The cheapest motorized Chinese Cobbler?

[SmartShop]

Ok, my keyway measured about 5mm so I looked for 5mm, 13/64" and 0.200" pins.  The cheapest shipping from the US option seems to be a pin from a garage door opener chain for $1.00.

I think that does it for ordering parts.  Now they just need to get here so I can do the tuneup job, make one piece for the motor tensioner and then screw it all together.

[SmartShop]

My first attempt at adding a MXL belt to my handwheel with foam double stick tape was a partial success.  It was a bit tricky to get the belt over the double stick tape but after I pulled out the backing, the belt is just a bit loose.  All but about 1/2" sticks but that 1/2" spot makes it a failure.

I'm going to pull off the belt and line it with regular double stick tape (no foam) and hopefully that will take up the slack.

What did work was my tape slitting setup:

 

That is a .2480" gauge pin spacing up a razor blade held in two angle locking CNC vises.

Sorry for the poor focus.

Edited December 11, 2020 by SmartShop

[SmartShop]

McMaster Carr has amazing shipping, my order is already here.

For anyone with an 8mm reamer, you can get a 6mm shoulder bolt with 6mm threads (they typically have smaller threads than the shoulder shank) and a 20mm long shoulder plus a low friction oil impregnated bronze bushing for less than $4.

The 8mm shaft fix is a bit more expensive because I bought stuff to do it twice (first time without drilling and reaming).

The 10mm shoulder bolt looks like it is going to work too but I might have to grind off the head of the bolt.  The 100mm long shoulder might be a hair too short but the stock shaft has no head so it will be fine either way.

With the Japanese ball bearing and a pillow block bearing, I should have precision shafts, bushings and bearings for all of the arms and the crank wheel shaft.

I splurged a little on chrome acorn nuts to dress it up on the crank side.

I'm going to have to strip down the frame, paint it, grind the arms smooth, paint them and make sure everything else looks presentable too.

[SmartShop]

My 8mm shaft is now 1/4" with low friction bronze bushings.  No machining required (on my machine), nothing is overly loose or overly tight and #14 brass washers are installed between every part.  Eventually I will drill and ream out the frame and arms to fit a 3/8" shaft which is closer to the original size but this was quick, easy and cheap.

I'm not trying to change everything to SAE hardware, it's just cheaper here.  My 6mm bolt/shaft is staying 6mm to match the threads in the frame.  My 10mm hand crank shaft is staying 10mm because going inch would require boring out the frame and the cams.  The parts would have been cheaper...

When I fully tear down the frame i'll ream the arms and frame so everything is bushed.

Any way to change the 8mm shaft to 1/4" with bushings, I bought these parts from McMaster Carr:

1x 91259A500

4x 1688K3

And a package of 4 #14 brass washers from the hardware store plus a 10-24 chrome acorn nut from Ebay. 

My 6mm bolt/shaft replacement is waiting on the 8mm reamer I ordered but it uses these parts from McMaster Carr:

1x 90782A115

1x 6679K11

And a 6mm chrome acorn nut from Ebay.  I'll need 3 appropriately sized brass washers.

My 10mm hand crank shaft replacement uses this part from McMaster Carr:

1x 92981A314

And an 8mm chrome acorn nut from Ebay.  I'll need 3 appropriately sized brass washers.  From Ebay I ordered a new Japanese sealed bearing and a pillow block bearing, ill need to make a spacer to hold the pillow block in the right place.  Turbo Conquering Mega Eagle suggested bedding in a bushing to maintain alignment of the hand crank shaft, i think ill bed my pillow block spacer to the frame for the same reason.

My 8mm bolt/shaft replacement is waiting on an adjustable reamer I ordered but it uses these parts from McMaster Carr:

1x 91259A428

4x 2868T56

And a 1/4-20 chrome acorn nut from Ebay.  I'll need 4 appropriately sized brass washers.

[SmartShop]

My partial success is now probably a success.  I added a layer of regular Scotch brand double stick tape on top of the foam double stick and now my MXL belt is adhered around the full diameter of my hand crank.

Once my MXL sprocket and toggle clamps arrive, I'll be able to motorize this thing.