Yes, but it won't budge
Originally Posted by E. von Hoegh
Yes, but it won't budge
You've probably seen this video (from your picture it looks like you already removed the rail bushing to access the hidden set-screw) but thought I'd post it just in case. You only mentioned a single set screw in an earlier post, there are two securing the stem assembly.
http://sinarnormaclavideoguide.s3.am...mbly-960px.mp4
If they have both been removed, I wonder if a gear puller could be rigged to work?
Have you tried while it is hot? Of course all the caveats about a properly fitting wrench apply here.....
One man's Mede is another man's Persian.
I'm making progress! After many days of soaking in Kroil the shaft can now be moved a bit—it can be rotated back and forth about 10 degrees or so. I still can't remove it, because it is very tight, but I'm encouraged. I'm thinking of freezing the assembly and then gently heating the aluminum to expand it. Any thoughts?
The steel and aluminium will always be about the same temp, because of the contact. Heating it will help; you've already succeeded.
Patience, thermal cycling, patience, wiggling, patience,....... But you got it free!
I used to work with an old guy; we dragged Model T and Model A running gears out of barns, out from behind barns, dug them up - literally- to restore and sell at Hershey. He was a real mechanic, and would spend weeks freeing rusted bits with heat, oil, light tapping, and lots of patience. He used furnace oil as a penetrant, and it works. We'd never heard of Kroil in 1978.
One man's Mede is another man's Persian.
That's not the answer I was looking for. You were supposed to say "Great idea—the shaft will pop right out!" I guess I'll keep on trying everything I can think of.....
Great idea!! The shaft will pop right out!
Eventually.
One man's Mede is another man's Persian.
If you need an extra low temperature soak you can bust up dry ice and add to acetone and then soak the parts you are trying to separate in that. Also possibly differential heating and cooling if the inner part can be cooled while outer part heated.
I just thought of something... are you sure there isn't still a setscrew holding it? I've seen two setscrews used, one to lock a piece and a second to lock the setscrew. One on top of the other.
One man's Mede is another man's Persian.
It sounds like you have either galling (transfer of aluminum to the steel) or corrosion of the aluminum. In either case, you will probably need to exert some longitudinal force while you twist, or you will eventually have a freely rotating but non-removable part. If it is galling, rotating the shaft will eventually create a groove in the aluminum, and when you finally extract the shaft there will be considerable damage to the hole, possibly preventing you from reusing aluminum part.
It is sometimes possible to use a bench vise, C-clamp, or large Vise-Grip pliers to press out a small shaft. An appropriately sized wrench socket, or even a stack of washers, may allow you to support the outer part as you apply force to the shaft. Of course, an arbor press is even better, under the hands of an appropriately skilled craftsman. (You probably want to avoid hydraulic presses, as one would have to proceed with the utmost delicacy, and this is not what those machines were really designed for.)
In any case, I suggest that you give some thought to pushing or pulling shaft straight out; if the problem is galling or a burr due to a setscrew tip, a single groove parallel to the shaft will be less problematic in the long run than an oversized hole would be.
Good luck!
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