Feed and speeds

[jthelen]

Does anyone have a chart for feeds and speeds?
I am doing V carving with Times New Romans font in Rams.
Rams has a skeleton feature that bases the depth of cut on the width of the letters. This make the G-code full 3D although the max depth is usually less then .25 inch. I am wondering how fast you guys cut this type of work? I have been do small jobs so it wasn't so critical, but now I would like to increase my throughput. I would like some reference to know where to start my testing.
I have been cutting around 60 to 100 Min per minute. (1 to 2 inches per second)
Thanks.
Jim

[Brady Watson]

Jim,
I have found that most materials v-carve very well at 1 to 1.5 IPS on the XY speed and .2 to .6 on the Z speed. You want to make sure that the Z speed isn't too fast...

Also, since there are so many Z moves with V-carving, make your safe Z .1 or .2" from zero. That way, the machine isn't plunging an inch above the material at .2 IPS & eating up time.

-Brady

[paco]

I have test, for a quite interesting bid, in soft wood (spruce?!) with a 135° V-bit with 0.25" stepdown (the fonts get actually machine in one pass...) at up to 4"/sec. at 16000 RPM with VERY good results... I decided to stay at this point to avoid vibration since the font size tested are'nt that big... but I would push some more with bigger letters/designs... though not in hard woods... this is different as the included angle gets narrower; "pointy" tool bit tend to drag the cut at the point area (could actually break) and this make the "bottom" of the cut less good... I do a carving in hard wood (Oak and Birch) with a 60° 3 edges at 1.5"/sec. with 0.188" stepdown roughing at 16000 RPM and I am shy to push more; I can "hear" the difference!
The suggestion to avoid quick plunge I agree since the tool bit have to bite from all it's shape from thoses plunge... since you wont encounter anything (scarp part) in V-carving you can set the safe Z pretty low to save jogging/plunging time...