JV Puleo

My 1910 Mitchell "parts car" project

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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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That's how my power steering pump works. It has 4 vanes and no springs and they are off set inside of the pump housing like how you did yours. I could spin it by hand and hear them moving around. If they move easily they should be just fine. 

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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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I don't have the faintest idea how that is done and I'm pretty sure I don't have the equipment - not having even a "smartphone." But... with luck, it may happen tomorrow.

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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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Thanks Mike. I always thought it would work but it's only when it does work that I can relax a little!

Edited by JV Puleo (see edit history)

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I think I can feel your satisfaction all the way down here in the South!!    That's a great accomplishment and a real validation of your problem solving and practical skills.  

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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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Nice job on the pump. Glad it all worked out. I also ordered a set of those handy expanding arbors for the shop.  Can't wait to get a chance to use them.

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Quite an achievement and superb work. Even your temporary jig for testing is very nicely made. I have learnt so much from your excellent photos and posts.

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Most excellent Joe!

I know you put a ton of thought into what design of pump to use and how to fabricate it.

There is a lot of satisfaction in getting a project like this done!

 

Will you have a way to control pressure (i.e. bypass valve?)

 

T

 

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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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I hadn't thought of that but it's a good idea. I'll incorporate that in the design.

 

j

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