Monday, April 20, 2015

New Crank for the Tablesaw

I have a 9 inch Craftsman tablesaw and broke the crank off that adjusts the height of the blade.  It broke apart where the shaft goes into the center, so there wasn't much hope of repairing it.  So I decided to build a new one.
The shaft is basically half an inch, so I took a half-inch nut and drilled out the threads with a half-inch drill.  It's too small to clamp, so I just held the nut in place with a pair of locking pliers.  My drill press isn't that powerful, so I had plenty of leverage to stop the drill and wasn't worried about it yanking the pliers out of my hand.  And it did lock up several times, as the drill bit would catch on the threads.  Then I took a 5/32 drill and drilled through one flat side of the nut.  The shaft has a flat side, and the original handle had a flat spot in the hole.  Then I threaded that hole for 10-32 for a set screw.

I used the same half-inch drill bit to drill through the center of a quarter-inch steel plate.  The plate is 5 inches across, which is about the same diameter as the original crank body.  I picked up the steel plate out of a shapes bin at  If it was a "shape", it would have cost more, but it has a notch on the edge.  The employee said that made it a scrap piece.  I don't know if the notch was made to mark it as scrap, or was a mistake while cutting a circle, so it ended up as scrap.  Either way, I got it at the scrap price.  I put a half-inch steel rod through the plate and the nut (it's one of the ones I used to wind my garage door spring when I had to install a new one) and then welded the nut to the plate.  I welded every side except the one drilled for the set screw, because I didn't want to risk fouling the threads. 

I pulled the original handle off the crank and drilled a hole for it near the outer edge.  I put the original lock washer (I don't know that that is what it is officially called.  It's shaped like an internal tooth lock washer, but the teeth are smaller than the shaft.  So when you push it on, the teeth bend and lock against the shaft, making it difficult to take back apart)back on.  The handle shaft is too long, since my plate is thinner than the original crank body, so I put an oversize nut on the shaft to use as a spacer.

Overall, it works pretty well.  The handle is a bit loose, probably because I messed up the lock washer taking it off, so I'll probably replace it with a true bolt.  And I really need to cut a hole through the plate large enough to fit an allen wrench or something through for the set screw.  There isn't much clearance between the plate and the saw, so getting a screwdriver back there is a pain.  But it does it's job, and that's what counts.

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