JV Puleo

My 1910 Mitchell "parts car" project

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I finished relieving the centers of all the gear blanks today. There is one milling operation left, the adjustment slots. These are 3/8" slots, each one of which covers 30 degrees. The gear will be held to the hub with cap screws or studs and, when installed, it will be possible to "fine tune" it's precise relationship to the crankshaft. I think this is important because we have no official timing information and, even if we did, it would probably be inappropriate to today's fuel and the slightly raised compression ratio. The location of the gear, concentric with the camshaft, is controlled by the hole in the center. These slots are 1/16" larger than the retaining screws. Their only purpose is to attache the gear to the hub securely.

 

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Here is the finished product. There are still a couple more minor steps before the blanks go out to have the teeth cut.

 

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Hi Joe, I just went to the local scrap recycle place in Columbia CT, named JSR  or  AKA "Johns scrap recycling"

 

The have some machine shop stuff for sale:  Two monster millers with 6 foot beds, with a huge CNC control box/station to run both. Got to be 8.5 feet tall to the tip up there.

 

Then a rack full of collet chucks which can be bought by the single piece or more, sold as scrap weight, not what it is valued as in a tool.  This is dirt-cheap pricing if you see something there.  These will NOT be scrapped, but the two huge machines may get cut up today. 

 

then a small specialized grinder ??? that one will not be scrapped, and sold by weight...they gave a close guess at $500. 

 

It is 5 minutes from here so I can go there with you if needed.

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Wow... I think the grinder is a "Tool & Cutter" grinder — for sharpening milling cutters. I'd love to have one of the big verticals but they are too big to fit through the doors of my shop - which is in the basement of our book warehouse. The only way I could get something like that in is to dismantle it and, even then, I'm not sure I could. I barely got the Brown & Sharpe in and it was dismantled.

 

What a great scrap yard though and thanks very much for thinking of me. If either was a "#2" size (they are probably #3s) I'd be on it in a heartbeat.

 

jp

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While I waited for a few small bits from McMaster Carr, I made some special washers for the timing gear hubs. I realize making your own washers is a bit over-the-top, but I wanted these to be of a specific size that is not readily available. First, I turned down some 1" 12L14 to .875 (only because I didn't have any that size to start with).

 

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Then drilled and reamed it to 5/16

 

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I'd intended that they be .100 thick so, to get this exactly, I surface ground them. This will give me a perfectly flat surface. The idea behind these is that they, and the studs that will eventually be screwed into the hub, are what holds the adjustment of the gear in place against shifting from the pressure generated by compression and the valve springs. It is, therefore, important that this interface be as precise as I can possibly make it.

 

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While I was doing this, it occurred to me that I should chamfer the edges of the 1/2" holes in the gear... they'll look better and it will remove a little more weight without effecting strength. The problem is doing it uniformly, so I ordered a two piece shaft collar and fit is as a stop to the spindle on my small drill press. This is an old, and not terribly precise machine I generally use for odds & ends...it doesn't have to be precise in this case because the countersink I'll use is self centering.

 

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That worked so well, I was almost shocked. I was then able to fit a hub to a gear, put it back in the lathe and turn the OD to be absolutely concentric with the hub. All of the gears ran with very little runout. On a job like this, where several pieces are involved, a tiny amount of runout is inevitable so I was very pleased with how close they came out.

 

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So... that is it for the time being on the timing gears. I emailed my gear-cutting friend to ask if he was still up for the job. If he isn't, I'll find someone else. here are the two sets of gears along with the "set-up" gears for both sizes and the originals I copied. The new gears will be slightly more than 1/2 the weight of the old ones. There are still a few more steps before they can be called "finished" but those should wait until after the teeth have been cut. The button-head Allen screws are temporary. I intend to put studs in the hubs and use locking nuts but I think that the studs will make fixing the hub to the camshaft more complicated so I will wait until after that is done to insert them. You can see both the front and back of the timing gear & hub on the right below. On the back, the hub is flush with the outside edge of the gear face.

 

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Next, I'll finish the crankshaft hub that I started, changed and now need to get back to.

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

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Looks fantastic, as usual.  Do you have a couple of pictures of the engine such that we can visualize where these items fit into the whole?  If not your engine, then maybe one similar?

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Strangely enough... no, I don't. I've never seen one complete or heard one run. It looked like this when I got it.

(The jugs were in the big wooden box bolted to the chassis in the first photo in this thread)

 

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I do have some photos of a similar car, apparently a 1911, or at least one with the later version of the same engine. When my engine is done, only the jugs, crankcase, crankshaft, sump, flywheel and timing gear covers will still be there. Many of the smaller parts, including the exhaust manifold, were missing and most of the others worn to a shred, bent or broken. It had clearly suffered the attentions of a very heavy-handed would-be "mechanic." What he didn't break, he lost. I've already made new cam followers, valve cages, rockers etc. Fortunately, the chassis is in better shape, although still missing some things.

 

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Your can see the big timing gear at the front of this engine. The covers are off – or missing.

 

Edited by JV Puleo
typos & corrections (see edit history)
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The gears are now on their way to my friend in Arizona who will cut the teeth. He's a little busy at the moment so it may be 3 or 4 weeks before they are ready. Now I will finish the crankshaft hub and sheave and, because I like to have at least two or three jobs running at the same time, I am starting on the tooling to finish machine the pistons.

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Hello Jv,I have a question with all the aluminum being used won't you need the weight for torque in the motor will the aluminum rods pistons gears etc be really light or is that what your going for,by the way phenomenal workmanship,   Dave

 

Edited by JustDave (see edit history)

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The idea that the engine "needs" the weight is a myth. Actually, the lighter everything is, the less stress there is on the crankshaft, bearings and every other moving part allowing more of the power generated by the detonation of the charge to be transmitted to the wheels. My goal is to reduce reciprocating weight while while keeping everything in balance and maintaining strength. There are a few places on this car where I'll actually add weight. Lots of engine parts were simply too heavy, not so much because they didn't understand what was best, but because heavy parts were often cheap parts. The situation was reversed on the chassis where they often scrimped on materials and made things too light. You will also hear that the cars "need" a heavy flywheel... that isn't really true although in a case like mine it is unavoidable because the cone clutch is part of the flywheel. That was something that was misunderstood at the time, Engineers were heavily influenced by steam engine practice which was far more generally understood. Just about everyone who was designing a motor in 1910 studied engineering before the advent of the automobile. Modern engines develop far more horsepower and run at much greater speeds with relatively tiny flywheels.

 

Think of the lengths they went to to lighten early race cars... drilling the chassis and about every possible part, sometimes weakening them to the point of breaking. Effectively, if every moving part of which there are multiples... like pistons and connecting rods – are identical in weight, those parts will be in balance. With other parts - like the gears I just made, the critical element is keeping them as light as possible and as uniform as possible - hence the careful spacing of the holes. It wouldn't do to drill them free-hand and have some close together while other were spread out. 

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Now that you explained it it makes better sense,I guess in my last life I must have been a steam engine mechanic,if the rods pistons etc are lightened will you have to take weight off the flywheel or will it be ok as is,still watching and still learning.  Dave

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As this job continues, I had to put the big chuck back on the lathe so I decided to do all the current jobs that needed it.

First... I started on the tooling to finish machine the pistons. I roughed the pistons out two years ago but dropped stopped for two reasons... I couldn't turn the final diameter until I knew what the bore would be and the problem of locating the wrist pin holes - something that looks easy until you try to do it. They have to be perfectly located in the center of the bosses and you have to be able to do that completely blind. This is looking down into the piston. The walls aren't as thick as they look - the photo is overexposed and you can't see the ridge around the lower end of the piston that provides a guide surface. I have 5 blanks and I know they are very close to uniform because 4 of the 5 weigh exactly the same amount, to the gram. The 5th is only about 5 grams heavier,

 

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I made was this device to measure the exact distance from the base of the piston to the edge of the wrist pin boss. I'll push the central piece down until it touches and measure the depth with a depth micrometer.

 

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Then, I made another piece that will be part of the fixture that will hold the piston on the face plate. It's a piece of 4-1/2 inch bar with a 2" hole in the center. The first step was to bore it to 1.990 and ream the hole to 2".

 

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I then did the same thing with the new sheave. In this case the hole is 2.370 so I had to bore it. I was pleased it came out perfect. Here you see it, with the original big sheave, on the guide fixture I made last week. This will allow me to locate, drill and tap the holes so the two parts screw together.

 

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Last up was the new hub. This is a piece of Stressproof I bought on ebay. Needless to say, steel takes longer so I started with a 3/8" hole. I will keep increasing the size until I can get my boring bar in, then bore it to 1.485 and ream it 1.5".

 

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The next few steps...

The piece that will be the "new & improved" crankshaft hub was drilled with increasing larger holes up to just under 1-1/4" – the largest drill I have. I then bored it to about 1.485, 15 thousandths or 1/64" less than 1-1/2".

 

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The next step was to finish ream it at 1-1/2." The reamer is one I bought on ebay. A new one would have been very expensive. I've found that industrial tooling like this is one of the few things that is consistently available at knock-down prices, probably because there is a lot of it and not that many small shops and hobbyists to buy it. In any case, it is probably .001 large – a clearance fit rather than exactly 1-1/2". In this case, that proved perfect, saving me the tedious task of honing the bore out to slip on to the crank. The fit is now almost perfect.

 

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Before going further with this, I decided to do an experiment. This is the first gear blank I made. I got the diameter wrong because I used the diameter for a 44-tooth, 12 DP spur gear, not realizing that the helical gears are slightly larger. Because I managed to get the V-groove for the belts wrong on two occasions, I thought it best to make certain I could cut the groove correctly. I decided to make this gear blank into a sheave. It worked, and this time I got the angle correct. I will probably use the sheave on a generator or alternator but that part of the project is a long way down the road.

 

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I then mounted an expanding mandrel. Because the bore of the new hub is slightly oversize, the piece won't press onto a conventional lathe mandrel. I only bought the expanding mandrel set a few weeks ago and already can't imagine how I got along without it.

 

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The outside was turned to 2-1/2", then one end was turned to 2.370", the inside diameter of the two sheaves I salvaged from the old hub by boring out the threads. The idea was to save the big sheave and to make a new, smaller one. At the last minute, I decided to try and re-cut the groove in the smaller sheave as well as the big one. It actually worked, so I won't need to make a new one and I'm off the hook on locating the three threaded holes that attach the sheaves to each other.

 

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The last thing I did today was convert the alignment tool I'd made into a broach bushing. Ordinarily,  you would never make one of these from aluminum but this is a one-time-use tool so I think it will be fine. Except, once again I broke my own rule and tried to do something fussy when my back hurt and I was tired. I managed to get the groove slightly off center. I'll do it again tomorrow. It isn't a major problem, just a wasted hour. A second groove in this piece will not keep it from working and, when it's done, it'll probably be going into the scrap bin in any case.

 

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Edited by JV Puleo (see edit history)

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JV, are you going to cam grind those pistons? I ask because as a teenager 50 years ago I had a machine shop turn a set of "semi" pistons for me and they turned them round and when I sent them to my engine rebuilder he said they were ruined because they were round and not "cam ground". Luckily I was able to get a second set but it was a costly mistake.

Howard Dennis

 

https://www.jalopyjournal.com/forum/threads/cam-ground-pistons.538613/

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No, I'm not. The reasons are fairly technical but, simplified a bit, cam grinding is a way of making thin wall, split skirt pistons conform to the bore despite thermal expansion. These pistons don't have split skirts and they have reasonably thick cast walls so cam grinding would not accomplish anything as long as there is sufficient clearance. I don't think it was even invented until the 20s and maybe later because the early aluminum pistons were also cast.

 

What engine were your pistons for? One of the problems I constantly encounter is that lots of collectors – and "old-time" mechanics – are full of collected "lore" while having no notion of the physics or the history of what they are talking about and much of which is simply old wives tales. Depending on how old your engine was, you may have been right and the engine rebuilder wrong. Remember, this is a hand-cranked, 1910 engine. It is a lot different from most any engine only 10 years newer...

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No Problem, Just passing on my experience from long ago with a highly respected automotive machine shop, established before your engine was built, who did my first rebuild on a 1932 Plymouth which had a motor almost identical to my current project a  1917 Maxwell. Later they did my 426 Hemi's. 

 

Unlike some I respect what the oldtimers accomplished and try to learn from them as much as I can because I don't believe I know everything nor do I think modern ways are absolutely always the best when dealing with century old machines.  

 

Howard Dennis

Purveyor of Folklore

Shade Tree Mechanic

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I'm not sure what I was thinking but the slot in the bushing was off-center. In a case like this, that is a critical error so, Sunday morning, I went back to the shop and did it again. This time it came out right.

 

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To use this, I pushed the bushing into the bore and then put a 1/4" key way broach in the slot. I set the broach with an arbor press. It isn't strong enough (nor is it bolted down) to push the broach through. It is important to get the broach straight. They are hard and therefore brittle and easily bent or broken. They are also expensive although this is from a relatively cheap import set I bought on sale because the box they came in was damaged. I don't use them often but they are a lifesaver when you need them. There other ways to do this, all of which are more complicated.

 

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I finished broaching with my "shop made" 20-ton press. In order to get the depth, It was necessary to push the broach through 3 times, putting shims between it and the bushing in order to deepen the notch.

 

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The result was quite satisfactory...

 

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This morning I cut the seat for a Woodruff key. This is relatively easy to do but it is very important that the seat be in the exact center of the round section (as it is equally important that the key way be in the center of the hole) or the key and its key way will not line up. In this case, they came out just about perfect although I will have to order some longer Woodruff keys.

 

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The last step will be to drill and tap two 1/4-20 holes in the bottom of the v-groove of the smaller sheave. These will go through slightly into the hub. The set screws will be nearly invisible there and they will keep the hub from shifting backwards, towards the engine, while at the same time permitting it to be disassembled easily should that ever be necessary. I'll drill the holes at 120 degree angles from the key way.

 

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The last step with the sheave was to drill and tap the holes for the set screws. To do that, I wanted a long center drill as the holes should be drilled with the parts assembled. I had to wait for that. In the meantime I did some more work on the tooling I will use to finish the pistons. This plate is about 7" in diameter with a 2" hole in the center. It will be the base of the fixture I will attach to the faceplate to hold the pistons while I turn them to finished size and cut the ring grooves. All of these piston finishing tools need to be as precise as I can make them because it isn't practical to do each operation to each piston, one at the time. That would almost certainly result in some variations. I will have to be able to put the piston in the fixture, do the appropriate operation and then do the same thing to the next piston, so the ability to replace the part on the machine with precision is critical. This is only the "roughing". This plate will be drilled for the mounting holes and then faced again while attached to the faceplate.

 

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When the center drill came in, I set the piece up in the drill press. Making the bits to hold the sheave & hub together, and this setup, took far more time than drilling the two holes did.

 

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As you can see... the set screws are too long. I'll just order more, a little shorter. I make that sort of mistake frequently which is one reason I have an entire shelf full of McMaster Carr boxes of fasteners. The other is that I frequently have to buy 25 in order to get 3. Although, I can say that they do eventually get used and often enough I get something done quickly because I have the necessary bits on hand.

 

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With this done, I went on to finish the hub. The first job was to trim the ends. The back half was trimmed to just a few thousandths longer than the thickness of the two sheaves. The front half was trimmed to .100 longer than the original. I did this for two reasons. I will probably move the hub back about 1/6" and, should it be slightly longer than the original in front, this will only serve to protect the end of the crankshaft/

 

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With that done, it was time to fit the hub to the crankshaft. The fit now is very close but I want a sliding fit with no appreciable play but not needing to be pressed or driven on. Keep in mind that there is a seal in the front of the timing case and the only way to reach it, and renew it, is to remove this hub. The original piece was .006 or .008 too large – a sloppy fit that relied entirely on the key and a tapered pin to keep it in place. For this job I used a "Flexhone." These are not intended to remove metal but to finish the bore and, if I had needed to remove several thousandths it would have been a long and tedious process. As it was, the honing took about an hour. The beauty of this is that, even if it is time consuming, it is almost impossible to take too much metal out and ruin the piece.

 

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A bit out of focus but here is the hub slipped on to the crankshaft. You can see that some nitwit, in the past, hammered on the end of the crank. This spread the end and complicated removing the original hub.

 

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The next step is broaching the keyway in the hub. I actually finished that job today but had downloaded these photos, and emailed them to myself while taking a coffee break, before I started that job so they will have to wait for next time.

Edited by JV Puleo (see edit history)

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Looking great Joe!  I've got a whole shelf of "25 to get 3" from McMaster-Carr.   With their reasonable costs and (for me as I'm in GA) one-day shipping, I probably don't pay enough attention when ordering things... easy to do "trial and error" with them. :)

 

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I find their web site almost seductive. Almost every time I try to buy stuff locally, it's always a wait to get it in at which point I say "why bother" and just order the stuff from McMaster. Of course, sometimes that "buy the whole box" is cheaper than the local hardware store - or so close in price that why not have the extras. I can't tell how many times I've been thankful I had the odd fastener on the shelf and could get on with things without having to run out.

 

j

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Here is the hub with the key way cut. This was tedious to do in my shop-made press but I'm happy with the way it came out.

 

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I then drilled and threaded a hole, directly opposite the key way, for a 1/2-20 set screw. This will give the hub a little additional holding power but, more importantly, will hold the hub in place while I drill it for its retaining pin.

 

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There are two operations left. Drilling the pin hole and milling the dog teeth in the end of the hub. Both are a challenge and I've given them quite a bit of thought. I have a plan for the pin hole but still am not sure how I will mill the teeth. I have decided that, rather than try milling the teeth in this part, I should first do the mating dog tooth end of the hand crank. That part is much more easily made so, if my plan doesn't work, I will not have ruined the far more time-consuming hub. With that in mind, I dug the crank out of a box of miscellaneous parts under one of my benches.

 

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You can readily see the problem created by the use of tapered pins. These are permanently stuck and it is impossible to dismantle this part without removing them. I hadn't the patience for that, especially as this part is heavily worn, slightly bent and I'm making a new one. I resorted to the power hack saw.

 

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The result was revealing. Another example of Mitchell "quality." Notice that, rather than a bronze bushing, the Mitchell people bushed the hole with Babbit. Babbit is a wonderful bearing material, for spinning shafts in a relatively clean, well lubricated environment. It is not, and never was intended for shafts that move only a short distance, are poorly lubricated and subject to short, intense pressure. This was well known at the time. They can only have used Babbit because it was cheap and, though not a good choice, would probably outlive the working life of the car. In 1910 virtually all mechanics of any sort were familiar with pouring Babbit bearings so, though a cheap choice, it was also cheap to renew.

 

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This view, from the other end, shows that when this bracket was cast, the core must have slipped. They used it anyway. The crank handle must have protruded from the front, under the radiator, at an angle.

 

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I probably worked on the hand crank because I didn't want to tackle the pin hole. This is the problem... when it was made, the key way was broached and then the hub and crankshaft were drilled and reamed together for a tapered pin. This is the only way they could have gotten the taper correct for the pin to seat perfectly and it would be the same today. In order to remove the hub, I had to drill the pin out so now I have a reamed 3/8" hole in the crankshaft. This is an extremely inappropriate place for a tapered pin as the hub must be removed to renew the front seal. MY plan is to use a straight pin, secured with cotter pins on either end. That, with the key and the set screw I've added, will be more than strong enough to hold the hub.  Drilling the hole in the hub to perfectly align with the hole in the crank is a the problem.  Based on observation of parts like the hand crank bracket, I cannot even be certain that the hole is perfectly centered in the crank. So, I will use the crank itself as the guide. The idea is to set it up in the mill so that a drill, 1/64th smaller, will pass through the center of the hole without touching the sides. This a tricky thing to set up and I spent two hours on it this afternoon without feeling I had it just right.

 

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I made the clamps you see bolted to the table to hold the crank while I drilled out the original, bent, tapered pin. They worked perfectly so if I can get the hole aligned with the center of the milling machine spindle, this should actually go quite easily. But, it's another job that takes hours to set up and about 15 minutes to do. Complicating the issue is that, in order to actually drill the hole, I have to raise the table. There is no way to get a "feel" for the job, which would actually, in this case, be the best way to be sure the holes were perfectly aligned. When I finally get this right, I will drill it and hand ream the hub to the finished size.

Edited by JV Puleo (see edit history)

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After several hours of trying to align the hole in the crankshaft with the spindle, and my third attempt at a method, I finally succeeded. To do this I made a 3/4 x 3/8 bushing out of drill rod. I reamed the 3/8 hole about .002 oversize and gripped it in a 3/4 collet in the spindle. This gave me enough clearance so that a piece of 3/8 ground stock pushed through the hole in the crankshaft could be aligned with the collet. Trying to do this with two perfectly reamed 3/8" holes wasn't working... if they were as little as .0005 off, the rod wouldn't move easily between the two points. I put a key in the key way and a socket head cap screw in the set screw hole to keep the hub tight on the crank.

 

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I then center drilled it and drilled a 1/4" hole. I held the drills in a collet rather than a conventional drill chuck because the collets are more accurate. It only works if you are drilling with a size that fits the collet.

 

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After which I drilled it 1/64 under 3/8". I had planned to hand ream it but it was coming out so good that I took a chance and reamed it in the mill.

 

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It was worth the effort. The job came out as good as I could have hoped and better than I feared it might. While doing this it occurred to me that I could make it even more secure by milling a short flat on the crankshaft under the set screw. I'll do that tomorrow... all day to drill one hole has left me pretty tired and, this time, I'll follow my own advice and wait until the morning. You can see from this photo that the hole in the crank was not damaged at all... I must have hit everything very close to dead on.

 

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Edited by JV Puleo
clearer wording / grammar (see edit history)

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This is brilliant and I need to make sure I understand this correctly as this looks like something that could come up again in the future.  

 

The 3/4 x 3/8 bushing was required because the collet your using is 3/4.  The inside of the bushing, 3/8, is for a rod to go in and it is that rod that then goes into the hole in the crank.  Once in the crank, you only need to position the other end (3/4) in you collet in the mill.  With the hub, crank and mill all locked in position, it was then a simple matter of removing the 3/4 x 3/8 bushing/rod combination and replace it with center drill, 1/4 dill, 3/8 drill (1/64 under) and 3/8 reamer.  Is that how it worked? 

 

 

 

Edited by Luv2Wrench (see edit history)

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1 hour ago, Luv2Wrench said:

This is brilliant and I need to make sure I understand this correctly as this looks like something that could come up again in the future.  

 

The 3/4 x 3/8 bushing was required because the collet your using is 3/4.  The inside of the bushing, 3/8, is for a rod to go in and it is that rod that then goes into the hole in the crank.  Once in the crank, you only need to position the other end (3/4) in you collet in the mill.  With the hub, crank and mill all locked in position, it was then a simple matter of removing the 3/4 x 3/8 bushing/rod combination and replace it with center drill, 1/4 dill, 3/8 drill (1/64 under) and 3/8 reamer.  Is that how it worked? 

 

 

 

 Yes... I think you've got it. Because collets are very accurate, any one would do... it was only 3/4 because that was the size of drill rod I had on the shelf. The 3/8" rod goes through the hole in the crank and into the bushing in the collet. When it passes through easily, under finger pressure, the hole is aligned just about perfectly with the spindle. Then it was just a matter of lowering the table and replacing the collet in the spindle for each of the drilling and reaming steps. I could have lowered the table and put a drill chuck in the spindle... I only used the collets because they worked with the size of the holes I was making. The left/right and in/out movement of the table was locked so that it could only be raised and lowered.

 

Usually, when you want two holes in different pieces to line up perfectly, you drill them together. That is what the factory did in the first place. My problem was that one hole was already there and I had to make the other one match it perfectly.

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