JV Puleo

My 1910 Mitchell "parts car" project

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You are spot on.....it's VERY time consuming......and most of our cars have 9 main bearings. After years of using it, figure 4 hours set up, and two hours per bearing. When we are finished, you can spin the crank with a pull of your pinky finger. There should be zero drag on a crank, and only the shear of the oil film breaking to get it to turn. We try to hold to the tenth when cutting bearings but usually across the the 9 of them we have a variance of 3 -4 tenths. Not too bad for a 80 year old hand bar. Temperature will affect the bar.......so its best to get the room at an even room temperature for the process...........good measuring tools, sharp cutters, and lots of light and time and they turn out great. Also, only use a very reliable source for pouring the bearings.............lots of issues with new to the game back yard operations.....we have also made shells over the years, and installed shells where there were none before..............very, very time consuming. We make our own cam bearings for all of our engines.....we find most shops just not up to the job. 

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The micrometer that came with my boring bar - which is the original tool, made by Starrett - doesn't measure in 10ths. I have a B&S micrometer head that does so if the device I made to set the cutting tool on the small bar works, I'll make another for the larger bar using the 10ths head. I'm not convinced it's critical to get much closer than .0005 though. There are only 3 bearings and what must be a slightly flexible crank (like nearly all brass car cranks). I'd think a Pierce 12 is a lot less forgiving. That said, it is always worthwhile to try t work to the closest possible tolerance  because if you don't try you'll never do it.

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I should add that I'll have to align bore twice. I plan to make shells as Mitchell used Babbitt in the aluminum crankcase. Since Babbitt doesn't stick to aluminum, they just put holes in the bearing seats to anchor the Babbitt. The original Babbitt is still there but I have no idea if they made any effort to get the holes straight in the first place. Since the Babbitt is about 1/4" thick I'm inclined to think they didn't. So, I'll have to bore it to get the Babbitt out and the holes round and in line, make the shells - which will call for facing the bearing seats since I'll want to include bronze thrusts on the shells, then pouring the bearings and boring it again. I have fixtures to hold the shells, which came with the boring bar, so I'll probably do that myself too.

Edited by JV Puleo (see edit history)
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I lucked out today. The saws arrived but the office is closed. fortunately, the letter carrier knows we are closed on the weekend so he left the package at the Post Office and I was able to pick it up.

I put the new saw on... (Actualy, its on backwards in this photo. I realized that after I'd taken it and turned it around.)

 

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And finished the cut.

 

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The piece of steel is actually about an inch too long for the travel on the mill but by sinking the saw into the T slot I was able to take advantage of the increased width and just made it without having to move the piece down.

 

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I'll switch the machine back to vertical tomorrow. This is enough for today.

Edited by JV Puleo (see edit history)
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This afternoon I changed the mill back to vertical. The only tough part is lining up the head with the body of the mill. Since it's very heavy, and you can't see the connection when it is close, it's a fiddly job. I've only done it four or five times - I suppose if I did it more often I'd be better at it.

 

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Then I drilled two holes in each of the two 4" plates. I broke off a center drill on the second hole so it took me a lot longer to do this than I'd intended.

 

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This is what I'm aiming for...a way to hold the crankcase steady and flat while positioning it under the spindle.

 

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I also discovered this interesting problem. The oiler had a connection on the outside of the crankcase for the center main bearing. But, the output end of that hole is nowhere near the bearing. In fact, it's in a place where it cant' be reached. The bearing itself has 4 holes but no provision for connecting it to the oiler. This will be an interesting problem to solve if I want to get oil to the center main under pressure. It looks as if the center main was splash lubricated and the oiler connection was just for show.

 

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Sounds like an engineer had an idea then a “ah, never mind “. We had a few fire hydrants in town that were done like that. They never ran the water lines to them! Of course it took a House fire for the FD to realize it.

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There is an odd "flaw" in the casting on the top that I think is directly opposite the center of the bearing...as if it was originally intended to drill down through the crankcase to the center of the bearing but for some reason they didn't do it. I may very well do that myself although it will require drilling a hole about 7" deep - I have to figure out if putting a fitting there to connect to the oil lines will obstruct the intake manifold...so it's another problem to solve.

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I bolted the fixture up this morning and discovered I still don't have enough travel in the table to get the holes I have to drill under the spindle. In this case because the bolts that hold the steel pieces down obstruct sliding the crankcase back.

 

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So I countersunk the bolt holes for flat head cap screws. With those below the surface I have pretty much unlimited adjustment room. But, with all the nuts and bolts I have, I don't have the right ones and our local hardware store (which is a very good one) didn't have them either. So, I ordered some. They'll be in late tomorrow. In the meantime, I have another job that needs doing so it's worth waiting for the right bolts. I have so much time in this I don't want to take any chances.

 

I also took a look at the center main bearing problem. The casting has a cruciform cross section directly in line with the center of the middle main bearing.

 

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And this odd "flaw" on the upper surface. I'm more convinced than ever that it was supposed to have a hole through the crankcase feeding the center of the middle main but that, for some reason, they didn't drill it. The fact that it has a connection for the oiler but that it goes nowhere is a tip off that they made another cheesy, cost saving modification. I'm not thrilled about drilling this hole but if I'm careful it should be fine. It doesn't have to be very big - just the ID of 1/4" copper tube. This is the top of the case opposite the bearing.

 

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Edited by JV Puleo (see edit history)
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My flat head cap screws cam in so I bolted the extension plates to the table of the mill. I should be back in business tomorrow.

 

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This also arrived. A piece of cored bearing bronze to make the center camshaft bearing.

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With the new flat head bolts in place I set the crankcase up on the mill. You can see how far it hangs over the front and the need for the plates to support it.

 

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I indicated the squared end of the torsion plate. It was out .003 in 6" so I left it alone.

 

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I also double checked the spindle though this is just my paranoia acting up.

 

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I am plunge milling the holes. For this I had to have a special end mill reground since the diameter needed is not a standard end mill size.

 

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It worked quite well.

 

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Then I clamped the cap on taking care not to move anything.

 

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Center drilled it and then drilled it 1/4" for the attaching screws.

 

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Then I took the cap off, threaded the hole and put the first insert in with a drop of Locktite on the threads.

 

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From this point forward when I drilled the 1/4" holes I made sure to put cap screws in the finished holes.

 

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The third hole was a pain in the neck due to the Mitchell companies very liberal idea of what precision means. This hole had a screw broken off in it which, fortunately, was so oxidized in place it didn't move when I drilled it out. I didn't get the entire piece out because the original holes must have been drilled freehand...

 

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It came out all right though... Believe it or not, this took just about all day with 4 or 5 operations that had to be repeated each time but now there are 4 holes in the crankcase and they line up with the new cap.

 

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Joe,  All I can say is "NICE WORK"!  Another part of a dead Mitchell is getting the breath of life and is better than new!

Al

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10 hours ago, JV Puleo said:

You can see how far it hangs over the front and the need for the plates to support it.

 

It's a shame nobody has invented 'sky hooks'.

 

I think I have probably missed something? When you drilled the top of the new cap how did you know the drilling position to match up with the hole you had milled in the block?

 

Silly me! I have just realised, of course the part hasn't moved because it is clamped to the milling table and the cutter and drill positions are the same. I apologise for me being thick.

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Well, that doesn't seem like an odd question - especially as I had to keep stopping to remember the order the operations was done it. The hole in the cap had to be drilled before the hole in the crankcase was threaded...

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Today I put the threaded sleeves in the mount for the water pump. You can see how off-center they are with each other.

 

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I centered them as best I could. The end mill left a tiny amount of thread on one side of the hole and a similar amount on the opposite side of the other hole. Since the hole is threaded and the insert is permanent, this isn't important. After the first hole was milled, I clamped it up to drill for 5/16 screws.

 

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Then threaded the hole. I bought a new tap for this... I only had one 7/16-20 tap and it is probably about 90 years old.

 

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The result is more than satisfactory.

 

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Here it is with the caps in place. They will be screwed down tight when it's bored.

 

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Then, because it's all set up, I located the hole for the oil filler/return.

 

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I planned to bore this out to .950 and thread it for another brass insert but, as the hole got bigger, I realized that the insert would have to cut into the wall of the casting. I decided to go to 13/16 and thread it 7/8-14 - the actual size of the oil connection...this isn't a part that will be taken out once the engine is assembled so I'm not as concerned about wear or stress on the threads. I will put a little Never-Seeze on the threads so it doesn't stick but since it will be constantly wet with oil from the bottom I don't think that is a concern.

 

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And I tried the oil filler to make sure everything fit.

 

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I thought today would likely be a total loss as I'm waiting for an end mill and some brass rod. I'd planned to make some inserts but the only thing that came in was the end mill. So... I set to work opening up and threading the holes that originally held the oiler in place. Two of these had screws broken off in them and one of those was drastically off center.

 

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For the third hole I had to take the extension plates off and set the crankcase on the table. I also had to work from the back as it was the only way to get the hole under the spindle.

 

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But, it worked ok...

 

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The last step was to put the extension plates back on, turn the crankcase around and to the two holes that are used to attach the exhaust pipe bracket. For this, I moved the center of the holes slightly. I'll still have to make a new bracket but now it will fit better.

 

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The crankcase bolted to my "boring bench", the bed of a lathe that was beyond repairing (and missing its legs)

 

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Since I have to make the boring bar, I needed to figure out just how far the tool has to be from the end to allow it to be withdrawn so I can re-set it. I also fnally figured out how the gearbox advances the boring bar so I'll have to make something for the rack that moves the box to attach to. All these details are incorporated in the machine but I'm only using the gearbox so I've some hard thinking to do to come up with a way to attach everything.

 

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Joe, You have a very good vision of where the project is now and where you want it to be when finished.  You are very thorough.

Al

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16 hours ago, JV Puleo said:

I also fnally figured out how the gearbox advances the boring bar

 

It would be good if you could share the information with us, when you get a chance. Since you started mentioning about line boring I have been watching some videos on the subject. None of them seem to show how the tool is advanced. To me It seems to be 'witchcraft'.

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That's all coming Mike. I'll show it when I make the fittings to attach it. It doesn't make a lot of sense as loose pieces but when it's all assembled it should.

 

j

Edited by JV Puleo (see edit history)
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In answer to Mike's question, I had to make this piece for the boring bar to pull against.

 

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With that done, I assembled the parts. It seems to work. I'm not thrilled about the weight on the end of that long bar but the only deflection I need to be concerned with would be between the pillow block and the piece I'm boring and I doubt it is deflecting at all.

 

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I will probably turn it by hand, I tested the electric drill and, to my mind, it turns much too fast. I don't need a mirror surface these parts...a very small amount of roughness might actually be good. But, for the main bearings I would like to motorize the bar like edinmass did and for that I'll pose a question since I'm guessing there is someone out there who knows a lot more about electric motors than I do. I need to turn the bar at about 60RPM. The thought came to me to use a gear motor but finding the right one is a challenge. I've no idea how big it would have to be since it will have to develop enough torque to turn the cutting tool against the aluminum casting and the iron bearing caps. Any ideas?

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9 hours ago, JV Puleo said:

I need to turn the bar at about 60RPM

 

They are available. The only problem is finding one at the right price. The one below turns at 56RPM

 

https://uk.rs-online.com/web/p/ac-geared-motors/4784847/

 

Thinking about it. There is a possibility that I may have a spare one for our Klargestor sewage treatment system. It would be 240 volt but I would have thought you could either use a transformer or it may run even slower on 110 volt? I will have a look this morning and see. If I have got one that still works I could send it over to you by airmail.

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DC motors seem to be more available but if possible I'd rather use AC 115 volt since I could just plug it in. I also have a couple of 240 volt plugs so that isn't impossible either although it would involve a long extension. This is one of those problem I'll be thinking about while I do the first two holes...just maybe I'll have come up with a possible solution by the time I'm ready to do it. The motorized boring bar is probably only needed for the final boring of main bearings and I won't be able to do that until I've made shells and Babbitted them so I'm some months from that. There is probably a simple solution, it just takes time to find it.

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The boring bars I have seen use a Bridgeport mill power feed motor/gearbox.

They are variable speed and can be found used 

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