On the vices and joys of machine tool reconditioning...

[ttrikalin]

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:




Transversely:

[ttrikalin]

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:





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:



I took no photos of going longitudinally with the parallels, but we are within 1 or two tenths over 6".

[steamer]

NICE!   Nothing wrong with that at all!    Progress on Tom....you aced that one!

Have you noticed that this can be very relaxing yet?.....or is it just me?


Dave

[ttrikalin]

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.





You arrange things as shown



You swing it up and down and find the max reading on the gage in the dovetail.

[ttrikalin]

NICE!   Nothing wrong with that at all!    Progress on Tom....you aced that one!
Have you noticed that this can be very relaxing yet?.....or is it just me?
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.

[ttrikalin]

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...

[steamer]

NICE!   Nothing wrong with that at all!    Progress on Tom....you aced that one!
Have you noticed that this can be very relaxing yet?.....or is it just me?
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

[Mosey]

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.   

[steamer]

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

[Mosey]

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 

[ttrikalin]

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... 

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...

[steamer]

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 

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