It looks like a setscrew on a pulley is loose.
Or the machine lost position at some point.
If it's repeatable, it's more likely a loose pulley.
I'm building for 2 year a DIY CNC and for the last 10 month trying to use it with no accuracy.
SETUP
table CNC 1500mmx1000mmx300mm
Extruded rails with Vslot wheels
1.5kw spindle
NEMA 23 - 345oz*in at 1/8
Belt GT3 and pulley (16T) with strong tension
Drivers DQ542MA at 24v
Controller parallel Breakout tBoard
Mach 3
WORKING
All systems in mach 3 are working OK controlling all movements and spinle
ISSUE
When I run the wizard from mach3 to drill a rectangular bolt (hole) pattern in the X axis (1500mm) the first and last drill hole are OK but the interior holes get misaligned in odd and even rows.(look picture)
http://www.cnczone.com/forums/attach...d=375586&stc=1
The error is always the same between rows.
I have changed motors, drivers, belts and pulleys but the issue remains.
I have swapped X and Y outputs from parallel breakout board but issue is always on X axis
why is this happening?
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It looks like a setscrew on a pulley is loose.
Or the machine lost position at some point.
If it's repeatable, it's more likely a loose pulley.
Gerry
UCCNC 2017 Screenset
[URL]http://www.thecncwoodworker.com/2017.html[/URL]
Mach3 2010 Screenset
[URL]http://www.thecncwoodworker.com/2010.html[/URL]
JointCAM - CNC Dovetails & Box Joints
[URL]http://www.g-forcecnc.com/jointcam.html[/URL]
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
It is always repeatable
X axis has 2 motors to drive it conected to the same driver
I have checked that before but I will re check pulley screws again
Thank you
I agree that it could be a loose pulley. Or a large amount of backlash.
You can see the toolpath from the picture. It drilled the leftmost vertical column of holes traveling up with the backlash causing each hole to be slightly low. Then it drilled the next column traveling down and the backlash caused each hole to be slightly high.
Steve
being backlash the top and bottom holes should also be misaligned (they are OK). Is this correct?
Are the holes drilled, or routed as circles?
Gerry
UCCNC 2017 Screenset
[URL]http://www.thecncwoodworker.com/2017.html[/URL]
Mach3 2010 Screenset
[URL]http://www.thecncwoodworker.com/2010.html[/URL]
JointCAM - CNC Dovetails & Box Joints
[URL]http://www.g-forcecnc.com/jointcam.html[/URL]
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
They are drilled with mach3 wizard 'rectangular bolt pattern'
The top and bottom rows would have been cut after a horizontal movement. Any vertical backlash skewing a column of holes lower would still be present as the head moves horizontally to a new column. So the top and bottom rows of holes could appear "perfect" even though they may all be misaligned by the same amount.
Steve
Is this a machine that uses belts instead of racks with pulleys instead of pinions? That works pretty well with 3D printers, which are very lightly constructed and need to move fast, but which don't have to contend with counter-forces. It works less well at moving the axes of CNC routers; the belts tend to flex too much, leading to inaccuracies like those in your pictures. If you post some detailed photos of the machine you built, we might be able to point out areas for improvement.
[FONT=Verdana]Andrew Werby[/FONT]
[URL="http://www.computersculpture.com/"]Website[/URL]
What's shown in the pictures has nothing to do with belt flex.
Gerry
UCCNC 2017 Screenset
[URL]http://www.thecncwoodworker.com/2017.html[/URL]
Mach3 2010 Screenset
[URL]http://www.thecncwoodworker.com/2010.html[/URL]
JointCAM - CNC Dovetails & Box Joints
[URL]http://www.g-forcecnc.com/jointcam.html[/URL]
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
I've tried in mach3 software to enable 1.5mm of backlash in X axis and the rows align the holes, perfectly and consistent, but with that I cannot do circles, because in all 2 transitions of the quadrant (were X axis inverts motion) I get a 1.5mm bump, meaning that backlash wasn't needed.
I send a photo of one of the 2 X axis motors.
Belt goes under the extruded profile
I still have this issue.
If I cut a wizard rectangular bolt pattern
in X axis the extremitiess holes are aligned just interior holes are missaligned between even and uneven rows. Y axis is OK
If I rotate the wizard 90 degree X axis is ok and the same missalignement occurs in the Y axis.
If seams to be software. Is there any alternative software that supports RNR 4axis breakboard?
Have you looked at the G-code generated by the wizard? Have you tried a known working code (written by hand or in some CAM software)? Thousands (if not millions) people use Mach3 successfully, so I don't think the software itself is the problem.
I have disabled backslash in software and belts are super tight, and pulleys and motors super tight.
X and Y axis have different assemblys and error is the same.
I believe now it could be setup of drivers DQ542MA or motor tunning Pulse Dir settings...
Unfortunatly I dont know what to look for.
Yes. Extrenal holes are aligned correctly, Missalignement only occours interior holes and are perfectly aligned between even and uneven rows.
will check that and try swaping them.thanks