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Messages - bdmsb

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General Mach Discussion / Re: Radius errors with G2 command
« on: November 25, 2009, 02:23:30 PM »
Change your IJ mode in General Config.

That's it! Thanks.....

General Mach Discussion / Radius errors with G2 command
« on: November 25, 2009, 01:25:34 PM »
I'm using CamBam to generate G code and Mach3 complains about a G2 command no matter how I define the hole in CamBam. The error message is:

"Radius to end of arc differs from radius to start"

I've tried using a drill operation and a profile operation with the same result. I haven't been able to ask CamBam about it and I'm beginning to wonder if maybe Mach3 has too restrictive settings on G code tolerances that can be lessened. I don't know G code well enough to puzzle out the G2 command. The hole is 1" in diameter cut with a 3/16 end mill:

G2 F20.0 X1.0469 Y1.2635 Z-0.0425 I-0.4063 J0.0

General Mach Discussion / Re: Handwheels stall the table easily
« on: November 25, 2009, 12:19:02 PM »
i am not a expert, but with the steppers going that fast to move the table at that speed you might need a faster pitch screw to keep the motors slower with more power.
just a thought

It's not practical to change the lead screw pitch on a knee mill. 5 turns per inch conforms to the manual markings. But I'm using 1:1 toothed belts on the motors. I could change the coupling ratio which would run the motors more slowly. Does  anyone know if this is a net improvement in operation of a knee mill conversion?

I could retrofit ball screws, but I'm not exactly qualified to do the work myself and know of no one locally who is.

General Mach Discussion / Handwheels stall the table easily
« on: November 25, 2009, 10:45:41 AM »
I'm adapting a knee mill conversion to Mach3. The motors are size 42 steppers with about 1500 oz/in of torque. With velocity set to 40 you can't stall the table to save your life. But a feather touch on a spinning handwheel stops it cold. I understand that this is because the wheel is a big lever arm. But it's shocking to see how little torque the motors have at speed when tested in this way, and how easy it is to stall the table with a bump to a handwheel.

Is this typical? It's not something you'd notice on a mill without hand cranks.

Also, is 40 or 50 ipm a typical top end for a Bridgeport conversion with stepper motors and without ball screws?

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