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CNC-2116 - Up and running, sort of (2015-03-21)

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Yvan256:
Sorry for the lack of updates but this whole project is driving me nuts, in a good way. People who have a CNC machine probably know what I mean.  :cheers:

I've done a few tests on my old Roland MDX-3 and found that it can cut MDF pretty easily but I have to go extremely slowly and with extremely thin cuts. We're talking about 0.005mm deep cuts at something around 30 cm per minute. Doing a 20cm hole in 3/8" MDF takes around 15 to 30 minutes... I forgot to time it so let's round the value to "forever".

The reason it's so painfully slow is because this machine wasn't designed for such hard materials and the spindle motor is barely up to the task. Using a 3.175mm end mill surely doesn't help but it's all I could find locally.

I still don't know how to use Mach3 or LinuxCNC but since the MDX-3 is basically a printer that you send text files to, I did the test cuts with a PHP program I wrote. I plan on making the whole thing available as a "dirt simple 2D" program. I'll try to have it able to export both g-code as well as Roland's own format. I'm also writing a "2D Roland Web Simulator" to have a top-view of paths for 2D-only Roland Modela files. It's great for debugging. :D

Seeing the results with such a weak spindle, however, has led me to rethink my bigger machine. The first version will use my Dremel 395, I already bought the bits #115 and #650 for resurfacing and milling, respectively. The planned upgrade is to switch to a Black & Decker RTX.

Since both the Dremel 395 and the Black & Decker RTX are extremely lightweight, the whole CNC will not require to be built like a tank, helping keep its weight down and helping with the portability factor. Ideally I'm trying to have the whole thing designed as an oversized briefcase so it's easier to carry around.

Given all this new information, the goal is again to have a milling area of 20x24x1 inches, the shorter Z axis should make it easier to keep it strong and as flat as possible to keep it "briefcase-like", with removable Dremel/RTX. Yes I know, a 24x28x8 inches briefcase is going to be huge...

Attached are test cuts done on a variety of materials such as old membership cards, hardboard and recycled plastic containers. As you can see from the photos, some tests went better than others.  :P

But at least, I'm having fun!  :D


2012-12-17-4.jpg is a NEMA 17 motor mount gone terribly wrong.

TopJimmyCooks:
subscribe  :cheers:

Yvan256:
The MDX-3 was busy yesterday after my last post, cutting a test part out of 3/8" (~10mm) MDF.

The motor was taken from an old 5 1/4" floppy drive.

tightwad:
I love your progress and I am working on re-working my mini-cnc machine.  It has never had the accuracy I wanted and the Z axis had play in it which wrecked havok cutting anything more than foam.  I needed to see various bearing options.  I found great prices on the 608ZZ bearings on ebay...I think I paid about $0.50 each for the ones I bought in the past.

Yvan256:
Yesterday I noticed that the horizontal cuts were not at 90 degrees. The MDX-3 had some slack in the horizontal axis assembly so I had to disassemble part of it just to access the bolt that had gotten loose. Really bad design as far as maintenance is concerned. :angry:

After tightening the bolt and putting it all back again the results were much better. I have not measured it but at least just looking at it you can't tell if the edges are straight or not. A great improvement!

I asked the neighbors below if the noise of the machine was annoying and their reply was "what machine?" I told them that if it ever was a problem to simply come and tell me. The fact that the machine is sitting on five layers of oversized bubble wrap sheets seems to prevent the vibrations from reaching the table it's on.

Since I can run the machine all day from my apartment, I plan on making the new bigger machine completely with the MDX-3 using smaller plates that bolt together. The bigger machine, once assembled, will be able to cut continuous replacement panels for itself if needed. The MDX-3 can only cut parts about 150x100mm, so that's quite a challenge indeed. The more I design and build, the more I'll see if it's possible. The number of panels will be high to say the least.

So this morning I started to design my new machine, starting with the Dremel 395 mount. I plan on designing and cutting the machine from the inside-out, going from the tool holder to the Z axis (top/bottom), then the X axis (left/right) followed by the Y axis (back/front).

The photos below are the first version of the bottom Dremel mount holder but I will have to cut it again. The two small round holes were supposed to be for cross-dowels but these were made for 5/8" panels and I'm using 3/8" MDF because of the cutting height of my end mill bit.

I'm currently cutting bolt+washer+nut assembly test plates so that the next Dremel plates will have the proper assembly holes.

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