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Can't figure this out...

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comeoutswingin
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Re: Can't figure this out...

Postby comeoutswingin » Thu Nov 17, 2016 12:18 am

Well that makes sense... My X, Y, A axis all seem to be holding the same settings? My Z is different.. I have no idea what these values should actually be?

a.JPG

z.JPG

y.JPG

x.JPG
5x10 LDR

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acourtjester
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Re: Can't figure this out...

Postby acourtjester » Thu Nov 17, 2016 10:50 am

I don't know what works best for your table but I normally have the acceleration 1/4 of the velocity, (velocity 200 acceleration 50). You should be able to tune each by using the keyboard arrow keys to move the X and Y, page up /down for the Z. Make changes to the numbers and see when the motor run smoothly with no stalling, increase the velocity until it stalls and drop back 10%, then move to the next axis. IMHO :)
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dhelfter
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Re: Can't figure this out...

Postby dhelfter » Thu Nov 17, 2016 8:56 pm

Those are the correct settings for your machine.
I still have no idea what could cause this especially on gcode that you have run hundreds of times before. I take it that it is random? If not a video of screen may help. If it is random when you see it slow down look at bottom left of screen and see what the commanded federate is.
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Re: Can't figure this out...

Postby dhelfter » Thu Nov 17, 2016 9:01 pm

Acourtjester. I also like the 1/4 rule but as you get above 200 to 300 on velocity it doesn't work as well in my experience. The acceleration on his machine would now be 175 which the machine can do without stalling motors however vibration becomes an issue.
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acourtjester
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Re: Can't figure this out...

Postby acourtjester » Thu Nov 17, 2016 9:29 pm

"200 to 300 on velocity it doesn't work as well in my experience" His scren shot for X and Y shows the velocity of 700 ?????
I was just using 200 as a reference to be sure they understood the 1/4 ratio.
DIY 4X4 Plasma/Router Table
CandCNC DTHC-IV & Feather Touch
Hypertherm PM65 Machine Torch
Drag Knife and Scribe
Miller Mig welder
13" metal lathe
Small Mill
Everlast PM 256 tig

dhelfter
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Re: Can't figure this out...

Postby dhelfter » Fri Nov 18, 2016 3:37 pm

I understand the 200 was an example.
What I was saying is as velocity goes up the ratio of velocity to acceleration most likely will not be able to be the same (25%)
On his system with 700 velocity, if you set acceleration to 25% that would be 175 inches per second squared.
On our large pipe machines the long axis is set to 3000IPM so at 25% the acceleration would be 750 IPSS or almost two gees!
Again not that these high acceleration rates are not possible, it is just that with sub 20,000$ machines they will usually vibrate way to much at those high rates.

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Re: Can't figure this out...

Postby Brand X » Fri Nov 18, 2016 4:16 pm

So when your machine jogs. (lets say in between cuts) it does so at 700 ipm.. Also at the end of the cut to home/start point.. I understand you can control jog speed in Mach, let say 40 % or so,but it still does not change the 700 ipm travel speed between cuts, etc.. If you have tip up, way less time to react. (IMO) Am I missing something here? Like you can control the 700 top end some other way? I run 35 on accel, because it seem like plenty for anything I cut..

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Re: Can't figure this out...

Postby gijoe54 » Sat Nov 19, 2016 1:24 pm

i had this same issue on my 5x8 , i had to factory reset all my parameters to undo all of the minor adjustments my programming did for kerf width and saved to the base programming. but the slop in the motor is worrisome. at one point a student i had drilled the table with the head and stripped a tooth on one of the drive gears, it wasn't enough to see, but it was enough to offset my cut lines by .055in.

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Re: Can't figure this out...

Postby tcaudle » Mon Nov 21, 2016 7:42 pm

I would consider pulling the motor and see if you can loosen the one set screw and use a gear puller to remove the pulley. YOumay wreck it so have another one ready . When you put the new pulley on line up the flat with one screw and use some cylindrical rated loktite (green) on the shaft then tighten the set screw. It won't spin any more. You will have to heat it to get it back off

Do you have a pendant ? either something is messing with your feedrates override in MACH or something is corrupt in MACH itself. Backup your whole MACH3 folder to a thumbdrive. Check to see what version of MACH you are running (Help/About) and then see if you have a copy of MACH with that release. You don't want to jsut upgrade MACH. You need to do a fresh install than do an install of the drivers and screens THEN copy in the XML's from your backup.

When MACH starts doing weird things like not reading the feedrates right from code its time to reload.


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