Sunday, January 3, 2016

1930 South Bend Junior Lathe - Back Together

It only took me a couple of months, but it's done.

The South Bend is back together.  Still it's not operational because I am missing a couple of things so far, but the main pieces (headstock, bed, tailstock, and saddle/cross slide) are all refinished and re-assembled.  Back gears put back in, handle on, reverse tumbler checked and re-installed, and the spindle has been re-shimmed.  You should know that the shimming was the toughest part of the rebuild.  Even drilling out the Gits oilers on the apron and bed lead screw were relatively easy in comparison.

I don't know if you've ever made shims, but when you want to really get accuracy, you redo the shims to make sure nothing has any runout.  Installing them is fairly easy.  Making them isn't.

I needed some good accuracy, so I ordered a brass shim kit off of Amazon - this was simply a set of brass sheets, each one of which was a different thickness, e.g. 0.001", 0.0015", 0.002", up to 0.015" .  Considering you have one on each side of the spindle (e.g. "four corners"), the resolution actually comes to about 0.00025" since I knew it would take at least 0.010" since I already had one installed and it wasn't enough.  Different combinations got me to exactly the thickness I needed, and gave me a tight spindle with no play, and the ability to turn the spindle in place.  To me, it had to be exact.

Again, it wasn't the installation of the shims - that's cakewalk.  It's cutting them out.  I took original shims, and essentially placed them onto the brass sheet and outlined them with a fine sharpie, then had to remove the outlined brass from the sheet.

On the smaller thickness sheets, it was fairly easy - I used regular scissors or an exacto knife.  But once the thickness got to 0.004", the exacto knife started to be unable to cut through.  I was worried about scissors being damaged, so I grabbed the tin snips.  Those are hard to manipulate, but they worked.  On the 0.015" thick stuff, making really small and fine cuts puts a strain on your hands.  I cut out 16 of those (both ends of the spindle and both sides), just in case I needed 0.09" of clearance.  I ended up not needing that, but I did it just in case.

Once done, I slapped it all together and had it operating as needed.

Now, all I have left is a motor.  I have an old 1.5HP (continuous duty, 2.5HP momentary duty) treadmill motor, and the speed controller from that (it's an MC2100, not an MC60), so I have to now figure out how to implement that.  Also, I must obtain the proper belts and install them.  At that point, I'll start working on making some change gears out of aluminum, and then it should be fully functional!  Nice to have an old relic back in the land of the living!

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