I'm really happy with my rack and pinion linear actuator. You can see a video of it in action here- https://www.youtube.com/watch?v=KRZ9TLhD0i4 You can see how I packaged the pieces here- https://www.shapeways.com/model/293549/randp.html?gid=ug (I'm having trouble uploading other pictures for some reason- it claims they aren't jpegs. Any suggestions on that?) I was worried at first because the racks wouldn't fit in the holes at first but after some cleaning and cramming, the excess powder came out and everything fit like a glove. I designed it around a cheap Chinese stepper motor I bought on ebay and it fit just as designed. I hope you like it and feel free to ask any questions.
What are you going to use the actuator for? Well done - i see you're good with electronics too - that puts you on my buddy list (You get that jpg error as it's too big in size - crop your pics to about 1600X1080 - that works best for me)
Thanks for your comments. Also thank you for the tip about the size of the photos- I shrunk them a bit and they uploaded fine. Now there are some still photos on the design page. As to what it's for...linear actuators can be used for tons of things- they convert the precise rotational movement from a stepper motor to precise linear motion. One thing I'm going to try soon is to use three of them together to make a tripod plotter/robot/pick-and-place machine. I have other ideas and I'll post videos if they ever come to fruition. Thanks again.
Good stuff, I've been looking around and not many people on SW are making functional components, It's seems mainly(understandably) art and asthetic parts. I'm interested in putting RP to "work" like this and it's encouraging to see efforts like yours. Thanks for sharing that.
Can the gear system be designed to accomplish exact 0.01mm steps/movement? Also, did you try it with a load? - how did WSF work out for you with a load? (thou i see its thick , still it tends to bend no?)
Exact 0.01mm steps? That's asking alot- 0.01mm is pretty fine. As it is now, no. I designed in a little backlash so it would fit together well. I think the cheap motors have some backlash to them too. They are steppers but are geared as well. So between the motors and the design, this isn't terribly accurate but with some tweaking on the gears and a different motor I think you could get decent accuracy. If you had a motor with 200 steps per rotation and did eighth steps so you had 1600 steps per rotation and with a small gear (2cm diam) with a really tight fit maybe you could get 0.04mm but I'm not sure this would be the solution for that. I was thinking you could attach a variable resistor to it to figure out it's position that way like a servo. As far as strength goes- again I haven't done tests on it. The motor can't tolerate a ton of stress but WSF is pretty strong. For like, hobby robots or something I think this would be plenty strong. But it is plastic after all. Would you want a plastic rack and pinion in your application? Do you have an application in mind? I can try to design something for you.
Well as crazy as it may sound i want to explore a mini Z axis-only 3d printer with UV curable resin. I have a different approach in mind - so far could not find ready-made mini linear actuators/sliders with a stepper that can move a plate on the Z axis with such precision of 0.01mm Saw few youtube of some guys staring this kind of project , here is one: http://projectguru.org/3dprinter-articles/3dprinter-blog
You can get this accuracy by having a stepper turn a threaded rod. 32 threads per inch = 1/32 inches per rotation. If you have a stepper that has 200 steps per rotation,a nut on the rod moves 1/(32*200) inches per step which is 0.004mm per step if I'm not mistaken. Having a stepper turn a threaded rod to get linear motion is how many cnc type machines work.
Here's a video of a cnc machine working with threaded rods that shows what I tried to explain above. (I just picked the video at random- thanks to whoever posted it.)
McMaster Carr has lots of parts like this. I would suggest you look at some CNC machine plans online. You only really need the z-axis but you can get an idea of what you need to do. You need a track that your tray slides on and a threaded rod and correponding nut (attached to the moving part) to drive it. This is doable and would be a great project. It doesn't seem like it would have to withstand too much stress. You could probably design most of it in WSF if you are good at CAD design and just mount the motors, nut, and threaded rod (and all the other stuff that can't be 3d printed.)
By the way, Instructables.com has a whole section devoted to CNC with tons of plans and designs for free.
I also found this great index page for all 3d printing parts http://reprap.org/wiki/Mendel_Buyers_Guide#Electrical_and_me chanical_kits_and_parts What type of arduino do you use and is it easy to write code to ? I would need one with 2 output controls for 2 steppers and 1 on/off switch Check out this video http://www.youtube.com/watch?v=IPmP0u1HuUM
Sorry mate, can't do that just now, on a different mission and all that but here's some brain food http://www.youtube.com/watch?v=4YZeX8ti7Io