Could this CNC machine design probably work?

Hi boys and girls! :slight_smile:

I had the idea of building an arduino powered cheap cnc machine
as a starting point of many projects that there
will come (pcb routing, prototype and case building etc).

Unfortunately my first attemp failed. :frowning:

Design failures:
1. The Y-axis was not in the middle. So the
portal moved asynchronus with 1-2mm appart. Bad.
2. The X-axis was too long and the supporting rails too near to
each other for my cheap 5mm leadscrew. So the axis bend back and forth.
Besides I wanted to use the full Dremel so it was way to heavy
and the axis bended even more. Really bad.
3. My overall design was too big for the cheap parts I used.

I hope I have learned from my design failures
and I came up with this design:

New design:
1. All parts will be manufactured out of 6mm MDF wood.
2. I have access to a Xing 4030 lasercutter machine
3. Working area will be approx. 15015040mm
4. The Dremeltool will be mounted with two hook-and-loop fastener at the
back and connected to the z-axis with a flexible axle.
5. The rails will slide through bearings
6. The leadscrew will rotate through bearings
7. Every axis will have two limiting switches
8. All electronics will be at the back (Maybe I wanna integrate a LCD
and a sd-Card reader, not sure where to place them).
9. On/Off Button
10. 12V Input
11. USB Input (from Arduino)
12. A fan for the EasySteppers
13. 8mm rails
14. 5mm leadscrew
15. The machine it selv will be 34x25cm and a height of approx 30cm (with stepper)

So my question is:
Could this CNC machine design probably work? :slight_smile: Realy I dont want to fail again…

A few renderings of my new design:







Nice drawings. How did you produce them?

The only potential issues I see are from manufacturing tolerances and misalignment and undersized parts. Only you can control the manufacturing process(es). You have given no real details on the bearings, rods, stepper motors, etc.

Could it work? Yes. Will it work? Can't answer that. If you take your time, cut all parts accurately, and align everything correctly, then the chances are good that it will.

store.makerslide.com has some inexpensive, v-rail, aluminum extrusions you might want to check out.

I dunno if I like your use of a Dremel flexshaft. If you've ever used one you'll notice that they don't like much bending and the line between the cutter and motor is going to put pressure on your gantry. If you added some kind of tall hook to hold the Dremel motor above the table it would work better.

One addition I'd suggest is a limit switch that you can touch the cutter against to get a good cutter-height-above-the-table reading. Without one you'll have to recalibrate the height by hand any time you change the cutter.

...and I agree with PaulS; very nice drawings.

Your design looks pretty typical of entry-level DIY machines so it should work OK. I agree that the flexible shaft probably is not that great in that application for the reasons mentioned by Chagrin as well as the fact that there will be a power loss in the shaft. Better to just mount the Dremel tool on the Z slide. I would highly reccomend looking at the wealth of DIY designs documented on CNCzone (http://www.cnczone.com/forums/diy-cnc_router_table_machines/) if you haven't already. I spent a lot of time looking at other peoples machines there before I built mine and was able to build a very capable machine that has served me well for over 2 years with no problems. A word of warning though: CNC is [u]extremely[/u] addictive! Although it seems to be a popular idea, I am dubious about using an Arduino as a CNC controller. You give up a lot of functionality that is available from either LinuxCNC or Mach 3 and as you still need a computer to serve as a GUI I can't see where anything is gained. For my machine I use a 10 year old PC I got for free running LinuxCNC. Outside of the cost of the motor drivers and power supply the only other hardware expensive was a breakout board for the parallel port which cost about as much as an Arduino.