Questions on using a moving gantry style mini-mill...

[Davek0974]

That's the point - there is no all-round, which is why it failed. The base metal is only just over-size for the whole job, once the perimeter is roughed the only fixture it has is the middle strut and that only had the tiny tabs or possibly onion skin - just not enough meat.

No offence taken JAZZ, speak your mind ;) There is a long story with these parts, not for here but suffice to say I have customers waiting and really wanted to get them done myself instead of farming them out - this has applied some undue pressure but I think I can win still.

My experience is all manual - I'm used to throwing in a 1/2" cutter, clamping the metal down and diving in at full depth and adjusting the feed to suit as I'm twiddling the handles. The learning curve here is staggering, my presumptions were originally to use a feed and speed guide - set those parameters and have at it - this was wrong by a long-shot and I realise that now. It probably explains why 90% of the videos i have seen on youtube are all running very light cuts.

There is a slim chance that the loss of power on the spindle is connected with my odd VFD issue - maybe it really is a duff VFD after all - the new one should arrive tomorrow and i'll be fitting that before running any more tests - another good thing with a UK supplier is that help is only a call away and they are very helpful ;)

I will get that set up, check my Z axis calibration, then run some simple tests on scrap before diving in again. The new cutters will be here for the weekend and I will switch to a more softly-softly approach to feed rates as it seems most others do.

[JAZZCNC]

The new cutters will be here for the weekend and I will switch to a more softly-softly approach to feed rates as it seems most others do.

Not too softly and most do cut too slow or too shallow but it's good idea to find your feet first before gunning it. When your settled you'll be surprised how much you can push the limits with right tooling and feeds etc.

If part has decent area to it then Double sided tape can work well if your not using cutting fluid or light amount of fluid.

[Davek0974]

Will try the DS tape, good point.

Would you agree with the "few heavy tabs and remove last" idea??

[JAZZCNC]

Dave this what I meant when said Aluminium bed is Ok but often you'll have Spoil board on it. So here's what I would do.
Fit spoil board that can be screwed into and surface it. Then I would change the Code and move the smaller part in wards and drill holes put screws where I have black circles on your last pick.

Then onion skin the both parts with about 0.3mm. Doesn't matter the large part will not be held down one side the rest will old it.

The skin then just breaks away and quick cleanup with De-burr sorts what's left.

I do this type thing all the time in shity 1050 2mm plate and works perfectly.

[Davek0974]

Points noted Boyan, BTW the coolant is working nicely - the cutter was clear even during the heavy cuts.

Jazz, the two screws in the small cutouts - they would be fitted after the finish pass on this features?

Spoilboard - MDF?
What sort/size for facing cutters?

[JAZZCNC]

Points noted Boyan, BTW the coolant is working nicely - the cutter was clear even during the heavy cuts.

Jazz, the two screws in the small cutouts - they would be fitted after the finish pass on this features?

Spoilboard - MDF?
What sort/size for facing cutters?

Yes screws with washers in cut outs after finish pass on pockets.

MDF, ply anything that can screw into really.

Facing cutter then widest you have but with such small piece then wouldn't take long if small.

[JAZZCNC]

Actually to be honest dave if spoil board is resonably flat then just for this job won't even need surfacing because your only profiling. The main reason I said surface is because 0.3mm isn't much so can easily cut thru if not flat but if you want to have thicker skin then don't bother with surfacing.