On 9/30/26 04:19, Luca Toniolo wrote:
I'm deciding whether to work on a LinuxCNC feature and would like to know first whether anyone would actually use it.

Today, when a rotary axis moves together with X, Y or Z, F applies to the linear axes only, and a rotary move on its own runs at F in degrees per minute. On a 4th-axis wrap, where the surface of a cylinder is cut with X and A, the surface speed therefore doesn't match F. The usual workaround is inverse time (G93) from the CAM.

The idea is a reference radius for each rotary axis, set in the INI. For example, `[AXIS_A] FEED_RADIUS = 25` puts A in the feed calculation as if it were a length at 25 mm from its centre. A move of A alone at F100 would then run at 100 mm/min on the surface at that radius, and X with A would run at F along the combined path. Siemens (FGREF) and Fanuc (a parameter) do the same.

Questions:
1. Would you use this, or does G93 from your CAM already cover it for you?
2. What machine: 4th-axis wrap, rotary table, something else?
3. The useful radius is usually the stock radius, which changes per job. Is a fixed INI value good enough, or would you need to set it from G-code?

A short "yes, I'd use it", "no" or "G93 is fine" helps. If nobody needs it, I'll leave it.

Luca

Luca;

I am cutting a buttress thread by distance y moves and # of revs stated in degrees during the move. Doing a 2 start thread by going down the part to the end, pick up the tool, rotate the work 180, drop the tool and come back in reverse to cut the 2nd thread.  I might use it, but my code works very well as is & has for years.  Basically what we have had for years works amazingly well. Please do not disturb working code.

Cheers, Gene



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