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

[Davek0974]

I'm glad i titled this part as fairly advanced ;)

Sheet cam can't isolate parts of paths, only complete entities.

I have taken all the 3mm holes off the job now and will use a steel drilling jig to drill them as a second op, five of them must match up with another part that is drilled and tapped edge-on a strip of 5mm alu so this part must be jig-drilled and to make sure holes match both parts get jig drilled.

That also speeds up the time on the mill.

It seems i have 3 options now,

1 - remove the loops at the ends of the slots and jig-drill after, cutting just a straight slot

2 - as suggested, create a duplicate part of just that area and cut between roughing and finish passes.

3 - Create a new layer and put three straight slots and smaller loops on the ends on it and cut that between rough and finish passes, allowing the finish pass to take the loops to final size.

I think I would try opt 3 as a first go, seems to make most sense to me - 3 short slots opposed to a larger path.

[JAZZCNC]

Several ways to do this and my way would be just like gerry's with operation just on that area before doing the final finish pass. Cam software makes how easy or hard this is to do but if you Cam program that is restrictive then it's easy enough to draw in geometry soley for the purpose of Caming the part.

Like said before it's just knowing the Cam software and thinking a little differently to how Cam program might want to do it.

[Davek0974]

Its my brain thats limited i think ;)

Messing with various ideas now, as you said, thinking differently to get the job done that matters.

[Davek0974]

Thanks guys, it seems the best way is indeed to duplicate that small area onto a new layer, convert it into a complete entity and cut as a separate process before the finish pass.

I tried a few other options and none seemed to work correctly due to the odd shape of the slots but I think this method will do it.

Certainly getting some practice at the CAD and CAM stages anyway ;)

[Davek0974]

Seems to work in simulation, all the steps now make sense and total time in Mach3 was about 6m plus a tool change, not bad I think. :)

How do you figure plunge rate? Same as cut, half as much etc??

Its fascinating seeing the difference in manual machining and CNC, a real eye opener and I haven't even got to cutting a part yet;)

I settled on 0.6mm DOC for the 2mm tool when pocketing the fine parts and 2mm DOC on the 5mm tool for hogging out the holes and roughing outside, then the final pass on the 2mm tool at 4.9mm DOC.

I have high-helix carbide tools listed as suitable for aluminium etc.

Hopefully good to go as soon as she's finished :)

[JAZZCNC]

How do you figure plunge rate? Same as cut, half as much etc??

Think you know this already but if at all possible then don't plunge ramp or spiral into material. In Both cases you want to enter quickly possible to stop heat building up in tool so use same feedrate. If you must plunge then 50% feed.

I settled on 0.6mm DOC for the 2mm tool when pocketing the fine parts and 2mm DOC on the 5mm tool for hogging out the holes and roughing outside, then the final pass on the 2mm tool at 4.9mm DOC.

When doing the pockets I'd spiral down full depth 5mm and cut full depth with 40% step over. Why waste the flute length.?

[Davek0974]

Thanks Jazz, all noted.


Dave