Z axis still loosing steps?
maybe this is a simple problem for someone out there...
started to build my DIY CNC router in Jan 2017, finished sometime in late summer '17, okay now it is built and control box done, very simple DM860A stepper drivers and a generic breakout board and old PC running windows 7. there are 2 RM1605 ball screws driving the Y axis and 1 for the Z and X axis all with the same pitch and all but Y axis are run on NEMA 34 motors running on 3.5 amps, the Z axis is Nema 34 5.6 amp because I thought it would be better with the heavy actuator. I started out with round linear rails and the machine ran okay but I was having a problem with the Z axis loosing - 2.5mm every time I would run a code out, and it was not consistent at 2.5, sometime it would be 1.5 mm but every project would have a problem I am using both Vectric and Fusion 360 and the machine is running on mach3. I looked for help here and it was suggested that maybe if I was using NSK or comparable square blocks and rails for a tighter tolerance. Well I went with HD20 blocks and rails( they are great ) and can you believe after fully building this machine (2 times) it is doing the same thing? is it something I am doing wrong in the mach3 software? I know that all diameter cuts are perfect , x and y locations are spot on, and testing the motors in mach3, also perfect. I have so many thing I would like to cut but I am a bit worried about wrecking good walnut and cherry stock I have planned. so if there is any advise or things to try please let me know
thank you
pat
Re: Z axis still loosing steps?
the X ,Y and A (slave Y ) axis are S20160 60V output 6.4 amp each and the NEMA 34 motors are 2A 8 wire. The Z axis has a S35060 supply and supplies 6.5A the NEMA 34 motor for that axis is a bit larger @ 5.6 amps. they are set to 1000 micrsteps via the DM860A microstep drivers on all 4 axis, and as far as a profile? not sure what you mean, if its important I am a hobbyist,
Re: Z axis still loosing steps?
How heavy is your spindle or router? It may be too heavy and the weight needs to be counter balanced.
Re: Z axis still loosing steps?
What are the model numbers of your steppers.
First you said 3.5 amps, then you said 2A??
What are your velocity and acceleration settings in Mach3?
In the Mach3 folder, run Drivertest.exe, and post a pic of the results.
The profile is an .xml file in the Mach3 folder.
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Re: Z axis still loosing steps?
yea sorry about that I started the thread away from shop and was guessing, didn't think the exact numbers mattered in the question but 2.0 is the right amp
here are the model numbers for the stepper
X and Y and A are all 34HST9805-0282 and the motor for Z is 34S9456
as far as the numbers in mach3
X = 2598V and 273A 199 steps per
Y = 1654V and 135A 200 steps per
A = 1654V and 135A 200 steps per
Z = 1707V and 184A 104 steps per
I tried to run the drive test but will not run? The steps per on the Z axis was much lower than the rest so I changed it to 200 and it made no difference in performance I just ran the router again after the change and nothing. I have attached a pic of the test I just ran it's very weird how the numbers change, is it possible there is something wrong with mach3? I can't run the drive test and can I fix that? anyway if you do look at the pic it is a program from VCarve pro and mach3. just a simple coaster set and after doing the 1st pocket code there are 4 coasters and the 1st one is 5 and should be only 2mm and it is on just one pass and then each one after that drops a bit more? okay I can't upload the file as it keeps coming back but the photo should help
Thank you
Pat
Re: Z axis still loosing steps?
Are you using a motion controller (no parallel port)?
Re: Z axis still loosing steps?
Reduce all of your acceleration settings to 75, and see if that makes a difference. You'll need to restart mach3 after making the changes.
Also, you can't just randomly change the steps/unit, as that wil change the distance the machine moves.
Re: Z axis still loosing steps?
using an old windows 7 PC with nothing on it but mach3 using a parallel port and a generic BoB
Re: Z axis still loosing steps?
If the machine moves, then Drivertest should run.
Try right clicking on it, and choosing Run as Administrator.
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Re: Z axis still loosing steps?
so it worked that way, I really think it might be software issue because I ran a 3D cut for a wedding gift and it worked fine? the problem seems to be worse on very thin material if that makes any since. It did cut this gift pretty good but having the material set @18mm it cut down 19.5mm so 1.5mm over. Another thing I noticed is when I set up mach3 for this project and I always do a" regenerate g-code " and then "go to zero" to check my location visually to be sure I am starting in the right place and I can see the tip of the tool is not touching the matrial, it looks to be about .5 to 1mm above the surface. I have attached both the snip file from mach3 and a photo of the gift I did today. And maybe I should mention I used Vectric VCarve Pro on both projects.
Thanks again
Pat
Re: Z axis still loosing steps?
Did you reduce your acceleration like I said?
Re: Z axis still loosing steps?
sorry guy's I had to go out of town for a few days (wedding) so on Sunday I will get back into shop, I really think there must be a problem with the way mach3 is seeing the gcode? like I said the other day, when I needed to cut the 3D wedding gift and it came out fine... well kind of anyway. the only bad part of the project was when I did the cut out and it cut into the waste board 1.5mm when I get home I will try the method you suggested Gerry and let you know .
thank you for your help and sorry it took so long to back to you, traveling sucks!
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Re: Z axis still loosing steps?
okay sorry about that, Gerry I did change the settings like you suggested and it made things worse... so I put it back for now. https://www.cnczone.com/forums/attac...d=407392&stc=1here is a bit of the code where the problem happened but it seems to happen on other files as well. I thought because it was so consistent maybe the table was off? but after testing all corners of the surface and the middle it all checks within about .5mm
Re: Z axis still loosing steps?
Is the cutter slipping in the collet?
Is the Z 0 height the same before and after a run?
Re: Z axis still loosing steps?
that's the part I don't get either? at the end of a run it comes right back to zero, right on the dot. it is very consistent so I went into the script editor in mach3 and made a change on the script for zero z axis and changed the thickness of the zero block thickness input line from 19.25mm to 17.75mm and ran 2 programs, both came out right? I use a caliper on all the measurements for setup and most everything I can when drawing or fabricating they are everywhere in my shop. And I thought maybe this was the problem from the start and checked it several times since then and it always measured right 19.25 mm and that is what was in the script, so go figure, right. For now it will be fine until the holidays are over and I can spend more time on it. Right now it is the script borrowed from GuruBrew and it had high reviews and I think the guy is great so I really didn't think that is the problem, but for now its working. I bought the ScreenSet 2010 and will install it as well after the holidays,
thanks for all your help guys and if you have any ideas please let me know
Pat
