Open source group project, anybody interested?

[Ross77]

Plenty of interest then.

Defining mid range could be a problem. linear rails, ballscrews and vfd spindle seems quite high spec to me....

theres enough flexibility for people to use what ever they need to suit their requirements. Although I dont think it wouldnt be very economical to mount a dremel on a machine designed to take a heavy vfd spindle?

Thanks Irving. thats perfect, knew I'd seen that somewhere. Is that the rotational force of the motor or the force required to push the axis?

If high speed is needed then would it be better to use belt drive? or would that cause problems with higher powered motors?

For the drivers has any one else seen the "CPLD tutorial" on cnc zone? from memory :whistling:

80V @ 7A with 5 micro steps and works out at £10 to 15 an axis. The only drawback is the chip is a tiny SMD so not very diy friendly. It was proposed to mount a preprogramed chip on a separate daugther board that could plug in to a 40 pin wide DIL and be sold cheaply so people could then build their own but it was never realised. any takers?

[irving2008]

Plenty of interest then.

....

Thanks Irving. thats perfect, knew I'd seen that somewhere. Is that the rotational force of the motor or the force required to push the axis?

No thats the effective linear force pushing back on the cutter. For deflection calculation purposes assume its both perpendicular and parallel to the direction of cut . For leadscrew/stepper torque calcs assume it adds to the load opposing the motion...

Also note in the previous calcs, a screw rpm of 360 means a minmum of a 12mm dia leadscrew for a 1m screw supported drive end only, or 16mm for a 1.5m screw assuming supported both ends (class B support). For bigger 2m screws you're into 20mm+ ballscrew class C support territory and big bucks.

[Ross77]

Thanks Irving thats what I meant but I pharsed the question wrong. I seem to have a problem getting the thoughts in my head to paper lol

is that 20N a worst case or would it be better to up it a little? Have you got any info for other materials or a table maybe?

I'm starting to see what you mean, this aint going to easy........efficient design isnt easy to build and requires good machining, sounds like the chicken and egg situation I'm in at the moment :heehee:

With regard to the design is space an Issue? ie. overall size. Because I cant help but think that this needs to be a fixed gantry design. The frame could then be as heavy as required and just move the table underneath. This would mean its twice as long tho.

Kip always said "router for routing and a Mill for Milling" or something along those lines.