Drawbot Spools!

paper spools

I got some spooled paper for my drawbot project!

The idea is it can feed itself. Perhaps I should look at having the Y axis done through a stepper motor driving the spool? I’d either have to drive the paper directly or vary the speed based on the radius of the spool.

I suppose having the stepper drive the spool with a wheel pressing against the outer part of the spool itself solves the problem.

Then I’d only have to implement an X axis. Might be sufficiently simple to have a pen lifter or multiple pens then.

I have a paper cutter but it’s very short.

Any idea how to snip off 18 5/8″ of paper?

Attaching drawbot spools to 1/8th motor shaft

RC plane parts

I just made spools with a 1/8th hole and then used a glue gun to fill the hole with glue and stuffed it on the motor. The motor has flats that are about 40% of the cross section.

It’s holding out pretty well but I’m concerned about it.

I’ve been back-grounding this problem for the past few days and it came to me today.

About 10 years ago I used to fly RC planes and they have collars with set screws that hold the wheels on (a few other uses too). Those parts are readily available. The picture above are Great Planes 1/8″ wheel collars. I’ll probably get some of those.

I will replace the set screw with a longer one. Then in the spool design there will be a key channel where the screw goes inside the spool.

Come think of it, a chunk of metal with a 1/8th hole drilled would work. Only problem I’d need to make some very small threads to get the set screw installed.

Spool for drawbot

spool

I wiped up some disks on Sketchup and then cut them out on CNC mill.

I glued them together using craft glue.

I used an 1/8th inch shaft dremel bit as a guide.

The steppers have a 1/8th” shaft (with a flat). So I figured if I made 1/8″ hole in the spool I could put them on with loctite.

I can’t figure out another way than to “glue” the spool onto the shaft.

It seems like a good idea to have the spool directly on the shaft of the stepper assembly as well.

I made the spool diameter 1″ and the walls 2″. That makes the circumference 3.141565″ or so.

I used 8 disks to make each spool.

One concern I have is that the steppers seem to get quite warm. I guess I need to make sure I have the right loctite. I have three kids. Silly company numbers their products rather than describes the differences. I suppose if I google the numbers I can figure out which one to use.