Solidcam: properly adjusting postprocessor arc interpolations, axis accelerations...

Solidcam: properly adjusting postprocessor arc interpolations, axis accelerations, deccelerations and velocities to achieve smooth motion during milling.

I've got a problem when there is automatic recognization involved in cam process (for instance when I use silhouette recognization on outter contour on part, or in iMachining) and my machines start "stuttering" they move jerky and tend to break tools more often or leave nasty milling marks and dents from where they stopped or slowed down on part.

I've tried doing something about it in the postprocessor vmid file
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but I'm just tapping in the dark, so please, can you tell me which values need to be imput so I can achieve smooth machine motion during milling.

allenp said:

Solidcam: properly adjusting postprocessor arc interpolations, axis accelerations, deccelerations and velocities to achieve smooth motion during milling.

I've got a problem when there is automatic recognization involved in cam process (for instance when I use silhouette recognization on outter contour on part, or in iMachining) and my machines start "stuttering" they move jerky and tend to break tools more often or leave nasty milling marks and dents from where they stopped or slowed down on part.

I've tried doing something about it in the postprocessor vmid file
Imgur: The most awesome images on the Internet

but I'm just tapping in the dark, so please, can you tell me which values need to be imput so I can achieve smooth machine motion during milling.

Click to expand...

By any chance is this on a Haas and if so do you have the HSM option?

If it's not on a Haas I would look at your machine's block processing speed and make sure you aren't giving it more code than the control can handle. Try reducing the cut tolerance. You mentioned arc interpolations - is it arcs that are the trouble?

When I'm drip feeding to my Fadal's they tend to stutter because of the high feed rate I'm running. The machine is moving faster than the communications. I doubt you are drip feeding but higher feed rates can also cause you to exceed the control's look ahead capability. Pretty rare really but just another thought.

yep arcs cause stuttering

allenp said:

yep arcs cause stuttering

Click to expand...

Ok, probably not a block processing speed problem. Do you use R or I, J, K and what control is this?

i, j
fanuc 18i, stama mc 14 machine.

does post put any other info to machine other than g code? I mean, is there any other hidden data that is transfered to machine which we dont see when we send data over through cimco edit to machine?

if not, I guess the problem must be in machine, or it's ability to read and decypher/connect paths of an arc movement broken down into pieces. and possible solution probably found in machine parameters.

if yes, what do i need to change in postprocessor to try and see the difference in behaviour of machine?

There are a few other things that could be doing it but I don't know that control so I don't want to lead you on a wild goose chase. Hopefully someone will step in that might have some thoughts.

On my Fadal control I have two codes G08 and G09. G09 acts as an "exact stop" which requires the axes to completely come to an accurate stop before continuing on to the next line; it's actually for deceleration at high speed. G08 immediately goes to the next line which allows uninterrupted interpolation but can make the machine bang around a bit. There is a similar code/setting in a Haas control that is actually called "exact stop" which is the intended purpose also. On CAM generated code it will seem to stutter because it is verifying axis position before moving on.

It sounds like you knew where I was going with the R vs I,J question. Sometimes it's a question about which one the control can execute faster, sometimes not.

Lastly, in the Haas control there is a setting to reduce the feed by a given percentage. By factory default it is set at 50% and I had what I thought was jerky motion but it was really caused by the feed slowing every time it hit an arc. I do know the Fanuc control has that feature so it is worth checking into.

That's probably all I got and I'm sorry I couldn't be more help. Good luck!

now we have new haas vf2 and there is the same problem with it as the fanuc machines.

so you say there is this setting... do you know where it is or what number is it?
what happens if you turn that setting off? it doesnt slow down on arcs?
how does it effect other operations?

View image: Screen Shot1

allenp said:

now we have new haas vf2 and there is the same problem with it as the fanuc machines.

so you say there is this setting... do you know where it is or what number is it?
what happens if you turn that setting off? it doesnt slow down on arcs?
how does it effect other operations?

View image: Screen Shot1

Click to expand...

Buy the High Speed Machining option for your Haas. You will have a trial time period as well, so when you find the parameter there will be a T next to it. The trial period is 200 hours, and you can turn it on and off. We used it for about a year this way before it ran out, but one big bummer is that the machine tells you NOTHING about how much time is remaining.

I suggest buying it just to get the motion control smoother in general.

where is that option on haas? how do i see if it's active or not?
secondly, what is good setup on postprocessor precisions arcs etc, from my link above?
accelerations and velocities etc.