Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: Cartierusm on July 01, 2008, 03:20:03 AM

Title: Jerky motion...yes I've read the other posts :-)
Post by: Cartierusm on July 01, 2008, 03:20:03 AM
I posted this on CNCzone today but thought I'd post it here too as I need to get my machine tuned correctly; plus I've watched some vids on youtube and now I know it's not running smoothly.

OK, I've used my cnc for a while now, about 1 year, but now I'm finally cutting my guitar stuff and I want to make sure everything is working the way it's supposed to.

When moving during a run the sound of the motors are jerky sounding and when looking at the ballscrews during the run they move in a somewhat jerky motion. Now the cuts seem pretty smooth and since I've never owned or used a CNC machine before I'm not sure if this is correct movement. So if you all can look at the video and tell me that's normal or not I would appreciate it. The sound is going to be the key as it's hard to see the motion of the machine, it's just cutting air I've turned off the router. The video is 15mb. I'll include my G-code for this particular run that you are watching to see if it's that. Its not jerky during straight runs.

Video: http://www.smokeproductions.com/cnc.avi

A little background on the machine, home built. Keling 425oz steppers, Keling 8078 Drivers, 48V 6.5A PS, Roton Ball Screws, Mach 3 V2.63, 10,000 steps per inch, 72IPM maximum and 10 acceleration for motor tuning. I just thought during a run it would run smooth during curves in a fluid motion?

After reading on here about the CV stuff I went back and took note of my CV settings: Motion Mode CV, CV Dist Tol. 180 is checked and G100 Adaptive is checked.

So what setting should I be using and is that my problem? Thanks so much in advance.
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Hood on July 01, 2008, 03:46:29 AM
Tried Sherline 1/2 pulse mode?

Please attach your xml.
Hood

Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Cartierusm on July 01, 2008, 11:33:14 AM
What does 1/2 Pulse mode do, all my cuts come out with the correct dimentions? Here is the xml file for some reason this forum keeps saying I already have a file uploaded with the same file name so you can view it or download it from my server. Thanks for the help.

http://www.smokeproductions.com/Mach3Mill.xml
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Hood on July 01, 2008, 01:13:41 PM
Sherline mode gives a longer pulse which some drives need.

Will look at your xml in a while but just so you know in the future, the forum only accepts a file once, someone has posted Mach3Mill.xml before so to post your xml you could rename it before posting. Using your forum name helps as well as people downloading the xml can then remember whos it is, so for instance you could rename it Cartierusm.xml

Hood
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Cartierusm on July 01, 2008, 06:01:03 PM
Thanks, I appreciate the help. I have been using my system for about a year but nothing critical and now I'm realizing it needs some tweaking and I have no idea how to start.
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Hood on July 01, 2008, 06:03:53 PM
Looked at the xml and it looks ok from first glance. Have you tried Sherline ?

Hood
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Cartierusm on July 01, 2008, 06:40:30 PM
Yes, I just tried sherline and turning off all the CV things on the config page, all that has no effect whatsoever, it runs the same.

A separate question, I just upgraded my PS to 48 V from 24V and now I get limit switches tripping after a couple minutes. My motor cables are shielded but not the limit and home switch cables, do you think it's just electrical noise, emi or rfi? And the CV problem was the same with the 24V PS I just switched over yesterday to get more torque.

P.S. I don't think I tried sherline with the CV enabled, Gerry at CNCzone told me to try turning off the CV as sometimes it messes things up, so I'll go try the sherline and CV together.
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Hood on July 01, 2008, 07:21:42 PM
OK have you run the driver test? its in the Mach3 folder, see what the graph looks like, you dont have QuickTime on your computer by any chance?.
 Also make sure your power supply doesnt dip in voltage when all the axis are moving.
Limits should really be shielded, you may get away with increasing the debounce.
Dont think CV would cause that problem but then again......
Hood
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: ger21 on July 01, 2008, 10:05:57 PM
Yes, I just tried sherline and turning off all the CV things on the config page, all that has no effect whatsoever, it runs the same.
......................

P.S. I don't think I tried sherline with the CV enabled, Gerry at CNCzone told me to try turning off the CV as sometimes it messes things up, so I'll go try the sherline and CV together.

Actually, I said turn off the CV options on the Settings screen and the general config page. I didn't say turn CV mode off. See if CV feedrate and CV Distance are turned off and see if that helps.
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Chip on July 01, 2008, 10:37:07 PM
Hi, Cartierusm

All in All, With small line segments, (short x## Y## moves), Your motors will Sing, Can you name that Tune !!.

But it dose sound, Sorta spread out and out-a little, No lost steps as far as you now. (Done a G00 X0 Y0 move to home after you finish the cut, Is it OK.

Moving your Acceleration UP till you start losing step's then back it off 10% or so, This will help close the Gap on achieving your F20 Speed, Ac-cell/De-cell (Closer Together).

On the Diagnostic Screen, Is the "Pulse Frequency", Locked in to a solid Value, "Should be", If your using 25K it should show a value above 25,000.

If it "Isn't",

A quick test is to run your G-code and move your mouse around in the Mach screen till the Pulse Frequency stabilizes to a solid value (Continue moving the mouse as necessary to keep it locked in during the Test).

It's a indication that you'll need to Optimize "Windows" for Mach"s use.

Hope this Helps, Chip
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Cartierusm on July 01, 2008, 11:25:58 PM
Sorry Gerry didn't mean to mis quote you. I didn't know what you meant by settings page, but I just checked now and I see what you mean, I'm a little slow lately.

I'm still a little fuzzy, ok there are 2 CV things on the settings page and there are 2 CV things on the config page as well as another CV check box, so I turn off the ones on the settings page and the 2 on the config page but leave the regular CV enabled? Also what do the settings refer to: CV Distance, CV Feedrate, CV Dist. Tolerance, G100 Adaptive Nurbs CV? I will see if I can find the answer to the definitions too.

I will check my power supply and see but this problem has nothing to do with the change over it was there before.

I did try the CV on with the Sherline but no difference. I've tried all configurations I can think of and it doesn't seem to make any difference. I don't mind living with it as long as it's working and cutting what it's supposed to but like I said before I though it should be fluid as it goes through curves.
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Overloaded on July 01, 2008, 11:31:39 PM
http://www.machsupport.com/docs/Mach3_CVSettings_v2.pdf
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Chaoticone on July 01, 2008, 11:32:26 PM
Cartierusm , Sorry if you have allready said, but what version of Mach are you running? Open Mach, help, about.

Brett
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Cartierusm on July 02, 2008, 12:12:00 AM
Gerry you are the man!! That worked, it's definately smoother, but I'll let you people be the judge of that. Here is a 12mb video of the new settings, same G-Code, same feedrate (I think) 36 IPM. I also went all the way on the acceleration on the Motor Tuning which was 37.5, the highest for my motor's velocity and I wasn't losing any steps just jogging around the table.

http://www.smokeproductions.com/cnc2.avi

I also did a driver test here are the results: Pulse Per Second in 25khz mode 23798, CPU Speed 2661, Apic Timing Constant 5592.

I'm not over 25,000 as someone mentioned should I try to remodey that? I'm not running Quick Time and I don't have any extraneous stuff running, it's a pretty clean computer.

I also did the diagnostic thing with my mouse and it stayed at 23,793. Time In Int. stayed mostly at 4 but occasionaly jumped to 10-11, all while running a G-Code.

P.S. I'm running 2.63, but I just upgraded from 2.45 but I had the same problem before that's why I upgraded.

I appreciate all the help you've given me.
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Cartierusm on July 02, 2008, 08:48:38 PM
So I just cut a piece and eveything seems to working fine. One of you said to tune the acceleration to the highest I can without losing step, so I did that. Now when the motors move they stop abruptly, which is no big deal if that's OK. I remember reading somewhere to set the acceleration to smooth not abrupt or too slow to spin up. So I just wonder if the abrupt stops are going to cause a lose of accuracy. If it really doesn't matter too much I'm going to slow it down so it's not so abrupt becasue now it's at the maximum.
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Chip on July 02, 2008, 11:33:49 PM
Hi, Cartierusm

In the end it's all a balancing act, Your acceleration value can be above or below your F-speed setting.

If your acceleration value is below your F-speed with short line segments, You may never see your True set F-speed during the job, (slower, smother).

If your acceleration value is above your F-speed, It starts runs stops at the F-speed, (harsher, more Abrupt moves).

Glad It's Working Better, Chip
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Cartierusm on July 03, 2008, 02:52:09 AM
I reset the acceleration to what I consider a sweet spot. Not so abrupt but no real spin up. I think it works better that way. If any of you would like to I'd appreciate someone videoing their "tuned machine" to run my G-code with the spindle off so I can see the way it moves and the way the motors sound, that would help a lot. It must be steppers though, just seeing someone else's would do me a world of good. Thanks.
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Hood on July 03, 2008, 04:02:46 AM
post your code and I will use i on my mill, wont be today but tomorrow I should manage.

Hood
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Cartierusm on July 03, 2008, 01:29:22 PM
It's in the first post. Thanks I appreciate it. It's only a 6 minute program but I don't need to see the whole thing.
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Hood on July 04, 2008, 05:28:50 AM
Heres a link to the vid thats it running the file from the first post.
Hood

http://www.youtube.com/watch?v=kYPy320j8nI
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Hood on July 04, 2008, 05:38:57 AM
Meant to say I was in CV mode (G64)

Hood
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Cartierusm on July 04, 2008, 02:09:46 PM
Thanks a lot, I really appreciate it. Now I know what kind of noises they make. I just assumed if it was running prefectly you wouldn't hear the fluctuations in the motors they would run smooth, but now I know. Have a good weekend.
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Hood on July 04, 2008, 02:18:57 PM
My motors do run smooth, the sound does vary however as you can hear, that is normal.
Hood
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: jhicks on July 04, 2008, 06:28:42 PM
I've read this and a few other posts with great interest and wonder if anyone can help me with a similar problem. I run a shopbot cnc router with mach latest download lock down and an Ascension controller for the past 2 years quite happily. last month we started to stall motors and it progressively has gotten worse. We have replaced basically everything except the motors now. New PC swapped with old, another new controller swapped, updated software, optimized PC's, replaced all cables including parallel cable, motor cables, connectors all soldered gold contacts, added back up power supply/conditioner, checked voltage at P/S and gecko drivers, verified incoming voltage, added new ground rod and new ground wires isolated from main power supply which is 380V 3 phase main. experimented with rapid and acceleration speeds/setttings, dialing up and down from a low of 100/10 to a high of 600/12, verified pulse settings at 5/5, restored systems, grabbed old and new xmls from back up files, ran tests as airt cuts, with and without rack and pinions engaged and with actual material under torque.

I've discussed with the Ascension designer/developer, exchanged many e-mails with BBarker THANK YOU Brian), and many other friends each familiar with either stepper motors, electrical engineers, proficient cnc users, mach users, and softwere folks all around the USA for the past 3 weeks.
The problem is MOTOR STALLS, growls,and stops on all, some or one axis under low or no load intermittently but with increasing regularity to the point of being totally useless.

When I dial speeds down, growl is diminished db level or seems to vanish but motor cant take any load and stops,, when I dial up, motor growl returns proportionatly with increased ramp and/or rapid and stalls under low or no load almost immediately (3 to 10 seconds)
My historical rapid speed was 425IPM, accel at 12, and a rather slow programmed cut speed generally between 160 and 200 IPM in plastics, foams, and wood stock.
My settings were always the same and all was well.

Folks at shop bot tell me steppers never fail, others seem to agree much less 3 at the same time and I'm dealing with a PULSE issue from parallel cable to Geckos but need an oscilliscope to really find out whats up.
If I do find some odd pulse wave forms, what would that tell me? and what would i do about it? I may have the opportunity to get to a scope next week.

PS voltageĀ  isĀ  at 65+V to PCB and geckos (I think 35V?) and I'm told those look right by other users of the same equipment and motors
Since everything has been replaced except the motors it seems its down to software/settings or motors.
My pulse driver test does not show a flat line but rather a series of hash marks from small to large in the shape of a triangle rotated -90 degrees consistently and repeatedly aross the screen with occasional single line spikes usually small but occasionally up to 80.

We have monitored task manager and see 90% CPU capacity at idle and nothing else runig from the 13 active system/utilities running.
Now if I take motors on cables, run mach, and move via arrow comands, motors growl within about 3 seconds after the key activation and simply stop with a continued growl until I release the command key.

Any ideas?

I've sent xmls, swapped xmls, tried the alternate mach driver test, and followed ever recommendation I've thought of or received to no avail.
After all this and many many conversations most folks feel its our power so I brought the set up to my home shop with cables and motors same condition.
All input is appreciated as we try to recover from 4 weeks now of zero production, tons of replacements, and effort, much help fom friends in the cnc community, with no forward progress.
Is it time to order/replace motors or what could cause this? More importantly, whats the fix?
Thanks
Thanks
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Hood on July 04, 2008, 06:43:23 PM
Can you post a screenshot of the drive test? Have you tried the optimisation steps?
Hood
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: jhicks on July 04, 2008, 11:28:38 PM
yes we have optimized. havent figured out how to attach to this forum but I'll research how till I get it posted.
I might have to post to my web site to accomplish this
Thanks
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Hood on July 05, 2008, 03:12:54 AM
if you use the full reply option rather than just the quick reply you will see additional options down at the lower left side. Click on that and you can browse to the file you want to attach.
Hood
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: jhicks on July 05, 2008, 08:14:08 PM
best I can do is a word documenbt with comparison of what we believe we should see and representation of what we do see. Am trying but when I select file from browse button, there is nothing getting attached? and no key /instructions on how to attach it to this note?
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Hood on July 06, 2008, 07:54:34 AM
The pulse looks bad but from what you say the average is its not really so bad. I dont know what to suggest as you seem to have done all, one thing to check however is you have the enhanced pulse enabled (General Config page)

If that doesnt help I think I would be stripping things down to the very basics and just set up a new xml with 1 axis and E-Stop, then keep adding the axis one at a time and then limits etc. Hopefully you will be able to run at the basic fine then as you progress you will find the problem.
Hood
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: jhicks on July 06, 2008, 11:59:51 AM
Thanks for trying. Have enhanced pulse and tried many other things like replace keyboard, mouse, and assorted changes as well as reverting to older xmls but to dat, the pulse stays the same. So I reinstalled on the P, same results and same pulse graph. Tried completely purged alternate PC with new mach install, different pulse stream (not better, just more irratic than constant) but same results oon motor growls. Seems this has progressively gone from intermittent to now constant. Either immediately on keyboard move or max 2 tyo 3 second delay then growl from motor.
I'm running out of options and beginning it must be the motor but everyone says its highly unlikely to be the motor much less all motors.
Not sure what it is but so far progress is negative.
Thanks again and I hoe this never happens to anyone else. Its a real head scratcher and terribly frustrating. :(
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Hood on July 06, 2008, 04:50:29 PM
Have you tried just setting up with one axis and only the E-Stop connected to see if it runs OK?

Hood
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: jhicks on July 07, 2008, 08:09:49 AM
yes, failure occurs within 1 to 3 seconds now. not clear how or why but seems worse than ever.
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Hood on July 07, 2008, 10:12:56 AM
I presume thats just with one axis connected? If so try another instead and see if thats the same.
Hood
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: jhicks on July 07, 2008, 03:47:38 PM
doesnt discriminate between axis. doesnt even matter if motors are engaged to rack or not. problem has progressed to poing where failure growl and stop occurs within 1 to 3 seconds from command on any axis smultiples or all.
Thanks for trying, this is quite the "sticky wicket" mate!
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Greolt on July 07, 2008, 07:55:20 PM
Jhicks

I have only just read through this thread so I might have missed it but what power supply are you using?

Is it a switchmode supply?  I always prefer a linear supply.

Is the voltage staying consistent as the motors start to move?

I have heard of this symptom before with switchmode supplies going bad.

Greg
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Cartierusm on July 07, 2008, 08:55:43 PM
Greolt, what do you mean by switchmode? I'm used to the terms unregulated, unregulated doesn't keep the same voltage, regulated keep the volts the same no matter what.

Anyway, I was having the limit switch problem tripping, so I rewired the entire CNC with shielded cable (already had it on motors), made sure no wires laid on each other and kept the PS outside the enclosure so no 120V inside, grouped only like lines together. What a difference. I honestly believe it runs smoother!! The limit switch problem went aways and it's definately quiter. Thanks for everyone's help. It runs super smooth now.
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Greolt on July 07, 2008, 09:10:33 PM
Cartierusm

Glad you machine is going well now.

I was referring to Jhicks problem.   :)

Greg
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Cartierusm on July 07, 2008, 09:19:34 PM
I know that, but I was still curious.
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Greolt on July 07, 2008, 09:58:58 PM
Cartierusm

You will have to ask someone more knowledgable than me how they work but this is a typical switchmode supply.

In hobby level applications they are usually cheap chinese built units. You get what you pay for.

I have never had much success with them driving cnc machines. When they get flakey they do weird things.

I prefer a good solid unregulated linear supply.  Simply a transformer, rectifier and cap with some other small incidentals.

Now that was to answer Cartierusm's question. 

Jhicks just check the output when a load is applied and motors stall if using a switchmode.

Greg
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: da21 on July 08, 2008, 03:09:48 AM
the power supply is the likely culprit  , check your power supply output both volts and current , preferably with a analog multimeter if you can   

it is possible to be the Motors , but as you say it's on all three then it's most unlikely to be them , but not discounting them at this time

Dave   
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Cartierusm on July 08, 2008, 03:26:59 AM
I have a question, I've read not only here but other places that it's best to use an unregulated power supply. Why is that? It seems logical to me to use a regulated power supply that keeps the volts exactly at what the PS is rated at.
Title: Re: Jerky motion...yes I've read the other posts :-)
Post by: Hood on July 08, 2008, 04:03:24 AM
I have a question, I've read not only here but other places that it's best to use an unregulated power supply. Why is that? It seems logical to me to use a regulated power supply that keeps the volts exactly at what the PS is rated at.
No expert here but I think one reason would be most drives do the regulating themselves so no need to regulate from the PSU, and also likely that a simple transformer, Rectifier, Capacitor style PSU will be much more robust.

Hood