Sentro Knitting Machine Drill Adapter (Bolt)

Re-worked the design to work with a 1/4-inch bolt with a 7/16th's-inch head instead of a 3/8-inch drive bit.
(6mm bolt with a 10mm head will work too, but there might be a little play in the head)

I'm using a 2-inch bolt with a washer, lock washer, and a nylock nut.

If you don't have a nylock, I'd use 2 nuts cranked against each other to lock them in place and/or locktight (thread glue) to keep the nut from backing itself off over time.

Because of printing variances, I like to make holes ever so slightly undersized so everything fits together tightly.

So after printing, I used a 1/4" drill bit to clean up and widen the hole for the bolt.

Then I heated the head of the bolt with a lighter and pressed it in backwards to ensure a perfect fit.