CNC 3D printer
 

Hey all,

I've been involved for a few months now with an effort to create an open-source 3D printer for around $400 in parts. It's a really cool system that's worth checking out; more details can be found at their website.

However, that's not the most immediate reason for my post. I'm working on adapting a 3-axis CNC platform (originally designed to be used with gearmotors) for use with stepper motors, as this will make it more compatible with the RepRap project. Currently the design relies on X and Y stages made of 3/4" Medium-Density Fiberboard driven along aluminum tracks by a threaded rod (pic). My question is: does anyone have an idea of what kind of torque requirements a stepper motor would have to have to drive those stages (particularly the bottom one)? If it's too high, I suppose I'll have to modify the design to use linear bearings, but those can get pricey. Does anyone know of a cheaper alternative?

Re: CNC 3D printer
 

this thing is awesome

i want one so i can make millions, haha

Re: CNC 3D printer
 

If you actualy have the device, it is easy to estimate the torque requirements empirically - remove the motors and twist the threaded rod. Easy to turn, tens of in-oz, hard to turn but can be done with fingers, several tens of in-oz. Can't turn it by hand, then measure it: Attach something to the rod (like a handle), and use a small weight scale to pull the end of the handle and read the ounces (pounds?) until it starts to turn. Multiply the inches away from the axis by the ounces of force, and then multiply by 1.5 or 2 to get the desired motor rating.

ON THE Other hand, this was probably a machining center first, and as such needed robust motors to push the work tool through the material. Now there is virtually no push needed, aside from overcoming the friction of the mechanism. Likely smaller motors(20-40 in-oz) will be fine.

Don

Re: CNC 3D printer
 

hey i read about this in a magazine, apparently they aren't very fast. They are still super cool though. Once I find a way to speed up the process I shall print mini-vivekbots and take over the world!!!:rolleyes: until then I still have pudding:)

Re: CNC 3D printer
 

Keep us informed on your build!

I hope you are successful! These things are amazing!:D

I can't help you with the motors, but I own a 3D printing business so I can help you with that kind of thing.

There are all kinds of 3D printers popping up!

Here is one that is due out SOON www.desktopfactory.com

Here is my latest print done on my Dimension BST 768.

This thing took 24.25 hours to print and used about $100 in material.

Sorry I had to censor this one, but this is by far the most complex model I have printed! This customer does 3D characters and has given me rights to show his model off, so I am not breaking a NDA or agreements.

I have lots of sample parts at photos.printo3d.com

Re: CNC 3D printer
 

I'm not sure what the current drive capacity of your stepper drive is... however, a cheap source for stepper motors is AutomationDirect who has stepper motors ranging from a NEMA17 framesize with 83oz-in of torque at just $19, to a NEMA34 framesize with 434oz-in of torque for (a still amazingly low price for the motor) $99.

If you need drives, they have a 3.5A/phase microstepping (to 10,000steps/rev) drive for $150. The drives can run off anywhere from 12 to 42VDC... so finding a powersupply suitable shouldnt be too bad.

Hope that helps... if more questions, just post.

-q