Tiny CNC machine - fun and fast to build...

[Chris D]

Hi Guys,

I spent a few days designing and building this machine. It's original purpose was to be used as a pen plotter. I am designing some motion control electronics and software (for personal use) and needed something more than spinning stepper motors to visualize the accuracy of those. So, I spent a day designing a simple and small bed mill style 3 axis machine. It is small, the table size is 8-1/2" x 11" and the Z axis travel is around 3 -1/2".

It took most of two days to build it and, for once, most of the materials I had laying around the shop so I didn't have to spend much to build it. In fact, I spent more on sealer and paint, than the rest of the machine (keeping in mind I am not counting the original costs of the "scraps" used to build it).

It is primarily constructed from MDF, with 8020 extrusions for the ways. Saddles are backed wth UHMW pads. Lead screws are SS 1/4-20 threaded rod - hand picked at the hardware store for straightness. Nuts are Acetal, and mounting hardware is 1/8" aluminum angle. The tiny motors are cute little Nema 17 motors - I suspect they should have enough guts to move a pen, but you just never know

During construction, I realized I built it a bit "heavy" for a pen plotter, so I thought I might as well plan to try it for some light milling (I do some PCB drilling etc.). I have a much larger CNC Router, so I have no "dreams" of this machine being a "heavy cutter". Anyway, I have a pnuematic pencil grinder that is about 5/8" in diameter, so I bored the hole in the headstock to accomodate that as a spindle (when I am not using it as a plotter). Don't know if it will work for milling / drilling, but you just never know, sometimes life throws you a little surprise.

I just thought I would share with you the little machine and to show you that there are other machine configurations besides the oh-so-typical gantry type. Hope you enjoy or perhaps even get some inspiration or ideas.

Chris

[rippersoft]

Way cool! Are the UHMW pads bought to fit the 8020 or did you mill these yourself? How well does it slide. I have heard pros and cons on plastic bearings.

Good job.

RipperSoftware

[Chris D]

Originally Posted by rippersoft Way cool! Are the UHMW pads bought to fit the 8020 or did you mill these yourself? How well does it slide. I have heard pros and cons on plastic bearings. Good job. RipperSoftware

I had some UHMW on hand, so I just milled up the pads. Most of them are very similar in size/shape to the 8020 pads. I would have used theirs if I had them on hand.

There is nothing wrong at all with using UHMW on aluminum extrusions - it is a very slippery interface between the two materials. It is very tolerant of dust and chips - perhaps not so tolerant of solvents etc. For dry cutting machines such as routers and PCB milling/drilling, it is a very good combination.

Don't know what others have said or told you, so I don't know what they are saying is bad about it. Frankly, for a dry cutting machine, like a router or PCB mill, I would take aluminum/UHMW over the "Gas pipe and bearings" combination. I mean let's face it, gas pipe is about as accurate as a baseball bat :-)

Chris

[ViperTX]

Chris....that's a nice looking little machine...congratulations.....

[ZipSnipe]

Looks very pro, job well done. Looks like some of that is cast, you do the casting yourself?

[CNCRob]

Looks pretty cool, Very well done.

[zoltan]

Hi,

Do you have any plans of the machine. The machine is cool. Could you share the plans with us???

Thank you,

Zoltan

[carlnpa]

Very nicely done..I like uhmw on 8020 myself, my experience follows yours, easy accurate, slippery, bearing. Try a little silicone spray for really free moving. Really much better than the pipe bearing setup which I have used and have partially relaced with uhmw/8020.
Thank you for the ideas.
Carl

[Chris D]

Originally Posted by ZipSnipe Looks very pro, job well done. Looks like some of that is cast, you do the casting yourself?

Sorry no castings here, this machine is made from MDF. Remember, it's original design purpose is that of a pen plotter.

Chris

[Chris D]

Originally Posted by zoltan Hi, Do you have any plans of the machine. The machine is cool. Could you share the plans with us??? Thank you, Zoltan

I don't know yet. Sometimes these things have a funny way of turning around from a "hey, here are some free plans and have fun building it" into a nightmare of:

Why did you do it that way...
I want to use (insert thing here) instead of (insert thing here)
Can you re-draw the machine in metric for me
Can you tell me where to purchase the brackets
I don't like the colors, can I paint it a different color?

Sorry to sound so nasty about it, experience shows me that often times a good gesture can turn into "freebie hunting feeding frenzy" that ends up being work rather than fun.

I don't know, I will think about it.

Chris

[Chris D]

Originally Posted by carlnpa Very nicely done..I like uhmw on 8020 myself, my experience follows yours, easy accurate, slippery, bearing. Try a little silicone spray for really free moving. Really much better than the pipe bearing setup which I have used and have partially relaced with uhmw/8020. Thank you for the ideas. Carl

Yes, the silicone spray is "magical"!

I don't mind using the "pipe and bearing" method, as long as Gas pipe isn't used

[joecnc2006]

Originally Posted by Chris D I don't know yet. Sometimes these things have a funny way of turning around from a "hey, here are some free plans and have fun building it" into a nightmare of: Why did you do it that way... I want to use (insert thing here) instead of (insert thing here) Can you re-draw the machine in metric for me Can you tell me where to purchase the brackets I don't like the colors, can I paint it a different color? Sorry to sound so nasty about it, experience shows me that often times a good gesture can turn into "freebie hunting feeding frenzy" that ends up being work rather than fun. I don't know, I will think about it. Chris

I agree with you people like to have alot of things handed to them, I provide dwg files for my model 2006 machine, and some people want me to diminsion everything for them. I do not mind sharing but I do not want to spend all my time doing all the detail fork for them, when they should just study the files and make the descisions them self. it really is not that hard.

for the most part most people take the ball and run with it, but there are a few that want everything, and this in itself is not good, because what if something does not work well for them and they do not know how to do a workaround for it they will be stuck and get a bad taste in their mouth about the whole thing.

joe