Moving right along for the lathe development:
This chuck and shaft it came from a cordless drill I bought for $2 at a Navajo flea market. Not having a gear puller, I was forced to cut the gear out off its shaft by using my Dremel abrasive cutoff wheel.
Business end of cordless drill
I really did not want to either dedicate or destroy my Craftsman or Dremel flex-shafts for this purpose. Having abandoned the idea of rebuilding my own motor, I started thinking about what kind of motor would deliver sufficient torque.
I have to drive 50 miles out of my way just to go shopping for my family. So I spend some additional time before-hand scanning pawnshops, flea-markets, and Goodwill with an eye toward finding cheap junk to disassemble and salvage.
Sometimes… the cheap junk can even be found at retail…
Riddle: When rummaging through junk yards is not an option, where can you find high quality mechanical components for R&D at the lowest possible cost, with free shipping thrown in?
Answer: Wal-Mart!
I found this “High Speed Metal Fan” for just $6!!!
Where to get a small motor with enough torque for a nano lathe?
The fan was a bit of a pain to take apart. Some brilliant person in China had decided to lock the screw threads after assembly with cyanoacrylate adhesive in the name of operator safety. You have the use just the right sharp and sudden pressure with the scredriver to break a bolt sealed like that.
This fan motor has a speed control!
I salvaged the pieces of wood I used to mount my electric-drill based headstock, for use as a test stand in developing the powered headstock. My worst difficulty was in linking the two together in such a way that the runout was not too horrible. After several attempts using different ideas for shaft couplers, I got something running nice and smoothly…
Headstock test stand, using a crude metal shaft coupler
If I wanted a publishable and repeatable design I had to get rid of the runout as much as possible, mainly for operator safety. My first crude attempts had even caused the motor to walk. This was caused by my not yet having learned to operate my drill press well enough to drill two collinear axes of different widths along the same shaft. I’ll get there, someday. But clearly, not now. And so I needed a simpler solution so someone else at my skill level for using powered tools still had a hope of creating this lathe.
I finally got my runout down to a nearly stet level… no walking… no humming… but the shaft was still sticking at startup, although if I pushed the shaft it would rapidly go up to full speed!
There was just a barely noticable bit of walk left that just suspending the motor mount in my hand got rid of… which implies I will likely need a spring suspension system under the motor mount as part of my design.
Test stand for headstock, using my best shaft coupler
I spent the last 3 weeks of available shed time, “climbing the hill”, toward an optimal shaft coupler design. I eventually found a part at Ace Hardware called a Pin Extender. It is made of rubber drilled to a 5/8 inch internal diameter (grips the drill chuck shaft quite well!), and at the narrow end has a built in 1/4 inch brass threaded bore. Just seeing it gave me the dazzling idea of cutting threads in the motor shaft. So $50 of research yielded me full circle in development…
The design path for the shaft coupler
