Rapids on NM200

[g29cc]

I am just curious, as I ve pm'ed Ihavenofish and he mentioned he was able to increase his rapid movement to a certain point before it would just plain stall and not operate.

I believe he mentioned 130ipm or 135ipm as the ceiling.

Well I just thought I would mention that while working with mine, we had the feed rate at 160% over ridden and when it hit a rapid move , it shot right to 160 ipm ( I have mine set to 100 ipm in the config files ).

It ran 160 ipm without a glitch for the short time that it did so before I realized what happened.

We replicated the "problem" again , and again no issues. It didn't seem to miss steps either. But we didn't run an entire program at 160 ipm. I tried it at other levels lower then 160 , again not a full program.

It ran smooth as silk at 160 ipm. I am going to try and set it up and run a program at that rapid speed just to see if it does miss steps or what happens.

If it works at 160 ipm , then I'll try a little higher till it stalls. It would be great to get 200 ipm rapids out of it reliably ! I be happy with 160 ipm rapids as well. I know rapids aren't the main concern as feedrates are and there isn't enough spindle speed to take advantage of the rapids cutting soft materials.

But I'll report back when I get the rapids ironed out and what speed I have them at.

[Frogblender]

At one point I had my nm135 running over 300ipm (I haven't tried that fast since I tightened the gibs, though). I needed an add-in PCI parallel port card to do it. 300ipm is a good novelty, but I went back to 130ipm, since a) rapids should only be a small fraction of a well-optimized G-code program, and b) at 130ipm the NM135 won't wreck itself if/when it crashes against the stops, but at 300ipm I figgered the story would be different. With your much-heavier NM200 table, crash damage might be proportionally greater.

Also, I don't know how you test out a new g-code program, but when I do it, my finger is poised over the estop, and it gets pushed often. Faster rapids would require a faster finger...

[ihavenofish]

i was running the nm200 at 175ipm a few days back, and the z at 200ipm. i had been having random stall issues so i simply replaced the control's PC with the one i was building for my router. as it turned out, the issue was *something* on the old PC. the new one not only doesnt stall randomly, it allowed MUCH higher speeds. i got the Z to 350ipm even, but i had to lower the acceleration to the point of uselessness. these motors seem to drop off in torque in a hurry, but it seems with the right PC they can push furthur than i thought.

ive left it at 100ipm and acceleration of 30 for the moment, cause i was just happy to see the thing running ten 15min programs on end with no errors. now i dont want to change ANYTHING! haha.

im working with novakon to find out whats wrong exactly with the old PC... might be as simple as a setting in the bios, or a piece of software installed is making trouble. th eonly real difference between old and new is the old is intel, the new is amd. these issues are so hard to diagnose cause its completely random. it could go a week with no stall, then hit one every 5 minutes.

[ihavenofish]

Well I just thought I would mention that while working with mine, we had the feed rate at 160% over ridden and when it hit a rapid move , it shot right to 160 ipm ( I have mine set to 100 ipm in the config files ).

if the settings in mach motor tuning say 100ipm, the machine WONT go over that no matter what you override and at the default 25khz kernel speed it CANT go over 147ipm.

the display in the control ui is the combined speed of all axes. so on a diagonal move in the xy, you could go 100x1.41, and x1.41 again in a 3 axis move making the absolute max rapid 198ipm even though no axis is going more than 100.

my machine was running smooth at a true 175ipm in any given axis with the kernel speed raised making the maximum physical diagonal speed near 350ipm.

i will say that after setting it all back to 100, it feels soooo sloooow, haha. i got spoiled for those few hours. i will try it again at some point, but at the moment i got work to do and dont want to induce any stalling.

i do agree that it will make crashes a little more dangerous and you want to make sure you are using hard limit switches. it will also put more wear on the gibs and ways, so youll want to keep an eye on them more often than normal if you do get the speed way up there. 175ipm is after all more than double what the machine ships at.

[g29cc]

I see....

I went and switched everything to 175 ipm acceleration 30 and ran a simple program cutting air and increased the feed to 150 ipm instead of its normal 15 ipm. Its a short program but functioned fine. I dont have alot of time to test things. But I do see what you mean about the total ipm , at one point rapid of all the axis brought the total to 340 ipm on Mach screen.

Those motors sure sound busy when they are cranked up !!!

I am going to play later if I have time and see if I can run a more complicated program at a high ipm and see what happens.

I ll have to double check, but I believe my clock is at 35,000 ? I just shut the machine down, and as soon as I hit the button I thought. Man I forgot to check my setting there......

[g29cc]

I should have mentioned also that it definitely was moving faster then it normally does ( when it was set at 100 ipm with the original 160% over ride ). You could move the axis in jog and it would read 100 ipm on mach screen and when it was running with the over ride in one axis only it was showing 160 ipm though ? It definitely sounded faster and looked like it was moving faster.

I am having some config problems though too. So that could be the cause as well.

I am still ironing out some issues.

[ihavenofish]

I see....

I went and switched everything to 175 ipm acceleration 30 and ran a simple program cutting air and increased the feed to 150 ipm instead of its normal 15 ipm. Its a short program but functioned fine. I dont have alot of time to test things. But I do see what you mean about the total ipm , at one point rapid of all the axis brought the total to 340 ipm on Mach screen.

Those motors sure sound busy when they are cranked up !!!

I am going to play later if I have time and see if I can run a more complicated program at a high ipm and see what happens.

I ll have to double check, but I believe my clock is at 35,000 ? I just shut the machine down, and as soon as I hit the button I thought. Man I forgot to check my setting there......

at 25k (default) you get 147ipm max. at 35k you get 205ipm max. of course it wont got past what youve set in motor tuning if its lower. mine came default at 25k, but maybe novakon is using 35k now. its somewhat irrelevant, but usually lower clock is more stable, so you want to use the lowest you can get away with.

my experience has been that a good long contouring program will show the faults in the speed and acceleration settings. sometimes you wont get a stall in basic jogging or pocketting cause its got momentum but it might stall in jerky motions in a program. by this im talking about stalling from lack of torque and not the type or random computer related stalling i was having.

they key here is that if its going out in a similar location on the table every time, its probably torque and youve past the limits of the machine. if it arbitrary and random, its probably the PC and you should be able to iron it out.

[g29cc]

Mine is set at 35k.

My next program isnt a big part, but has lost of contours. I ll see what happens with it.

[ihavenofish]

Mine is set at 35k.

My next program isnt a big part, but has lost of contours. I ll see what happens with it.

are you actually cutting at these speed, or just rapids, or just air testing?

ive been actually cutting at 100ipm in wood. spindle is a bit too slow, but in certain woods it works well enough.

[g29cc]

Right now I am just air testing.

I had some wood grips I was making on the machine, but went back to my other machine because it has a 10,000 rpm spindle and 4000 rpm just doesn't cut it.

[g29cc]

I did cut a few parts today from 6061 aluminum .050 doc with a 2 flute insert 3/4" diameter using APKT inserts ( if I recall correctly ).

120 ipm through the entire program. It moaned a little under 100% cut, but nothing to make me cringe or anything.

I believe if I had better holding ability, and lessened the cuts to .025, I could easily hit 150-160 ipm cutting feedrate without issues. Though I didn't try it. I just played a little today to see if it would work.

I am bummed I don't really have time to screw around too much with it. But I am having some configuration issues in Mach3 that are tying me up from getting my project done. Or else I would be playing a little more.

I took some video of it at 120 cutting some parts. I ll post that later.

[ihavenofish]

well, dont cut fast for the sake of it, make sure youre in the right feed range for the material. at 4000rpm, you might be pushing too hard there and wearing down the tool.