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laser cut CNC linear axis

by peter_, published

laser cut CNC linear axis by peter_ Jul 15, 2010

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Summary

This is a design for a /really/ inexpensive linear axis mechanism for an open source selective laser sintering 3D printer that I've been designing (but it should be generally useable for anything that requires a one or two axis system). This is a follow up to the selective laser sintering alpha one dual Z tables that I recently posted ( http://www.thingiverse.com/thing:3390 ).

The innovations in this system are its extremely minimal vitamin count -- only a handful of bolts, washers, and nuts are required. It also uses several long pieces of kapton tape as a linear slide bushing, to dramatically reduce friction and drag (though regular old scotch tape may work just as well ;) ).

Instructions

http://builders.reprap.org/2010/07/changing-game-and-using-kapton-tape-as.html

( the design was prototyped with 3mm material, but the material thickness isn't critical to the design ).

The bolt holes should snugly fit 6-32 bolts.

Update (from some questions recieved from folks who have made it: )

The width of the top plate (the one with 13 screw holes + 1 shaft hole, and the big curvy notch at the bottom) is 95mm wide by 102mm high, to help get your scale right.

The steppers that I’m using are KP35FM2-035, which I get at Sayal Electronics ( http://www.sayal.com/ActionIndexP.asp?ID=162138 ), which has a bunch of stores in and around toronto, ontario, canada (and also an online presence, I think). These typically go for about $5, and I think they have a NEMA-14 footprint, with a 5mm shaft diameter.

All the bolt holes are sized to snuggly fit 6-32 bolts, and you will likely have to tap these if you're using a material like acrylic (you can typically self-tap them with the bolt itself through a softer material like hardboard). The bolt holes are 3.4mm dia, while the gear hub holes are 4mm in diameter, making the gears loosely fit (and have a bit of play to find their place -- but you could certainly try cutting the gears with smaller holes to see if that works better). I used 3/4 inch length bolts, but some (for the gears) protrude out, so 1/2 inch would probably be more appropriate for these.

I put a small washer on the underside (but not the top) of each gear to dramatically reduce the friction -- without the washers, the hardboard version doesn't work very well at all, but with them it works quite well. In addition, between each of the structural plates, I placed washers to give a little extra travel height for the gears.

I have added two SVG files with the parts already layed out, that I used for laser cutting. There are some extra gears in there, just to fill out the space. I just put them in a ziplock bag full of gears for later tinkering, or give them away to friends who think they're the coolest thing ever :)

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Inspired by this (as well as other things like CoreXY and Tantillus Spectra wires), I prototyped a XY stage: https://www.youtube.com/watch?v=5F9-HIbBYwc

Sep 22, 2015 - Modified Sep 22, 2015
peter_ - in reply to jonnor

I've been waiting for someone to do this for 5 years! Thank you! :) It looks great!

Made it with 4mm plexiglass, cut with my laser

Found a few bugs:

Gear hole is too tight for a 6-32 bolt: had to make it bigger....

Spacing between the 2track was a bit too much. Moving section would "twist" and "squeeze". Made it 1mm narrower...works fine !

Other than that, this is a pretty good design !

Thanks! The MDF is a little more forgiving than acrylic, so I'm glad to hear that it worked out! If you have a second, it would be post a picture -- I'd love to see it in acrylic!

I'd love too, but I don't know how to post picture !

If you have an account with a website to somewhere like flickr.com, you should be able to upload your pictures there; when you have done that they usually have a link beneath or to the side which you can copy and paste into a comments box and it will either appear as an image or people should be able to click on the link and view the image in its original location.

Hope this helps,

Cheers,
David

p.s. I'd love to see more pictures as I'm new to 3D printing and would love to build something to help with my classic car project!!

I'm in Europe, so I can only get metric bolts. 6-32 in metric is M3.5.. which obviously isn't sold anywhere. So I got M4, which fits surprisingly well =)

glad to hear it! i think the bigger sizes tend to thread the hardboard a little better, which is kind of nice. how's it working?

It's working fine, I cut it out of acrylic though. I had some problems at first because I had 3mm shaft motors, I now have NEMA17 5mm shaft ones. I still have to cut a new motor mount, things are duct-taped at the moment. Very happy with how it works although the acrylic might not be rigid enough. A printer made with all transparent acrylic would look /totally awesome/ though.

that sounds really great! want to post some pictures to share your work? :)

This is great! There is some info on gear calculations that might be useful at this link: http://www.reprap.org/wiki/Gears:Simultaneous_Meshing_with_Rackhttp://www.reprap.org/wiki/Gea...

this is fantastic, thanks for your work! :) (i like your solution -- i was trying to simultaneously solve for all unknowns given tooth pitch ;). what does alpha represent?)

the machine you designed looks really neat, what is it for?

i propose that if no one has before used the 6-gear (+2 linear gear) configuration, that it be named the jansen-moses configuration ;)

Alpha is the angle of the small gear after the final rotation. I added a new explanation about this to the wiki article.

The motor assembly is for the next-generation of this project http://www.thingiverse.com/thing:978http://www.thingiverse.com/thi...

i like the name :) but i would be surprised if we were the first to come up with this design...

Modular Snap Blocks

Do you have the cad files for this? Sketchup ? Etc?

The SVG is available at the bottom of this page -- you should be able to load it up in a vector graphics program like Inkscape.

Wow cool gear generator!
Perhaps it might be worth mentioning how Vitaly (of http://contraptor.orgcontraptor.org) does Linear slides. He uses PTFE. Check it out:
http://www.contraptor.org/make-sliding-elementshttp://www.contraptor.org/make...
FYI.
Also, you might want to get some lexan for the Gears. (even plexi would be better). However, I assume you are just prototyping still. As I do the same thing. Use the cheap MDF / Masonite then go to the more expensive stuff.

Ril3y
http://blog.synthetos.comblog.synthetos.com

thanks :). yup, i just use hardboard for prototyping because it's silly inexpensive -- about $6 for 16 sq feet at home depot for the 3mm material. Something rigid and slippery like PTFE or block HDPE would probably be ideal for cutting the gears and things, but I'd first have to source them then give them a try in the laser cutter. Acrylic (plexiglass) is what I normally use, once the design works. ABS would also be a neat thing to try, too.

Bloody awesome design here Peter.

What's so nifty is that it's completely extensible. There's no limit to how long you could make that track, provided you can get a large enough extension cable.

I'm imagining all the things you could do with this. From automatic focal length measurement to all sorts of laborotory automation. How about a stop motion rig? :D

peter_ - in reply to Gav

This is exactly what I was hoping people would see and say! "Imagine all the things you could do with this!". While I'm trying to design an extremely low cost 3D printer to make it 3D printing more accessible, a set of CNC axis are so very generally useful.

You're definitely pegged a pretty fantastic design element -- you can make the axis pretty long, and only have to worry about sagging or a little support if you're using thin material. Conceivably you could cut (or print) the track out in sections, then just tack on as many sections as you need l
ength in the axis. Completely modular, and /so/ inexpensive.

This has about $7 of components in it -- $1 for the hardboard, $1 for the screws, and $5 for the stepper! :)

Why have the motor move at all. If you fixed the motor you could have rollers for the track to slide on so it was supported. very very cool. 8-)

That's definitely a design possibility, but that's similar to moving a table rather than having the (current) gantry design -- it would increase the footprint of the machine by double per axis, and for a 2 axis system it would increase the footprint by four times! Put another way, for a given surface area, your workable area would be reduced to one quarter of the size of that area, instead of the total area (minus borders) with a gantry system.

How are you designing the gears? Or should I say in what software rather?
Very good work bud. Wish this was around before I need my xy plotter for stepper code testing.

Ril3y

Thanks! I really hope people find it useful. I should have a new x/y version out soon, just wanted to hear people's comments before I did another iteration :).

I use a simple online generator to make the gears, and save them to a PDF when I print them. Then I import the PDF, copy out the gear, and there you go :).

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