JV Puleo

My 1910 Mitchell "parts car" project

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The valve cages were one of the first things I made. I only had one original. The same was true with the pistons. I only had one of them. A good friend and vastly more talented machinist offered to make patterns to cast new ones. They are semi-finished now and I'd post the photos but they are stuck in hopeless photobucket... I'm unable to copy them or export them and haven't the patience to sift through the onslaught of adds that sight belabors you with. In any case, it would not be an exaggeration to say that the problems associated with finishing the pistons have kept me awake at night. I think I have them sorted out now so they may well be the next big project. I have 5... one extra for setups and tests. Remarkably, in their semi-finished state, 4 of the 5 weigh exactly the same to the gram. When the pistons are done, I'll be making connecting rods. That should be interesting.

 

Look for a Brown & Sharpe Combination Square... that is an 18" one. Don't buy a cheap import... old is better than new in this case and be sure to get the three pieces that go with the scale. The selling prices are all about the same, regardless of whether it's good or bad, so there is no reason to get a poor one. I think I might have $25 in this one.

 

 

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I started with the holes in the timing gear. These are to lighten it, the goal being to get rid of about half of the weight without weakening the gear. I started with my usual drawing to work out the mathematical details. These are actually 63/64" holes and 1/2" holes arranged in two circles.

 

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I put the test gear in the milling machine and attached it to the rotary table with the clamps I made last week. I'm not really thrilled with these but they will work for this job.

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The holes are spaced 30 degrees apart and arranged so that the outside edge will be about 1/32 inside the relief when I mill it. There are 3 gears, so just drilling the center holes took some time. Tomorrow I'll drill the center holes for the inner circle and start actually making the holes. I was going to do some of this in the mill but I've since decided it will be a bit more foolproof if I do it in the drill press. These center holes will allow me to locate the drill perfectly.

 

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Edited by JV Puleo (see edit history)
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Guest BillP

This is good stuff. Years ago, every town had a dozen guys doing just this sort of thing. Whether it was rebuilding an old Lozier, building a dirt track stock car or overhauling a dump truck, Bridgeports and South Bends were making chips. What the Brits call "men in sheds". One example is the Kiwi Burt Munro.

 

Thanks Mr. Puleo

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After rechecking my numbers, this morning I drilled center holes for the inner circle of holes.

 

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Before I went further, I thought it would be a good idea to see how the next proposed step worked. I clamped the blank to the drill press table and located the first hole in the inner ring with my alignment tool. Because the little piece of 1/2" ros had a tapered point to match the hole, it is self-centering. I leave the clamps loose and allow the tool to find the center before tightening them.

 

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The next step was to drill out the inner ring of holes. These are only 1/2" so it is a simple matter of centering them and then drilling. After drilling the inner circle, I also drilled the outer circle at 1/2" and used a large countersink to chamfer the edges of the holes.

 

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With the inner ring done, I located the first of the outer ring. At this point I chickened out on the 63/64 holes. It looked to me as if the web between the big hole and the two adjacent small holes might be a little thin so I used with a 55/64 drill. Having done it, I suspect the larger drill would have been ok but I like the proportions here a little better. Unfortunately, the big drill makes a high pitched screeching sound that annoys the ladies in our office as it goes through aluminum so I put off finishing this until the end of the day.

 

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I did have other things to do so it wasn't until 5 that I got to finish this. I'm quite satisfied with the result but it is a long process. There are 24 holes in each blank, each of which represents two or three operations. It is a lot more time consuming than it would appear at first glance and I'll be happy if I can finish the other two blanks tomorrow.

 

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Edited by JV Puleo (see edit history)

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Yeah, that looks really good... hard to believe that you've got two more to do.  I've got a job to do at some point that is pretty similar so I'm really enjoying learning your techniques.  I will not need quite the precision and the material will be thinner so I think my new (old) Buffalo 18 Drill Press will be able to handle the work.  . 

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All of this could be done without the milling machine and the rotary table. It might not be quite as precise, but the differences would probably not be visible to the human eye. I'd just coat the surface with dye chem... draw the circles with a sharp protractor and see how much high school geometry you can remember. I'm guessing you've got chain sprockets to do. I find it makes a huge difference to draw the whole thing out on paper, full size, to get the measurements and even then I find myself making changes on the fly.

 

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Does your drill press have a hole in the center? If not, you'll have to think of a way to block the work piece up and bolt it tight. It is very important that the piece be held securely... I managed to slash my leg open drilling a thin piece of metal many years ago when the drill caught a burr and spun the piece. It's astonishing how much torque these old, slow drills generate.

 

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Yeah, I saw a picture of a guy with a busted eye socket/nose/face in general from something coming loose in his drill press.  I didn't need much more explanation on the dangers after that. 

The part in question is the friction disc (the one attached to the prop shaft).  I don't have a photo handy but it is just a circle with some holes in various places around it.  I don't have a hole in the DP table but I would have the work mounted and clamped anyway so not an issue.   I will make a simple index type mount so that I can get the holes at a consistent distance from center and more less at the same angles.  The actual angles and the actual distance is not a big concern, the same distance and same angle is the concern.  It should be pretty straightforward and seeing how you break things down, build tools/clamps/etc, is an inspiration and makes the impossible seem much less impossible. 

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I've always thought that a simple indexing fixture could be made from a gear. You'd need one with either the same number of teeth as the number of holes or a multiple of the number of holes. As long as the work piece is mounted on some sort of axle it can revolve on, all that is necessary to make the holes uniform is a solid support for the piece. Alignment is easy as you have two circles, both with fixed center points. The arc of the circle will always pass under the spindle of the drill at the same angle. Its dividing the arc uniformly that poses a problem... hence my gear idea.

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Having finished the decorative holes in the gears, I have two more drilling jobs to do before I start milling the reliefs in the gear faces. First, I needed to drill the hub flanges for their mounting studs.

 

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The holes in the flanges get threaded. The corresponding holes in the gears will get milled into radial slots covering about 15 degrees and making it possible to "fine tune" the position of the timing gear after it is installed. I then drilled out the three holes in the aluminum fixture the gear is sitting on. I'll use this as a tool to hold the hub when I thread the holes in the flange.

 

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I used a drill the same size as the hole to locate the flange and fixture directly under the spindle – then used the drill press as a threading guide to make sure the holes were straight.

 

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The last drilling job was center holes for the brass threaded inserts that go into the crankshaft gears. I'll drill, counterbore and thread these holes on the drill press when the inserts are ready.

 

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I finished with starting on the inserts. The brass bolts are made of 270... an alloy that is strong but does not machine as well as the common 360 I usually use. That's not a serious problem but it takes longer to make them. I had three done by the end of the day and my back was telling me I'd had enough. I will probably finish the crank gear blanks tomorrow.

 

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Edited by JV Puleo
typo (see edit history)

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As simple as this job was... once again I underestimated how long it would take. Each bolt had to be drilled...

 

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After which, I threaded them. The threads were started using the lathe to keep things straight. Because they have such a thin wall thickness, it is critical that the thread be straight. This brass is tough to thread so I only started the thread here. When they were in five or six turns, I took the bolt out and put it in a vise where I could use a bigger tap wrench with a lot more leverage.

 

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Next I had to turn down the heads. This proved trickier than I anticipated because the thin wall thickness of the drilled bolt leaves relatively little strength. In order to stiffen the bolt I put a stainless screw in it, center drilled to match the tail stock. That way, it was both stiffened and supported on the outside end.

 

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After all that... actually turning them down went quickly. This is another job where 80% of the time goes into the setup.

 

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The final step was to drill, counterbore and thread a hole in one of the gear blanks and try the inserts. It went in, tighter than I had expected, probably because it is almost impossible to keep everything perfectly concentric. Nevertheless, what irregularities there are will be invisible to the naked eye.

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Tomorrow I will put in the last five inserts and face the blanks to the proper thickness.

Edited by JV Puleo (see edit history)

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Wow.. so you threaded the *inside* of the bolt?     I in turn ordered my first HSS blanks so I'm just a *little* behind you. ;)

I got a video I need to send you as well... I was able to get a MT3->MT2 adapter secured into the tailstock... as such, I'm now the proud owner of a tailstock that accepts MT2.  I've already got a MT2 chuck and I've ordered some center drills.  Your thread is inspiring!!

 

 

Edited by Luv2Wrench (see edit history)

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All I did was turn the bolts into threaded inserts... after you've been doing this for a time, you'll start to notice all sorts of ways to "make something out of something else."

 

Do you know what your headstock spindle taper is? I was thinking that you could really use a collet set... the best solution is to get an adapter that takes 5C collets. The adapters can be expensive but the collets are cheap and readily available. In any case... I have a complete collet set with drawbar and adapter for my Hendey Tie Bar that I'd loan you until you can get a better setup... I just wonder if the spindle taper is the same.

 

You are probably better off using a tail stock live center with an MT3 taper... the bigger the taper, the more surface area there is and the less it will slip although taper size isn't so important with the centers as it is with drilling. That said, you'll need the adaptors down to MT1 to use taper shank drills so nothing is wasted. Get a drill chuck with the biggest taper shank that will fit.

 

jp

Edited by JV Puleo (see edit history)

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I looked at the spindle last night and I could not tell what the taper is.  The opening is 1.25" and I could not discern a taper in the first 5".  The other end of the spindle is 1" but that is nearly 24" away so I'm not sure that really contributes to the taper.  My guess is that there was something that went into the spindle that had the taper.  It looks like a 5C collet is pretty big, I wonder if that would work in this spindle?   As always, a very generous offer from you to help, and I'm very appreciative. 

 

The tailstock is not a real MT3 taper but rather I believe it has been adapted (hacked) to hold a MT3 to MT2 adapter.  I'll send you the video and I think it will make sense at that point.   I could most likely use an MT3 live center but I would need to modify it a bit to mount securely in the tailstock. 

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I will check the parts when I get int the shop. Maybe I should send you the adapter to try in the spindle.

I had a similar issue with my 1880s Prentice Bros tail stock - it was a jarno taper. I (very carefully) centered a #3 morse taper reamer in the chuck and gently fed it on to the reamer, using lots of oil and going very slowly. It worked a charm but I think I spent an entire day on it. If you could put a MT reamer in a collet it would be a cinch to get it perfectly straight. I like this idea!

 

j

Edited by JV Puleo
typos (see edit history)

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If one uses an adapter to put MT 2 tool into MT3 (or MT4), how do you get the adapter out again? I am thinking of something like an MT2 collet with a drawbar.

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Most MT adapters are long, have a tang at the back and a slot for a wedge to dislodge the tool. Some are shorter and have two flats to take a wrench. Those can be a problem if you want to get the tool out of the adapter but it can usually be done by hitting the end with a plastic hammer. Collets are less of a problem... the collet itself is dislodged by pushing the drawbar forward. The adapter is knocked out with a "knock out bar"... I made one of DOM tubing and put an aluminum end on it so it doesn't mar the pieces in the spindle.

 

Further... for collets you need a short adapter with an open back. I'll photograph one tomorrow.

 

jp

Edited by JV Puleo
Addition & typos (see edit history)

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Here is the blank with the holes drilled, counterbored and threaded...

 

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When the inserts are in, I put it back in the lathe to turn both faces and the diameter to the finished size.

 

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This what they look like finished. Obviously, they still need the teeth cut. It needs a key way as well but I am reluctant to put that in until I've fitted the gear to the crank. I think they should be lapped out about .001 to .0015. That is a fussy operation and the lapping may round the corners of the key way so it is best left to last. Neither are difficult and there is little chance I'll screw that up and ruin the part.

 

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For Spinneyhill... this is the sort of adapter that would work with collets. I believe these are shorter than MT3 collets so the collet would pass through leaving room to dislodge out with a knock-out bar. The one on the chuck is MT4 to MT3.

 

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I had some errands to run today but between them was able to finish a couple of items. First, I finished the second crank shaft gear blank. Then, since the lathe set up for this, I refaced the timing gear hubs. I'd left the flanges 3/8" thick, intending to put studs in. I wanted to turn the face after the studs were inserted but, in thinking about it, realized that would cause a problem when it came to attaching it to the camshaft. This hub will, effectively, be a part of the cam.

 

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Here they are finished... The original gears were attached with a woodruff key and a tapered pin. The result was that, in order to do anything to the gear, you had to remove the cam from the engine. For a lot of reasons I wasn't happy with this so I've adopted the separate hub. This idea isn't original to me, I found it described in the PM Heldt, 1911 engineering text, albeit as a feature of expensive cars.

 

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Tomorrow I will mill the reliefs in the faces of the timing gears. For this, I'm using a special end mill, 1" in diameter with a .250 radius. I bought three new 1" end mills on ebay and sent them to a tool grinder. It turned out more expensive than I'd anticipated but the three mills should see me through this job and the connecting rods that I'll get to later this summer. Both require radius cuts for appearance and because they are much stronger than a simple square cut. I re-zeroed the mill and set up the rotary table before quitting for the evening.

 

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Edited by JV Puleo (see edit history)

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Guest BillP

This is to me, fascinating work. The energy of the mind goes directly through the lathe, through the mill, to the piece and then to the engine.

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Aside from unloading my "new" second-hand jointer and proof reading an article, I managed to spend most of the day in the shop. Having set the timing gear blanks up for milling last night, I started on them. I'm not thrilled with my clamps – although they actually didn't create any problem – I suspect because the plug in the center of the gear prevented any side-to-side movement. All they had to do was hold the piece down. This job created a lot of chips... hot ones, a few of which found their way down my shirt. It's not very pleasant but comes with the territory.

 

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The relief is .250 deep on each side. I made four passes at .050, then two at .020 and the last at .010. There are some little chatter marks around the edges, not as apparent in real life as in this photo. The clamps held fine but there was a very small amount of vibration in the rotary table. None of this is critical, or even important, and there is a good chance the marks will polish out easily. I finished milling all three gears by the end of the day.

 

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The center section now gets turned. The gear face is 7/8" but the centers will be .375 thick. I'll do the next step in the lathe with the blank mounted on a face plate. I've had lathes for 40 years now, all of which had a face plate and this will be the first time I've actually used one.

Edited by JV Puleo (see edit history)
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It didn't rain today – as forecast, so I mowed this morning but still had time to get into the shop to start again on the gears. After a wuick run to Lowes to get two more 10mm bolts I set the test blank up on the face plate.

 

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I used the centering tool I'd made for the rotary table to get it perfectly in the center of the face plate. This worked just about perfectly and I was able to remove 1/4" of surface across the gear.

 

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When polished, I should be able to eliminate the machining marks left by the end mill. Although it does not look it in the photo, the surface is actually flat. The lathe leaves a much smoother surface.

Edited by JV Puleo (see edit history)

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Very interesting to see the final product after seeing all the pieces and steps that went into it.

 

BTW... what is the swing on that lathe? 

 

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Nominal 15". It will actually take about 17" depending on whether you need the saddle to pass under the work piece.

 

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