Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Garyh on June 23, 2008, 07:46:26 AM
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Hi all, just built a new router with stepper system and Z axis seems to pulsate when running a 3d file. I have tryed all types of motor tuning with
the same result every time? The Z is 1:1 with ball skrew 5mm x1 rev. lift,X-Y have 34 to 72 belt drive and 26t pinion drives,all drives jog around
the table fine. Cuts 2 1/2 fine but when i try 3d files Z seems to run rough. Any help would be great.cheers.
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Are you running straight off the Parallel port? Are you running in Exact stop or Constant velocity more? Can you post your code?
Brett
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Hi Brett, Yeah am running of the parallel port, i don't quite know what Exact or Constant velocity mean but will send you this
Gcode file. Its just a simple curved surface file to test machine.i tryed 3 different computers today but all do the same thing .It seems
to be pulsing in Z and X and not running smooth. Thanks for the reply.
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G61 places your machine in Exact stop mode and G64 places it in CV mode. There is a G64 in your code which is good. The code is tiny segments. Have you changed any of the CV settings from dafault Mach?
Brett
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Brett , no i havent changed these settings! It looks like if this stepper system wont play the game i think i will change to a
servo system. Cheers Gary.
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Brett, just got a few pic's of my 650-Z router .The steppers are 2550 oz/in showing reduction drives.
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Brett, just got a few pic's of my 650-Z router .The steppers are 2550 oz/in showing reduction drives.
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Thanks Gary, nice looking machine. Any chance you could post a video of it running the code that is giveing you problems? That would help to trouble shoot a lot. Is the path it is running true and just sounds bad or is the z getting out of place?
Brett
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Brett, the path it is running is true but Z & X which are both moving at the same time are both struggling to move smooth.
The feed rate then drops right off.
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Gary, please post your xml file and we will have a look.
Brett
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Brett, just running my laptop with the same file with same problem?
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Gary, I think it may be your motor tuning. Try this, tune all your motors to the slowest axis. Steps per will stay the same, but turn your accel and vel. down to match slowest axis and see if it smooths out. It will be slower of course but not so much on this file. In a blended move, one axis will limit the others speed.
Brett
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Brett, I tried to send a video see if this works.
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No Gary, that didn't work. :(
Brett
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Brett. the video file is abou 4.5meg it won't let me send it.
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Brett, many thanks for your help. I have made a decision to take the stepper system out and replace with servo system. It appears the stepper
can't handle blend when doing simple 3d machining. Tryed all different motor tuning settings etc. with no luck, once again many thanks. Gary.
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Gary, it's up to you but maybe you can get the steppers sorted. :) I'd really hate for you to go to the trouble and expense of that and still have a problem. :(
Brett
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Yeah Brett, you would think just a couple of clicks and it should be up and running.there doesn't seem to be an easy fix.????
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I wish I could see what it is doing. The code is tiny line segments so I wouldn't think it would be very smooth unless you get your CV settings dialed in. I have only done very little 3D files as my machine has a slow z. Hopefully someone else can help out here. If the steppers will move the machine, should be able to get them to run smooth. Maybe not fast, but smooth. I have a friend who is great with 3D files. He is out of town till Friday but I'll alert him to your post. Hopefully someone else will have you sorted by then.
I have sent you a personal message.
Brett
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can you put the vid up on Machs YouTube and we can view it from there.
http://www.youtube.com/groups_videos?name=artsoft
Hood
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Gary, this is a link to a stepper machine running a 3D file. Might help some.
http://www.youtube.com/watch?v=bApuwkkXTb8
Brett
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Hey Guys, type in Jerking Stepper in Youtube to see the problem!
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Have you run the drive test to see if that looks ok?
Can you swap over drives to see if the problem follows the drive?
Also check your power supply voltage to make sure it is steady when running all three axis simultaineously.
Hood
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Hood, done all your questions still no change? have to slow down to 2400mm/min to get rid of the pulsing.My old servo system
ran 5000.
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I would certainly expect faster than that if it is 1:1, my Bridgeport has steppers with 2.5:1 reduction and I get 2500mm/min on all axis so would think you should be looking at atleast 5000mm/min as I doubt its any heavier. Not sure what size steppers you have as its hard to say from a pic but look like they are about 916oz/in. What drives are you using and what is the stepping on them?
Hood
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I'd check the power supply out too , both volts and current wise when all axis are moving together.
no voltage drops on the cables etc .
Dave
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Hood, the stepper motors are 2550 oz/in. and 201 drives.
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Hood, the drivers are 203v at 1 tenth not 201's
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Hi Garyh,
Here is an interesting thread that may or may not interest you.
http://www.machsupport.com/forum/index.php/topic,1724.0.html
RC
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Geckos are good drives but these are big steppers, the bigger the stepper the slower you will be able to spin it, or at least thats been my findings.
Hood
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RC or Brett or any other Mod/Admin, what about moving this post to the general, probably belongs there and will be seen by more.
Hood
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RC, that was very much the same problems as i'am having .I loaded Quantum and had a lot better run today, still have a lot of tuning
to do yet but has realy made a big difference, many thanks for that.