zz22/ttrikalin/lathe_bed/IMG_1278_zps13ccc3cc.jpg)
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Exactly Tom,
I see you have the South Bend right side adjustable foot which helps a lot taking the twist out of the bed.
Glad to see you back! :ThumbsUp:
Dave
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Well, Dave, I have to say that getting the bed to level was a very difficult thing...
To give you an example, these are the measurements of the average slope at 7 points. Setting 0 for the middle of the bed, the points are -16.5", -10.5", -3.5", 0", 4", 12", 17".
These are the longitudinal and transverse slopes I measured at said points with the lathe bolted on the bed, without shims in either pedestal, headstock and tailstock side.
(http://i810.photobucket.com/albums/zz22/ttrikalin/lathe_bed/unbolted_zpsc594a499.jpg)
These are out of tolerance, but not too bad. I started shimming, and I appreciated how badly you can twist the ways by putting in the wrong shims. This is with wrong shims:
(http://i810.photobucket.com/albums/zz22/ttrikalin/lathe_bed/bad_zps39e117e1.jpg)
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And this is where I decided to stop:
(http://i810.photobucket.com/albums/zz22/ttrikalin/lathe_bed/final_zps0989ff08.jpg)
1. I am still out of the precision lathe tolerance specs, but it is not too bad.
2. Once the headstock is bolted down the negative slope at the headstock side will change. In fact, bolting down the headstock (if the headstocks ways are straight) should straighten the left hand side of the bed. Further, the headstock will be scraped in to align the spindle axis, so this little deviance will become immaterial through other means.
3. Thus, considering only the rightmost 6 measurements, we are almost within specs.
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You can't take the twist out with the foot? :headscratch:
Mine came out very easily with the foot....but you are absolutely right about the bed being limp spaghetti!....You'll need to do it again with the belt tension on by the way...but that comes way later.
Dave
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Exactly Tom,
I see you have the South Bend right side adjustable foot which helps a lot taking the twist out of the bed.
Yes, Dave, though in the measurements I have take here, I have the tailstock foot screws slack. I will use them to take out any twist remains in the end. So the current tailstock measurements are based on shimming...
Good to be back, albeit briefly... Next time I will be able to work in the lathe is in two weekends from today...
tom
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....but you are absolutely right about the bed being limp spaghetti!....You'll need to do it again with the belt tension on by the way...but that comes way later.
Indeed...
Seeing how flimsy the bed is, I am of the opinion that this is very close, at this stage, and that I will have to revise the shimming scheme once I have the carriage on, and the belt is tensioned and so on.
Right now I care for the bed to be decently straight because it will be used to mark up the saddle.
I was not planning to continue shimming and twisting till I am within specs at this point. I was thinking to proceed with next steps:
1. scrape in the saddle
2. scrape in the tailstock
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Alright....now that makes more sense.
The area of the bed under the headstock is a good reference surface, but if it's not behaving alignment wise, don't sweat it too much, as you will be mounting the headstock there and you adjust the headstock into alignment with the outside ways. The rest of it is important though!
Looks like you have a crown? I would bolt it down and recheck things....that may take the crown out....or just change it.
On the other hand....it's very small...by lathe standards....
Once you start scraping, you will need to check level daily!....
I had a little rise at the far left hand end of the bed under the headstock, it was in one side of the V way of the bed...about .0005"/4" .and on the headstock, it was sitting down on 3 of the four feet anywhere on the bed. It would rock a good thousandths except in it's final resting place where the errors cancelled each other. At that point, the headstock spindle was pointed down .004"/12" and to the rear .0015"/12"....not good, so I said the hell with it and just scraped the headstock into alignment at that position....which its not going to move from anyway....and that worked. Scraping the Vee/flat ways of the headstock is a very sensitive area...it doesn't take much to affect a big change.
Dave
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How much wear in the tailstock?.....height and rocker?
you may want to do the saddle first, then do the headstock. Then re-scrape the tailstock base, and then either shim the base, or if you do what I did and make a new tailstock base all together and leave it high and scrape it in.
Once your saddle is scraped in, you can check the check the inner ways for alignment with respect to the outer ways with a V block and a DTI.
OH.....and don't make the mistake I did, Check the bore of the tailstock for wear....These little guys have really soft iron castings and the bore on mine wore about .004" bell mouth and I had to line bore and lap it straight, and then I made a new quill.
Check it first, as you are using it as a measurement reference for headstock/tailstock alignment.
Dave
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Additionally, something else to check
My bed wasn't machined correctly at the factory. The rear V ways were .007" higher than the front ones, thought the leveling surfaces were co planer. Dave at Forrestt City found this while he was setting mine up on the grinder.
Now he took as much as he could out to make it right...but not all of it. I there fore don't have agreement between the Vway level and the machine reference level surfaces. That's OK....if you allow for it while scraping. But don't ASSUME that they are co-planer just because South Bend says so. They might not be ! The headstock was not scraped in right either!....so I had to correct it.
I scraped the saddle level to the top reference surfaces of the bed ways so that when I level it in it's normal method, the top of the saddle should be level too.
Assume nothing....measure everything!.....and if possible, measure it in two different ways.
And Check that level every day for calibration! Ask me why I state this...... ::)
Dave
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It may be of interest to note the following:
I have the original SoB metal bench, which is rather heavy duty. The bed of the bench top lathe can twist because:
1. The blue bench, on which the lathe is mounted, is bolted on a twisted garage surface.
2. The upper surface of the bench is not perfect: The bench surface where the HS and TS feet are bolted are not really coplanar. This required shimming between the bed and the HS foot, and (removing the small factory padding) between the TS adjustable foot and the bench.
Changing the location of the lathe in the shop will affect #1, and thus throw the lathe out of level. I have decided that I need the flexibility (no pun intended) of moving the lathe around. So I went for the solution that Colchester lathe Co suggested for avoiding fluctuations that have to do with the floor's dimensional changes: Mount the lathe on a sturdy base, and support the sturdy base on three points on the floor.
I have devised this contraption:
(http://i810.photobucket.com/albums/zz22/ttrikalin/lathe_bed/IMG_1271_zps3bb23546.jpg)
The black base is heavy gage steel, and bolted together with the bench, they make a steady platform on which the little bed resides.
The headstock side has two large screws, reside on aluminum feet:
(http://i810.photobucket.com/albums/zz22/ttrikalin/lathe_bed/IMG_1273_zps2c39d028.jpg)
and the tailstock side has one screw in the middle. These three points should automatically restore the same geometry when the base&bed is lifted on the screws. The smaller screws resting on wooden blocks are to ensure that the whole thing will not tip. They are really slack.
(http://i810.photobucket.com/albums/zz22/ttrikalin/lathe_bed/IMG_1274_zps8be9a473.jpg)
This is how the base looks when lifted up:
(http://i810.photobucket.com/albums/zz22/ttrikalin/lathe_bed/IMG_1277_zps1f519985.jpg)
In tests, I have lowered the base on the casters, moved it to a different place, lifted it up on the screws, and measured the slope of the bed, It is exactly repeatable!
My thought is that the black base and the blue bench, bolted together (heck I can weld them also), are a sturdy platform for the little bed... If needed I can reinforce the black base greatly by welding more beams on it... but there is little need for it it appears till now...
Of course this will not be as robust as bolting the blue bench on 6" thick concrete. The contraption should be adequate for for light, finishing cuts... and good enough for heavier cuts. This is, however, an empirically answerable question, which will be answered when it's time to do cutting tests.
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My bed wasn't machined correctly at the factory. The rear V ways were .007" higher than the front ones, thought the leveling surfaces were co planer. Dave at Forrestt City found this while he was setting mine up on the grinder.
[...]
Assume nothing....measure everything!.....and if possible, measure it in two different ways.
Yes, Dave, the other Dave at Forest City grinding brought the front and rear ways to the same height... He told be about it when he did the grinding...
Indeed, each time I will use the lathe bed as a markup I will verify level... Too much to muck up by being sloppy in that respect.
tom
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Tom
My base is bit similar. I would minimize the affects of the less than qualified base by putting a washer under the foot at the mounting bolt location.
This will result in the bed sitting on 4 pads...but two are rockered so it's basically kinematically stable. I don't think these sheet metal bases add that much to the bed stiffness....too tiney...and flexible....
I think Myford mounts their beds as described.
My little 9 cuts to the limit of the power I can get to the spindle very nicely, about 1/2 HP.., though I don't use her for "hogging", just small stuff.
http://www.modelenginemaker.com/index.php/topic,2558.msg43064.html#msg43064
Dave
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Alright....now that makes more sense.
The area of the bed under the headstock is a good reference surface, but if it's not behaving alignment wise, don't sweat it too much, as you will be mounting the headstock there and you adjust the headstock into alignment with the outside ways. The rest of it is important though!
Right on. This bed has been ground, so I take it that it is within less of 0.0005" straight and parallel for the length of it (as per discussions with the other Dave, at Forest City).
The point is now, can we mount it in the same way as the other Dave mounted it on his grinder...
Looks like you have a crown? I would bolt it down and recheck things....that may take the crown out....or just change it.
On the other hand....it's very small...by lathe standards....
Right again... The front Inverted V (more so that the rear) has a U shape. I think that to take this out I have to raise the headstock side a bit more...
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That base of yours is far more rugged than mine....I think it will be fine...but you know that already from your measurements.
Dave
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Ahh
Here's the article I was looking for .....
http://www.wswells.com/data/howto/H-3.pdf
Dave
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Thanks!
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If you need anything Tom...just hollah! 8)
Dave
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huh, i need more tiiiiiiiiiiimeeeee... :paranoia:
This great dictatorship of 24 hours is a day for everyone is very unfair! I want more.
:Doh:
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I hear ya man!......me too!
Dave
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Just caught up with your whole thread Tom. Nice stuff
good luck for the rest of your journey on the rebuild
Steve
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Well, well, half a year after me last post I found some courage to ask Anastasia's permission to take a scraper in me hand today...
I caressed it, sharpened it, polished it, and had at the upper surface of the cross-slide.
[In a previous post I though I had finished this, and then Nick Mueller and Dave pointed out that I had not...]
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Hey Tom,
It only seems like it takes forever. It gets there. Courage buddy!....You'll get there.
Dave
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It only seems like it takes forever. It gets there. Courage buddy!....You'll get there.
Thanks, Dave. If anyone knows, it's you...
This is the story of picking up from where we stopped several months ago...
I use a very light amount of blue, and then rub on a part of the surface plate that has no hi-spot blue on it, to polish the bearing points and make them more evident. Thus, the photo has crisp contrast.
This is not too bad as a starting point. Some steep mountains in evidence.
Most importantly, the right side does not have as great a density of points. The whole surface on the left has to be brought down a few tenths.
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/642F37FC-E790-4547-8F6A-6BBBD87C59E6_zps3nltvpm9.jpg)
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That's looking good!....I'd just break that up a bit, as actually, that's all you really need on the top slide.....how's the parallelism with the flats on the Dovetail?
Dave
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An intermediate phase... This is 3 passes later, a result of the following brain fart:
In the first 2 passes I was brought the surface 'straight down'. I started getting points in the right upper side, but still had a 'hole' in the right-lower corner. Instead of doing 2 more passes straight down, I did the 3rd pass on half the surface (below a diagonal, should be easy to see from the lower density of points lower and right) to switch the plane and start filling in the whole surface.
That's looking good!....I'd just break that up a bit, as actually, that's all you really need on the top slide.....how's the parallelism with the flats on the Dovetail?
Dave, this for sure messed my parallelism, which was within 2 tenths before I started messing with this... but I can very easily restore the parallelism by scraping the much smaller surface of the sliding surface of the cross slide...
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/E7FE5221-3FB2-40F8-808C-B01D3C725DD3_zps9cet4azf.jpg)
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This is one pass later
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/843125ED-CA3D-4D45-A6E5-AD1ABB5B5312_zpsz08bf2gc.jpg)
And this is where I decided to stop, 4 or 5 passes later.
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/5AE4A5A3-37FE-4AF8-8EBF-84948D72AA81_zpsuddq4uut.jpg)
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Tom! it's good!.
Get your parallelism and move on!.
Going to do the saddle next?.....where's the rest of it stand?
Dave
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Then, as per Connelly, I used the cross-slide as a template to scrape in the lower surface of the swivel base of the compound cross-slide
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/3ACFC3BD-9C32-4B35-94A4-269B41799697_zpsabkmeowt.jpg)
And mark up like in the following photo. This is after 3 passes on the swivel base.
Some steep points are evident. They catch the light and seem pretty bright in the photo.
They also remove lines ('scratches') of blue from the cross slide upper surface.
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/1FE993E6-1A6B-4DA3-8FCE-EC1F0F5BA946_zpshcx0odk5.jpg)
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This is 2 passes later. I think it is getting there, and it is pretty decent...
It still has some high points, but the whole surface carries.
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/8CFD1C4A-8C47-4B0F-858C-767FBD72B791_zpszu8kywuy.jpg)
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YUP...the front bearing "circle" on the compound gets worn quite a bit because of chips being present when the compound is turned. Mine was over .002"!.....but it came down quick!
Dave
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YUP...the front bearing "circle" on the compound gets worn quite a bit because of chips being present when the compound is turned. Mine was over .002"!.....but it came down quick!
Yup... you are right, this was the wear pattern I observed... This is one pass before I stopped. I did cleaned some high points.
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/0C3FC2E1-636F-40D8-85D7-BC3CDE5F0F38_zpsgd5g9n5m.jpg)
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Next steps:
1. I will re-check and restore parallelism between the surface of the cross slide and the bearing surfaces of the dovetails.
2. I will touch up the prism master, to work on the dovetails
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Parallelism on the compound base is easy to check..you can use a micrometer until you get real close, then you can use a pair of parallel and check it on the surface plate.
Good plan on the cross slide!
Check your master, and don't handle it much while you do it. It took about a year for one of my masters finally settle down and stop moving around. Till then your always touching it up.
Take your time here on the dovetails. it will be paid back later when you align the saddle to the spindle axis.
I'll post my set ups for you if you're interested. It's the toughest part of scraping in a lathe, as its a little nerve racking till you get into it, then you realize it's not that bad, and you just do it. Like a lot of things in life :Lol:
Dave
Dave
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Thanks, Dave.
Any setup pointers are
very welcome...
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I'll dig them up and post them. Here if it's alright with you.
I trust you have a good master square?
Dave
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I'll dig them up and post them. Here if it's alright with you.
Of course!
I trust you have a good master square?
Nope.
I am scraping in a 4x4" angle and will toucH up my squares.
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A good square can be had for fairly cheap money on the Bay....but that is your call.
I'll dig it up.
Dave
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I've got a bottle square but it must weigh 20lbs... :naughty:
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I have a set of new fowler squares but I do not know their tolerance.
Because there are three in the box I can check them vs each other and scrape them in (if needed) using the carbide blade.
What's wrong with this plan?
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Because I will need it for setups, I started scraping in a 4x4 90 degree angle. I bought it from enco three years back. It is a 'precision ground' one.
The plan is to
1. ensure that the sides are flat and then
2. make the angle 90 degrees by differential scraping.
Sides:
Perhaps it was ground precisely and moved around since then. The first markups showed contact in two quarter size areas in opposite corners. I do not have a photo of the first markups, but i do have a video of the scraping process... as engaging as watching paint dry... May post it -- what the hell...
This is where I stopped last night (a lot of blue, we are scraping areas). This is side A.
A bit of a hole in the upper side, close to the right corner.
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/0CBE96C1-6FEE-4F3B-B7EC-6CDFD751D219_zps1pcctm9o.jpg)
This is side B:
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/6A097875-59E4-4C07-8CC9-635E102863DE_zpsr5qkmto8.jpg)
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The same setup tool with way too little blue, and the next pass lines marked. Side A:
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/34C62340-97EF-45BE-B4FB-9DB839C6102E_zpshx85vzmv.jpg)
And side B:
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/FE14A3D5-F46E-4F6F-9F5E-FB531CE3BF81_zpsmp342e5a.jpg)
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I will also edit the video (it's 2-3 hours long) to post, to show the evolution of the mark up in the first (roughing phase of scraping).
For this part I will move to the second phase to increase the bearing throughout the surface and correct the geometry... I have thoughts about how to achieve a good 90 degree angle, by using the surface plate, this part, and one of the three Fowler squares I have (they are el cheapo, but I can touch them up)...
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And this is the master prism... on its way to become a real master... It needs 10 passes or 50 to become like Dave's crazy master.
An overview photo, showing that the bearing is not uniform:
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/508FB785-F0C6-4820-81BB-BD7B5C3921D1_zpso1qjp67m.jpg)
And some close ups from left to right.
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/F6F2AFB0-178D-448C-8C30-85FF04F949AE_zpso7jsnmxk.jpg)
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/12BF353E-530D-4279-AD0F-5CDF6F945878_zpsd2jrpadk.jpg)
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/84DEED2E-0315-4C6E-9F44-B51D6C33109A_zpscprbocs0.jpg)
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/5A29429F-8089-4C9A-B518-EF99EF96B00D_zpsakd3yh0p.jpg)
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/B1ED0507-F3AB-4A8A-81D4-CB264630E284_zpswequfxbu.jpg)
Next round I will take photos with the real camera, the zoom with the phone camera is rather off.
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Tom,
Here's the setup I used to check the saddle for square on the machine. The precision square is known accurate. I have precision gage pins sized to touch the master side dovetail at mid span of the dovetail that the square is up against, and VERY lightly clamped in place. What I found here is that the you have to be careful clamping it such that the square blade was truly horizontal. The cross slide dovetail was finish scraped complete before I did this. I only scraped the saddle to the bed to get the correct specification. I seem to remember .0002"/6" concave.
With your square, you could clamp a parallel down the side, and rest that against some gage pins. In similar fashion.
Remember now, you have to get the flat dovetail surfaces parallel to the bed reference surfaces also, so you need to have a precision level and another set up for that. I used this and it worked pretty well. I was careful in my use of parallels in that I checked them prior to use.
(http://i164.photobucket.com/albums/u27/mcandrew1894/Southbend%209A/2012-10-08_11-45-56_472.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Southbend%209A/2012-10-08_11-45-56_472.jpg.html)
(http://i164.photobucket.com/albums/u27/mcandrew1894/Southbend%209A/2012-10-08_15-09-43_472.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Southbend%209A/2012-10-08_15-09-43_472.jpg.html)
And in the other direction.
(http://i164.photobucket.com/albums/u27/mcandrew1894/Southbend%209A/2012-10-08_15-12-27_276.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Southbend%209A/2012-10-08_15-12-27_276.jpg.html)
(http://i164.photobucket.com/albums/u27/mcandrew1894/Southbend%209A/2012-10-08_15-10-47_791.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Southbend%209A/2012-10-08_15-10-47_791.jpg.html)
It's very helpful to have a set of precision shim stock set (.001 through .010") available as it lets you dispense with some math and measure errors directly with the level.
One other thing, I relieved the center section of the saddle a bit so that I was landing on 4 distinct areas, and then scraped straight down once I got the above geometry correct. It was still slightly relieved when I was done. It will make your job easier if you do that as the whole thing is statically indeterminate.
I biased my marking towards the front shear. I pushed down on the front edge of the saddle, and let the mark up happen on the rear. I then scraped that until I had the geometry and the bearing simultaneously. It seems hard, and it's not particularly easy, but it's not as bad as it seems in that it all happens slowly.
(http://i164.photobucket.com/albums/u27/mcandrew1894/Southbend%209A/2012-10-08_15-17-48_882.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Southbend%209A/2012-10-08_15-17-48_882.jpg.html)
see the back way surface hasn't quite carried yet...but it's on its way.
(http://i164.photobucket.com/albums/u27/mcandrew1894/Southbend%209A/2012-10-08_15-14-59_158.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Southbend%209A/2012-10-08_15-14-59_158.jpg.html)
The saddle on my lathe was going uphill .010" front to back, and .003 left to right, Low on the headstock side and to the front. and it had to match the bed, which because the bed was ground, it didn't. Also it had a twist in it, and was only sitting on 3 of the 4 wings and that had to be addressed first. Of course, I took the twist out in a direction that the whole part needed to go to remove the tilt. Some of this is best down with a good flat file. It will save you some rather awkward scraping as these surfaces are pesky to deal with.
(http://i164.photobucket.com/albums/u27/mcandrew1894/Southbend%209A/2012-10-08_15-16-14_321.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Southbend%209A/2012-10-08_15-16-14_321.jpg.html)
Make sure your blade has some radius to it. ( the one in the back is about right for me)
(http://i164.photobucket.com/albums/u27/mcandrew1894/Southbend%209A/2012-10-09_07-53-06_600.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Southbend%209A/2012-10-09_07-53-06_600.jpg.html)
Once you get the saddle to bear correctly, and have good geometry....check your rear gib mounting surface. Mine had quite a bit of twist in it, and it showed up on the gib also. That took a while to sort out as well.
Dave
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Thanks much for this detailed write up.
I will get ut fully when I set mine up the same way.
Did you scrape the upper surface of the saddle for esthetic purposes?
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Yes.
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Before scraping the saddle in, I had to finish the master to be workable (it will be made better over time). So I continued with ~10 rounds from the previous state of affairs, which was this:
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/508FB785-F0C6-4820-81BB-BD7B5C3921D1_zpso1qjp67m.jpg)
I am scraping on the welding table, using a lazy Susan to position the scraped part so that I attack it from different angles. I lock the revolving Susan with two finger clamps from Harbor Freight.
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1287_zps326b074a.jpg)
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That'll work!
Dave
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This is the master after ~8 rounds:
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1300_zps435eb425.jpg)
And this is it after ~10 rounds, with a lil pinch of blue added:
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1305_zps3eae189d.jpg)
And this is a series of close ups. Left 1/4:
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1306_zps0999cf2a.jpg)
Next 1/4:
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1307_zpsd852cc38.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1307_zpsd852cc38.jpg.html)
Next 1/4:
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1308_zps3707b1fb.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1308_zps3707b1fb.jpg.html)
And the last 1/4:
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1309_zps175a9fee.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1309_zps175a9fee.jpg.html)
The master still needs a lot of work, but it is flat enough to mark dovetails.
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That'll work!
Dave
Dave, our posts crossed. Yes, I think this will do it.
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Officially, the first component to be completed (apart from the bed, which was ground last year :insane:) is the compound cross slide. The bearing surfaces on the lower side are very flat and mark up pretty nicely on the plate. The upper surface is not parallel to them though.
-----+ +----+
A | | B |
| | |
C | | D |
-----+ +----+
In the photo below, points A and B are at the same height, and so are points C and D. A and B are 0.001" lower than C and D. Connelly says the difference should be 0.
Note also a little 'hole' or 'valley' at the inner edge, between B and D.
So I am scraping C and D down. :)
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1311_zpsec295268.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1311_zpsec295268.jpg.html)
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Tom,
Make a few passes staying violently away from the edge of the master. As a matter of fact take two passes staying about 1/4" away from the edges of the master. I ran into this scraping my angle master in that it's really difficult to mark it without influencing it. I believe your crowned in the middle ....if the middle hollows out, you'll know where you are. As it sits, you need more coverage up to the edge to reach the inside of the dovetail accurately.
I resorted to making a flat master to mark up the angled master. This was from a Master Scraper at Moore, whom I brought the master too to check my work. He said these small masters can be tough and that was the way he recommended to fix it.
I would try to hollow it out a bit so you know you sitting on the periphery. Then let the bearing progress towards the center.
Tough bit, but keep going!.....
(http://i164.photobucket.com/albums/u27/mcandrew1894/tooling/P2050079.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/tooling/P2050079.jpg.html)
Dave
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After some scraping' the updated height differences have equalized quite a bit:
I am calling this OK for now -- we are within two tenths :pinkelephant:
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1315_zps70c5f9ce.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1315_zps70c5f9ce.jpg.html)
Note that this leveling is not critical; the lathe tool does not pivot or move on this surface. It marks decently for now.
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1314_zps0177a0fd.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1314_zps0177a0fd.jpg.html)
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And we're talking two crossed passes here....don't go back to roughing it...just relieve it a bit to make sure it's not crowned.
Dave
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Tom,
Make a few passes staying violently away from the edge of the master. As a matter of fact take two passes staying about 1/4" away from the edges of the master. I ran into this scraping my angle master in that it's really difficult to mark it without influencing it. I believe your crowned in the middle ....if the middle hollows out, you'll know where you are. As it sits, you need more coverage up to the edge to reach the inside of the dovetail accurately.
I resorted to making a flat master to mark up the angled master. This was from a Master Scraper at Moore, whom I brought the master too to check my work. He said these small masters can be tough and that was the way he recommended to fix it.
I would try to hollow it out a bit so you know you sitting on the periphery. Then let the bearing progress towards the center.
And we're talking two crossed passes here....don't go back to roughing it...just relieve it a bit to make sure it's not crowned.
OK, will do this first time I go down to the garage these coming days. Thanks for catching a possible error!
I will continue posting what I did till tonight, with the understanding that I will have to re-check after the master has been checked and remastered!
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The (to be remastered master) with a lot of blue on it and the back screws in place (will make appropriate insulated handles... )
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1316_zpscc140538.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1316_zpscc140538.jpg.html)
And the compound slide, with the internal dovetail ready to be touched:
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1317_zps35f99d48.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1317_zps35f99d48.jpg.html)
And this is the touchup. You cannot see it clearly, but it has a 'hole' in the distal front. The tip in the front colors for one and a half inch, then there is a valley for 1 inch or so, and then it colors.
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1320_zps6237ea04.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1320_zps6237ea04.jpg.html)
I removed some blue and repeated, and then very lightly touched it up with the scraper.
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It's hard to say for sure Tom, but a small change in procedure like I described, if it is flat will POP right away, and you'll only be a cycle or two away from being flat and Knowing it.
Just trying to prevent you chasing your tail like I did.... 8)
Additionally, don't handle that master to much. Your hands will make it move around from thermal effects, and you'll go back in the morning and find a different result and wonder why.....ask me how I know this.... ::)
Dave
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Our posts crossed again....NICE HANDLES! :ThumbsUp:
Dave
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It's hard to say for sure Tom, but a small change in procedure like I described, if it is flat will POP right away, and you'll only be a cycle or two away from being flat and Knowing it.
[...]
Additionally, don't handle that master to much. Your hands will make it move around from thermal effects, and you'll go back in the morning and find a different result and wonder why.....ask me how I know this.... ::)
Excellent points.
Next time in the garage I am fitting insulated points handles , and I am checking that the center is not crowned as per the test you described!.
Pending this check all today's posts are tentative...
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By the way this is the imprint on the master after the touch up.
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1319_zps77f8e8ac.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1319_zps77f8e8ac.jpg.html)
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And after 4-5 touches and light scrapes this is the best photos I could take (very light blue on the tone remastered master). Left part of the dovetail:
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1334_zps86727749.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1334_zps86727749.jpg.html)
Right part of the dovetail:
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1335_zps5f1c434e.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1335_zps5f1c434e.jpg.html)
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Next task did not involve ay scraping, just marking up for the swivel base upper surfaces...
The upper bearing surfaces mike within a tenth of the basal surface of the part at various points throughout their length.
As per Connelly, I am going to be using the basal surface of the compound rest as a template, and the master to do alternative markups to plan my scraping.
Here is the template, and next to it the part in its wooden holder.
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1336_zps1b4130a2.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1336_zps1b4130a2.jpg.html)
Touching up:
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1337_zps56573e64.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1337_zps56573e64.jpg.html)
Wipe pattern on the template:
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1338_zps5355095e.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1338_zps5355095e.jpg.html)
and imprint on the part... one side
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1339_zpsb610e4ba.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1339_zpsb610e4ba.jpg.html)
and the other side
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1340_zpsd0a98274.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1340_zpsd0a98274.jpg.html)
Hmm :-\ Not sure how to think about it...
Next post is the touch up with the to-be-remastered master...
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And this is the touch up with the master...
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1341_zps735dec36.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1341_zps735dec36.jpg.html)
And this is marking the other side... (Shoot, I did not get a photo of the first side's imprint on the part... you may be able to see it here though)
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1342_zps40256386.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1342_zps40256386.jpg.html)
and this is a good view of the one side, and not a good view of the other...
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1343_zpse5223b77.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1343_zpse5223b77.jpg.html)
I have to think about the geometry here... and may haps do measurements on the surface plate...
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And a couple of tools...
This is nice for putting blue on dovetails... a small 45 degree prism with a piece of leather JB welded on it. Got it from Peregrin's website... www.metalscraping.com. I bought his CD, it has good materials. I learned stuff.
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1344_zps57e67bab.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1344_zps57e67bab.jpg.html)
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And this is my interpretation of Dean's indicator stand...
See the instructions here: http://www.deansphotographica.com/machining/projects/indicatorstand/indicatorstand.html
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1346_zpse0ff028c.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1346_zpse0ff028c.jpg.html)
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1349_zps36ec291a.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1349_zps36ec291a.jpg.html)
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1348_zpsb291c718.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1348_zpsb291c718.jpg.html)
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Didn't know about that site....seems very informative!
Dave
....not Deans Site....the scraping site.
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Tom
I am looking at your compound base, and noticed the difference in mark up between the compound and the master....it's subtle...but
if you look at the mark up with the compound as the master, on the left side near the dial end of the part, you will see some burrs....these are not present in the mark up with the master.....at least I don't see them
Do a thorough deburr with a stone that will get into the mouth of the dovetail, and mark it up again using both the master and the compound, it should print the same.
My compound base was worn near the front and on the sides near the pivot. Remember that the master covers the pivot area, while the compound slide does not.
Looking good buddy! More importantly, YOUR THINKING!.....It's a real mind game isn't it? 8)
Dave
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It is such a mind game isn't it? I love this thread, great work, great advice, and what a machine you'll have in the end. Hugh.
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It is such a mind game isn't it? I love this thread, great work, great advice, and what a machine you'll have in the end. Hugh.
Yep it is a head scratcher...
Well, I thought about it on the way back from work tonight and I have a theory...
Assume that
1. The template, i.e., the two basal bearing surfaces of the compound slide are flat and on the same plane
2. The master is a plane (flat).
Then the following geometry can explain the markings. I will show the photographs and how they square with this theory.
(http://i810.photobucket.com/albums/zz22/ttrikalin/Notebook3copy_zps1cf760ab.jpg) (http://s810.photobucket.com/user/ttrikalin/media/Notebook3copy_zps1cf760ab.jpg.html)
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This is the marking of the side with the points (A) and (B) using the template (compound slide). Only a thin strip marks, suggesting that it is on the correct longitudinal plane. It is not as wide as the template base, because the template base marks the inner part, near the dovetail (see the wipeout pattern in the third photo)
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1339_zpsb610e4ba.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1339_zpsb610e4ba.jpg.html)
The marking of the same side using the master (prism). Note that a big flat surface marks, suggesting that the surface is on a plane (is flat).
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1359_zps55a94c2e.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1359_zps55a94c2e.jpg.html)
This is the wipeout pattern of the template (compound slide). In the photo the top sliding surface touches on the area marked (A) and (B) in the schematic.
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1338_zps5355095e.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1338_zps5355095e.jpg.html)
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This is the side with (C) and (D) in the schematic. Shown is the markup using the template. It marks more in the front (left side in the photograph), which is in (C). An explanation is that (D) curves slightly down -- shown in the schematic 2 posts above as an exaggerated curving.
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1340_zpsd0a98274.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1340_zpsd0a98274.jpg.html)
This is the marking with the master (prism). Effectively this side of the swivel base (side C-D) is crowned, and the prism has been applied to the side marked (D). Thus it marks mostly near the right side in the photo (D) but not near (C).
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1353_zps0daa2ba5.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1353_zps0daa2ba5.jpg.html)
Note that when marking with the template, the intensity of the blue marks is higher at (C-left); when I marked with the master prism, it marked more at (D-right), because I happened to orient the master prism on that side.
Finally, note the wipe pattern in the swivel base -- the template. In the photo you should be looking at the lower bearing surface. It has been wiped in its width but on the right side, which corresponds to (C). Its left side corresponds to (D) and it is relatively less wiped because of the curving of the surface near (D).
(http://i810.photobucket.com/albums/zz22/ttrikalin/IMG_1338_zps5355095e.jpg) (http://s810.photobucket.com/user/ttrikalin/media/IMG_1338_zps5355095e.jpg.html)
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I think that I will repeat the markup after checking the flatness of the master as per Dave's comments yesterday, and see if I get the same story with careful markups.
Before scraping too much, I will do additional tests, by measuring height on the surface plate using the tenths indicator. However for this I first have to check the parallelness of the swivel base, on which the swivel rests:
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/FC1D3968-9EB2-4C65-A999-7F707FD80AEC_zpsdv2sa8sz.jpg) (http://s810.photobucket.com/user/ttrikalin/media/Scraping/FC1D3968-9EB2-4C65-A999-7F707FD80AEC_zpsdv2sa8sz.jpg.html)
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If you find any burrs then I can only conclude your theory is correct. I'm glad you are cross checking your mark ups.
Dave
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Tom
A situation that can arise while scraping a dovetail is the top of the blade hits the angled part of the dovetail before you finish the cut into the mouth of the dovetail and it leaves a burr. Just be on the lookout.
Dave
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Today I made thermally insulated handles for the master prism... There are 4, made of blue delrin.
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/9E94BC08-5ECE-40E3-B7C1-E8CB5A7A7E21_zpsapqpqx9a.jpg) (http://s810.photobucket.com/user/ttrikalin/media/Scraping/9E94BC08-5ECE-40E3-B7C1-E8CB5A7A7E21_zpsapqpqx9a.jpg.html)
Closeup of the side ones, which are permanent... The derlin sleeve fits over a 1/4' aluminium rod piece which has been locktited in the master. The derlin has been JB-Welded on the aluminium handle; I did rough up the rod with the corner of a file to give the epoxy something to bite on.
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/F8886649-AA85-4B73-AC74-499D4CE4120F_zpsv95ak2sx.jpg) (http://s810.photobucket.com/user/ttrikalin/media/Scraping/F8886649-AA85-4B73-AC74-499D4CE4120F_zpsv95ak2sx.jpg.html)
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The back ones are counter sunk and tapped for an 8-32 screw. They are removable
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/F76E5497-428A-4450-B1F7-DAD6B9949F6F_zpsunzgxmws.jpg) (http://s810.photobucket.com/user/ttrikalin/media/Scraping/F76E5497-428A-4450-B1F7-DAD6B9949F6F_zpsunzgxmws.jpg.html)
and all these are done on the brass bed Sherline...
(http://i810.photobucket.com/albums/zz22/ttrikalin/Scraping/F068EA9A-C1F7-4F9B-9825-C25F9E2A215F_zps014odpcp.jpg) (http://s810.photobucket.com/user/ttrikalin/media/Scraping/F068EA9A-C1F7-4F9B-9825-C25F9E2A215F_zps014odpcp.jpg.html)
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Tomorrow morning I was planning on flushing the transmission fluid -- but I may check the master and the repeat marking up of the compound base, and make some measurements on the surface plates instead. I am not in the mood for tranny flushing (what mood would that be?)
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Nicer handles than mine Tom! I don't have any!.... :lolb:
If you get a good mark up in the morning after it's been left alone for a while, you'll be in good shape.
Dave
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OK, a month later i found 5 hours of undisturbed shop time... and I progressed bit with the scraping and checking of the surface alignment...
Here is how it looks... we are at the edges of my metrology instruments... most of which are crappy...
Cross-slide:
First, as shown in a previous post, the lower surface marks well, fully, and the slides are coplanar (based on the marking).
So I am checking the upper surface in various points A-G; I use similar sheets for other surfaces.
(http://i810.photobucket.com/albums/zz22/ttrikalin/Lathe/cross-slide_assembly/IMG_1391_zps468e0551.jpg)
Because the upper bearing surface marks well (previous posts), I use a gage block to get the (relative) average height at various spots like this:
Here is measuring the average, and the measurements. They are in agreement, with a tenths indicator, rounding to the closer tenth.
(http://i810.photobucket.com/albums/zz22/ttrikalin/Lathe/cross-slide_assembly/IMG_1390_zpsc0b4bbba.jpg)
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This is another test of the directionality of the surface. It sums up the error of the surface, and of the parallel, which has a tolerance of 2 tenths over its 6" length. I did not mike the parallel -- I will... Before doing so I am not making corrections with scraping... I will be chasing me tail. I do not have better tools...
Longitudinally:
(http://i810.photobucket.com/albums/zz22/ttrikalin/Lathe/cross-slide_assembly/IMG_1398_zps48477908.jpg)
(http://i810.photobucket.com/albums/zz22/ttrikalin/Lathe/cross-slide_assembly/IMG_1399_zpsda69afe6.jpg)
Transversely:
(http://i810.photobucket.com/albums/zz22/ttrikalin/Lathe/cross-slide_assembly/IMG_1401_zps04498cc6.jpg)
(http://i810.photobucket.com/albums/zz22/ttrikalin/Lathe/cross-slide_assembly/IMG_1400_zps90ac010b.jpg)
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Measuring cumulative errors with the swivel compound on the assembly (without gibs or tightening), just resting :) . I use a 0.500" gage block to measure the two sliding surfaces. These are after achieving uniform markup with the prism master and the compound slide lower surfaces as a template.
Right side, then left:
(http://i810.photobucket.com/albums/zz22/ttrikalin/Lathe/cross-slide_assembly/IMG_1393_zps18e2ca81.jpg)
(http://i810.photobucket.com/albums/zz22/ttrikalin/Lathe/cross-slide_assembly/IMG_1394_zpsd44de35d.jpg)
Transversely -- here shown with the swivel base rotated in an angle, but the measurements are within 1 tenth for all angles I checked, all around:
(http://i810.photobucket.com/albums/zz22/ttrikalin/Lathe/cross-slide_assembly/IMG_1395_zps1f3e4cf4.jpg)
I took no photos of going longitudinally with the parallels, but we are within 1 or two tenths over 6".
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NICE! Nothing wrong with that at all! Progress on Tom....you aced that one! :praise2:
Have you noticed that this can be very relaxing yet?.....or is it just me? :ROFL:
Dave
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And then for measuring dovetails, I admit that I could use a tenths mike, and gage pins in the dovetails, but I found it too unreliable a technique the way I do it...
Also I needed an excuse to machine something, so I did an ... interpretation of nick mueller's dovetail measuring jig...
This jig is in need of enhancements, but the measurements I get at this stage are repeatable and stable. The current jig, suggests parallelism of dovetails within 1/4 of a thousandth.
Note the two brass legs have been filed to a hemisphere using as a gage a .25" milled hole in the corner of the small flat piece of brass shown on the surface plate.
(http://i810.photobucket.com/albums/zz22/ttrikalin/Lathe/cross-slide_assembly/IMG_1406_zps229e0652.jpg)
(http://i810.photobucket.com/albums/zz22/ttrikalin/Lathe/cross-slide_assembly/IMG_1408_zpsb1e348a9.jpg)
You arrange things as shown
(http://i810.photobucket.com/albums/zz22/ttrikalin/Lathe/cross-slide_assembly/IMG_1404_zpsf973c0ef.jpg)
You swing it up and down and find the max reading on the gage in the dovetail.
(http://i810.photobucket.com/albums/zz22/ttrikalin/Lathe/cross-slide_assembly/IMG_1402_zps84fc5908.jpg)
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NICE! Nothing wrong with that at all! Progress on Tom....you aced that one! :praise2:
Have you noticed that this can be very relaxing yet?.....or is it just me? :ROFL:
Dave
Oh yes, Dave, this is relaxing -- just that I do it once a month... and I wish I were doing it more often...
BTW,
According to me this jig needs the following improvements:
1. solder a ball bearing of 1/8-5/32 diameter at the bottom of the brass feet -- the filed hemisphere is not a true sphere.
2. add a resting leg with thread adjustment close to the indicator, so that the jig can rest on the dovetail and need only a minor swing up and down to make the measurement.
3. knurl the brass screw knob...
Anyways, I made it from scrap cutoffs, and worked with dimensions of available (to me) scrap.
-
Also, when measuring with the parallels, I could have flipped the parallel, measured again and averaged out the deviations. Like rollie's dad method of what not...
Next time...
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NICE! Nothing wrong with that at all! Progress on Tom....you aced that one! :praise2:
Have you noticed that this can be very relaxing yet?.....or is it just me? :ROFL:
Dave
Oh yes, Dave, this is relaxing -- just that I do it once a month... and I wish I were doing it more often...
BTW,
According to me this jig needs the following improvements:
1. solder a ball bearing of 1/8-5/32 diameter at the bottom of the brass feet -- the filed hemisphere is not a true sphere.
2. add a resting leg with thread adjustment close to the indicator, so that the jig can rest on the dovetail and need only a minor swing up and down to make the measurement.
3. knurl the brass screw knob...
Anyways, I made it from scrap cutoffs, and worked with dimensions of available (to me) scrap.
Check out machine tool reconditioning....he recommends welding steel rebar together and polishing the ends....but your description of the additional items is correct
-
Have you guys considered getting professional counseling? .0002"/6"? You are kidding?
Does the concrete floor move that much when you walk around in your shop?
Seriously, I am flabergasted at this fine work! Nice going! I have a nice 10K here, that I'll send over for you to practise on.
I can see where it would be very relaxing.
Mosey in admiration. :praise2: :praise2:
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Mosey...you would be surprised. It takes a while to take down .0005". It's a slow process, and requires concentration ....you need to "listen" if you will accept that analogy...to what the mark up and the measuring instruments are telling you....and you can get lost in it, and the cool thing...at least for me, is it kind of blocks out all the superfluous crap going on around you...and you just get focused...maybe I'm hypnotizing myself with the movement of the blade...I don't know.
Dave
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I see how scraping could be quite hypnotic and take you into the zone. I have experienced something like that in a workshop for sharpening Japanese planes and chisels.
What would be very interesting to me, would be a discussion of aligning and scraping in a tailstock on a lathe. First, checking it's height, angle, and then making it fit.
Mosey :thinking:
-
Have you guys considered getting professional counseling?
[...]
Well, yes, but Forrest Addy and Rich King do not do any scraping classes in the northeast... at least not this summer... :facepalm:
Thanks, Mosey,for the kind words but as Dave said, this is a very slow process, and even if you mess a pass or ten, you will correct it later...
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I see how scraping could be quite hypnotic and take you into the zone. I have experienced something like that in a workshop for sharpening Japanese planes and chisels.
What would be very interesting to me, would be a discussion of aligning and scraping in a tailstock on a lathe. First, checking it's height, angle, and then making it fit.
Mosey :thinking:
Mosey...First you make sure the quill fits the housing correctly. Then you check the taper to the quill. It should be aligned accurately.
If you have made a new tailstock base, you leave it tall, and scrape the flat and V to bring the height down to the known accurate headstock.
Don't think that just because South Bend scraped it, that they did it right! My headstock was pointing down and to the back by .004" in 12"!...From the Factory!
On a rebuild where you are not making a new base, You check the fit of the quill, and the alignment of the taper....then the fit to the base, then scrape the base to fit the bed and align the spindle in the correct alignment with respect to the bed ways. THEN you scrape the headstock to lower it to the new tailstock height. Tailstocks always wear "rocker" and Low.
Dave