Being kind of dumb and optimistic about my abilities, I said, "Sure, I can make that." Of course, I didn't consider that my hobby-grade machine tools were not even capable of doing the job, nor were my skills up to snuff. Fortunately, I know Phil Oles...
First up was to find an appropriate material, and that was a trial. I tracked down a local machinist in Elizabethtown named Jake Hitz, and he had some material that was very promising - and very expensive! It's called DOM steel. DOM stands for "Drawn Over Mandrel" and it basically means that it is made so that there is no seam, and the dimensions are very precise. I bought two 3" long pieces, and each piece was around 50 bucks! I bought two because I was so sure I would screw it up the first time. As it turned out, with Phil's help, we avoided that fate.
Phil's equipment is also hobby-oriented, but his lathe is enough larger than mine that it would handle the 4.5" outside diameter of the workpiece. He started by installing his four-jaw chuck, and "dialing in" the workpiece so that it turned perfectly straight. He then turned the outside and bored the inside just to ensure that the lathe was up to the task. It was... barely.
I went over to Phil's, and we turned just over half of the length to the correct outside diameter, and then started boring. Here's where hobby equipment shows its limitations. We had to limit our cuts to only 0.014" per pass, and using the slowest feed rate it took about 4 minutes per pass. We needed to remove nearly half an inch from the inner bore, and I did that in one marathon 5.5 hour session at the lathe.
While I was doing that, Phil prepared a "plug" on his other lathe to test the bore. It was very precisely the diameter I measured on the crankshaft end, plus 0.0005" (half a thousandth). When that would barely slip through the bore, it was done. The fit we achieved was so tight it actually created a bit of suction!
Once that half of the work was done, I took it back to the Grant St. Garage and tried it on the B18 engine I had just bought. It worked great, and convinced me that Joe was right about the need for that tool. I had convinced myself that the brand new housing and seal I bought did not fit right, but with the alignment tool, it was clear the tolerances were spot on:
I returned the workpiece to Phil, and he carefully aligned it in his lathe and turned the rest of the outside dimension to final diameter. Then we together completed the rest of the bore, taking extreme care so that it matched the entire length of the piece. When done, I took it back to Grant St. and tried again. The first test was to ensure the housing would slide from one end to the other, with no play. It was spot on.
I then tested both ends against the crankshaft, and found a good fit. The next step: turn it into two pieces so it could be used to make a tool for Joe and another for me. I used my Logan lathe for that, and it stretched its capabilities to the limit!
The left picture shows the start of the process, and finally, an hour later, it was parted into two pieces. The lathe chattered and complained the entire time! I had to wear heavy ear protection.
Once I cleaned up the cut faces, I moved each piece to the milling machine to use its ability to precisely hold and locate the work. The task was to drill and tap two holes exactly across the center of the ring, for the crosspiece used for pressing and extraction.
Once that was done, I prepared, drilled and tapped a pair of cross pieces, and everything fit.
The tool actually has two uses. When you buy a new housing and seal, it comes with the seal already installed. To reuse the seal, it must be removed without damaging it. It turns out that a simple setup on the 20-ton press makes easy work of that:
Once that is done, you liberally oil both inside and outside surfaces of the tool, and slide the housing into place. The fit is so tight, it's easy to get it crooked and bind it in place, but it is definitely possible. As my sainted mother used to say, you just have to hold your mouth right. Then, slide the whole assembly onto the crank:
The big center bolt is used to press it back out should it bind, but in my testing I was able to remove it without needing that.
So, here's the matched pair, soon to be separated forever. Joe's will live in Carlisle, and the other will reside at the Grant St. Garage. I will deliver Joe's within the week.
This wouldn't have been an instantaneous process in a real machine shop either, but I'll bet a huge lathe with a heavy boring bar could have done it in a quarter of the time. So, even though I have enough material to make two more, I will NEVER try this again! If you want to buy 3" of 4.5" DOM steel tube, let me know...
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