Author Topic: Corrected problem of positive shift not being shown on DRO's  (Read 24173 times)

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Offline lokey

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Re: Corrected problem of positive shift not being shown on DRO's
« Reply #30 on: April 20, 2009, 05:56:13 AM »
Hi, the machine purchased is located at

http://www.zenbotcnc.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=zenbot&Product_Code=zenbot1216&Category_Code=Products

I do not have any other information on the control box.

When I tried the calibration axis feature to change the steps per inch, the circles would cut as ovals.

Offline lokey

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Re: Corrected problem of positive shift not being shown on DRO's
« Reply #31 on: April 20, 2009, 09:15:04 AM »
Hi, I down loaded a free version of KCAM 4 set the steps per inch to 1112 and ran  G code:
G0 X1
G28

and repeated code many times and the dial indicator showed no error.

The problem is not with the Zenbot I am missing a setting some where in Mach 3 that is causing the accumulating positive shift of 0.0015 that is not showing up on DRO's.  How do can tell what version Mach3 I have. Maybe I downloaded the wrong version. If anyone knows please let me know. Best regards
« Last Edit: April 20, 2009, 09:59:57 AM by lokey »

Offline Greolt

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Re: Corrected problem of positive shift not being shown on DRO's
« Reply #32 on: April 20, 2009, 07:37:54 PM »


The problem is not with the Zenbot I am missing a setting some where in Mach 3 that is causing the accumulating positive shift of 0.0015 that is not showing up on DRO's. 


No I don't know of any Mach setting that I have not already suggested.

Glad you have it working to your satisfaction now.

Good luck with KCAM.

Greg

Offline lokey

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Re: Corrected problem of positive shift not being shown on DRO's
« Reply #33 on: April 20, 2009, 10:31:45 PM »
Hi, KCAM is not the answer I am looking. It only shows that the the problem is not with steps / unit. I paid to use Mach3.
I am still looking for solution to the accumulating shift problem or is there away to get a refund?

Offline Greolt

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Re: Corrected problem of positive shift not being shown on DRO's
« Reply #34 on: April 21, 2009, 12:29:18 AM »
Lokey

I am only a forum member and not an employee of Artsoft.

Just one of the thousands of happy Mach3 users.

I am sorry I am not able to help you.

I do wonder why Zenbot are not helping you with your new machine.

Suggest you send an email to Artsoft regarding your refund request.

Greg
« Last Edit: April 21, 2009, 12:33:36 AM by Greolt »

Offline lokey

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Re: Corrected problem of positive shift not being shown on DRO's
« Reply #35 on: April 21, 2009, 12:43:10 PM »
Hi, thank you I greatly appreciate all the help that I received in trying to solve this problem.
Thanks again to all the members and best regards

Offline Dan13

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Re: Corrected problem of positive shift not being shown on DRO's
« Reply #36 on: April 22, 2009, 02:43:24 AM »
Hi Lokey,

Just went through this thread, and it looks very familiar to me ;) I had this same problem a while ago. To sort it out, what you're seeing is lost steps upon reversals. An easy test can be made to prove it. You don't need to home your machine and read the dial indicator after that. Leave the same setup with the dial indicator and use incremental jogging in Mach3. Set the increment to, say 0.005", then jog one increment towards the dial indicator (remember the reading), then one increment backwards, then again towards. The dial indicator reading theoretically should now show the same as the first time you jogged towards the the clock. In your case I'd bet it would show 0.0015" off.

If this is the case then your loosing steps on reversals. Your stepper driver expects the direction change pulse to appear in a particular correspondence with the step pulse. Some drivers work on the leading edge of the pulse, but most, I think work on the trailing edge (don't quote me on that). For the last case, for example, it means that a pulse is registered be the driver only at the trailing edge. So depending on when the direction pulse occurs relative to the step pulse, you get an axis reverse in the correct moment or not. If the direction pulse is sent "late" then all the steps(actually one) sent till that moment would still move the axis in the previous direction.

Theoretically, changing the active state of the step pulse should solve the problem. But sometimes it doesn't work (as it was in my case). Sometimes, the break out board messes up things. To check this you'd have to bypass the beakout board and feed the signals form the PP directly to the driver. Assuming your PP output voltage is sufficiently high for the driver.

If you want to learn more on the subject and my path in solving this problem, follow the thread "HELP! Accumulative moves" on Mach3 Yahoo Group, at

http://groups.yahoo.com/group/mach1mach2cnc/message/102773

And also the thread "HELP! Accumulative moves - Good News" at

http://groups.yahoo.com/group/mach1mach2cnc/message/102937

Daniel

Offline lokey

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Re: Corrected problem of positive shift not being shown on DRO's
« Reply #37 on: April 25, 2009, 09:56:38 AM »
Hi Daniel, thanks I tried you’re your test procedure and it show that every time I moved the axis there is 0.0009 accumulating shift in the plus and minus direction that is not showing up on the DRO’s.

Using different control software and using the test  procedure showed no problem.

I did notice that in ports pins config. under mill options that Mach3 is not allowing me to select No Home Switch. I do not have the Homes enabled, is there another way to enable the selection?

If anyone knows please let me know, thanks again and best regards