What do you really get for a $350 desk top engraver ?

i think one thing that i could try to see if things improve would be to swap out 36V power supplies for some 48V supplies i think i have 4 of them in another box that i can steal or borrow just to see if it improves and with some extra power?

it might be that the X axis is under powered compared to the tandem Y axis and that could be why it shows up on contour cutting? that would be pretty easy to do and not redesign things from the ground up in the process It might point me in a particular direction?

machinedude wrote:

it might be that the X axis is under powered compared to the tandem Y axis and that could be why it shows up on contour cutting? that would be pretty easy to do and not redesign things from the ground up in the process It might point me in a particular direction?

• What does the unwanted surface look like on contour cutting?
• Is it a repeating pattern, or random marks/gouges?
• Does it happen at all speeds, or just some?
• When you specify 'contour', do you mean any cutting involving the X axis, or only certain motions?
• Belt profile and pitch?
• Pinion pitch diameter?
• Still using the CL57T drives?
  • Have you modified any settings inside the drive?
  • LCNC output steps per mm or inch?

This should help to narrow down if the problem is primarily due to the coarse motion system you have, or a tuning/settings issue.

Unless the motors are losing steps, I don't think you need to change motor voltage just yet.

straight cutting in the X or Y direction seem fine, It is when i have both axis moving together doing a cut it shows up. direction seems to make no difference. i have not seen any kind of gouge marks. it like a very slight chatter. i have tried micro stepping from 4,000 to 12,000 and that made no noticeable changes to rule out resolution being an issue. it seems like osculation either mechanical from a belt flexing against the pinion i guess tuning on the feedback could look that way as well, DOC and speed seem to make no difference.it only shows up on radial cuts i have not seen any surface finish issues facing or on the floors of any cuts. i can go 1" deep and cut 1/16 with the side of a 5/16 3 flute at 30 to 40 IPM on my Y axis and things look great? Like i said it's just really odd and hard to pin point a cause.

the belts are a 3mm pitch arc tooth and i think it has a .907 pitch diameter and the OD is .872 (24 tooth)

same drives and i have not done anything with the settings internally. i do have the cables for that just never got the far into the tuning of the drive.

things are set in inches i LCNC

i'm not losing steps the closed loop feedback to the drives seems to be doing what it should be doing for that part of it. i have the drives dealing with everything too on that end.

Those drives have more-or-less infinitely adjustable microstepping.

HIGHLY recommend adjusting the following alarm setpoint.  I have similar drives (Nema34's) from Stepperonline, and the following alarm was set to 4000 counts from the factory.  They've got 1000-line (4000ppr) encoders, which means from the factory they won't alarm for a full turn.

Once set to a reasonable level, you can see if they are actually losing a few steps.  I'm also wondering if your g-code is output with lots of line segments instead of arcs and you need to adjust your G64 P-value (or turn it on).

i was wondering if the fact that the Y axis has a lot more power than the X axis that would cause the feedback loop to work harder on the X axis and lag behind the Y axis? that would explain why it shows up on cuts when the X and Y are moving together.

adjusting the alarm set point might show this like you suggested. i just have to figure out how to make that adjustment i'm guessing that is done in the drive with communication cable they send with the kits.

as far as programming goes i should not be getting line segments on arcs and my geometry should be clean. i have seen that when importing files though. But i can look around at settings to double check.

machinedude wrote:

i was wondering if the fact that the Y axis has a lot more power than the X axis that would cause the feedback loop to work harder on the X axis and lag behind the Y axis? that would explain why it shows up on cuts when the X and Y are moving together.

adjusting the alarm set point might show this like you suggested. i just have to figure out how to make that adjustment i'm guessing that is done in the drive with communication cable they send with the kits.

 

'cause the feedback loop to work harder...' is not a meaningful statement.

Your X axis has one motor, and that motor only has to move the head.
Your Y axis has two motors, but each motor has to move half the head weight/inertia plus half the gantry.

There may be a significant difference between X and Y power/torque requirements, but that's probably due to bent or misaligned components and not a massive difference between X and Y inertia-per-motor.

Having said that, if a stepper motor-driven axis has more friction (or load) than the motor can handle, it doesn't 'lag behind'.  It will lose steps.  It may lose a couple steps every so often, or a bunch of steps and stall completely.

But it doesn't just run slower due to increased load.  Your axis motors are not a cordless drill that slows down when you stick a big bit in and overload the motor.

Yes, you need to install the tuning software, connect to the drive (drive powered on), and adjust the alarm setpoint value.  Be prepared for a horrible experience as the software is unintuitive and not well translated.

Do you have clear photos of the problem - i.e. surface finish - and a sample of the gcode used to cut when the issue appears?

what i said before was phrased as a question because i am in territory i know little about but thanks for the detailed answer to help me understand better.

i did download the software last night and had a look at the manual (PDF) and it sounds like the software is about as good as the manual

as for the lost steps i have not seen anything that shows that has happened if it is it would have to be pretty small and not obvious by eye. the only time the drive alarmed was in a stall from cutters loading up before i added the mist.At one point i even had a glass scale and DRO hooked up to see how accurate the belts were and did not see anything but that was with no loads involved.

i don't think i have any programs that are simple mostly 3D milling tool paths. I can probably do some testing this coming weekend. Anything during the week is pretty hit and miss for me since i work the night shift.

all the code i do is in fusion 360 if that helps any? i can't remember if i had smoothing in use or not that could be something to test i guess.