StirPlate Transmission pt.3

Not much left to go now and Ill have the mechanism for stirring through the entire range of rpm's I could possibly want. I haven't given the enclosure much thought since the last blog entry where I showed the pics of the hacking and butchering I've done on the crappy little enclosure I got from Radio Shack, excepts to think that I want something a little sturdier. Ive spent so much time with this gear box, or transmission, or whatever you choose to call it, that I can hardly bear to put it in that crappy, flimsy enclosure. I also wish I still had those heating elements I got from Science Surplus last year, or the year before. They would be perfect for adding heating capability to a stirplate. I'm not even sure if I can find that kind anymore, and I certainly cant get 2 for $4 anymore(can't remember exactly what I paid, but it was obscene). Oh well, no heat on this one, its a first build. I wanna do another with metal gears that wont melt and, of course, heating elements!  All inside an enclosure made from sheet aluminum bent on a tiny brake, like this one. There is a shared shop around here you can pay by the hour or get unlimited access to a fully equipped machine shop for $1200/year that has every damn thing. I haven't paid for time there but did go talk to them and fill some stuff out, look around etc. Id like to have some sort of a paying gig before I put any money down, even though you aren't allowed to run a business from the shop, it would be nice to be making a few dollars, just a few, that would be awesome.

Here are some pics of the transmission/gearbox/frankenstein after remaking the pivoting bar and rethinking the design a bit. The big aluminum one will carry the magnet(s). Its bearing, one from a r/w head from a hard drive, will turn about the same axis as the pivot bar pivots, so it never moves with gear changes and the belt maintains a constant tension. It has a groove matching the other pulley(borrowed indefinitely from a cd-rom drive) machined around it. I put a different, bigger, gear on the servo because leaving that idler gear then adding the pulley, and therefore length, I needed to get further out to keep my linkage at a kosher angle.

You can see the end of the bolt at the bottom of the pivot bar is not all the way screwed down. Itll all work out when the big aluminum pulley is mounted.

Here's a side view for good measure. You can actually see in this pic that the linkage is not yet attached to the copper gear. I still had to work out the height, which is now to the top of the pulley, not the idler, like it was. 

Wow, look at that clearance lol. You can scarcely get a piece of paper between the black pulley and the aluminum one. Im considering taking a bit more off the od , but I really don't want to, since Id have to remachine the belt groove too on top of making a special arbor just to turn that little bit off. Screw all that, besides, its not rubbing or anything, it actually has about .04", plenty. The copper gear and black pulley are not on the same plane, so they miss each other by a lot.

Look at how fat I have made this dog. Thats not why I took the pic, though. If youll notice under her 'arm', you'll notice a white streak or something. That's a steak bone. She never lays like that either. She is actually laying on it to 'protect it' lmao. She's a trip lol. Im gonna stop feeding her off my plate like I do, cause damn lololol