incorrect feed rate

[blarkscnc]

Quick sanity check is to program a move along your longest axis and time it. Calculate a feedrate that should take a round number (10 seconds maybe) and use a stop watch. This will let you know if you're in the ballpark.

So command a 120mm move at 1200mm/min. Should take 6 seconds.

Don't feel bad - I've had to do this myself from time to time.

Thanks for the reply spumco, although I'm not really a gcode master, but if I do x200 f1200 the "fset" is at 1200 but the "Fact" is at 3000 which is what I have set at max velocity. So not sure if thats the right command I have done or not, yep I'm a noob alright.

*edit* ok I have figured out my gcode mistake will try the stopwatch again.

[ger21]

But if I go by the this it is saying 1200 and cutter breakage continues until I get down to 30% (360). So either the readout is wrong or the actual feedrate of the machine is wrong but uccnc is reading it as 1200. But I know that at that feed of 360mm/min cutting alloy was a disaster.

That doesn't mean that the feedrate is not correct.

[blarkscnc]

Quick sanity check is to program a move along your longest axis and time it. Calculate a feedrate that should take a round number (10 seconds maybe) and use a stop watch. This will let you know if you're in the ballpark.

So command a 120mm move at 1200mm/min. Should take 6 seconds.

Don't feel bad - I've had to do this myself from time to time.

ok so it is about 6 sec. redid another operation just a simple pocket and another cutter broken, not many left, been an expensive excersize so far. I don't quite understand how a feed rate on a certain material can differ so much from one machine to the next. Alloy is alloy regardless of the machine.

[spumco]

Next sanity check:
Please post:

1. Material being cut
2. Cutter diameter
3. Cutter # flutes
4. Cutter material
5. Cutter coating, if any
6. Depth of cut
7. Width of cut
8. Cutter RPM

And we can double check that the cutting parameters are reasonably appropriate - regardless of whether it "worked before" under other circumstances.

[spumco]

but if I do x200 f1200 the "fset" is at 1200 but the "Fact" is at 3000 which is what I have set at max velocity.

I just noticed this...

Exactly how did you program the move in the MDI (manual data input) field?

Did you program "G0" or "G1"?

[blarkscnc]

but if I do x200 f1200 the "fset" is at 1200 but the "Fact" is at 3000 which is what I have set at max velocity.

I just noticed this...

Exactly how did you program the move in the MDI (manual data input) field?

Did you program "G0" or "G1"?

No I sorted that out, yes I did G0, my mistake

Next sanity check:
Please post:

1. Material being cut - 6060 and 6061
2. Cutter diameter - 2mm
3. Cutter # flutes - 1
4. Cutter material - Carbide
5. Cutter coating, if any - none
6. Depth of cut - .3mm
7. Width of cut - 10mm pocket but obviously using cutter diameter
8. Cutter RPM - approx 13000, but I did go up and down to test.

And we can double check that the cutting parameters are reasonably appropriate - regardless of whether it "worked before" under other circumstances.

Thanks for the help spumco much appreciated. I think the feed rate is correct after much research and a little bit of math. I tried a 3mm single flute at 1200 .3mm DOC and was better but went south a little bit after a few runs. I've gone through about 12 2mm cutters today so I'm a bit grumpy and bewildered why I seem to be getting random results. when I had the operation which was set at 1200mm/min and reduced to 30% the 2mm cut was fine then it wasn't. tried the 2mm on the stepcraft with an operation that I had done before at 1200 almost instantly snapped 2 cutters. went to 3mm cutter same feeds and was ok on the stepcraft then started to get built up edge when I wen to the cbeam machine, maybe the cutter went dull? As the settings are what I used before, I cut out an rc shock tower see image, and now it seems the settings are not working or for some reason I am doing something wrong.

[ger21]

Is the material the same?
Are the cutters the same?

Small cutters are very fragile, and it doesn't take much to break them.

[blarkscnc]

Yes the left over piece this was cut from is what I'm using to test. The piece in the photo I can't remember if I used a 2 flute or single flute but was definitely a 2mm. I used the settings from the stepcraft website as a baseline, in fact I have actually gone through feeds and speeds with you before Gerry over on cnc zone

https://www.cnczone.com/forums/general- ... tware.html

I had forgotten about this but in that thread it seems, for that part at least, that 1000mm/min ad .2mm DOC with a 2mm 2 flute gave me some success. I remember I had changed over to a single flute and was impressed with how it went, now not sure what is happening. I may go back to these settings and try again tomorrow with the .2mm DOC as .3mm might be too much for the 2mm.
Oh and better order some more cutters

[blarkscnc]

Bit more luck today, definitely seems better at the .2mm DOC for both 2 and 3mm cutters. Feed for the 3mm at 1200 and 1000 for the 2mm which is what Gerry had suggested in the other thread for the 2mm, not sure why I had the 2mm/.3mm programmed at 1200 in the operation but that is what was throwing me off, I made that cut 2 years ago and cannot for the life of me remember if I had actually used a 2mm or 3mm but its definitely in there as 2mm and at .3mm DOC, as that turned out ok I just assumed it was going to be again but no. Anyway it seems a lot better at the moment. Thanks for the help guys, its my first real build and certainly not as experienced as I would like but I am learning and thanks to the forums and you guys that help is making it a lot easier.