[dzeta]

Hello everybody,
I started to design a desktop mill based on pocket NC and robotdigg just for fun but now I'm wonderning if it would be possible to actually build it.

Curently the machine is roughly 450*450*570 without the enclosure

Here's what I want :
- High dynamic
- At least .01 repeatability
- High rigidity
- Process aluminium "efficiently"
- An enclosure for coolant
- Steel frame
- 100*100*120 working area

I have a few years experience in 5 axis CNC machining but absolutly nothing in design nor electronics so I could really use some advice on few things :

1) I overlooked all the calculations needed during the design process so I used placeholders for the spindle, servos and the belt and pulleys so i need some guidelines to properly size the servos and ballscrew

2) Do I need to make a proper bed or bolted steel plates can work ? I think I need some weight

3) Do closed loop servos need home switches ?

I forgot to mention but i don't intend on making this build profitable. It will take the time and money needed.

[awerby]

It's hard to say anything about your project from what you've provided here. Is this going to use a trunnion, or have a pivoting/tilting spindle? It's easy to specify all the things you want it to do; making it actually do them is harder.

1. A small machine like this doesn't need massive motors or screws; the structure needs mass, though.

2. I'm not sure what you mean by "proper". Welded steel holds together better than bolted, but the process introduces distortions that have to be dealt with. Fortunately small weldments are easier to heat-treat and grind than large ones.

3. Home switches make it easier to establish and re-establish position if the process is disrupted or a part is replaced in a fixture, but they aren't absolutely essential to the function of a servo motor.