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Author Topic: Cut not going into corners?  (Read 682 times)

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Cut not going into corners?
« on: January 25, 2018, 08:48:23 AM »
Any ideas what I'm doing wrong here? I'm trying to cut a pocket into Plywood, the pocket is 12mm wide and 40mm long with corners radiused at 3.1mm. I'm using a 6mm dia cutter but only one of the corners is actually cut completely, it's like the cutter is anticipating the corner and moving earlier. The G Code was compiled using Sheetcam and looks perfect in simulation so fairly sure the problem is not here but is with Mach 3. Also I'm sure I've done this successfully before. Any ideas? I'm stumped.
Picture here https://www.dropbox.com/s/87xllsubd2i9yo3/2018-01-25%2013.55.15.jpg?dl=0
« Last Edit: January 25, 2018, 09:04:34 AM by cncbobuk »

Offline Davek0974

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Re: Cut not going into corners?
« Reply #1 on: January 25, 2018, 09:40:01 AM »
My first guess would be that your acceleration settings are too low for the speed travelled.

If this is a new issue then something must have changed - corner rounding is nearly always due to poor acceleration/speed settings

Try going into exact-stop mode instead of constant velocity (CV) mode.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives
Re: Cut not going into corners?
« Reply #2 on: January 25, 2018, 11:34:21 AM »
Hi Dave, thanks for that, you are of course right I remember now having this problem before. I'm always a bit reluctant to set acceleration too high as I always think this is a recipe for losing steps however setting "Exact stop" has cured the issue for now. You prompt is much appreciated. I will have a play with acceleration and see what happens. Cheers,
Bob.

Offline ger21

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Re: Cut not going into corners?
« Reply #3 on: January 25, 2018, 11:43:06 AM »
Try setting "Stop CV on Angles<" to 89 in General Config.
Gerry

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Offline Davek0974

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Re: Cut not going into corners?
« Reply #4 on: January 25, 2018, 02:51:15 PM »
Good you got going:)

Sound like you might benefit from spending some time and doing a tune-up - if the speed is ok, just increase acceleration in steps until it sounds bad, jerks or loses steps then back off maybe 10-15% and test it.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives