CNC milling for under $400

[clarkspeed]

I have been geeking out on this thing for about 3 months now and posting on other forums and FB. I even have a magazine interested in seeing my setup. A 3D printing colleague told me about this possibility about 1.5 years ago and it sounded like total BS. So I started digging around the internet and found the V1 Engineering website and their MPCNC (mostly printed CNC). It has a very good support forum and some amazing project results for a small investment. So I took the plunge just to see what it could do. I slowly acquired all the parts over a 3-4 month period. When I finally had a break on my 3d printer I ran all the parts needed. I assembled this thing in a couple hours, ran a test print with a Sharpie pen, then ran some pockets in wood. I immediately put an aluminum plate on the bed and it went right through it. My eyes were, and still are as big as saucers everytime I use this thing. I have now progressed to mild steel and seem to be advancing the machine capability for the rest of the user base. Just like the 3d printer, I have suddenly found 50 projects I want to do, and so far, just ripping through them. Truth be told, it is not a simple process to produce parts and it is not super fast, but if you have either machining, programming, design, or 3d printing experience, you are already ahead. And if just cutting flat plate, even better. And the satisfaction of seeing a machine you built making chips is better than sex. Well not really, I exaggerate, but I think it is still super cool. 

[calZ]

I've looked into a lot of the CNC router options that claim they're capable of cutting aluminum, but I've never been convinced the stiffness is there to get super accurate. What kind of tolerances are you capable of holding?

[Derek]

Is that built out of GPO3? 

[clarkspeed]

The only tolerances I have checked were just spot checks to see if I was in the ball park. Seemed to be well within .010". I have not run anything that demands better than that but a lot depends on the style of cuts you do. I am most off in the Z axis, but that is due to my inconsistent way of setting 0. Eventually I will add stops to the machine to eliminate that problem. If you build the machine correctly, success with metals is quite easy. But after running it into the ground for a couple months, I have found consistency to be the main issue. Anything that can loosen up will loosen up and it is not always easy to identify the problem. But by modifying a few parts, lock-tite, and a maintenance schedule for tightening, I am getting much more consistent results. When I am happy with that I will concentrate more on accuracy and precision.  Although a few people have done it, I would not use this for continuous production work in metal. But it seems OK for some nice 1-off parts.  I think a few guys have used their large format machine for cutting sheet metal shapes out of 4x8's which I found interesting.

 

Derek, I had to Google GP03. If you are referring to the walls that is just plywood. If you are referring to the machine parts, it is just a good quality 3d PLA filament. I think it is one of the most rigid materials you can print with. You just can't leave your machine out in the Florida sun.

[clarkspeed]

I just ran some aluminum buttons that sit on top of my spring perch top hats. Holes and diameters seem about 0.010" off. But again I suspect the precision is fairly good and more a problem of accuracy. I think with the little practice I could dial this in if I need to. In the next few weeks I want to run some positional location tests to see how accurate I can center punch holes.

[Dat73z]

Looks neat. Do you have any closeups of the surface finish you are able to achieve? 

[clarkspeed]

Here are some shots of my test parts. It looks like most of my tolerances are around 0.010". I am starting an upgrade to hopefully bring that in. My goal is at least center drill hole locations within a few thousands. Surface finish can be as good as you want . The pics all all rough cuts without a finishing pass.