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

[Davek0974]

Will be using two Mach3 profiles. Only one spindle will be in use at any time.

Looking for ways to switch all the control lines needed -

Vfd supplies
vfd control and fault lines
vfd speed lines
limit switches for Z axis in two positions
homing for z axis in two positions
cooling pump for 24k spindle
probably others....

The programming for the CSMIO plugin I gather will need to be the same for both profiles?

[Davek0974]

Odd programming?

I am cutting some plate for parts on my Bridgeport conversion project, had some good success and a couple of oddities. The most annoying one is my motor VFD has shut down twice now with an error that shows as short-circuit on motor phases, each time i reset and it carried on ok, there was a month between faults - the annoying part is i don't have the fault relay in my e-stop loop (yet) so the motor quits and the motion caries on - snap goes another £8 tool :(

The rest of my issues are experience, or lack of, related so in the end i worked them out, but I'm getting pretty good at re-homing and starting over with modified code ;)

[Davek0974]

7000rpm on a 8mm 2-flute cutter too much?

Just been trying to carve a lump of 18mm thick ally for my Bridgeport conversion, using a 2-flute 8mm HssCo tool at 7000rpm, 900mm/min and 1.6mm DOC

All the features went without hitch, the perimeter decided to bog-down after getting about 9mm deep and stalled the axis.

I have a feeling the height of the wall blocked the coolant/air and allowed the tip to build-up. I need to fit two coolant jets i think at 90deg to each other.

I have re-cammed the profile starting from 8mm down and increased rpm to 8000 and reduced step-over a little.

Will see what happens tomorrow.

[routercnc]

Hi Dave,

That used to happen to me a lot. Slot milling over 8mm risks poor chip evacuation and clogging of the tool. I've seen people machine the outside material completely away (i.e. an outer pocket to leave the central island, not a perimeter slot). But then you need to be able to hold the part in the middle which isn't always possible.

Another option is to use something like adaptive machining to mill a larger width slot than the tool.

I tend to reduce the DOC when over 8mm into a slot and that works OK. I vacuum out the slot on every pass and give a quick spray of WD40.

[Davek0974]

Adaptive does look good but none of the CAM software i have can do it.

I tend to pocket the part out, leaving tabs etc to hold it, on the 8mm tool i used a 12mm pocket so two passes, but when the tip is deep in the pocket the air/coolant cant reach it and i was not paying enough attention i guess.

I'll see if i can rescue the part with the modified paths and some extra air blast.

[Davek0974]

Beginning to think i may never get this part cut :(

I increased the speed to 9000rpm, and dropped the feed-rate a little as well as reducing the DOC a little.

Good news was that it picked up the position ok.

It made it about three passes then bogged down again, this time i hit the stop button pretty quick.

Restarted and after a couple of passes cutting air, the motor turns off!
No message on the VFD or screen.

I gave up at this point and went in for dinner.

So, why would the motor turn off if Mach did not know and there was no fault on the VFD?

[Davek0974]

No idea why the motor turned off, it run ok tonight. Even managed to get the part finished.

Reduced DOC to 1mm, feed rate to 800mm/min and rpm up to 9000.

I think the issues may the cutter itself, not being designed for aluminium, just a standard two-flute slot drill.

Now i need to flip it over, align to the axes and find an accurate way of picking up the x&Y datums.