Repairing a broken Thumler's Tumbler (Vibrating polisher)

Picture of Repairing a broken Thumler's Tumbler (Vibrating polisher)
TechShop San Jose's Thumler's Tumbler had a couple of issues: The center shaft that held the cover on had come loose, and it made a odd noise when running.  Time for some exploratory surgery!

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Step 1:

Picture of
Take the bowl off the top. Flip the unit over, remove the four screws that hold the base on. 

Turn it over again and peel the neoprene sheet off. 

There it is! The shaft broke out of the base, and the motor cracked the mounting plate.

There wasn't enough clearance to weld a plate on top of or below the existing plate, so I opted to cut out the broken part and weld in a fresh piece of metal.

Step 2: Cut out the bad parts

Picture of Cut out the bad parts
(Not shown - using VCarve Pro to create a template of the five holes in the middle, and an arbitrary 6" diameter circle to cut out the bad metal).

Using TechShop's Flow Waterjet cutter, I first sliced a piece of 1/8" scrap steel using the template I created. Next I positioned the damaged base plate in the exact same position as the cutout piece, using the 4 holes where the motor mounts as references.  I cut the bad metal out, and got a perfect fit.

Not shown - marking the rotational orientation of the center part -- the motor must be positioned such that the anchors still fit in the holes near the edge of the rim. 

Step 3: Weld in the good, and clean it up

Picture of Weld in the good, and clean it up
I MIG welded the fresh steel into the base, and ground down the top side to ensure a good fit. The bottom was left un-ground, as it didn't need to be finished. 

After welding i sandblasted the piece.  Since it was previously powder coated, the red finish was stubborn.  I decided to leave it rough and try a non-standard powder coating technique.

knife1412 years ago
Nice job! I like it when things get repaired rather than thrown away.