3-Axis CNC Mill Project

[Hobgoblin]

Just to clear a few things up.


I do welcome the feedback and criticism good or bad as it helps to keep in mind the planning and checking process.


The purpose of this project for me is, first of all just to be able to, and then for as said engraving, hard woods, plastics (acrylic lexan etc) and possibly aluminium. This isn’t unachievable with this setup, however trying to skim a cylinder head or reproducing engine parts is.


Achieving a level table, parallel axis and zero backlash can be achieved with the right setting equipment, depth micrometers height vernier's DTI's (which I can borrow freely as I do this stuff for a living but on a much greater scale), as for backlash if any is present when finished this can be compensated for in the software I intent to use to control the machine.


Vibration and tool chatter will be a problem in certain situations and of course it won’t be as easy to overcome as removing some of the inserts from a cutter to stop such resonating because this isn’t a large machine with a large face milling cutter.


But I can only try to design what I can afford for the intended purpose and strengthen it where possible. Reducing depth of cut, feed per tooth per rev, spindle RPM tweaking all the basic parameters if in a situation where I’m still getting chatter/vibration.


I was actually quite impressed by the overall mass of just the base once it was assembled and it certainly isn’t flimsy stuff even the 20x80 is very strong.


I have considered making some brackets coming off the bottom corners of the frame that, once the machine is levelled at the base, will also bolt into the ground.


In the final stages of designing the next steps at the moment, all the planning for the traversing carriage, the guide rails, ball screws, stepper motors, and brackets needs to be carefully considered so that I don’t encounter any parts fouling on others.


The machining area should be about 400x500x150mm when complete but thus depends on how things develop; there will defiantly be room for A3 though.


Thanks.

[John S]

as for backlash if any is present when finished this can be compensated for in the software I intent to use to control the machine.




Thanks.

Backlash compensation in software is a fudge at best.
When a cutter is doing a circle, at the 4 quadrant points the tool is free to move and will grab in the climb milling direction whilst the software is working out which way to go.