Only cuts 60 degrees of a circle

Machine: 130W custom build
Board: LaserBoard
Firmware: Smoothie

Problem: Only cuts 60 degrees of a circle.

I’ve just got my machine built and I’m doing the first tests. First off I did a square with no problems, but when I try to do a circle it just does the first 60 degree arc and quits - always the exact same portion of the circle, even different circles of different diameters in different positions in the workspace. LightBurn reports that it’s busy (at 20%) and I can’t get anything to work after that besides restarting LightBurn and the LaserBoard. I’m just doing a line cut at 20mm/sec and 100% power, (I have my current limited to 6mA). The gcode looks fine to me - obviously the square is just four G1 lines where as the circle is many more. So it would seem that the Smoothie buffer is getting full and hanging up. I’m thinking that there’s a setting in LightBurn or the config.txt file that I need to tweak, but I’m not finding anything yet. Any ideas of what I should do?

Figured it out. Buffer is filled as soon as gcode is sent, but USB is disconnecting when laser fires. Buffer is then depleted producing exactly the same arc each time. Now just need to figure out the power issues causing the disconnect.

Could be RFI/EMI on the USB cable. Make sure it’s as far away from the HVTs and high voltage wiring as possible. If you have one, try a USB cable with a ferrite core on it.

I think I do have a USB cable with a ferrite core, but it’s mini-B. I’ll see if the core is a detachable one. If not I might even have one of those knocking around.

I just did some testing and it disconnected when the chiller kicked in, so it might not be laser firing but load from the chiller, (laser wasn’t connected). I’m running through more tests now, but I’m narrowing it down, (and tidying up my wiring on the way!)

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Chiller? I’m surprised you don’t just run a length of copper pipe outside :slight_smile: Nothing beats the cooling power of a -40° winter night!

Seriously though, if the chiller is kicking in and causing the voltage to dip on the AC input, that could be affecting the PSU for the Laserboard as well, causing its output to momentarily drop out. Might be worth moving the chiller to a circuit on the other AC leg (A voltage dip on one leg corresponds with a voltage push or spike on the other leg - PSUs typically deal with pushes and spikes better than drops/dips).

I’m revisiting everything electrical-wise tomorrow. Putting the chiller on a different circuit seems to have cured that problem, but when the laser fires I also get a disconnect. That could be a load issue like the chiller or a HV interference issue, (or both). But I’m heading in the right direction.

I only got the chiller for when we get those hot +40F summer days. :smiley:

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