My 1910 Mitchell "parts car" project

[Mike Macartney]

I only thought about doing this on my MGBV8 roadster when Moss sent an uprated spring that was way too larger diameter to fit into the oil pressure relief valve housing. Below is the modified oil pressure relief valve with adjustment bolt and lock nut on my MG.

 

[JV Puleo]

More progress on the ball turning tool...

First thing yesterday I shortened the upper piece, with the dovetailed slot, to 6". The dovetail slot will hold the sliding piece more securely than my initial design accommodated and my major worry is that the long cantilevered may not be stiff enough. Vibration will make getting a good surface on the ball impossible so anything I can do to shorten the tool is an advantage. I'm using a stub arbor to hold this piece. I probably should have done this the first time but it was necessary this time because I now have only 1/4" of metal around the hole.

 

 

Then the piece was set up to drill center holes for a row of set screws.

 

 

While this was going on, I also cut a piece for the slide.

 

 

The set screw holes were drilled & tapped in the drill press. I cjould have drilled them in the mill but the drill press gives me enough height to tap the holes at the same time and assures that the threads will be absolutely straight.

 

 

Here's the piece with the holes tapped. I'll use soft point (brass) top prevent burring on the slide.

 

 

I then milled the dovetail side of the slide using the same cutter that I used on its mating piece. That way I'm certain the angle will be identical.

 

 

Because of the dovetail slot, its hard to get an accurate measurement for the width of the piece so I made it a bit oversized and milled it down... the last cut was only .005

 

 

And the slide in its slot. This came out pretty good... good enough so that I'm even satisfied with it.

I've no concerns that the set screws will hold it tight.

 

 

Because the mill is set up for it, I may go on to the lower piece of the attachment before finishing this.

[JV Puleo]

I confess that these parts aren't going to make much sense until I assemble the tool. For now, it's mostly showing the technique in making them.

[mikewest]

Joe I got the paper , thank you. Is there a difference in them? Did you see the pics of the model a truck? Mike

[JV Puleo]

The tracing paper is a little less than .002 and it's 100% rag (i.e. made entirely from cloth). That is probably the tougher of the two. The other paper is Strathmore Wove - with about 85% rag content. It's a lot more commonplace and may be easier to work with but measures .0035 thick and probably compress about .0005. I don't think the tracing paper will compress at all. I'm going to make the finished gaskets for the oil pump out of the tracing paper.

 

Yes on the Model A's. I'm sure you are right re the '30 that's really a '29. I know practically nothing about Model As but I can tell the difference between the 28/29 style and the 30/31 style. Which reminds me of the one car story my dad told... that when the 31 Model A came out he thought it was the most perfect car he'd ever seen and it was impossible to improve on! He would have been 15 in 1931.

Edited December 5, 2018 by JV Puleo (see edit history)

[JV Puleo]

I haven't got a name for this piece... the ball turner has to drop down below the spindle of the lathe so this is the piece that allows that. It's 4" long and gets two 1/2" slots located 1/4 from the edge on opposite sides.

 

 

 

I made this first because I was concerned that the slots might not come out exactly 1/2" wide. The slots will hold a tongue - a steel tongue & groove joint. I can easily control the with of the tongue but not the slot. It turns out my worries were misplaced. I then milled the tongue on the base plate of the ball turner.

 

 

It is easy to get the first side correct. The trick is getting the opposite exactly the same since you have to take it out of the vise to flip it over. For that reason, it was set up with the end flush with the vise jaws. That way, all you have to do to get the measurement correct is line up the end of the workpiece with the jaws.

 

I faced the end off... which assures me that the cutter is exactly on the edge, then moved it in 1/2" to cut the tongue. Except, I made an error and cut it too deep. Ordinarily, I'd be upset by that but I've probably never made a mistake that was easier to work around. I started again on the other side... as you'll see shortly, the area where I removed too much metal is going to be milled away so nothing will remain of my error except these photos.

 

 

This is the final result...

 

 

This joint will be bolted together and probably welded as well but I want to be able to completely assemble the tool before I have any welding done.

With that done, I was able to drill the hole for the pivot pin. This is the setup – with the two pieces sandwiched between two angle plates and aligned on the center hole I drilled earlier. The upper plate gets a 3/4" hole and the lower place a 1-1/4" hole that must be exactly concentric.

 

 

I drilled and reamed the 3/4" hole through both pieces, then removed the upper plate and centered the hole with a piece of 3/4" ground stock.

 

 

This is the result.

 

 

My error is the cut in the front edge. Fortunately, it's only a little more than 1/4" deep and about 1/2" of the top of the plate is going to be milled away.

[JV Puleo]

In my original design, I intended to rotate the tool post with a worm & gear. I bought the parts ($12.00 on ebay) but as I've been working on this some reservations occurred to me. For one thing, making the pieces to hold the worm is complicated and the entire setup makes the tool rather long - possibly too long to work if the ball it is turning is small. Last night another idea came to me to use a spur gear. Being an inveterate pack-rat, I have a few of these that I think were change gears for a small lathe that I scrapped a long time ago. This one was about the right size but it needed to be bored to 3/4" and the thickness taken down to 1/2". It took me some time to figure out how to do this as there was nothing to indicate. The original center hole was badly worn and had a keyway in it. I opted to use the 3-jaw chuck which will center on the OD of the gear. It's not as accurate as indicating with a 4-jaw but certainly close enough for this.

 

 

I bored the center hole to get it straight and reamed it to 3/4" then faced it off until it was about .525 thick. I then surface ground the remainder, getting both sides flat and parallel.

 

 

The gear gets attached to the upper portion of the tool with some flat head cap screws. In order to make certain the holes are in perfect alignment, I made a sleeve of 3/4" ground stock and bolted the two pieces together. I've several holes and center holes to drill before I break the mill setup down.

 

 

And, this afternoon the bag of pumice stone came in. This is an extremely fine abrasive - it feels like powder. I mixed it with the oil in the testbed and ran the pump for a couple of hours. I'll leave that running while I work on the other pieces for a few days at least, then take the pump apart to see if it's sufficiently lapped in. This is the technique RR used to quiet their timing gears.

 

Edited December 7, 2018 by JV Puleo
spelling (see edit history)

[Luv2Wrench]

BSF nuts came in the mail today, thanks Joe!!

 

[JV Puleo]

I don't think I've ever changed a design so much while actually making the parts. Were I in the business then, I'd have driven the factory guys mad - changing things in the midst of making them.

[JV Puleo]

While the setup was in place I also drilled center holes for the socket head cap screws that will hold the pieces together. On the first one, I broke off the end of the center drill - I was running at too low a speed. That is a real problem because you can't just drill through the little piece of high-speed steel now embedded in the bottom of the hole. It isn't a mistake I make often but I've found the best way to get the piece out is to drill the hole from the opposite side. That is what I'm doing here, using a 1/4" drill as the finished holes will be 3/8". Usually, as in this case, it ruins the point of the drill but resharpening small drills is relatively easy.

 

 

I also drilled center holes for the two flat head cap screws that will attach the gear to this piece.

 

 

Then reattached the gear using the ground stock sleeve I'd made earlier to ensure proper alingment.

 

 

I drilled them first with a #7 drill. Then threaded the holes in the gears. The holes in the upper portion of the tool were then drilled out to 1/4" and countersunk. These are 1/4" flat head cap screws. I really should have used 10-24 because the countersink came very close to the bottom edge. It did work though and once assembled there is no reason for these to ever come out again.

 

 

Aside from some finishing touches, this piece is nearly done. The next step was to mill the large relief in the lower half of the tool to receive the gear. I set that up on the rotary table.

 

 

This is a 1-1/2" end mill. I could have used almost any size but this will allow me to mill the entire relief without having to reset the distance from the center of the pivot point. It is tedious though. That said, it looks as if the finish I'm getting is as good as I could hope for.

 

[JV Puleo]

This is how the two pieces fit together.

 

 

Though isn't really necessary, I decided to mill a radius on the front face of the lower piece.

 

 

With that done, I started fitting the smaller gear. This will be connected to a hand wheel so that I can turn the upper piece indirectly.

 

 

The hole is drilled and reamed to 3/4". This is larger than it really needs to be but as I'm using two old gears I found in my "box of miscellaneous mahcine parts" and the gear has a 5/8" bore, I'll have to bore it out a bit larger and thread it onto its shaft.

 

 

Today's last job was to make a 3/4" pilot for the counterbore.

 

 

I'll finish the pilot and counterbore for the smaller gear tomorrow.

[Luv2Wrench]

This is going to be a radius turning tool, right?  Are you copying one or rolling your own?

 

[Mike Macartney]

Joe, there is something very satisfying about making useful bits of equipment out of scrap parts and bits of spare metal. Keep up the excellent work. 

[JV Puleo]

The design is all mine, which is one reason why I'm concerned it will work at all. I may have pushed the envelope a little too far this time but the only way to find out is to finish.

[JV Puleo]

This morning I set the piece up to be counterbored. I have to use the mill for this because the counterbore has an MT4 taper and drill press is MT3.

 

 

This went quite smoothly... the gear just fits inside the counterbore.

 

 

I then started on the gear, boring it out and threading it 3/4-20. Ordinarily I would never use such a fine thread in cast iron but in this case I plan to locktite the gear on to its shaft and the fine threads will give it more surface area go grip.

 

 

With that done, I started on the shaft. Were this a real production machine the gear and shaft should be made in one piece but that's a lot of extra work and for a one-off, not really necessary.

 

 

The end of the shaft was then threaded and the gear screwed on.

 

 

This all went according to plan... except when I went to insert the gear and shaft I discovered that it is slightly out of round and the hole is too tight. I'm not really surprised by that. I was thinking that if it fit perfectly I'd be very lucky. It didn't so tomorrow I'll have to think of a way to fix it. I could buy another counterbore but they are expensive and I'm thinking I can accomplish what I need with the boring head. We'll see...

Edited December 13, 2018 by JV Puleo (see edit history)

[JV Puleo]

As so often happens, an answer to the problem of the counterbore for the gear came to me late last night. I remember that I had another, bigger end mill. The hole is a little larger than I'd like but much better than buying a $150 counterbore to do one hole. I started by aligning the hole using the counterbore I used yesterday.

 

 

Then put the big end mill in the machine and redid the hole.

 

 

There's plenty of room now. I also reduced the thickness of the gear so that it sits a few thousandths below the surface.

 

 

This shows how it works, with the small gear turning the larger one and swiveling the top part of the tool.

 

 

The next step was to cut a notch in the gear shaft to receive a set screw.

 

 

With that done, I attached the gear with Locktite. I'm also using a hin bronze thrust washer under the gear.

 

 

And, I need a handwheel to turn this gear. I went through my box of miscellaneous machine parts but found nothing useful so I started making one of aluminum.

 

 

I got the hub turned down by the end of the day... tomorrow I'll finish this.

 

[JV Puleo]

This morning I set up the rotary table and milled grooves on both sides of the hand wheel.

 

 

My grandmother would have said I'm "gilding the lily" but I like things to be finished looking. Besides, if it works, I'll probably be using this thing for the rest of my life.

 

 

And I made a little brass handle to turn the wheel with.

 

 

I'm at a loss to say what this part should be called. It's the spacer that will adjust the tension on the pivot pin and retain the thrust bearing. This is a particularly fussy part as it's height will probably have to be adjusted by grinding. But, that was enough for today.

 

Edited December 14, 2018 by JV Puleo (see edit history)

[JV Puleo]

After starting on the piece above I realized I'd made an error in the design...not one to be terribly concerned about as it's easily fixed but I need that piece to be about 2" in diameter. I have some material coming Monday I can use for that so I started on the sliding piece that carries the tool post.

First I cut a shallow groove down the center to give me a reference point. It didn't look right and sure enough, the vise wasn't square with the table. I don't know how that happened...perhaps the last time I mounted it I forgot to square it.

 

 

So, I recentered the piece and in a center hole for the tool post and one to locate the slot I'll be milling.

 

 

Then I took the slide out of its carrier and centered it in the mill. The piece of aluminum against the back jaw of the vise is there for the edge of the dovetail to engage. I was afraid that if I tightened the vise up enough to mill safely, I'd distort the angled cut on that side. It actually worked quite well. I drilled out the hole until it was larger enough to get the boring head in.

 

 

And bored it out to 1.308 - the hole size for the 1-3/8-16 tap.

 

 

I was going to tap it in the mill but I got to worrying that I might dislodge it. Hand tapping a hole that big is tough and a lot of pressure is exerted on the piece. So, I decided to mill the slot in the front of the slide first.

 

 

That went ok, but I suspect the ends closed up a bit from the pressure of the vise. It's not a real problem... I'll just turn the head of the center pin down a tiny bit. I then set the piece up int drill press to tap it. That old Craftsman wrench in the picture belonged to my late father. He was about the most unmechanical person I've ever met but when he got married, in 1950, his older brothers told him he'd need a set of wrenches for jobs around the house. I've no idea where that came from because they were as unmechanical as he was. In any case, I don't think he ever used them but I found them in the cellar when I was about 12 and appropriated them for my toolbox.

 

 

You can see how I had to bolt it down... hand tapping a hole this big is a real pain in the neck – or for me, a pain in the back. Nevertheless, it came out well. Heres the slide with the adjustable tool post I made months ago.

 

 

I'm almost there now with just a few bits still to make. I'd really like to finish this so I can get back to making car parts.

[JV Puleo]

Today I fitted the parts I'd made on Saturday. They did take a little adjustment but once everything moved freely I gave the upper section a light surface grinding and screwed in the base of the tool post, this time with Locktite on the threads.

 

 

This is how it's intended to look, with the slide passing around the shoulder bolt that serves as the center pin.

 

 

I'm waiting on some materials - actually, I knew they were arriving today but not until the end of the day. In the interim, I decided to make the radius adjustment tool.  The radius the tool cuts is a function of the distance between the center of the pin and the point of the turning tool. In order to set this accurately, I had in mind to make a post that will plug into the socket head of the shoulder bolt. It is purely a coincidence but I had both a piece of 3/8 hex stock and a 3/8 hex broach. They had nothing to do with this job - I bought them years ago to make a tool for swedging the ends of the radiator tubes. I've never followed up on that because it's just possible that a usable radiator will show up and I'm years from needing it. The first step was to drill a hole through a piece of 1" stock. The hole was determined by the size of the pilot on the only 1/2" counterbore I have.

 

 

Then it was counterbored. The only purpose for this is to minimize the amount of metal I'll have to cut with the broach, never having done this before.

 

 

After it was counterbored I  turned it around and drilled & reamed the other side 3/8" then set the piece up in the press.

 

 

This went exceptionally well... better than I'd expected.

 

 

Then I drilled and tapped the end for a set screw to hold the hex stock in place.

 

 

The last step was to turn the end of the gage to 3/4". If you put the point of the cutting tool up against this 3/4" diameter piece it will cut a 3/4" radius. I will make some sleeves in different diameters to slip over the gage to get the other sizes. Here you see it in place... needless to say, it comes off once the tool is set.

 

Edited December 17, 2018 by JV Puleo (see edit history)

[Mike Macartney]

Even more I have learnt from your excellent posts. I would never have thought of using a broach in a press. Thanks.

[JV Puleo]

Yesterday I had one of those days when everything seemed to fight back. This is the piece that will bolt to the saddle. Somehow, I managed to mil the tongue crooked... the vise had shifted slightly and I didn't double check it before I started. Thankfully, I was able to correct the problem but a job that should have taken an hour took four.

 

 

The center hole needed to be counterbored for a 5/8-11 cap screw. I wasted time looking for a 15/16 x 5/8 counterbore then remembered that I have several 15/16 end mills. If done carefully, there is no need for a pilot - that really only needed when counterboring in a drill press. So I made one of my centering devices - a 5/8 piece of ground stock in a 1" to 5/8 steel bushing and centered the hole in the mill.

 

 

I don't often use the word "perfect" but that is how this job came out.

 

 

I then had to make a plate for the cap screw to attach to... this actually was a simple job. I even did it by eye since none of the measurements are really critical.

 

 

The center of this piece was drilled and tapped for 5/8-11.

 

 

Here are the pieces assembled.

 

 

Now I have to calculate the measurements for the plug that will hold the central pin in place. This has to be quite precise so I started on it but will continue tomorrow when I'm rested and perhaps thinking more clearly. The brass pieces you see here are .004 shims indended to keep the two pieces slightly apart so they don't rub when the top section turns.

 

 

 

Edited December 19, 2018 by JV Puleo (see edit history)

[JV Puleo]

This morning I made what I hoped is the last part... the plug at the base of the pivot pin. Unfortunately, I got so wrapped up in the job I forgot to take more pictures. This was a fussy part because it has to fit precisely to keep the pin from wobbling...

 

 

So here is the radius turning attachment finally assembled...

 

 

It has some problems. First, the old lathe change gears I used aren't exactly concentric so it binds slightly. This isn't a major issue. It may wear in and the binding is more of a nuisance than anything else. I may be able to adjust it out. Also, I don't think it is rigid enough. I'd half anticipated that because I'm using a ground shoulder bolt for the pin. It is about .004 undersize - perfect for a slip fit in a reamed hole but in this case, I probably need something like .0005 clearance. I first noticed this potential problem last week and bought some bushings with the idea of correcting it...but first I want to try the simple fixes. The best mechanic I've ever known used to say "start with the simple things first." I have to remind myself of that all the time because my natural instinct is to start with the complicated things.

[Luv2Wrench]

How are you planning on getting half a tenth?  Is the bushing already that size or maybe you're grinding that?   The only way I can get below a thou is to use a file instead of a cutter in the lathe and I have to continually test because I don't have an indicator that reads tenths. 

 

I can't wait to see the results you get with the rig.  I'm thinking of taking the radius tool that came with that smaller lathe I picked up and see if I can adapt it to the Hendey.  I'd love to turn some bead roller dies when I get back on the Metz.  Having an ogee die that matches what is on the fenders would be a huge help in getting those things back in shape.

 

 

[JV Puleo]

 

Not half a tenth, half a thousandth.

The bushings are about .002 oversize on the OD to provide a tight press fit in a reamed hole. Often they compress a tiny amount, but not enough to give me the sort of fit I want for the pivot pin which, now that I think about it, will be taking all the downward pressure exerted on the cutter. I've already started the new pivot... basically, I'm making a shoulder bolt but I'll have to drill the center out because I need to broach it so I can use the sizing tool I made. Fortunately, the dimensions allow that. The new pin is .001 oversize (where the shoulder bolt is .003 undersize). After I have pressed in the bushings I'll use a barrel lap to fit the pin. I did that with the cam followers so I know you can get a really good sliding fit with perhaps .0005 clearance. You don't really measure it as much as feel it although I do have a 10s reading indicator.

 

Actually, I'm pleased with this change in the design. Like always, I made it more complicated than it had to be and thus made issues for myself. I think that fixing this may also solve the binding problem.

 

Did I send you the copies of the illustrations of the fender dies? I know I've sent them to someone. I'm not certain they would be difficult to make with a rotary table.

Edited December 20, 2018 by JV Puleo (see edit history)

[Luv2Wrench]

Right, too many zeros running around in my head!   I've never been very good with numbers which is funny given I work programs for a living.   Yes, I have have the illustrations.  I think I could turn them on the lathe with either a tool ground to the form or the radius tool.  

[JV Puleo]

I'm not either which is probably why I was never attracted by engineering. As it is, I keep two calculators on my workbench, double check ALL my numbers and make written notes as well and I still make errors.

[chistech]

I quit when I run out of fingers and toes!

[JV Puleo]

Starting the re-design. The first step was to take a piece of 1" bar and turn it down to .750 + .001

 

 

Then I put it back in the lathe, faced off the bit end and drilled it through at 3/8"

 

 

I then turned it around and threaded it 3/4-16 - the standard 3/4 fine thread since I don't want to be bothered making a nut in an odd size.

 

 

I was lucky I had a fine thread nut to test it with. Otherwise, I'd have to have ordered some and wait to do this part.

 

 

Then I drilled it about 2-1/4" with a 7/16 drill. This is only to serve as a guide for the broach. I'm only broaching the head of the pin...there is no need to try to force it through the whole length.

 

 

I started the broach in my arbor press then moved over to the larger press...

 

 

And that's it. Now I have a pivot pin that is .001 oversize. This went much more smoothly than most jobs...

 

 

 

The metal is 12L14 - free machining steel. Were this an industrial job you'd want a tougher metal, probably hardened and ground but how much is this going to be used if it does work? I can't imagine wearing it out but if I do, I'll just make another.

Edited December 21, 2018 by JV Puleo (see edit history)

[JV Puleo]

With the new pin finished, I now have to get the other parts ready. The first thing I did was correct the odd error I made in milling the radius on the lower section of the tool. The 1-1/2" end mill I used was tapered. I've never seen a tapered end mill aside from one for cutting dovetails and the taper is very shallow. In the end, this actually was a help because it forced me to make the slide larger and to work n the dovetail I made but I wanted to correct the problem where it showed. To center the piece I used this 3MT center, turned down to 3/4".

 

 

Which allowed me to set it up on the rotary table so that the radius would be uniform. You can see the odd tapered cut clearly here.

 

 

I then reassembled the pieces and clamped them up in the drill press to drill and tap a hole for a bolt that will attach the upper and lower pieces securely, The idea is to get them so solid that when I drill and ream the holes for the pin it will be as if I was drilling a solid piece of metal. This is the only way to keep all the pieces in perfect alignment. First I drilled a 5/16 hole through both pieces.

 

 

Then swiveled the upper piece out of the way and tapped the lower one.

 

 

I drilled the upper piece out to 3/8" and bolted them together. With them securely in place, I was able to get a good reading for the depth of the bushing I'll have to make.

 

 

I'm making this bushing out of aluminum just because it is easier to work. The depth is calculated to allow for a .125 bronze thrust washer between the bushing and the gear.

 

 

All of which takes a lot less time to explain than it did to make it. I always have a problem reading my depth micrometer - it works backward from a conventional mic and for some reason, I always find it confusing. In any case, I took my time and it came out to exactly the measurements I wanted.

 

 

This was made to be a very tight press fit. I think it's OK... the real test is to see if I can put the pin back in with everything bolted up.

 

 

Which, thankfully, it did although it isn't as loose as it was. This is a good example of trying to make something that is actually more precise than the machines I'm making it with. That is really the essence of manufacturing...unless we could do that, we'd still be in the stone age.

 

 

 

Now I have to set everything up in the drill press again, drill and ream the hole for the pin, press in bronze bushings and lap the holes so that the new pin has an extremely small clearance.

 

 

 

Edited December 22, 2018 by JV Puleo (see edit history)

[JV Puleo]

I like quiet days in the shop... which this is because everyone else is off doing Christmas stuff. With the two pieces of the radius tool clamped and screwed firmily together, I located the center of the pin hole.

 

 

And using that setup, drilled and reamed the holes to 7/8". I then pressed in 7/8 x 34 bushings... but it looks as if I forgot to take a photo of them. I did discover that the press fit reduced the ID of the bushing very slightly so that the hardened shoulder bolt now fits somewhat closer than it did. I've decided to test it with that bolt in place rather than hone the bushings for the new one I made. If it works, all is well. If it doesn't, I still have an alternative. At this point, I'm waiting on a thrust washer which was supposed to be delivered today but since the building is closed up, I suspect I'll have to wait until Wednesday for it. In the meantime, I decided to drill and tap the holes that will hold the offset plates in place.

 

 

I was going to clamp these together but the press is so tight that I took a chance and drilled the holes as is. These are 5/16" holes, the drill size for a 3/8-16 thread.

 

 

Then removed the upper plate and tapped the holes.

 

 

The other plate was then drilled to 3/8"

 

 

And the holes counterbored for the heads of the cap screws.

 

 

They look pretty good. The fit is so tight that I doubt any welding will be needed.

 

 

Here it is set up on the lathe saddle.

 

 

Next I have to do the lower section. This is a little more tricky because it's longer and has a rounded end. I have to give that some thought but at this point I think that as soon as these holes are in place and the thrust washer arrives I'm ready to test it.

 

 

Edited December 25, 2018 by JV Puleo (see edit history)

[Luv2Wrench]

Looks great!  Seeing it on the lathe gives a lot of context.  What's the big slot on the bottom for?

[JV Puleo]

The piece that swivels is attached there. The whole thing is cantilevered so that it fits under the piece being turned.

[JV Puleo]

I then drilled and tapped the holes in the lower plate. In this case, because the end is rounded, I had to use this old B&S Milling vise so I could put a square up against the side to get it straight,

 

 

Then, because I had time, I put a hole in the center of the short piece... just to lighten it a bit and for looks. As you'll see, this was a mistake.

 

 

Because I then did a trial assembly...

 

 

And discovered that I'd miscalculated the offset... it's about an inch low. If I hadn't drilled that hole, I could just shorten the piece. Now I have to make it over.

 

[Luv2Wrench]

You're just making the cantilever piece over, right?   Obviously you'd like it to be perfect the first time, but making that piece again isn't too bad.   When you make it a little shorter, might you also add a piece to rest against the saddle?  Perhaps make the piece that hangs down thicker such that it naturally rests against the saddle?  Looks like that would provide a lot of support to offset the downward force from the cutting tool... though I may not understand how it works.

 

[JV Puleo]

That's a good idea. I'll make a piece that will go up against the front of the compound when it is all bolted up. After I posted the above the thrust washer I needed arrived so I was able to fit it and do a quick adjustment. I don't think it could have come out any closer...there is about .003 to .004 clearance between the upper and lower pieces. I still have a slight binding problem but I think I'll remedy that with a little lapping.

 

 

The replacement part is all set up in the mill but its the end of the day and I don't want to make another error so I'll leave that for tomorrow.

[JV Puleo]

Here's the old piece and the new piece. I learned something here. When I made the original piece is was very careful to mark the holes precisely although they were drilled with the piece they attach to. When I made the new one, of course, the threaded holes were already in place and I was worried that the new holes would be ever so slightly off and it wouldn't go together as it should. I was very relieved to find that the new piece fit perfectly.

 

 

Then I assembled the device on the lathe. Now is the real crunch. I have to test it. It certainly looks good... whether it works as well is yet to be discovered.

 

[JV Puleo]

It works - but not very well. There are some problems I will have to address but I want to give it a rest and come back to it rather than charge in.

[Luv2Wrench]

49 minutes ago, JV Puleo said:

It works - but not very well. There are some problems I will have to address but I want to give it a rest and come back to it rather than charge in.

 

That's fairly typical when I create something of that complexity.  I figure if I can get it close to working then a few tweaks will usually get it all the way there.  Hopefully that's the case for you as well... it certainly looks like a solid tool.

 

[JV Puleo]

I am reasonably certain I can get it to work but there is a problem with tool geometry that I hadn't anticipated... because of the diameter of the headstock spindle, it is hard to get the cutting tool to the back of the workpiece. I have an idea - and I'm going into the shop today to fiddle with it. If it works it is so simple I'll be having one of those "DUHH!" moments.

[JV Puleo]

It looks as if missed a crucial element of design in my radius turner. They are mostly used to make balls with threaded holes for machine handles. When you do that, you drill and thread the hole first and then screw the piece on to a bolt or threaded rod which can be held in a chuck or collet. What I failed to notice was that in almost every case the ball projects some distance from the chuck. The problem I have is that I'm making Banjo fittings. There is no threaded hole and the projecting piece that I have to hold the ball with is short. The trick is getting a tool that will work in the small space available. So, I'm now making a different type of device using a boring head. Fortunately, I have an extra boring head - a cheap import I bought years ago. I used it a few times and then decided that if I wanted to do precise work, I had to get a good one. The old one has been on the shelf ever since so the expenditure for making this thing is minimal. This type of ball turner won't make concave surfaces but I think the need for that is minimal and not difficult to do in other ways.