NativeCAM Speed Overrides Might Not Be Safe

04 Jul 2018 01:08 #113361 by BrendaEM
I worry about the default preference speed overrides. I feel that nothing should be above 100%, for safety sake.

Thank you for your consideration,
04 Jul 2018 06:08 #113389 by tommylight
I set that to 200% on all my machines, just in case.
04 Jul 2018 17:35 - 04 Jul 2018 17:48 #113430 by BrendaEM
That is humor, correct?

The first non-touched test of my CNC over a small pocket in a scrap of plywood. As you know the Gcode created by NativeCAM controls the spindle dynamically during the cut. It requested 26,000 rpm. I think that the VFD likely would not agree to accommodate that, but if it did, that would be my motor, right there.

Then I thought: what if I was using a Bridgeport or benchtop mill, and surfacing with a flycutter, an unbalanced tool which is not an unusual operation to do with the surfacing operation in NativeCAM. I would not want to run a fly cutter at 130% speed.

The dynamic speed system in NativeCAM is pretty sophisticated for an ad-hock improvisational milling program, but with my Ronco Huanyang VFD, I run the spindle at a constant RPM so the current draw doesn't ramp up often.

No, I don't trust my VFD as far as I can throw it. It's pretty light, grasps well, and should go for some distance. With a brittle plastic housing and circuit and heavy metal heatsink inside, It would make a satisfying sound when it hits the pavement.

As you know, I am such a proponent of NativeCAM, that I've given it a standard place in my user interface design.
Last edit: 04 Jul 2018 17:48 by BrendaEM.
04 Jul 2018 18:59 #113435 by tommylight
No it is not humour, i actually set all my machines to go to 200% feed over ride.
As for spindle that should be programmed in the VFD so it can not go past what the spindle motor can handle, although i have pushed some 3000 RPM ones to over 4500 without complaint.
Fly cutter at 130% is .....well depends, on a mill that can do max 500 RPM that is still good, but on a mill that does 6000 RPM ( a Hurco i am working on ) that would be to much, but also dependent on the size of the fly cutter.
04 Jul 2018 19:32 #113439 by FernV

BrendaEM wrote: I worry about the default preference speed overrides. I feel that nothing should be above 100%, for safety sake

The concept of NativeCAM is to let anyone set it's preferences to what he/she likes.

I never had a complaint about this and only a few comments on this.

When you go through feed and speed tables, you will note that at 100% tool engagement, it is slower than at 50%. So with the option, anyone can do what he/she likes. If they want no override, they simply set it to 1.0.

There is no way I am going to remove the option.

What is the reason you do not do it if you do not like it ?

The following user(s) said Thank You: BrendaEM
04 Jul 2018 21:45 - 05 Jul 2018 01:00 #113444 by BrendaEM
I am sorry if I wasn't clear. I would never suggest removing such a useful option. I am glad and impressed that it is there : )
"....The dynamic speed system in NativeCAM is pretty sophisticated..."

It was the default value being greater that 100% that worries me. People may run tools at the threshold/border of their maximum RPM.

It's not mine, but fly cutters like this worry my at over 100%, actually over 50% : )

BTW, thank you for NativeCAM. It's a great addition to LinuxCNC.
Last edit: 05 Jul 2018 01:00 by BrendaEM.
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