Feed Rate uncontrollable?

[cncmage]

I just finished my first cnc machine using the hobby cnc board and am running Deskams NC software and using some files created in artcam. The machine works great at max speed of 43in/min. I just tried slowing the speed way down to 2in/min to prepare cutting aluminum but I noticed i cant seem to alter the speed at all.

My g-code is providing the commands F2.0 for 2in/min feed rate but it seems like the hobby cnc board is not listening to them.

Funny thing is that I thought I had been changing the speed ever so slightly for the last week to fine tune my cutting but now makes me think i was not changing the speed at all, lol.

Any ideas?
Thanks,
CNCmage

[WP1]

The HobbyCNC board has nothing to do with the feed rate. All it does is act on the step and direction signals generated by the software to drive the steppers.

If the feedrate is not changing it is a software issue. I can't tell you there though since I've only used EMC and Mach2.

Pete C.

[ger21]

Are you using the Dos Desk NC? The website says something about jogging at maximum feedrate. I'm wondering if it doesn't support F words in the g-code? Did you try slowing it down with the slow button on the screen?

[cncmage]

I tried slowing it with the buttons and it does seem to control plunge rate speed fine but not feed rate.
It also seems to only execute the F2.0 command on the line of the actual g-code line it inhabits. All the rest of the g-code lines after it seem to run at max feed rate.

[ger21]

Try it with F2 on every line and see if it works.

[joecnc2006]

i thought when you set up your toolpath in art cam it askes for feed rate? what did you set your motor tunning at in your cam program?

[ger21]

Originally Posted by joe2000che what did you set your motor tunning at in your cam program?

You can specify a feedrate in your CAM program, but you probably need to configure the post to put an F on every line. IF the post is configurable.

[cncmage]

Eureka, I got it!
My default start velocity in Desknc was set at 31.5in/min and I was trying to cut at a feed rate of 2in/min so all the cuts were starting out way too fast and not able to slow down fast enough since I was trying to cut small circles in aluminum.

Anyway I got it now

Thanks guys,
CNCMage