How to speed up arc cutting?

[Hack]

Title says it all. How can i speed up the cutting of arcs in TurboCNC?

Thanks

[Bubba]

Hack,
No, the title doesn't really say it all.
So the only answer I can give to make it cut faster is to increase the feed rate!
NOW,
WHAT are you cutting this on (mill, router,?), WHAT kind of system do you have driving this (servos, steppers, and what kind of power do you have to drive what ever it is that you are driving), WHAT are you cutting (foam or hardened steel), WHAT are you cutting it with (1/32 end mill or 1/2" end mill or what), HOW fast can your spindle rotate, WHAT depth are you trying to cut per pass (.001, 1")???????????
All of this is inter-reactive and MAYBE you are cutting it as fast as it can be right now!
We don't have nearly enough information to help you out.

[Hack]

I am cutting mostly plywood and solid wood with my homemade router table. Using 1/4" carbide router bit PC laminate trimmer (20 some thousand RPMS) depth of cut .11 (less than 1/8"). Using 276 oz steppers with xylotex board and cutting striaghts at 15ipm but when I get to a curve it slows WAY down. I was thinking that the pulse with setting affected the speed of arcs. Or that another setting in turbocnc affected them?

Thanks

[ger21]

What version of TCNC? I believe this was a bug in version 3.2x? Version 4 has an "arc factor" setting that can be adjusted to get the correct feedrate in arcs.

[Hack]

I am usign v4 - Where is this arc factor setting that you speak of?

[Bubba]

Hack,
The arc factor is under the "General Config" section in the Configure Menu.
It is on the right side just above the "Machine:" and in my setup, it is the default 1

Something else to consider, is the feed rate is set in your case to 15IPM, so that will be the speed on the arc (vector analysis speed), so while it may look slow, it may actually be running properly??? Tony G did a writeup some time ago about a problem similar to this in the yahoo group. I will try to see if I can find it (no promises) but it may shed some light on your situation.

[Hack]

I checked and mine is set at 1 as well. Do I want a higher or lower number to make it go faster?

Thankss

Hack

[ger21]

From the manual:

Arc Factor: This option provides a method of adjusting timing loops used when cutting an arc to the speed of the computer. Values less than one increase the loop speed, those above one decrease it. If you notice lost steps while cutting arcs decrease this value to 0.8 or less.

[Parameter]

Bump, hey Hack, have you got the issue resolved? In my case, sometimes arcs are fast, sometimes darn slow, seems to have something to do with the processor but that is a Pentium 233, 128MB ram runing FreeDOS and I only cut wood at 12IPM!

I wonder if the same happen with other softwares when in tight arcs...

Para

[Parameter]

Ok, I think I found the culprit in another post. Using R values for arc mess up a bit turbocnc, so I had to remove the use of R values in bobcad before generating my code. Seems all right to me now.

Hope this help anyone with this problem.

Para

[Stevie]

I found cutting arcs wierd; for one thing if I try to increase the feed override it slows it down; lower it speeds up; once you get used it; guess it works fine

[Parameter]

It's because you increase the loop time that distance operations, this makes the loop longer, thus the arc get done slower. This is the way it works and once set should not really need fiddling.

I realised running from file is sometimes slow as it need to read each instructions in blocks. Thus no hard-disk power save feature may be enabled. From a file on a floppy, you'll end-up burning cutters and making a 15 minutes job last for hours...

Experience is getting in but, damn learning is costly these days...

Para