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Author Topic: motors juttering or losing steps when using feed override  (Read 1601 times)

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motors juttering or losing steps when using feed override
« on: February 02, 2016, 08:08:05 PM »
hello all,

thanks for having me, im fairly new here...im a 100 dis vet.... i have use of only one arm, so please excuse my typos, i go fast and miss letters ... ive been workin m y 0704 for about a year, ive finally gotten to the point thats it time to start ruining bits and endmills LOL...

so im tryinhg to make a spanner wrench till i get the power drawbar done... ive got the cam mostly figured out and found feeds and speeds that agree with thestock motor..

sooooo...im dry cutting the spanner program.......it runs great, i chased the emi issue for a while and finally fixed that problem by rearranging wires and using emi magnets on all of the lines...
gibs adjusted to .001 lash in booth directions, not overly tight....it refs all home nice and smooth with no problems.
 20IPM feedrate...
.040 stepover
motors are 560oz n23's
tuned to 100ipm at 15 acceleration
6061 aluminum
1/2 inch endmill 3 flute
ive added 1 shot oilng to all the ways and dovetails, so its well oiled.
running mist coolant
now if i let it run at 20ipm it has no problem, i was playing with the overrride white it was dry cutting air..i turned it up to max which is i think 260% and at the very limits of the x+and y+ it jitters like its losing steps...as i turn the override back down, the closer i get to the original 100% the jitter/vibration gets less, when it hit about 130 its gone...
i did notice that if i turn the acceleration up on the x and y motors the jitter becomes worse even below the 100% override setting

is it justa matter of im turning it up too much or is it because the gibs are too tight at the extremes of the x and y axis..i was guessing its not a too tight ituation because it doesnt do the jitter/vibration in any other situation..like ref all home
i did a search, naybe im not keying in the right words , if its been covered i would surely appreciate being pointed in that direction..

rick
RET SSG Gonzales
5th SFG
DE OPPRESSO LIBER

Offline ger21

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Re: motors juttering or losing steps when using feed override
« Reply #1 on: February 02, 2016, 09:48:54 PM »
It's a known issue with high feedrate override settings. Try programming at 100ipm, and start with a feed override of 20%. It should then be smoother when you increase it.
Gerry

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Re: motors juttering or losing steps when using feed override
« Reply #2 on: February 02, 2016, 09:56:15 PM »
awesome...im glad it WASNT ME SCREWING SOMETHING UP///LOL
i will just program accordingly...thank you sir
rick
RET SSG Gonzales
5th SFG
DE OPPRESSO LIBER
Re: motors juttering or losing steps when using feed override
« Reply #3 on: February 03, 2016, 10:42:49 AM »
feedrate over ride I have found as of late has been pretty stable.  There was issues with it a few years back where it ignored motor tuning.  That I believe to have been solved.

So with that being said, what version of mach3 are you using?
What electronics are you using for motion?
I had the Xylotex cnc controller and it would allow horrible resonance into the motors.  It would build up, sound bad then finally stall the motors. I chased that down for a year or so.  Putting some sort of dampener on the motor solved the problem.
https://www.youtube.com/watch?v=8Am69_F93yA

Does the video look and sound like what you are dealing with at all?
Pictures of the electronics and rest of the setup would help alot.
Re: motors juttering or losing steps when using feed override
« Reply #4 on: February 03, 2016, 02:00:13 PM »
its what i downloaded from the downloads page,
im using
 c35s board
5056D drivers

it definately doesnt sound  like that...it sounds like when the motor hits the end of the travel and sits there losing steps

 i think the version is R3.043.466
RET SSG Gonzales
5th SFG
DE OPPRESSO LIBER
Re: motors juttering or losing steps when using feed override
« Reply #5 on: February 03, 2016, 08:01:22 PM »
Are your motors extremely hot?  Did you set the dip switches on the 5056D`s to the correct amps for your motors?

If so, try this, take switch 4 and flip it on then off 2 times within one second, you know the setting took if the motor makes a noise. 

Re: motors juttering or losing steps when using feed override
« Reply #6 on: February 03, 2016, 09:55:07 PM »
the x motor warms up ... 109 deg no more.............at fast machining feedrates 150ipm 115 or so .... but no not hot at all
they are set to 4.9A peak 3.9A rms
i tried a spare new motor i had and swapped the driver out to a new spare i had with no change
yes the motor makes a niose when i try your suggestion

ger21s suggestion worked, so its the software or the BOB somehow.. but if i tune the motorsa to 275 ipm then program cam to 275 ipm it screams right along with no problems, it only haoppems on really high feedrate overrides which i realistically wont be doing anyway

« Last Edit: February 03, 2016, 10:01:52 PM by 1hander »
RET SSG Gonzales
5th SFG
DE OPPRESSO LIBER