Question regarding machine starting to skip

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jefflangendoerfer
Posts: 9
Joined: Tue Jun 04, 2019 1:56 pm

Question regarding machine starting to skip

Post by jefflangendoerfer » Fri Apr 17, 2020 2:13 pm

I have my BB running Nema 23's on a small C6040 Chinese Engraver
I am experiencing what appears to be one of the motors skipping a step- Here are the details

-The machine will run the operation fine, sometimes up to 4 times in a row
-Sometimes it appears to skip a step (or more) and when it does, it is always in the same exact spot
-The spot is the first touch down after the spindle leaves the 0,0,0 location
-To make things fun, it is a a diagonal move
-The skip causes the spindle to fall short of its intended target on both the X and Y axis.
-The X axis gets off track by 2.5mm and the Y gets off track by 1mm

I have removed both stepper motors and made sure that neither axis is binding
I have slowed the rapids down on both motors all the way to 60IPM

Any input would be greatly appreciated

Thanks!

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Doug
Posts: 125
Joined: Fri Feb 02, 2018 4:56 pm

Re: Question regarding machine starting to skip

Post by Doug » Fri Apr 17, 2020 4:42 pm

Please create a "bug report" and attach it to a post. When you do this, make sure that a gcode program that demonstrates the failure is currently loaded. This will give me a copy of your gcode program and your configuration.

Also if possible, please note in your posting the line in the gcode program where the failure occurs. Also, please note the version of software that you are currently running.

I'll load everything up here and see if I can simulate the problem.

jefflangendoerfer
Posts: 9
Joined: Tue Jun 04, 2019 1:56 pm

Re: Question regarding machine starting to skip

Post by jefflangendoerfer » Mon Apr 20, 2020 4:41 pm

Hello Doug,

The bug report was too big to attach, so I emailed you directly.

Thanks for all your assistance. as always.

You are top notch.

All the best,

Jeff

jefflangendoerfer
Posts: 9
Joined: Tue Jun 04, 2019 1:56 pm

Re: Question regarding machine starting to skip

Post by jefflangendoerfer » Tue Apr 21, 2020 9:16 am

Hello Doug,
as a follow up to our conversation yesterday, I ran the following test last night:

I ran my engraving opp 10 times in a row with no shift in position, no stalling, no skipping etc.

THEN, after the 10th run and the Spindle parked as it should at 0,0 .394(z height) I clicked the "home" button for the Z and changed the Z height to .395 and pushed enter. The Z height changed to on the display to .395.
I do this so that the Z will cut .001" deeper on the next run.

I then pushed "play"/start, and during the first rapid to the first cut the X axis lost/shifted position and the first cut was off approximately .04"

I will send you the updated bug report, G code file and a few photos to go along.

Thanks!

Jeff

jefflangendoerfer
Posts: 9
Joined: Tue Jun 04, 2019 1:56 pm

Re: Question regarding machine starting to skip

Post by jefflangendoerfer » Tue Apr 21, 2020 9:21 am

ps- It did this even after I set the idle power to .75 amps

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Doug
Posts: 125
Joined: Fri Feb 02, 2018 4:56 pm

Re: Question regarding machine starting to skip

Post by Doug » Wed Apr 22, 2020 3:16 pm

I ran your program at least 20 times (each time, manually homing the z axis to .395 before I start. No failures. Any suggestions on how I can simulate the problem?

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Doug
Posts: 125
Joined: Fri Feb 02, 2018 4:56 pm

Re: Question regarding machine starting to skip

Post by Doug » Wed Apr 22, 2020 7:28 pm

Have you tried running your program at a different location on your machine? If the machine is binding in a specific spot, then moving to a different place on the machine should either eliminate the binding or cause it to occur at a different spot in the program.

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