Just Pulley-ing My Leg

 A year or so back, I had heavily modified am early 1940's tiny lathe with the intent of using it to turn pens.  There are a number of small lathes that are likely cheaper than the cost put into that one, but for some odd reason, I love the old iron, and did it anyway.

The results were, less than stellar.  Indeed, it did work, but I had to take my time because the stepper motor did not have enough torque.  And that is with a small pen.

So, enter the next chapter.  Someone over on the hobby machinist forum sent an old sewing machine motor to me (think Pfaff 130, and you have the footprint of it), just for the cost of shipping.  With the pulley that was on it, I found myself in a bit of a quandary - I needed more modifications to see if this would work.  So, I set about creating a new belt tensioning system.  I patterned this variation off of a cars alternator - where it is installed and then tightened over an arc-bracket.

I made the bar using my drill press, because, I didn't have a rotary table large enough for the arc (mine is 4", the arc is 8" - but that is due to only having a scrap bar with an 8" arc that was an off cut for the 127-tooth compound gear), and also because I was too lazy to drag out the milling machine onto a cold back porch and cut it.  Really, it was because I was way too lazy.

But, it was close enough for what I needed.

So, I drilled a series of holes, then used an endill in the drill press to smooth out the arcs.  I drilled a few extra holes in some bar stock, and used a 1/4"-20 bolt to put it all together.

Next, I needed a pulley.  So I grabbed another off-cut/drop (2" diameter aluminum), chucked it up, and made a 2L pulley that was as large as this lathe could accept, but small enough to fit (1.950" with the belt).  This was faced, drilled, then reamed.  It was then turned on the boss, then the flat part of the pulley, then the angles.

The result is a usable 2L pulley to match the one on the sewing machine motor.

I wired the motor to test it, and once that checked out okay, it was time to put it all together.

This immediately feels like more torque than the stepper.  But, the proof is always in the pudding.  What is the end result?  Let's give it a try. I ran through the normal steps preparing a pen blank (this time, I chose a  gun-metal "mini" bolt action pen kit from Penn State Industries - I have a lot of family that love the regular ones, so I thought I'd give this more "unique" variant a whack.)

1. Usually, mark the blank lengthwise to keep grain lined up.  In this case, it's small, and I was fixing another pen while I was at it, so this step didn't matter.
2. Cut off two chunks to fit your pen tubes, about 1/4" longer than the tubes themselves.  Again, this was small enough, and I was using a scrap blank I had from another project.
3. Drill the centering hole for the blank(s).
4. Glue in the tubes.  Many people just use CA glue.  I have always loved 5-minute epoxy for this.
5. Barrel-trim the ends to get it flush with the brass tubes (don't take off brass or it might not fit).
6. Put the tubes on the appropriate bushings, then on the mandrel, and turn.
7. Once to slightly larger than size, use the lathe to sand the blanks.  Get as high a grit as possible for the best finishes.
8. Remove from the lathe and assemble according to the instructions. 

So, once I got to the lathe part, I grabbed a photo.

They do look fantastic (I had two on there - I was repairing another pen while I was at it).  Then, assembly prep :

Then, the final assembly.

While the motor was slightly "under-powered" (It IS a 1/5 HP sewing machine motor), it still did the trick.  I do have to take things a little slower with this, but it does mean I don't have to drag out the larger twin for this little thing.  I can simply pick it up, clamp it to a work bench, plug it in, and turn a pen.