Saturday, March 31, 2012

CNC - Part 2

EDIT: Some new pictures of fresh PCBs can be found here. END EDIT

My last post talked about the CNC machine I built. This time, I have some pictures, and a little information I gained since last time. This will mostly be a gallery post.

This is the design mine was based off of

This is how it came out (pretty different)


A Dremel from eBay (chosen for its cylindrical shape)

12 TPI lead screws (less blurry in real life)

Delrin Nut (chosen for strength and low friction) that fits the lead screws

Rails and structure
Motors, EasyDrivers, and other circuitry to interface to the computer
    So these are all the parts that went into it, really. I'm sure I'm forgetting some stuff, but these are the main elements. But now, let's move to the fun part!

    These are the files I've produced and milled. They were made using, which I found here. I milled them using a 30ยบ V bit, putting at a 0.01 inch depth, giving me a 0.017 inch cutting width. The material I'm cutting on is a "dog tag" from the school my brother and sister go to. On the other side, they have a symbol for theater or something, so you would receive one if you participated in the school play. They let me use theirs.

Do-do-doo, do dodododooo... It's the Nyan Cat!
    A funny little story about this one. I asked my brother if he wanted the Red Sox logo or something on the back of one of his tags. He said, "No, I know exactly what I want: the Nyan Cat!" This was totally unexpected and really funny. So we found the image, processed it, and milled it out.

We did a couple of other dog tags, too 

And here, of course, is my logo! A bit faint, but not too bad
    So there they are! I'll try to go into more detail about later, as it's really helpful but has a difficult learning curve. Hope you enjoy these etches! The next step is circuit boards!


  1. I'm the guy who from HAD whose been trying to build one of these for a few months now. Seems like this came together pretty easily for you - do you have a background in shop skills / fabrication? How long did it take? What kinds of tools did you use (and were they cheap, or professional quality)?

    I wanted to see if I could build a single axis to play with, but after a couple months of trying to build one, I could never make it move smoothly. Maybe my shop skills aren't good enough, not sure. The Mantis project seemed to lack a lot of important information for me, such as HOW to properly fabricate the required parts.

    I blogged my experience and collected posts / data here:

    Here's a video of one of these 'test' axes, notice how 'sticky' it is. I've tried self-aligning bearings, as well as sanding the rods a bit, but nothing helped. Eventually I decided to stop :(

    Any advice? :)

    1. Hi!
      I have pretty limited fabrication skills, at least in the skills needed to make this machine. There is a file on the makeyourbot wiki that was intended to be sent to a ShopBot, but it turns out you can load it into Sketchup and measure the dimensions of all the parts. I got these measurements and cut them out with a power saw. For the matched holes, I had a friend do the drill pressing, though it looked very straightforward. I agree, though, the website is pretty vague on how to fabricate the machine...

      I looked at the link in your Vimeo and found on thing that I might have changed. It sounds like you got some rod at a local hardware store? I decided to get these 'precision rods' from McMaster-Carr. I think they are machined from a much harder steel, so they are perfectly straight. Using those and some WD40 along with the same bushings you used, I had great results.

      You should keep going with it! It took me about three months on and off to get it all working, and it still needs some adjustments. I really love having it though. It makes circuit boards and I'm learning a ton about Linux systems and 3D modeling and so much other stuff!

    2. Thanks! I think you're right: precision rods seemed like the solution to me at the time as well, but I was so burned out from trying to build it with what I could afford at the time that I lost heart.

      However, I can now afford to get the 'good stuff', so I think I will order those precision components and give it a go.

      I'm really surprised you only used a power saw to make the cuts! How did you get the cuts to be so exact? It seemed to me that even a small difference of ~0.002" could cause jamming - how do you achieve those tolerances with basic tools?

      Thanks for the encouragement, I'll give it another go :) I was planning on making my machine a bit larger than the original Mantis (but based on same structure) and using it to make rubber stamps, stencils and etchings for printmaking.

      I really like your spindle assembly! Could you share any more info about the design files or BOMs you came up with? A Dremel seems like the smartest option for general projects, but I did notice a small amount of 'jitter' in the pieces you produced. Do you feel like it can be overcome with more tweaking? I wonder if at least some of the jitter is due to software settings + source file resolution as well. When I get my hardware up and running, I was planning on trying to hook into ReplicatorG, as it seems like a pretty popular and well-supported program these days :)

    3. The precision rods have worked excellently for me! Definitely a higher upfront cost, but it seems worth it. I'm glad your trying again!

      I think that it's not a matter of how precise the saw is, but the holes. As long as the bottom and back edges form a ninety degree angle, they can be lined up to each other. For example, I cut out both side pieces and used some scrap boards to line up the bottom and back edges (they were longest) and then drilled it. When I was putting it together, I had the bottom edges mounted on one board and the back edges on another, so they were lined up just like I had drilled them. Sorry if that's a bit unclear :).

      I liked the Mantis for the same reason - it looked like if I wanted to make it bigger later, it wouldn't be too difficult.

      I don't have a design file for the way the Dremel is mounted, but I could easily make one, or just send you some pictures. I'll try to put it in Sketchup and either post it or send it to you. I agree with the jitter issue. The things I posted here were really my first ones. I was using a conical bit to cut them and duct tape to hold them in place. I got a 1/64 end mill for circuit boards and things came out much better. Have a look at the newest post - I haven't tried ReplicatorG. I thought it was for 3D printers, but I guess they are kind of the same thing as this. EMC2 has worked great for me, but it is a whole Linux distro, so you can't do all your normal computer stuff.

      Best of luck!

    4. So I cooked up a Sketchup version of the X-axis carriage, the part that holds the Dremel and Z-axis stepper motor. You can download it here -

      If it needs any clarification, just respond!

  2. Nice! That helps! I'm just about ready to build my Y and X axes, so I've been thinking a lot about the Z axis assembly this week :)

    Did you take the Mantis' lead and epoxy the Z axis stepper motor into place? I'm thinking of mounting mine on top, pointing down, but we'll see. Also, in the second picture of this post, I see what looks like a flat metal strip bent into a curve coming from the top of your Z axis, almost where the leadscrew might be traveling - what is that?