Worm/motor support metalwork. Box tubular sleeve Pt.2

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Countersinking the inside of holes drilled in the square sleeve required some inventiveness. I was lucky to find a brake bleed spanner which fitted a stumpy countersink with a hex shank.

I found a length of scrap alloy bar with a central hole. Into which I inserted the countersink. The far end of the bar was inserted into the square tube with a length of 1"x 2" [25x50mm] batten to act as a fulcrum. This packing piece ensured the countersink remained vertical during the actual cutting.

By pressing down on the other end of the bar the countersink was forced down into the pre-drilled hole. By cranking back and forth on the brake spanner [wrench] I quickly obtained a nice deep countersink in each of the four holes. I can now bolt the worm housing onto the top of the sleeve and the entire drive assembly down onto the main plate.

Once the csk. screws were inserted from the inside the heads were almost flush with the inside of the tube. This allowed plenty of room for the stepper motor without any contact with the slightly protruding screw heads. Job done!  👍

The image [right] shows the new motor housing and worm support resting in place on the base plate. Not the curve on the 10mm base plate! Just the price of employing scrap metal? I shall have to invert the plate to stop the motor housing from rocking. I doubt it can be flattened without serious cosmetic damage even with packing pieces.

The entire mounting will soon have to come apart anyway. I have to cut the ends of the axis bearing plates square and to the same length.I was never very happy with the jigsaw and filing process for squareness or accuracy of length. The problem is making a decent stop for the miter saw. The DeWalt stops are absolute crap!

I fixed a block with G-cramps for the plates to stop against.
Tightening the crappy, DeWalt hold down moved the plates away from the stop no matter how hard I pressed them towards the stop! Eventually I had the four PA plates with square ends and all of the same length. There followed much sanding to clean up the surfaces before reassembly. I also re-drilled all the holes to 11mm to allow greater freedom for the furniture [flange] nuts.

I have made a new motor-worm plate from 10mm aluminium and notched it to go around the wormwheel. My attempts to use a hole saw from both sides and meeting in the middle, were not successful on the earlier motor plate.  With each hole offset to the opposite one by several millimeters. This time I bored right through from one side only after drilling a pilot hole of 5.5mm to match the hole saw's 6mm.

The sheer size of the larger pulley boss [30mm] makes it hard to find solid metal to drill the end of the worm housing. The 34tooth pulley rim is also very close to the wormwheel requiring very careful set-up. It would be easy to lock up the wormwheel with the pulley rim.

The ATM scrap metal gods are smiling on me again. Half a dozen cylindrical lengths of aluminium plus a much larger disk on this latest visit. Just what I needed. 

Click on any image for an enlargement.

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