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My 1910 Mitchell "parts car" project


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Yes...There is nothing about the Mitchell that suggests they expected it to have a working life of any more than 5 or 10 years and, as we know, by 1920 there were virtually no 10 year old cars on the road except perhaps in very rural areas. However, I have been mulling over possibilities. The first was a flanged fitting with a ring of 10-24 screws holding it in. I made a drawing last night and started on it this morning. This time I'm using brass as I have a big piece of brass bar that is more than big enough.

 

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After milling the radius I cut the end off, faced it and tapped it 3/8-24

 

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But...I'm having 2nd thoughts about that solution. It would require drilling and tapping the housing and to do that I'd have to drill straight down into a sharply curved surface. I probably can do it using the fitting as a guide but the more I think of it, the better Greg's idea of a central bolt sounds. While I though about it I used some very course grinding paste to lap the fitting to the case...

 

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That worked reasonably well...but I'm still in a quandary about the best way to attach it.  I took some measurements (as best I could) and it looks as if I have no more than 3/8"  clearance inside the case to work with...but, I'll have to think of a better way of getting a real measurement. I'm going to do another drawing tonight - drawing things helps me work out the measurements - to see if this is practicable. I don't think there is a question that it's the best solution if it can be done.

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I worked out some dimensions. The only fly in the ointment is the thickness of the "nut" inside the housing. I'm not sure how to calculate that accurately but I'm working on it. If I can get something in there that will work, this will be an elegant repair...

 

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Posted (edited)

I probably have 3/8" - and maybe 1/2". That would just about do provided I made the through bolt and nut out of steel, use a fairly fine thread and get both mating surfaces quite close so that a paper gasket will have no problem sealing it. It's a challenge... but as you've often said, "if it were easy, everyone would do it". I've played with some other designs as well so I'm sure I can do it, just not sure of the best way.

 

jp

 

 

Edited by JV Puleo (see edit history)
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Was thinking the plug size would not need to be too large.

 

Early Buick used one of the 3/8” - 7/16” lower hold down bolts for the back cover as a drain, so something that size may work. Might take longer to drain but that’s not a big deal.

 

Just my thoughts

Rodney 😀😀😀😀😀😀😀

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Make sure you place a magnet in the plug to pick up metal chips..........you can get them at harbor fright that are very strong.......I use them in all our cars.........

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I will...I have 4 of them in the engine.

 

The drawing above isn't going to work. To get a better measurement of the clearance I put a lump of modeling clay in the housing and dropped the ring gear in...

 

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Then took it out and cut it at the lowest point.

 

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It isn't a perfect measurement but it did tell me that I have, at most, 1/4" clearance - not enough for that design.

 

I do have an alternative in mind...two of them actually but one I like better than the other. Keep tuned!

 

 

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1/4 was about what I was guessing. Those early cars were very efficient with materials use.........

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And they were very good with castings. Foundry techniques were probably about as good as they ever have been around the turn of the century. By calculating the outside and inside radiuses I can get the thickness of the casting which, at this point, looks to be 5/16" though it needs more checking. If so, and I can come up with a means of positioning it in the mill, I can thread a hole in the bottom of the casting. I'm going ahead and making the needed parts while I work on calculating more precise measurements...but 5/16 is probably enough to use a 3/4-16 hollow bolt in . It would have at least 5 turns in the thickness...

 

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Posted (edited)

 

So...after thinking about this a great deal over the last few days I have come up with a plan. Clearly I can't put any kind of nut inside the housing - there just isn't enough room. I can thread something into the housing because by all my calculations it is between 5/16" and 3/8" thick. On Saturday I bought a contour gauge - something I'd seen advertised but never had a need for. I used it to measure the outside radius of the housing and came up with 3". It isn't perfect...as a casting it was never designed to be a machined surface so mating something to it is a real chore. Today I made another brass piece, this time using a 3" cutter.

 

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Then spent too much time lapping it to the housing with 80 grit lapping compound. I'm still not completely satisfied but I am certain I've go it within "gasket" tolerances. The problem is that it has two contours at 90-degree angles to each other and you can only make one of them with the mill. Interestingly enough, there is a tool for cutting a lap with 2 different contours. It's used in the optical business (or was when I was making lenses, 45 years ago) and is known as the Oldfield Lap Cutter. The gentleman who ran it in our shop - who was in his 70s when I was in my 20s, insisted it had been invented by Barney Oldfield. I always though that was a bit nutty but come to find out, Barney did own the patents and derived a considerable part of his income from the sale of the machines.

 

After about 3 or 4 hours of hand lapping I got it pretty close...

 

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It's not perfect but close enough to press on. Then I started on the center bolt that will hold it in place. It has a 3/4-16 thread on the OD.

 

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The ID is threaded 3/8-24

 

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As you can see, it's short. The brass piece is thicker than it will be but I need the extra length to hold it in the chuck to indicate it. Also, since I don't have a precise measurement for the thickness of the case, the depth that the bolt screws in will be regulated by the thickness of the big brass washer.

 

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The boring and threading of the differential housing will be done in the mill. I've come up with a way of to hold it but may have to call on a friend to help set it up...

Edited by JV Puleo (see edit history)
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This morning I put the brass "boss" in the lathe to reduce the thickness, drill and ream it.

 

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I've revised my design a bit so I have to put this aside for the time being until some new material arrive.

Because I have to order some metal I also put the rear end on the mill table. I will have to make some pieces for this part of the job and want to order them at the same time.

 

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This will be bolted down to the table while supported in the two clamps grey you see. This will allow me to turn it so I can get the place where the threaded hole goes directly under the spindle. The clamps are the rear spring perches. I actually have two sets of these - these came in the "spare parts" box with the chassis. They have to be raised 1-1/2" above the table to give me enough room to adjust everything.

 

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After that, I went back to the axle seals. These pieces will be the caps on the end of the new seal housing.

 

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I bolted the two pieces together so I could bore and ream them at the same time.

 

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Then mounted them on this fixture I made a long time ago for a different job to turn them round.

 

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I just got them round before quitting. I'll do the finished size in the morning.

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I turned the caps down to the finished size this morning...

 

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Three pieces, these two and the pressed metal cover for the end of the axle tube have to be drilled and the housing threaded.  The holes have to line up perfectly both so the cap screws will go in and so everything is centered in the axle tube. I hadn't given much though to how I was going to do that - or rather I though I had some fixture bits that would work but that wasn't the case so I've spent the rest of the day making them.

 

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I still have to make two special washers...but this is how it will work. The piece and in the center and the ring at the top, when all bolted together will hold all three pieces in alignment and tight enough so that I can drill the hole.

 

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Posted (edited)

First thing today I finished the 2 additional washers I needed.

 

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And bolted it all together...

 

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Then I set up the small dividing head in the drill press...

 

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And located the holes using the other seal holder.

 

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At this point I discovered that the 3/4 nut on the end of the through bolt kept the piece from fitting in the jaws of the dividing head so I had to run to the hardware store and get a 3" socket head cap screw - the round head will fit. With that done I started on the holes and all was going well until I broke the center drill.

 

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It took some time to straighten this out but, fortunately, I was able to ... I went on to drill all the holes. These are "thread" holes...the holes in the cover will have to be enlarged but it's critical they all line up so I'm doing the small one first.

 

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I threaded 4 of the holes...and I'll keep on with this tomorrow when I think I may finish (though I thought that on Wednesday)!

Edited by JV Puleo (see edit history)
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I drilled it out from the back...the trick, of course, is to get the hole in the right place but it was easier than I expected this time.

I took everything apart and found that the broken piece was in the "cap"...the thick steel piece with a hole in the center.

A piece of the tip of the drill came out easily but there was a chip dug into the metal. Because it's hardened, if you try to drill from that side the drill will be ruined and the hole will wander. so...

I flipped it over and put the piece back in the dividing head. Then I located the previous good screw hole using the drill in the chuck and lowering it until is passed easily through the cap...then advanced the  dividing head (10 turns, it's a 40:1 reduction) and drilled it from the back. I expected it to damage the drill bit but, in this case it didn't.

 

With that done, I put it all back together using the drill bit as a locating pin - actually 2 of them - put it back in the dividing head, locating it the same way, and finished drilling the hole in the aluminum.

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Posted (edited)

 

Believe it or not, I finished the seal holders.

I began the day by tapping the remaining 4 holes.

 

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I also enlarged the holes in the cover plate and screwed them all together.

 

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Next, I set the mill up to cut the slot for the rivet head on the inside of the rear axle tube...since it's a round head rivet, I'm using a 3/4 round nose end mill.

 

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And...it didn't fit.

 

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That gave me pause. I can't make the slot any deeper and wondered if I'd have to scrap the whole thing. I put the piece in and rapped it with a plastic hammer...then pushed it out to see if it would be marked where it was hitting. It seemed to be hitting on the top (though you can barely see the mark in this photo).

 

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Because I couldn't think of anything better, I reached in and filed the top ot the rivet ...actually, very slightly. I don't think I gave it any more than a dozen passes with the file. Lo and behold, it slipped right it!

 

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So, I put the sheet metal cover on and tried it. It fit perfectly.

 

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Then I dropped the ring gear in to make sure there was enough clearance with the cap screws that are a little proud of the sheet metal. This is intended...the cone shape of the head will keep sheet metal piece perfectly centered.

 

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I then did the second one. I knew this one would not slide in...for some reason the ID's of the tubing aren't identical. But, you must remember that this tubing was never intended to be used this way. To fit the second seal holder I turned it down, .001 at a time until is slipped in - without having to do anything to the rivet.

 

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This one fit just as well as the first...

 

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So, aside from putting the felts in, these are done. I won't do that until its time to assemble it. The felts are soaking in oil and I see no point in assembling it and having them dry out as there is a lot more to be done here.

 

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Edited by JV Puleo (see edit history)
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I'm moving along finishing jobs I'd already started. I finally found a source of 1" balls that were not hardened. In testing the originals, I find they weren't hardened either but the real reason I needed them was that I can't machine a hardened ball although, if I think it's war4rants it, I can harden them after they are machined. The price was about $7.00 each - if you buy 1 or 2 - and about 1.00 each if you buy 10 or more, and they have a $20 minimum order so I ended up with 20 of them when I really only need 2.

 

To drill the ball, I put it in a 1: collet with a stop behind it so it can't slide further into the collet. I also set up my jig for drilling a hole to a precise depth.

 

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It isn't perfect by any means but allows me to get withing .010 or .015, which is close enough for a job like this. The hole was drilled.

 

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And tapped 3/8-24

 

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And I screwed in a piece of 3/8-24 threaded rod to test it. I'll order grade 8 threaded rod for this job but, for once, I'm not ordering it before I'm sure of the dimensions.

 

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The ball on the original Pittman arm is worn - though I don't think it shows all that well here. It's out of round abut .050. That probably isn't critical but I've set a goal of getting the steering as good as I possibly can.

 

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I then made 3 more...I need 2 but since I have 20 balls I might as well have a couple of extras.

 

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Probably a bit late now but an alternative would have been to obtain suitable ball bearings.  Anneal them in order to drill the holes and re-harden and temper. 

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Today I got most of the Pittman arm done...starting with drilling out the old ball. The steel is quite soft - much softer than I'd expected so I see no reason to harden the balls. If they only wore .050 in 110 years I doubt it will be a problem in the future.

 

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It was a little tricky finding a way to drill and ream the hole in the end since there is no good way to hold this in a vice. I ended up bolting it down to the drill press table with a plate under it. The idea is to get it mechanically straight...it's actually not straight and maybe never was.

 

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Drilled and reamed out to 5/8"

 

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To make certain the face of the hole is perfectly perpendicular to the hole itself I faced it with a big counterbore.

 

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Then back to the lathe to make an insert...

 

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Turned down on one end to .627 to give it a press fit.

 

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And the end trimmed to be .005 short of the hole in the arm.

 

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Then I turned it around and did the same thing on the other side...drilled and reamed it to 3/8"

 

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The next step was to machine a 1" OD concave to hold the ball. I did this with a 1" round router cutter - which, since it's made of High Speed Steel, works just fine...although the photo stinks!

 

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You can see it better here...

 

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Then I pressed it in...

 

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And this is how it will work. I'm waiting on the 3/8-24 castellated nuts I'll need to secure it but they should arrive tomorrow.

 

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Posted (edited)

The bits I need to finish the Pittman arm arrived at the end of the day - as I expected so today I worked on the setup to bore and tap a hole in the bottom of the differential housing. First I made these two clamps to go on the mill table from my spare set of rear spring perches.

 

 

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Then put the rear end up on the table...

 

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It is reasonably heavy but nothing like a PI Rolls...

I confess I'm really tanking my time with this. It is a fussy job and there is little or no room for error. I put the brass "boss" that will be attached to the casing on and leveled it in both directions.

 

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It doesn't have to be absolutely perfect, hence my using this little antique machinist's level. But to look good, it has to be close. In order to bore and thread the hole I need to attach this to the casing. I had thought to use Super Glue Gel but in looking around I have some Locktite epoxy for metal that has a much longer drying time - 24 hours rather than a minute or two - so tomorrow I'll glue it on and, with any luchl, I can finish the job on Friday.

Edited by JV Puleo (see edit history)
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I was away yesterday but went into the shop early to glue the brass piece to the differential casing. I'm using a 2-part Locktite epoxy meant for steel or concrete. The instruction say that it needs 24 hours to reach full strength so my other errand was a godsend - it kept me from rushing the job.

 

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This morning I bolted down all the pieces and carefully adjusted the rear end so the brass piece was level in both directions. Then lined it up with the spindle.

 

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The first step was to drill a center hole in the casing.

 

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I'd no sooner finished this when I discovered the internal oil pump on the mill was squirting oil all over the floor, a problem that comes from the fact that I've never used or set up the built-in coolant pump. I'm not sure why the lubricating oil gets into the sump but it does and a permanent fix isn't worth the time it would take. As it is, this has only happened once before so it's about every 2 or 3 years that the sump is completely full. In any case, cleaning up the mess took a good 3 hours out of the middle of the day but at least it didn't effect the setup on the machine. when everything was ready to go again I drilled a hole through the casing. The drill is 1/64 smaller than 1/2"...to minimize pressure on the brass piece.

 

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Then I used an 11/16 end mill to bore the two pieces together. Since the hole in the center was 1/2", I'm only removing 3/32 on the radius of the hole.  The rear end vibrated a little but, to my relief, the glue held fine.

 

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The last step was to thread both pieces together. Again, I was concerned that the glue might not hold so I was very careful doing this and use a new tap. It went as well as I could hope but you never know how something like this will work until you do it.

 

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And, I'm finally able to see the thickness of the iron casing - which appears to be close to 3/8" - about what I'd calculated but it's still gratifying to know there are enough threads to hold this thing together.

 

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Now I have to remove the brass piece. I'm hoping I can soften the epoxy by heating it...there is more to do here but from this point forward it's relatively easy or, better still, doesn't involve working with unreplaceable parts.

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Looks good Joe.  I would just leave the epoxy and thread the pieces together.  If the epoxy didn't let go with all the pressures from machining it's not going to leak oil.  You could probably use a Dremel to clean up the excess epoxy.

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I did think of that and it is tempting but I think I'll try my original plan and if I have a problem sealing it I can always go back and re-glue it. Tricky part here is the top surface of the brass piece. I made it as level as I could but I cant' be sure it actually is mechanical perpendicular to the hole. In most circumstances that wouldn't matter but here a fitting will be screwed in and it has to be sealed with a gasket. To make sure the fitting isn't slightly cocked vis-a-vis the face of the brass piece, I'll have to face it - perhaps taking a few thousandths off...

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I applied a little heat - with a propane torch to the brass piece today...and it came right off. Better yet, the glue sidn't stick to either piece and just peeled off so I didn't have to clean anything up.

 

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To refine the brass "boss" I started with this piece of 3/4 rod threaded to 3/4-16. It's actually something I made for the test gear on Ed's White so it's using a previously made fixture for a new job.

 

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I screwed the boss on to face it off. In this case, I painted it with dye chem first to show how it was slightly out of level. It wasn't much and I redu8ced it about .005 at a time, not wanting to take off any more than necessary.

 

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Then I took a few thousandths off the OD - which was also slightly out of round. Not enough to notice but why not since it was all set up.

 

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This will get drilled and reamed to 3/4" now but before I do that I started on the fitting that will go into it. Fortunately, the bar passed through both chucks so this time I'm not wasting any material.

 

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Turned down to 3/4" (actually about .002 under).

 

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Then threaded. In this case I don't want the relief I usually put in so I single pointed it about half way, pulling the threading tool back as it reached the end of the cut. It is'nt a very good system and not very accurate...but it will do in a pinch. I then used a die to chase the threads to the finished size.

 

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Then cut the piece off...

 

IMG_4529.JPG.4405be06085f8bd64698c05f4fb517c1.JPG

 

It still needs the head finished and a threaded hole in the center. I had planned to make it 3/8" but I can't find any magnets with a hole in the center small enough to go in the end of the 3/8" plug so I'm going to go up to 1/2-20 and use a 3/8" OD magnet.

 

IMG_4530.JPG.70af4414c3cafc095ee99e6b27bb7ee1.JPG

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Because the machine was set up to cut the right thread, I started the day by making a little centering fixture...

 

IMG_4531.JPG.4f22f998d47b0afce22756ff98d251ee.JPG

 

Then went on the the piece that screws into the rear end housing...I faced it, then drilled & tapped for 1/2-20.

 

IMG_4532.JPG.b7a7120e2c2156718099a83c8032613a.JPG

 

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That just about completes this part...I'll adjust the length once I've seen how much it protrudes on the inside,

 

IMG_4535.JPG.b20a2e90c62d6680611bae73f94eaaf7.JPG

 

Then on to the brass boss. I put this in the chuck and screwed in the centering fixture, then indicated it so that the threaded hole was dead on.

 

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Then drilled and reamed to 3/4"

 

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I also put a deep chamfer on the inside edge of the hole. This is to allow room for the tiny fillet below the head of the screwed in piece...

 

IMG_4538.JPG.d9b1a66676402dbfa4c0d6c22a5a2c01.JPG

 

I had to enlarge the hole slightly with an expansion reamer to get it to fit nicely, then cobbled up two temporary gaskets and screwed it together.

 

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Then I took it off the mill and set it in its stand. This was the first time I was able to see the inside.

 

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It protrudes into the casing a little too far - about 1/8". This was actually planned since I didn't know the exact thickness of the casting. It's easy to shorten it but to lengthen it I'd have to start over. Tomorrow I'll shorten it slightly and make some proper gaskets.

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Posted (edited)

I've had one of those days you'd like to miss...I started by shortening the drain hole fitting by .130 and making some gaskets. It's very simple...just punch a hole in the material and turn it down between to sacrificial pieces of aluminum.

 

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That went easily enough. I made 6 even thought I only need 1...it being much easier to turn more than one.

 

IMG_4543.JPG.59b513dec548c7922274bea9effa2c6b.JPG

 

Then assembled it on the casting using a thick paper gasket on the bottom. My idea is to test it without using gasket goo...if it dosen't leak, then adding some gasket shellac will only help.

 

IMG_4544.JPG.fea097d918c454f9d3c1f16f3cf36506.JPG

 

The shortened fitting worked perfectly...

 

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Then I put in some oil to see if it leaked...

The oil is the stuff I drained from the mill a few days ago. It's much lighter than gear oil so if this doesn't leak, the gear oil certainly won't.

 

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As I type this its been sitting for an hour or two and so far there is no sign of a leak...but - in turning the casting over I took a very close look at the underside - something I'd never done before. It's so dirty that I never noticed this.

 

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There is a braze repair...from the look of it, it was done a long time ago but I have to presume that the casting cracked at some point. I can't say this was welcome news - even if it does appear to be solid, I'm not sure what to do about it. If it were just a crack I'd look up Ed's metal stitching friend - who, oddly enough, lives quite close to the shop, but I can't see trying to melt the braze off. Finding another rear end casting is probably not realistic - I doubt there are many on the loose so I will probably have to live with it. It doesn't disturb be cosmetically - it's in a location where you'd have to crawl under the car to see it and, when painted, may not show at all but I worry about things like this. If it cracked "why"? The gears themselves are not worn at all - which is not consistent with some other parts. That may be the result of spotty engineering or it may be that something was replaced at some point. I am going to press on with this, if only because I have no other choice. The saving grace is that if I can find another rear end casting, most of the parts I've made will fit it.

Edited by JV Puleo (see edit history)
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I've had a singularly unproductive day today...I fiddled with some of the motorcycle parts and a few other odds and ends. I did make two beveled washers for the steering...these will go under the nuts that old the new balls in place.

 

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I have two grade 8 studs coming for this. They haven't arrived yet but you get the idea of how it will work.

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Joe,

 

I have to say I'm absolutely amazed by this.  You have essentially been machining and rebuilding this car almost from scratch.  It brings up a few questions that have been puzzling me for some time and I'd love your response:

  1. Do you have some particular love for a 1910 Mitchell?  This has got to be a full time project not leaving you very much time for anything else!
  2. Are you a trained machinist by trade?
  3. Do you ever get frustrated with the work, or is it just an endless labor of love (i.e. "...integral nut A goes with bolt B...Oh they don't fit, well, I'll just go spend another few hours machining a new bolt, no problem, la la la")?
  4. Why are all the people with your level of expertise never to be found in most auto-repair shops, which currently seem to be filled with ignorant trainees who do shoddy, poor-quality work as a rule.

Once again my admiration for your dedication and skill.  Let's see the old girl on the road again soon.

 

Best wishes,

 

Tom

 

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Posted (edited)

Thanks for the compliments...to answer your questions...

 

1. No. In fact, I'm not terribly impressed with the Mitchell. But, the cars I am impressed with are totally beyond my means. This was literally the largest brass car I could find that was within my limited budget. And yes, I do work on it practically every day but my real work is something else entirely and I do that at night, at home on my computer. (I design, edit and write books on antique arms.) My magnum opus is a book on the Ketland Family and the Anglo-American Arms trade from 1760 to 1830 - now on hold because I need to get into the National Archives and they are still closed.

 

2. I was actually a typesetter and printer...the machine stuff has always been a hobby and, in fact, I have no formal training at all.

 

3. Yes, I do get frustrated at times, especially when I find myself doing something over for the 2nd or 3rd time but that doesn't happen often and I believe you have to keep plugging on or nothing will ever get done. Today, for instance, I had a bad case of the slows.

 

4. Because there is no money in it (or at least most see it that way). But, I don't agree that the skills are altogether vanishing. The difference is that the people who have them now - and in the future - will not come from the traditional "auto repair" world. A good example, aside from myself, is my neighbor. He has a degree in electrical engineering and works as a software engineer. He's also a skilled blacksmith, an authority on Viking era weapons and is building a car in his garage. I met him through the Practical Machinist Antique Machinery & History forum.

 

Since you are a Doctor, I'll share a little story: I went to a sale at a local machine shop that was closing. There was a large Leblond geared head lathe - at least as big as mine. My first thought was "he'll never sell that" - I was wrong - it had been sold already - to a local plastic surgeon.

 

I'll add that this sort of work takes a certain amount of imagination and willingness to read a lot of material - not just about cars but about engineering and machine tools. The information is out there but if someones notion of "research" is doing a google search, they are out of luck.

 

Edited by JV Puleo (see edit history)
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Dr. Thomas, I have a few opinions about mechanical skills. The Auto repair trade has changed a lot since I was first a mechanic in the later 1970's and then briefly { 1 full year plus about 6 months as a Teacher on call } a High School Auto Shop teacher later 1980's. 

 The basic mechanical components on modern vehicles are very dependable compared to 50 years ago, some automatic transmissions excepted. Better materials, machining and assembly procedures and lubrication make the "nuts and bolts " side of the machine close to trouble free over a normal service life.  Still lots to go wrong , particularly the very complex electronic management systems plus the normal brakes and at high mileages suspension related wear.  

 But once you make the basic machine as trouble free as a modern vehicle the work a mechanic performs today is largely electronic trouble shooting , plus brake and suspension parts changing. 

A modern mechanic will not very often preform internal engine work . 

At one time engine work was a staple of the mechanics trade. These days if an engine goes bad it is usually replaced with a good unit or if the car is several years old often the car is replaced all together. 

 After I left the Automotive world I switched to being a Marine Engineer. This field , and others involving large , very expensive from a Capital cost point of view machines, is where you find very skilled people today. Oilfield , Stationary power generation, Marine , Bulk materials handling , Aircraft , Rail transport. Chemical and Petro chemical processing etc. These are the areas where very expensive , complex machines wear and fail and need specialized repair skills.

 Auto mechanics are still very skilled people , but the changing nature of the job has made the traditional mechanical skills less important than electronic troubleshooting and related skills.

Edited by 1912Staver (see edit history)
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Posted (edited)

Today I took on one of the jobs I've been thinking about for a long time but it's finally at the point where I have to do it. Replacing the bearings on either side of the ring gear. I really don't like the Hyatt bearings which, in my experience, don't wear well over time. The gears themselves are in nearly new condition but look at how galled the thrust side of the ring gear is...

 

IMG_4550.JPG.a9823854a99ef69d7e7aef47fb9ae9ec.JPG

 

The projection measures 2-1/8". My idea is to turn it down to 2" and press internal races for heavy duty roller bearings on, starting with the smaller side.

 

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For this, I trued the lathe up...it cuts a .003 taper in 9" - not great but as close as I've ever gotten it. Since I only have to go 3" that's only .001 - which is close enough for a press fit.

 

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I had a lot of trouble with this. The finish was terrible and I changed the cutting tool - something I really don't like to do after the job is set up because it's almost impossible to get it perfectly set. The finish was better but I still took it easy, taking off .010 at a time. When I got down to within .020 of the finished size the end burred...something I hadn't expected and didn't know exactly what to do with so I took an even smaller cut...and it rapidly because obvious that this is a pressed on sleeve. I shouldn't be surprised but I hadn't noticed it. In any case, I did another small cut and literally peeled the sleeve off.

 

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It turns out that the actual size of the piece is 2" and all I have to do is get the sleeve off. This is actually a relief since I'm no longer obsessing about turning it to the exact size. With this off and the piece cleaned up I took a close look at the other one. The sleeve is as plain as the nose on your fact...but until today, I'd missed it. Tomorrow I will try heating it with my torch. Maybe it will expand enough to just slip off. The poor finish was a result of it being a high carbon steel. It wasn't hardened (or I wouldn't have been able to cut it with my HSS tooling) but it's not a material I would choose to work with if I had a choice.

 

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Edited by JV Puleo (see edit history)
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I have to say Joe you and this Mitchell were destined to come together. I doubt anyone else would ever be able to put in the dedication and devotion to quality workmanship that you have. Your thread is like an online course in machining but the subject matter is so interesting there’s no way your “students” would ever get bored or even look away. Of course having met you in person and getting a little tour of your shop is just icing on the cake. Your thread is the first thing I look at each time I come to the forums. “What has joe posted today?” 

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With all of Joe's upgrades, its not going to be a Mitchell anymore........it's going to be a "JP Special". I expect the car to drive five mph faster, and be twenty times tighter and signifigntly better in handling. Maybe we should call it the "JP Ghost".

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On 7/14/2021 at 6:55 PM, JV Puleo said:

The information is out there but if someones notion of "research" is doing a google search, they are out of luck.

 

This is so true of a lot of things, and I have found particularly when it comes to research about vehicles built prior to WWII. Someone reads something on Wickipedia and then becomes and instant "expert". This especially applies to vehicle history. I have found in the past decade that due to the prevalence of the use of a computer - information at the touch of a button, that original research using period documents is now considered a "time waster" by many people. This even applies to people who consider themselves authors,writers etc. who then are upset that they may have to travel to get to a collection of material that can give them the answer. That costs $ and time, they may not have, but refuse to accept the fact that the knowledge that they know exists may take more effort then the touch of a button. Some of us that have the resources of period information that we have gathered for decades are now held in scorn because we do not instantly help someone who has a question - only their lives/needs exist with no consideration for us. Our archives should be theirs now because they love a particular make and model, it is owed to them to have that information, images, photograph.

I know I have some of you shaking your heads now thinking "really"? Yes, unfortunately is the answer.

I have long been a appointed historian for the village in which I reside, NY State laws say an incorporated village has to by law have a historian. The state historians organization over 25 years ago told us at the first meeting I attended that " you are a public historian, not a private historian, you should not feel obligated to do research for private individuals who demand your knowledge". Many people do not understand that and when it comes to automotive history want their questions answered yesterday. I am not bitter nor want to appear that way but look at my sharing of information etc. the way Austin Clark did when addressed to the library of his L.I. Automotive Museum he would get a letter stating " Send me everything you have on a 1931 Cosgrove" , no ssae, no please, etc. Austin would state to me ( I worked for him as his librarian as I have noted previously) "here is another one for the recycle file" that meant it went in the trash basket.

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Posted (edited)

 

 

Wow...thanks guys.

 

Ed, by my calculations, if the Mitchell turns at 2000 rpm, it will be doing 63 MPH. That is faster than I'd want to go with it but the goal is to make it possible...My real goal is to build so that it can run at 1600 to 1800 all day... and pull up most hills without downshifting. I think that is reasonable. I was very impressed with the pulling power of a 1907 Packard 30 I drove about 40 years ago (the only Packard I've ever driven)...I don't think the Mitchell has the displacement needed to get that amount of torque but my goal is to get it as close as I can. This car will weigh much less than the Packard so I may do it.

 

Walt, that is all so true. My specialty is the 18th and early 19th century Anglo-American gun trade. I've spent hours in the British National Archives reading period documents and will do so again when I can. I've never hesitated to share what I've found but if someone "demands" it...in anything other than a polite manner - and expects me to spend hours looking up relevant material, they have another think coming. There are a couple of so-called authors who have tried this. Invariably, they are the ones that don't own any of the necessary books much less have spent any time in the archives.

 

Automotive history is much the same. Most of the published material is, at best, superficial and much of it just repeats old wife's tales. The primary documents are not readily available on the internet - and likely never will be. Years ago I had a friend who, in his youth, fought in the Russian Civil War. He used an old Russian proverb that I liked..."tell a lie a hundred times and it becomes the truth."

 

I went on with the differential today. Overall, this has come out as good as I hoped although it gave me a few anxious moments yesterday. Having done one side, I put the larger side in the lathe today.

 

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I was gratified to see that this ran almost perfectly true. I've found so many questionable things in this car that it was a pleasure to find something that was actually well made though I'm guessing that Mitchell didn't make the rear end. It seems much more likely they bought it from one of the many trade suppliers at the time although it may have been made to their specifications.

 

This is the side that was badly galled by the thrust bearings. They fit so poorly that I'm thinking they may have been replaced at some time. In this case, as I turned it down, the sleeve pressed over the projection on the gear is much more evident.

 

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I was very careful turning this, taking cuts of only .005 at a time. The problem is that the sleeve is high carbon steel while the casting is cast iron. Theoretically, this calls for a fast speed on the steel and a very slow speed on the iron so I had to compromise and, of course, since this is the only one I have it's not something I wanted to take any chances with. (Actually, working on original parts ALWAYS involves chances. More often than not, you don't know what the materials are or how it was assembled. The fact that this sleeve was there in the first place is a good example.)

 

When I got it down to about .010 thick, the sleeve cracked and I was able to peel it off.

 

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Then it was just a matter of turning the remaining part of the casting down to 2".

 

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Now I have some new parts to make to fit the bearings. Even though that involves quite a bit more work, this was the critical part of the job and I can be a little more relaxed about the rest.

Edited by JV Puleo (see edit history)
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Posted (edited)

Ed...I've a question you probably know a lot more about than I do.

I have to fit thrust bearings on both sides of the gear. Originally it had a big, old fashioned 3-piece bearing on the drive side and just a steel washer on the reverse side. I've solved the reverse side issue but the drive side is more complex because I only have about .700 to work with. (I've yet to break out my fancy depth micrometer so I don't know the exact measurement). It looks as if I can use a bearing that is 18mm wide - .709, My question is: how much end play is appropriate - obviously the bearing can't be tight - it has to be able to move freely so I'm thinking .003 to .005. To get that I may have to surface grind the bearing races - but only a few thousandths.

 

The depth of the pinion is adjustable so I can mate that to the drive gear after I've installed it.

Edited by JV Puleo (see edit history)
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I think your right on the money. I would shoot for the middle. Certainly nothing less than .003. Plan on taking it apart and assembling it a half dozen times. 

Edited by edinmass (see edit history)
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