Been a nightmare couple of months, kinda fell off the face of the planet for a bit there. Still wicked busy (which is a good thing), but I haven't had time to tinker and such. Not having the time to actually DO anything left me at times with sketching out various ideas and little code snippets. Well, today I had a few hours to myself with no pressing emergencies, and declared it a Tinkering Day. Actually, I had a few hours yesterday also, during which time I completely rebuilt the Frankenbotic Thinganator with new stepper motors and ULN2003's instead of discrete transistors. I'll post an update after I set it up and work in a code fix that corrects for the radial distortion in the renderings. Way too much geometry was needed.
However, I have a need for something much more useful.. so I set out this morning nice and early for Home Depot for some supplies.
Now, those that know me know I am the master of epoxy and duct tape. I went into Home depot with a budget of sixty dollars, and came in at around fifty, because I was able to get the lumber I needed from a "cull bin", where they toss odd leftovers of whatever, and charge next to nothing for them. From the bin I was able to find a partial sheet of 3/8" plywood, which fit my needs and cost a whopping fifty cents. Next over to the cabinet hardware, where I got two sets of ball bearing drawer slides for twenty five bucks (the most expensive part of the project). Next, the hardware aisle, where I grabbed a couple of two foot sections of 1/4" threaded rod, two three footers because they were cheap, and a couple of handfuls of the various hardware odds and ends like some washers and screws.
By the time the kids got off the school bus I had the basic framework cut and laid out, then hit the box of those steppers I love so much, and pulled out the epoxy. It was fully assembled with epoxy curing by the time dinner hit the table.. wired up while watching TV and chatting with the wife.. and threw some basic testing code at around 11pm. Total time from concept to working prototype: fifteen hours.
My Arduino-driven, 13"x13" travel, slow but extremely accurate (screw drive, gear-reduced stepper) XY table. After a small amount of testing, I will be adding the wooden gantry and another screw-drive stepper to complete the project... to raise and lower my dremel on the XY table... poor man's CNC. Fifty bucks, not including the Dremel (off brand one at that).
This may be my most abhorrent-to-reasonable-engineers project to date. And yes, I am fully aware I need some more epoxy for those mounts...
It's VERY slow.. but it works and has an impressive amount of torque. When the photo was taken, it was running a simple sketch just moving the platform back and forth and left to right.. flawlessly. High resolution CNC router, anyone? With these steppers and their built in gearing, one rotation of the drive shaft is 2048 steps.. dang high torque ones at that. More than enough to drive the threaded rod and move the table. Then take into account the drive screw is twenty threads per inch, and you get well over 40,000 steps/inch. Sure, it moves like two inches a minute... but I don't care about that, really..and of course I know actual accuracy will be a miracle if it's within a sixteenth of an inch reliably. So far-- it's working, which is never a bad starting point... I should have something more to show on this in a couple of days.
Good to be back, doing all the things I shouldn't!