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My 1910 Mitchell "parts car" project


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Now to a really fussy part... the sliding vanes in the pump. I don't have much experience making really small things. My machines are really more suitable for larger items but I can't avoid this one. I need two pieces of bronze 3/8" thick and about 1" long. I couldn't find anything close in the shop and I'm not prepared to spend a large amount buying 10 times what I'll need. In the end, I opted to make them out of a piece of bearing bronze I have. I'm wasting a lot of metal but at least the job is progressing. The first thing was to drill a 5/16" hole in the center. This is just for reference purposes so when milling it down I'll be able to see when I'm close to the correct size.

 

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I faced off the ends so that it would grip securely in the milling vice and milled off most of one side.

 

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Then flipped it over and milled the other side using the flat portion I'd made as a reference point. That way the two sides will be relatively parallel.

 

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I also milled the ends square.

 

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I've got the thickness relatively close, about .050 oversize. Now I need the surface grinder again so I spent most of the day replacing the broken belt. This time I used a piece of conveyor belting I must have bought for this job and never used. In fact, until I started looking I'd forgotten I had it. Three hours of frustration and struggle finally got it on. I don't bend as well as I once did and this is a very dirty job done largely in the dark behind the machine with my back up against shelves of parts. However, for the moment it seems to be working.

 

I did get to use this little grinder vise, having only recently realized what it was for. You can hold small parts or parts that are non magnetic and grind the perpendicular side perfectly square without taking the piece out of the vise.

 

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We call it a "permanent magnet chuck" but I don't know what the British term is. It might be the same. Another trick was to glue the piece down with pitch. I've only read about that and can't see how it could be terribly accurate. Years ago, when I was making lenses at the Peerless Optical Company, we glued the glass to an iron holder with pitch.

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I made a little progress today. This part is VERY fiddly...take off a tiny bit too much material and you have to start over but so far, It's worked better than it has a right to. I took the width of the vanes down to about .005 wider than the roter. This is so, when they are assembled, they can be ground and lapped together. The thickness was another issue. First I tried putting the piece in the little vise but it isn't designed to hold something at the upper edge so it cocked the piece slightly. I ended up trying this method...blocking the piece on the magnetic chuck. I have done this before with not-so-good results but having no choice, I tried it again.

 

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Fortunately, it worked a lot better this time. With both sides ground, I lapped the surfaces. Grinding is very good but even here, a lapped surface is a little flatter. You can see, from the shiny spot, the slight variation in the surface. This was literally invisible to the naked eye and would probably defy measuring with anything I have.

 

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I lapped it until the vanes fit tightly into the rotor. They have to slide easily when finished but I will leave that fitting until all the pieces are ready to go together. The slots are really perfect... the end mill leaves the upper end about a thousandth wider than the bottom because as you deepen the cut the cutter is passing by that point much more often. I doubt this is or any consequence...in most circumstances, it wouldn't even be worth mentioning. Whether this degree of precision is necessary is questionable but I have a rule that if you work to the closest tolerance you can, and fail to hit it right on, most of the time you're still good to go.

 

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The vane piece now needs to be cut in half and I have to make a fixture to turn the outer radius which will match the inside of the pump liner rather than the diameter of the rotor.

 

I'll keep my fingers crossed but it looks as if I may have really fixed the grinder belt too.

Edited by JV Puleo (see edit history)
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I am still finding your reports and detailed information fascinating and very informative. I remember hearing or reading about pitch for holding parts for machining before. I found I had a spare Clarkson Autolock chuck for my Archdale mill. I am going to modify a drill chuck to fit into this so that I can drill with the milling machine. With the link you sent me about the practical machinist forum I may be able to find a instruction book for my Archdale mill which may help me understand the machine a bit better.

Edited by Mike Macartney
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Good. Quite a few of the PM members are in the UK. The site gets people from all over the world (just like the AACA) but aside from Americans UK residents are the most often heard from. I've never heard of a Clarkson Autolock... your mill must have a tapered bore to the spindle. Do you know what the taper is? It's most likely NMTB 40 or 50... the standard adopted in the late 1930s. I am reasonably certain that it was commonplace in the UK also but I admit to being weak on British machine tools. The premier site for general machine tool history is, however, lathes.co.uk.

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Now to finish the sliding vanes...

The first step was to make a fixture that will allow me to turn the leading edge with a radius of 2.128 – the actual measurement of the inside of the pump body. I cut a piece of aluminum bar, faced the ends and reamed it to 1".

 

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It was turned down to 2.2" – slightly smaller than the finished size.

 

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Then slots were cut, exactly as I did for the rotor but, in this case, a little deeper. I want the pieces to come out a bit too long so they can be fitted after the radius is in place.

 

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They were then drilled and tapped for small set screws to hold the vanes in place.

 

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After attaching the vanes to the fixture I set it up on an expanding mandrel. This will be a little stiffer than the expanding arbor I used earlier.

 

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And started turning it down. I ought to have milled about 3/8" off these first. The turning took a lot longer than I'd anticipated because I was concerned about the ability of tghe fixture to hold the pieces secure and didn't want to stress it any more than I had to.

 

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Eventually, I got there. Of course, while doing this I thought of a better way to do it but it was too late to go back and this seemed to be working.

 

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Here are the vanes with the rotor. They are still both too long and a bit too tight. They have to move freely in the slot but that will be a matter of lapping the vanes and the slot. In a real industrial setting, the slot would have been finished by grinding but I haven't the skill to do that and my grinder is pretty worn. Maybe when I get my better grinder back together I'll try something like that.

 

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Now I have to fit the rotor to the pump body. It was purposely made a few thousandths oversize because I need to do the final fitting with the bushings in place.

Edited by JV Puleo (see edit history)
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Fitting the rotor to the pump...

Here it is at its original diameter, just touching the bronze liner.

 

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I set it up in the lathe with the dial indicator and decided to take it down .002 at a time. I haven't any good way of measuring just how much oversize it is so I figured that I couldn't get in much trouble with a measurement that small. I doubt I'd be able to do this without the dial indicator.

 

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In the end, I took it down .022. I suspect there is a slight taper to the bore of the liner but I doubt that will affect it too adversely. In any case, all that is left now is to fit the vanes into the rotor and assemble the pump. Then I get to test it and see if it actually works.

 

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The gap here is not as large as the picture makes it look. The rotor is slightly longer than the pump body to allow for gaskets and very thin thrust washers on either side. In fact, it may be too short and I'll have to reduce the thickness of the center portion but I'll figure that out when the time comes. I'm off for a few days on a trip so I won't get back to this until next week.

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I only got back from Canada late last night but was able to find some time for the shop today. I have to fit the vanes to the slots in the rotor and, for this, I have to reduce their height a little. The pieces are awkward to hold in the little grinder vise so I came up with this fixture.

 

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This should hold them flat in the grinder and I can do both at the same time. If it works as planned, the back edges will be parallel with the front edges.

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On ‎11‎/‎14‎/‎2018 at 2:16 PM, JV Puleo said:

Good. Quite a few of the PM members are in the UK. The site gets people from all over the world (just like the AACA) but aside from Americans UK residents are the most often heard from. I've never heard of a Clarkson Autolock... your mill must have a tapered bore to the spindle. Do you know what the taper is? It's most likely NMTB 40 or 50... the standard adopted in the late 1930s. I am reasonably certain that it was commonplace in the UK also but I admit to being weak on British machine tools. The premier site for general machine tool history is, however, lathes.co.uk.

I am fairly sure that the Clarkson Autolock has a No.2 Morse taper. Which means I can easily fit a drill chuck into the Archdale milling machine. I want to make a rivet set to enable me to replace two pan head rivets, with domed head rivets, that match the other rivets in the Humberette bonnet (hood). I have bought a 1/4" ball end drill to do this so I will be able try drilling with the milling machine.

 

Looking forward to seeing more of your posts. Presumably, the Allen headed screws don't mark the vanes that they are holding?

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They have pointed tips so they put a tiny mark on the vane. But, those faces of the vane have to be lapped to fit the slots in the rotor. They go in now but have to be pressed. For the pump to work, they have to move very freely so I doubt the mark is important and may not even survive the lapping.

 

#2 Morse is very small so that can't be the spindle taper. Also, as far as I know, morse tapers were never used for milling machine spindles. Practically every milling machine built since the late 1930s has NMTB tapers or some version thereof. Before that, the most common were Brown & Sharpe tapers. B&S tapers were so efficient that end mills were usually held by the taper alone like drill chucks are in a big drill press.

 

If the collets that go into the Autolock chuck have a #2 Morse taper (which is much more likely) you'd still be limited to smaller sizes.

Edited by JV Puleo (see edit history)
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The first step in fitting the vanes was to reduce their height. They were probably .050 or more too tall and that's a lot of grinding so I milled them flat with the fixture using the fly cutter I'd used on the exhaust manifold.

 

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Then into the surface grinder to get a truly flat surface.

 

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I pretty much guessed where to stop but they came out nearly perfect. I had to lap the sides some to get them to slip in and they are still a tiny bit tight but so far I'm pleased.

 

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Now I needed to grind the ends so that the rotor and the vanes are exactly the same. I took a piece of aluminum tubing, left over from something else.  Coincidently, the ID was almost perfect (and didn't have to be perfect) so I put it in the lathe, faced it and cut off a piece 3/4" thick.

 

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Then put a hole through both sides and threaded it 5/16-18

 

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I'm putting my soft-tip set screws in the threaded holes to bear against the vanes. The pieces were assembled on a surface plate to get at least one side as flat as possible.

 

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The ring is purposely shorter than the rotor to make certain all that it does is hold the vanes in. I want the rotor to lie as flat as possible on the surface grinder.

 

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All of that worked just about perfectly. After grinding one side I flipped it over and ground the other side. Now the rotor and the vanes are identical in length, still about .018 longer than 1 inch. I still have to drill the vanes to receive the little springs that force them out against the pump liner but now my back hurts from standing up all day so I'll follow my own advice and get back to this later.

 

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Edited by JV Puleo (see edit history)
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I went into the shop today planning to finish the vanes. After turning the heat on, I went up to the office to check my emails and was greeted by an overdue notice from my internet provider. The "on-line' help function was just frustrating... I checked my bank balance and there was no way the payment was due much less overdue. So, I wasted two hours driving to the storefront only to discover they were billing me $200 for what was supposed to be a "free" modem. If that wasn't bad enough, they did the same thing last month and I wasted the middle of the day straightening it out. And what a treat. I had to go to a shopping plaza on what can only be considered the worst day of the year. They did correct the error - or so they said. I'll believe it when I see it. So... because I was still pretty angry I thought I'd do some preliminary things for the next steps. First I fitted the temporary pump shaft necessary for testing...

 

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Then I printed some gaskets. My idea for getting the gaskets perfect was to print them and then cut them out. This is Strathmore wove writing - a rag content paper about .0035 thick. I think it will compress to .003 and, as it is an expensive rag content paper, it should be very tough.

 

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I set up the mounting plate that will be used with the test rig in the lathe. This needs the center hole bored out to slightly more than 2"

 

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The real tricky part yet to be done is to drill the holes for the little springs that push the vanes out. These are a nominal 3/16" in diameter and I do not want to make a mistake because making the vanes was so much work. I used a piece of bronze left over from a part I made for the milling machine, drilled a center hole and then took it out with a 3/16" end mill.

 

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A clever idea but it didn't work. The hole was too tight. The springs need to be able to compress inside the vanes and there is no extra space to work with. I then enlarged the hole a little using numbered drills and finally got a reasonable fit with a #10. The spring as you see it here will compress completely in the hole which is .270 deep. I actually plan to drill the hole .300 deep so now I know it will fit before I risk the finished parts.

 

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I am a little concerned that the springs might fail but they are captured so if one breaks it still can't get out of the vane. In theory (at least) when the vanes are moving easily they should work through centrifugal force. In any case, I've gone too far to quit now. The only choice is to finish and test it.

Edited by JV Puleo (see edit history)
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One of my friends – who knows a heck of a lot more about modern cars than I do – suggested using a power steering pump and I suppose I should have looked into it. But, it would be an act of God if it fit in the space available and experience with fitting parts made for something else didn't leave me thinking it was worth pursuing.

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Drilling the holes for the springs. I used the little fixture I made for the grinding to hold the vanes in my small drill press. This delicate stuff is tough for me because I'm not really set up for it but in this case, it appears to have worked. The first step was to drill the center holes.

 

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Then I drilled the actual holes .300 deep using a stop on the quill of the drill press set to go no further than that. The vanes are .350 thick so there should be .050 of bronze between the spring and the face of the vane.

 

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The drill press is pretty worn out, despite my having overhauled it a few years ago. It runs out a little but, since I don't want the springs to be extremely tight in the holes, this is acceptable. I now think the springs I bought are a little too long and about twice as strong as I'd like so I'm going to try to find some that are weaker and, hopefully, a little bit shorter.

 

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As it is, this will be a real bear to assemble. That said, I intend to run the pump for a few days with a mixture of light oil and pumice stone to lap the vanes into both the rotor and the pump body. If I can assemble it, these strong springs may serve that purpose well.

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The moment of truth for the pump is fast approaching. I ordered some lighter springs, special dowel pins, and shorter mounting cap screws. They should arrive in an hour or so. In the meantime, I cut some gaskets using this incredibly cheap import circle cutter - which worked just fine.

 

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I also machined a plate to hold the pump while testing it.

 

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And built this test bed.

 

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I ransacked the shop looking for bits to use - everything here is made from odds and ends left over from other jobs. I was able to find a large pully for the pump shaft and a smaller one for the electric motor. It is a 1725 RPM motor. Using as 9" pully on the shaft and a 4" pully on the motor I should be able to replicate the pump running at 51 MPH. I had planned to test it at a higher speed but I'm reluctant to spend too much on testing, at least until I'm certain it actually pumps oil.

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Joe, what the top rpm you can get out of your lathe or vertical mill? My lathe will turn 2500 and my mill 2000, so I often use them to spin things like my pumps and alternators to test them. One time I even chucked in a transfer pump when I needed to drop a full fuel tank. Much easier than using a hand held drill motor that’s for sure. Just needed longer hoses.

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Top end on my lathe is about 650 RPM... it's a plain bearing lathe built around WWI. I did think of that but when I've seen if the pump actually works I plan to set up the entire oiling system, including a way of replicating the connections to the main bearings so I can test everything and adjust the relief valve. All that will take weeks and I need the lathe to make the parts I haven't done yet so a test bed on a bench seems the best solution. It's a lot of extra work but I think the oiling system is so critical that I can't take any chances it doesn't work and, since I made it all myself I do have my doubts. My mill is a lot faster and I confess I hadn't thought of using it that way but since I'm halfway there I might as well press on.

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A guarded success today... it isn't right but I had the pump drawing oil when something stopped it. When I took it apart I couldn't figure out what but I suspect the tolerances are a little too tight and the rotor was binding. I'll be back to it tomorrow. I also tried it without the springs but that didn't work... I didn't really expect it to because they are still just a little tight in their slots and the springs I was using were a bit shorter than I think they should be. Tomorrow I'll try slightly longer springs.

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Do you think it heated up enough to cause any expansion and dissimilar metals expand at different rates? It’s not all the same type of metals is it? Just wondering. Your work is excellent so I don’t suspect a mechanical design fault. Would fiber type vanes be better if it’s the vanes binding? I’m curious as I’m learning watching your whole build process. 

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It didn't get hot enough to make any difference so I'm not sure exactly what happened but part of the problem is that this was the end of the day and my back hurts when I've been standing up all day. Not too surprisingly, an idea came to me late at night so I'm looking forward to getting back to solving this. It isn't impossible that I'll have to make a different rotor - I'd thought of that earlier but want to see this through first.

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This morning I took the pump apart again. Sure enough, I'd mismeasured the pump body - or maybe forgot to check the sizes of the parts. The rotor was actually .010 thicker than the height of the pump body. Adding .006 for the thickness of the gaskets, I still had an interference of .004. So I put the rotor and vanes back in the surface grinder and took about .010 off.

 

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I then used a piece of the gasket paper under the rotor to get a clearance of .003 and put the pump back together with slightly longer springs behind the vanes. It is tricky to assemble but thankfully, once done and on the car, it will probably never come apart again. I put everything back together on my testbed and turned the motor on.

 

IT WORKED!

 

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And, there were no leaks...

 

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Even though it doesn't show, the motor was running when these last pictures were taken (the point & shoot camera must have a very fast shutter speed). It took a little while to prime itself but it did self-prime and as soon as oil was flowing it was relatively quiet. I've ordered a bag of FF pumice powder to mix with the circulating oil. When it arrives I will run the pump all day for several days - maybe even a week to lap the vanes into the pump body. This is a very fine abrasive, more used as a polish and this is the technique RR used with the Ghost and PI timing gears - and probably the later cars but I don't know much about those.

 

I'm only about halfway there though. I still have all of the oil lines, the oil manifold and the holder for the filter screen to make and all of them have to be fitted to the engine. That said, the lapping can go on unattended while I start on the remaining parts.

Edited by JV Puleo (see edit history)
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To make the remaining parts of the oil system I need to make 3 large banjo fittings and for that, I need the ball turning tool I started about 6 weeks ago so, I'll work on that now while I wait for the pumice stone and lap the vanes in.

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Yes. I've designed a simple, spring-loaded pressure relief valve. It will have to be regulated by the strength of the spring so I presume a certain amount of experimentation will be involved. The testbed has those long protruding arms in front to eventually hold the remainder of the oiling system. The goal is to set the entire system up as it will be installed on the engine with the oil lines going to mock crankshaft bearings so I can get an idea just how much pressure it will generate. But, in order to make the remainder of the oiling system, I need a ball turning attachment as I've designed the connections using 3 large banjo fittings and I have to make those. This is all in keeping with my attempt to keep all of the modifications consistent with what a clever machinist could have, or would have made at the time or maybe up to 1915. The pump is self-priming but I am thinking some sort of one-way valve on the input line is in order... I just haven't thought of a way to do it yet. I have some modern ones but they use plastic balls so if I'm going to true to my goal, I'll have to come up with something a bit more archaic. I'm also concerned about durability and a little afraid of a valve that could malfunction and block the oil input which would be a disaster so that's a part I'm still thinking about.

Edited by JV Puleo (see edit history)
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I'm not sure how pertinent this job is since it's tool making - but it is a tool to continue the oil system project.

I made the adjustable tool post for the ball turning attachment 6 or 8 weeks ago and I'm only now getting back to it. The tool post slides on a pivoting plate to adjust for different size balls. This will be the piece the tool post slides in. The first step was to cut a piece of 3/4 steel, 2-1/2" wide and drill and ream a 1" hole in the center.

 

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The hole is simply a way to hold the piece on the lathe as I want a radius on both ends.

 

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Turning something like this is a PIA because it is an intermittent cut and the spinning workpiece generates a lot of torque. If I take too big a cut, the belt that drives the lathe slips. There is a fix for that but it happens so seldom that I've never gotten around to making the parts I'd need.

 

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It did come out all right...

I then put it in the mill to cut a 1-1/2" slot down the center.

 

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Unfortunately, the only end mill I have in this size has a slight radius on the face - something I'd forgotten about so the bottom edges of the slot aren't square.

 

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While the piece was centered perfectly, I put in a center hole for the pin this piece will swivel on. The hole has to be drilled with another piece - one I haven 't started on but this will allow me to locate it perfectly in the drill press.

 

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I decided to sleep on that one... and last night I remembered that I had a whole box of odd, shallow angle dovetail cutters. I've no idea what these were made for. I bought them as a box lot on ebay thinking I could use one to cut the dogs for the crank. I still haven't figured out how to do that but I must have 20 of them so I chose one with a 5-degree angle and recut one side of the slot. This is actually a huge improvement in the design - one I'd previously thought I couldn't do. The cutter worked a charm.

 

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The last step on the mill was to square the opposite side with a conventional end mill.

 

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This part isn't done I still have to drill and tap holes for set screws and I made a really stupid error and made it 3/4" too long. Next week I'll have to shorten it and for that, I'll have to make another quick fixture. That said, I'm really pleased with this part and reminded once again that I really need to look at my drawings. My memory just isn't all that great regarding dimensions.

Edited by JV Puleo (see edit history)
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Joe, I am pleased you are showing the machining and building of the ball turning device. I am sure many of us are learning a lot from your interesting posts.

With regards to the oil pump pressure relief valve - have you considered fitting a screw behind the spring so that you can increase or decrease the oil pressure?

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