Author Topic: Newbie building a PMR 6CI  (Read 9536 times)

Online b.lindsey

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Re: Newbie building a PMR 6CI
« Reply #30 on: July 16, 2018, 01:53:21 PM »
You are showing some nice set-ups using the face plate. Still following along and enjoying your build and pictures.

Bill

Offline propforward

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Re: Newbie building a PMR 6CI
« Reply #31 on: July 16, 2018, 02:12:48 PM »
  I've since learned of a very simple concept where a longer rod with a point sits in your tool holder and pushes into your center punch.  It rotates a short distance from the work on a fulcrum showing a much exaggerated display of how far out of center you are as the long end wobbles.  I need to make one of these soon!

Having this tool removed all the aggravation of setting up 4 jaw chucks and other arrangements for me. A very useful tool indeed!
Stuart

Offline vdubjunkie

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Re: Newbie building a PMR 6CI
« Reply #32 on: July 17, 2018, 03:51:19 AM »
You are showing some nice set-ups using the face plate. Still following along and enjoying your build and pictures.

Bill

I really appreciate you saying so.  I'll tell you one thing.  When I mounted the cylinder to the face plate, I learned quickly how important it is to cinch it all down very tight!   :old:
“It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

Offline vdubjunkie

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Re: Newbie building a PMR 6CI
« Reply #33 on: July 17, 2018, 04:09:17 AM »
The week of 3/19/17 I did my first bit of smaller plain turning as I built my lower valve head. 

I had seen people mark up a cylindrical piece just like this before and now I'm finally doing it for myself.  You may also notice I finally ponied up for some dykem.



You may notice a fillet at the base of this post.  I wouldn't have thought to do this, but rcdon did it, and I really liked the detail.  Little things like this really make the difference in the final product.  Most people who see the engine probably won't notice, but I always will.



With plenty of crappy extra 3/8" extensions and a socket to fit the die, I sawed an extension so I didn't have to wait until I could spend the money on a tailstock die holder.  As of this writing I do have one, and anxiously awaiting the chance to put it to use.



Here I am with the threads complete, die still on the part and the nut I used to verify, also showing my ugly poor man's die stock holder   :P



Now I begin to part it off.



“It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

Offline vdubjunkie

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Re: Newbie building a PMR 6CI
« Reply #34 on: July 17, 2018, 04:42:00 AM »
The week of 3/26/17 was exciting for me and the amount of work I completed is the result.  I completed the lower valve head and finally got to turn brass.  My god do I love to turn brass.  Clickspring on youtube has some pretty great videos of primarily brass turning and it is mesmerizing!   :popcorn:

Since I learned a technique to quickly true up cylindrical parts in my 4 jaw chuck, I don't use the 3 jaw chucks ever.  They are just not accurate enough.  However, when it was time to turn brass, I decided to do what I could to get the jaws as accurate as I could.  I don't even want to admit how I went about securing my dremel to the tool post holder, but you can see what is going on here.



This will become a valve rod packing nut



This process for tapping threads worked fine, albeit slow.  I just had to make sure I gently followed the pulling of the tap with the rotation of the tailstock wheel.



Before I do too much else, I'll take advantage of these threads to break off the edges of the lower valve head.



Here we go again.  Want to see every single step of this turning operation?  Well, you're here, so I'll just assume..   :ROFL:  Why am I so fascinated by seeing the dykem slowly disappear with each turn of the dial.  You may notice that I didn't go right up to the line.  After I take it to dimension, then I'll get the edge exactly where I want it.  This will be no surprise to those with any experience I'm sure.  But, I didn't think of it.  I had to see it for myself.



Now, the plans call for a much narrower flat of hex.  Again, I followed what I saw rcdon do.  I definitely feel like it is an improvement.  It just makes it stand out a bit more.



Here you can see that I've tapered both sides of the flat.  Again, small details and all that. 



I'm very pleased with how this pair turned out.  These are by far the smallest pieces I had attempted at this point and it was absolutely thrilling to see them complete and pretty.  Yeah, I failed to remove the dykem for the picture.



I've chosen to use a different poor man's method of not having a tailstock die holder for this part.  Since the die was round, not hex, I used the flat face of the tailstock (nothing in the morse taper) to push against the back of the die holding it flat against the part.  Then I used my large channel locks to turn the die.  This was actually much harder that it might seem.  I took my time to make sure I didn't tweak the threads and the result was very good.



“It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

Offline propforward

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Re: Newbie building a PMR 6CI
« Reply #35 on: July 17, 2018, 02:49:26 PM »
Great progress - and I admire your drive to find solutions. Although the dremel thing has me nerbvous. Please take care!

Good results though. Interesting idea - grinding the 3 jaws. I have to be honest, having had good success truing up a 4 jaw chuck having studied the technique, I am considering just mounting a 4 jaw and being done with it. With a bit of practice, centering the 4 jaw does not take long, and when you do it often enough probably produces better results than the 3 jaw. Maybe? Food for thought anyway. I do know of some machinists who swear by that approach. Then again I know some machinists who just swear.
Stuart

Online Tennessee Whiskey

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Re: Newbie building a PMR 6CI
« Reply #36 on: July 17, 2018, 08:07:57 PM »
Just catching up here. I also built this one and it’s one of the first that I “show off” to explain our hobby. Really nice work Prop.

Cletus

Offline vdubjunkie

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Re: Newbie building a PMR 6CI
« Reply #37 on: July 18, 2018, 04:04:09 AM »
Great progress - and I admire your drive to find solutions. Although the dremel thing has me nerbvous. Please take care!

Good results though. Interesting idea - grinding the 3 jaws.

Thank you.  While you might see some duct tape in that image, rest assured it was much more secure than just that.  The grinding of the jaws was yet another idea I got from somebody else.  I used a washer at the back of the jaws to clamp down on so that the jaws would actually be as they should during the grinding.

I have to be honest, having had good success truing up a 4 jaw chuck having studied the technique, I am considering just mounting a 4 jaw and being done with it. With a bit of practice, centering the 4 jaw does not take long, and when you do it often enough probably produces better results than the 3 jaw. Maybe? Food for thought anyway.

I can tell you definitively that the accuracy I achieve with my 4 jaw far surpasses either of my 3 jaw.  The only reason I ever mount them up is for hex.

Just catching up here. I also built this one and it’s one of the first that I “show off” to explain our hobby. Really nice work Prop.

Cletus

Very cool.  Do you have any pictures to share?  What were some of your favorite parts or surprises, biggest challenges, etc?

“It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

Offline vdubjunkie

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Re: Newbie building a PMR 6CI
« Reply #38 on: July 18, 2018, 04:27:00 AM »
The week of 4/2/17 did not produce huge items, but I started being able to fit parts together.  It was maybe even more exciting.

With the piston rod packing nut, I was able to chamfer the top edge after I began parting off, opening up that space to be worked.



Before any kind of polishing or anything, showing it off mated with the inboard head.



The valve head is up to bat next.  After a quick face off, I worked up to my tap size drill.



I found this method of tapping on the lathe plenty satisfactory previously and it worked well again.



Now it begins to take shape.  Notice the use of a fillet worked into the transition from vertical to horizontal plane of the part.  Again, thanks rcdon for introducing this sweet little detail to my mind!   :praise2:



Here's the whole gang lined up, fitting rather well.  I'm over the moon at this point.



The whole gang resting at home!   :naughty:




“It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

Offline vdubjunkie

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Re: Newbie building a PMR 6CI
« Reply #39 on: July 18, 2018, 10:25:20 AM »
The week of 5/7/17 is where my blissful progress took a detour.  Not finding much in the way of explanations on how to do layout, I decided on a poor method of marking out the holes on my base and went with it.  The method itself wasn't disastrous, and if I'd stuck with my marks, I probably would have been ok, given the allowances.

Here's the base marked out and mounted to my milling table.  No dykem was used as the base had been marked out for months by this point.  Mounting to a milling table with a single slot can be challenging at times, and this was no exception.  You'll notice my center finder set up to find my first hole.



Drilling the first hole..  All is still well.   :stickpoke:



We may have already gone sideways here.  The problem compounded in this way.  Not feeling terribly confident about the layout, I decided to "double check" myself with the graduations on the machine hand dials, moving from one hole to another.  They are, after all, precision instruments.  When I first ran into the scribe being off from the position found by hand dials, I chose to go with the location found by the hand dials.



Worse yet, when I fail, I fully commit.  Even though I believe I knew it wasn't going well, I chose to continue.



Fortunately, Keith Appleton has described, in one of the many videos I've watched, how to repair cast iron base issues.  I simply need to obtain some cast iron rod, turn it to diameter, and loctite it in each hole.  Once a hole is filled, take the material down to appropriate height of the base surface.  This will take some effort and be a well established and memorable learning lesson for me.

“It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

Offline propforward

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Re: Newbie building a PMR 6CI
« Reply #40 on: July 18, 2018, 02:42:37 PM »
Sorry to hear about that. How come the hand dial positioning was off? Did you go from the wrong datum or something? Or are the dials not right?
Stuart

Offline vdubjunkie

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Re: Newbie building a PMR 6CI
« Reply #41 on: July 19, 2018, 12:51:28 PM »
Sorry to hear about that. How come the hand dial positioning was off? Did you go from the wrong datum or something? Or are the dials not right?

Well, it's been well over a year and my self preservation tried to block it.  However, I'm pretty sure it's as simple as the part not being set up perfectly parallel to the table.  :Mad:  It's one of those things where it is difficult to imagine I would have made that mistake, but also difficult to imagine it was anything else.  The dials are good.  I use them all the time.
“It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

Offline vdubjunkie

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Re: Newbie building a PMR 6CI
« Reply #42 on: July 19, 2018, 01:12:13 PM »
The week of 5/28 was very exciting indeed.  Knowing I would not create/acquire a dividing head any time soon enough, I developed a plan B for marking precision spaced holes.

The outer head calls for evenly spaced holes while the inner must work around structure.  I used a layout program to draw up the circles and place the holes appropriately.  The plan would have been a good one if the printing had been fine enough detail.  As it turns out, they were not.



I cut out the templates and used some Elmer's white glue to temporarily affix them to the heads.



If you look closely, you'll see the punch marks created before removing the template from the part.



My crank disk bad casting became a perfect base for these drilling operations as I would much rather accidentally begin drilling into it than the table of the machine!



I began by drilling a small pilot sized hole, then moved up to the tap size drill for the threads I would later cut into the cylinder.  The reason for stopping at that size will become obvious to those not already aware.



Marking the orientation is absolutely key here in order to wind up with a proper cylinder position.



It's a bit of extra work, but totally worth the result.  I found center of each hole and used it as a guide to drill through to the cross slide.



Here is that worth-while result of which I spoke!   :LickLips:



Again, orientation is vital.  These center line marks will be used to ensure that orientation is correct when I begin drilling.



With my line centered in the hole, it's time to clamp it down and get to work.



There's those beautiful results again.  Once the holes had been "transferred" to the surrounding parts, I drilled the holes to final size.  On the head and cross slide, they were drilled to a "slip fit" size for the bolts to squeeze the parts tightly together as they grabbed the threads cut into the cylinder.



Every so often I make efforts to engage one of my kids to see if they might have interest in this hobby.  I'm certain it will be much more interesting when the engine is purring along doing real work.  This is my youngest's hands using a home-made tap guide to ensure the tapping is well perpendicular to the work.  These are relatively easy and even fun to make.  With care, they are highly effective too.



Doesn't look too bad eh?  Nobody who doesn't try to put the parts together will ever know that the holes aren't perfect.  I generally have to twist that outer head around about a hundred times before I find the correct orientation. Fortunately, I won't be doing that too much once the work is all done.



When I first put these three pieces together with bolts, I have to admit that I was feeling pretty special.



« Last Edit: July 19, 2018, 01:16:39 PM by vdubjunkie »
“It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

Offline propforward

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Re: Newbie building a PMR 6CI
« Reply #43 on: July 19, 2018, 01:21:00 PM »
Well, it's been well over a year and my self preservation tried to block it.  However, I'm pretty sure it's as simple as the part not being set up perfectly parallel to the table.  :Mad:  It's one of those things where it is difficult to imagine I would have made that mistake, but also difficult to imagine it was anything else.  The dials are good.  I use them all the time.

Oh yes, I see. Well, I've screwed up many parts in a similar way. Seems like successful machining of parts is about 90% set up and 10% actually working on the part. When I take the time to make sure everything is square and true, the parts come out well. What a surprise.

Cylinder looking great though!
Stuart

Offline vdubjunkie

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Re: Newbie building a PMR 6CI
« Reply #44 on: July 20, 2018, 02:06:33 AM »
Thanks again prop.  I appreciate all of the encouragement.  As I continue to work on parts, I realize how much better I can describe what I've done recently.  I'm trying to get all of you readers caught up!

“It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair