JV Puleo

My 1910 Mitchell "parts car" project

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Posted (edited)

I took a break from the Mitchell to work on the split camshaft bearing.

Here is the problem... The car is a 1909 Jackson. It threw a rod which blew out the side of the crankcase and bent the camshaft like a pretzel. At the request of the owner, a friend of mine had the crankcase welded back together. It is a brilliant welding job but, of necessity, some of the welds were in the middle and front camshaft bearing saddles. After several engine shops declined to work on it, I agreed to give it a try. I may well have been overestimating my abilities here because I've been working on this, on and off, for two years. The first problem was to bore out the camshaft saddles so they were round again and in line. I did that on my lathe (I'll post a picture later)... and finally got the cam back into the engine. This is a multiple part cam. The lobes are pinned to the shaft. Unfortunately, the "professionals" who made the cam put the battered original bearing back on then pinned the lobes with taper pins which they peened over. It's difficult to remove a tapered pin even if it isn't peened but in this case, I can't even tell which is the small end. After fiddling about for months trying to figure out how to drill them out without ruining the lobes or the cam I decided a split bushing would be a safer option.

 

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The bearing is made from a piece of bearing bronze cored stock. It is larger than the finished size because the last step has to be turning it to the finished OD using the hole in the center to hold a mandrel. I've already drilled the holes for the cap screws that will hold it together so today I milled the ends square. This is to make room for an oil pocket.

 

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The flats I put on the bearing serve to locate it so the ends will be square with each other.

 

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Edited by JV Puleo (see edit history)
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Rule number one.....never weld on a block, head, or crank case. Rules number two to ninety nine is see rule number one. That being said, the weld looks like it was very well done. Every surface must be reset to be sure everything is square, round, and in line. Looks like it would be very challenging to get it all done correctly. Way beyond my skills.........form all your previous work and postings, I’m sure you will get it done right.........👍

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Thanks for the vote of confidence... the only condition I made regarding my attempt was that there were absolutely no guarantees. I said "I'll try" and I have to assume I was the source of last resort. I agree re: welding but that was done long before I saw it. You're also correct about nothing being square or straight. In order to align the camshaft I had to make a set of fixtures. One end clamped to a 1-1/4 ground bar centered in the front and rear mains (the center main is badly off center from the welding). I then aligned the boring bar based on it being parallel to the crankshaft. I don't know if it will work but it looks to be straight and the measurements at the front and rear are pretty close to dead on. I have to make the front camshaft bearing as well but that's easy compared to the center. I also had to take about .030 off the top of the crankcase after bolting it flat to the table of my milling machine so the top is now parallel to the faces of the main bearings. As it is, it's all bolted up tight to an old lathe bed with 1/2" steel plates bolted to the crankcase in lieu of the blocks, to keep it from twisting.  Four of the eight holes for the lifters also had to be cleaned up so this has been a long project with lots of time in between working on it just thinking about how in the world to proceed. I will have to bore the center main in line with the front and back and make an oversize bearing shell for it - another piece I've never attempted before but I will have to make bearing shells for the Mitchell so the experience will serve me well.

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I knew I had these somewhere.

 

Milling the top of the crankcase flat. It was critical to make a fixture that held it perfectly flat and to bolt the entire thing down to the table.

 

579315942_Jackson1a.thumb.jpg.b8c6fc092f8da5422c09d206216a867d.jpg

 

The crankcase set up in the lathe. I took off the saddle and used it as a horizontal boring mill. The boring bar is from my portable boring bar. The piece in the main bearing saddles was used to get the exact measurement.

 

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You can get an idea of what I was dealing with here.

 

720051143_JacksonEngine4.jpg.5918ddb0018bda514ce13b67524eb796.jpg

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JV, I am very impressed with your work on that job. Hopefully it will come out well, and put another veteran back on the road. 

I am also faced with making my own split camshaft bearings.

The older, experienced, engine reconditioning people here do it with clamps around the job after slitting the stock. They actually use hose clamps, 4 jaw chuck and a steady. And a lot of thought regarding machining sequence. As their waiting time for this type of 'recreational' work is out to 14 months, I intend having a crack at it myself. Awaiting the arrival of the correct alloy stock.

They suggested an OD oversize of .004" for clamping crush, (on 36mm journals) and either a hone finish or to make a test piece first to arrive at the correct ID. 

I have seen it successfully done with hose clamps for a Hup model 20 centre main bearing. And if it is unsuccessful, I may be able to fall back on the Puleo method. One of my slit bearings has a thrust flange on it, just to make it interesting. Two others are un-slit cylinders, which appear fairly straight forward.

 

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Posted (edited)

I thought of making a clamp but this bearing is very thick - the finished OD is just under 2" and the camshaft is 7/8" so there is no crush. It has to fit the hole perfectly and is then held in place with a set screw. I'm still debating how to make the main bearings and for those, I suspect the clamp idea is the way to do. My mains need one thrust surface on the front and back and two on the middle bearing so I'm thinking of a clamp in two pieces that the shells can be mounted in. When I get to that, I'll first align bore the crankcase so that all of the raw holes are identical. That way, the same clamp will work for all of them. It will probably be quite an operation. The original bearings are Babbit poured directly in the aluminum block with pins in the aluminum to keep it from turning. Now that I think of it, the caps are iron and the Babbit is very thick, more than 1/4". I suspect the original journals were hardly align bored at all and they relied on the thick Babbit to "straighten" the crank.

 

The method PM Heldt describes as being the most common is to make the two halves and solder them together after which the piece is machined as if it were solid. Then it can be heated and the halves separated. I don't have enough confidence in my ability to solder them perfectly and Heldt does say that there is a high failure rate in doing it that way when they fall apart before being finished. I may try it some time just to see if I can do it. Heldt also illustrates a set of fixtures used to make split bearings but to me, they look like far too much work to make a single bearing.

Edited by JV Puleo (see edit history)
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Pouring the Babbitt onto the case is problematic, and over the years I have seen a handful of failures. I have seen others make shells and they have worked out fine........also way beyond my abilities. Repairs such as these are not only challenging to figure out how to do it, support the work, etc......it’s the time EACH process takes to figure out as not to ruin anything, or make a mistake that doesn’t show until a bunch of processes further down the project. The thought process on repairs like these are often ten time the actual machine work time........again, also beyond my abilities. The trick to every pre war car, is to know your skill set and abilities, and have a bunch of friends who have other talents to help you out along the way........the most important thing is to do no harm and cause bigger problems. Hand operated custom machine shop work is a fast dwindling skill.......most of my go to guys over the last twenty five years are retired or will soon be........it’s getting harder every day to get projects done.

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I don't think there is any doubt about any of that. But, on a more optimistic note, there are people like myself who don't come from a background that encompasses these things but do it because we want to. That probably doesn't get the person who just wants to take his parts to the machine shop very far but it does mean that new people are coming along who at least know how to do things... we just don't see it yet. I know at least one who is 30 years younger than me but he's a software engineer by profession. One of the best things that have happened to me is the advent of CNC - which I personally have no use for but has made all sorts of functional and otherwise perfectly usable machine tools really cheap. I've hardly paid more than scrap metal value for most of my shop and some of the machines were give to me.

 

As usual, Ed's observations are spot on. It is difficult to explain to someone who doesn't do this sort of thing how much thought goes into making or fixing something before you ever touch a machine. I have notebooks full of scribble drawings of parts - that I discarded before ever starting on them. I suspect most people think it all comes from Amazon and they can get it delivered in 2 days.

 

I think pouring Babbit into an aluminum crankcase is a very poor idea. The pins were there because it doesn't stick - or doesn't stick well and having it as thick as it is on the Mitchell is just shoddy work but I don't expect the makers expected the cars to last more than 5 years which was about the life expectancy of a 1910 car. Very well made cars, Pierce-Arrow, Locomobile, Packard, etc. often lasted because they could be made into trucks. The cars that survived intact are anomalies.

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With regard to PM Heldt's description of soldering the halves together. If combined with a hose clamp it may assist in the machining of the surface on which the steady runs. But I think two clamps at that stage would give sufficient rigidity. My bearings are 3" long, plus support length, hanging in a small 4 jaw chuck. With the stock out of round after slitting, turning the steady track will be 'gently, gently'.

And we have finally seen full view photos of your lathe and mill. (Perhaps I missed them in an earlier post). Well preserved and robust older machines always look good to me. Excellent.

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Thanks for sharing the photos of the crankcase repair work. I always thought my solutions to overcome problems were quite good, but your thoughts and work knocks my efforts into a cocked hat! I agree with Bush Mechanic, it is nice to see complete photos of your lathe and mill. As I have said before Joe - fantastic thought and workmanship.

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This is how the crankcase is mounted to work on it. Aluminum crankcases are VERY flexible. It was dut to an excellent post by Ivan Saxton on this site that I first realized how critical this was. There are 1/2" steel plates bolted to the upper face of the case using the original threaded holes with lock nuts on the inside. Then the entire case is bolted down to this old lathe bed made into a work stand. This is all critical when it comes time to bore the main bearing journals.

 

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I also finished the cap. I don't think I spent half an hour on this - the obvious result of having done it before and having some practice. I think this is the best knurling job I've done so far, another example of the value of doing something enough times that you start to get the hang of it. On the far right is a crankcase breather I bought from McMaster Carr. When I got it and realized how simple it was, I decided I could make one that would look much more "in period" out of an old compression fitting. The thread on the bottom piece, originally intended for a flare fitting, is 1/4NPS so I'll need a tap.

 

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I was at loose ends yesterday trying to think of what to do next so I decided to have a go at making a thumbscrew. I used a piece of 12L14 - free machining steel. I drilled and reamed it 1/4" and then counterbored it 5/16" (the diameter of the socket head cap screw end). I knurled it first... because I wanted all the thickness to withstand the strain. Then I cut it off with the lathe cutoff tool.

 

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I looked pretty good, so I brazed the screw in place from the top and then faced it off so that all that shows of the brass is a tiny line around the head and the filled in hex.

 

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And replaced the cap screw in the pressure relief valve. I realize this is a little overkill but I get a lot of satisfaction from little details like this.

 

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Today I split the cam bearing, something else I've never done before. The first step was to measure the distance between the top of the bearing and the center of the hole to calculate how much to raise the table - hoping to get the slot exactly in the center. It's the distance between the top of the 3/4" shaft + .375 (half the thickness of the shaft) + half the thickness of the saw.

 

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Then set it up in the mill and took a light cut.

 

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It seemed ok... so I proceeded. Cutoff saws run at a very low speed - I think this was turning at 66RPM and I took very light cuts. The idea is to get as smooth a surface as possible on the inside of the cut. Here it is with the first side done.

 

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And finished. All in all, I appear to have done the math correctly. I'm going to lap the inside surfaces then drill, countersink and tap the holes for the cap screws that hold it together - maybe tomorrow. Like that last step threading, this sort of thing is tension inducing and I'm worn out from it. I'll go on to something simple for the rest of the day.

 

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More like boring. With the slow spindle speed and slow feed, it takes forever. I suspect I could have fed it faster and could have taken deeper cuts but having it come out good is a lot more important to me than doing it fast. If I do more of this sort of thing I'm sure it will get both easier and faster.

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Posted (edited)

Sometimes I'm not so sure. I did tell the owner of the car that I wasn't surprised several engine shops turned down the job. If I were in business, I might have also but the real problem was that very little of what I've been doing falls into the purview of what engine shops do. Chances are, there are few - or none - that have the equipment and some of the machines I've been using I got after I took the job.

 

Today I pressed on with the bearing - I'm starting to think it will come out all right and want to see it done. First I drilled out the holes in the upper side of the cap for the 10-24 cap screws.

 

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Then counterbored the holes because they have to sit well below the surface. I need 3/8" between the bottom of the counterbore and the inside surface and, lucking the pilot on the counterbore is exactly that. I also set a stop on the drill press quill just to make sure.

 

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It's amazing what you can do with this crummy old drill... but you have to be very careful and bolt everything down tight. I then tapped the holes in the other side of the bearing. Always a bit worrying because bronze doesn't tap all that easily and a broken tap here would be a disaster.

 

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I also lapped the faces... this is my old way of doing it, a piece of 220 wet or dry on plate glass with a little light oil. This is lard oil - once the standard for fine cutting oil. (That is what Harry Pope used when he cut the rifling in his barrels)... fortunately, you can still get it. I finished up with the lapping plate but this way is faster and probably about 90% as accurate.

 

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Everything lined up and it went together as well as could be hoped. It isn't actually perfect... the two halves are probably about .003 out of square with each other but I designed this to accommodate that and never expected it to be any better.

 

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The next step is finishing the inside hole which isn't easy because neither the hole or the piece are round anymore. The next idea only came to me today while I was working on this. I measured the dimension across the hole at its smallest...it is .650 which is what it should be, mathematically, but things rarely come out so close. I took a piece of 1" bar - it is actually the original dummy camshaft I'd used in the oil pump, and turned it to .650. The idea is that if it fits smoothly and without any "shake" in the hole it will be straight and I can then indicate the 1" end to bore and ream the now oblong hole.

 

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It seemed to come out fine. It slides in but there is no wobbling. If all goes well I'll put it in the 4-jaw chuck tomorrow, indicate the hole in the center and bore it.

 

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Edited by JV Puleo (see edit history)
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On ‎4‎/‎14‎/‎2019 at 3:27 PM, JV Puleo said:

I knew I had these somewhere.

 

Milling the top of the crankcase flat. It was critical to make a fixture that held it perfectly flat and to bolt the entire thing down to the table.

 

579315942_Jackson1a.thumb.jpg.b8c6fc092f8da5422c09d206216a867d.jpg

 

The crankcase set up in the lathe. I took off the saddle and used it as a horizontal boring mill. The boring bar is from my portable boring bar. The piece in the main bearing saddles was used to get the exact measurement.

 

IMG_0608_zpsrdpvd8j8.jpg.bbc0add2c1253e8e5d52f58e98195f6c.jpg

 

IMG_0606_zpsn1gfbmpg.jpg.3616a652f69486a4b54140e404397d8d.jpg

 

You can get an idea of what I was dealing with here.

 

720051143_JacksonEngine4.jpg.5918ddb0018bda514ce13b67524eb796.jpg

 

That's a lot of weld. Was the crankcase heat treated to help normalize any welding stress ?  Cryo treat before machining ? I would be afraid after a number of heat  / cooling cycles once the engine is run again things will move around and throw all your careful machining out of alignment.

 

Greg in Canada

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I have no idea. It was done years before I saw it.

 

 

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Greg, sometimes in life you have to take a chance. The part was scrap and nothing else was available. Good on Joe for helping to get this old car engine back on road.

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In thinking about it, I wonder if the crankcase actually gets hot enough to make a difference? I don't imagine it gets hotter than hot oil and I've never been scalded by the oil when I drained a hot engine...maybe 140 to 150 degrees? This is only 40 to 50 degrees hotter than the ambient temperature on a hot day in New England.

 

This morning I bored and reamed the hole in the center. First I set it up in the 4-jaw chuck and indicated the guide piece I made yesterday.

 

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Then bored it round again.

 

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I took it out to a little less than 1/64 under the finished size - about .012 and reamed it with a 7/8 reamer.

 

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This is it... it fits the camshaft perfectly.

 

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Now I have to double check some measurements and turn the OK. That is the really tense operation because there is just about no wiggle room.

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I seem to be having a good day so I decided I might as well try the next step. I put the bearing on a mandrel and turned it down to the finished size... 1.925

 

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It fit just about perfectly...

 

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All that is left is to make the oil pockets and the oil groove.

Then, because I have to finish the intake manifold in order to get measurements to finish the oil manifold I soldered one of the elbows to a spare piece of tubing. This is to hold it while I file and sand.

 

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I also started on the special bolts with built-in standoffs that will hold the manifold on...

 

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This is also an experiment in making identical pieces, something that is a lot more demanding than most people think.

 

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I finished up the special intake bolts today. The next step was to turn the diameter that will be threaded. I then single pointed them about 85% of the way.

 

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And then screwed them into a die.

 

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This gives you nice uniform threads that are really straight. It's practically impossible to start a die on the end of a piece like this and really have it run straight. (Or at least it is for me) but cutting away most of the material first, in the lathe, ensures that the die will run straight.

 

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Then I shortened the heads - the extra material was there to provide a better grip in the hex collet. I then set up the radius tool and put a slight crown on them.

 

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All done.

 

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Beautiful work Joe. Having done some like this myself in the past, I can really appreciate your work. The average person only gets as close as inserting or removing a bolt, never thinking twice about them. Making them, especially custom ones like these which actually are still kind of simple in design, gives a whole different appreciation for something lots of us use everyday.

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I see it as all in the way of practice/ At some point I have to make the high-dome bolts that hold the wheels together so I'm anxious to work out the details. By the time I get to that, I should have a "bolt making" process sorted out. I could have used hardware store bolts and standoffs from McMaster Carr but I think this looks much more as if it was always that way.

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