You could test printing PLA which can be done without a heated bed, and you might be able to run your heat bed off a 24/12v converter if you have one (which needs to be rated for your load) to bridge the time until your 24v heat bed arrives.
I understand, maybe I will continue with my motors since it’s actually not very bad. I’ll rather put this money on other tangible improvements.
Thank you very much for your time and for developing such a great board/firmware like the duet!
@darkstarone It doesn't fluctuate at all, the temps are perfectly stable (unless I open the door of course). It's a very sluggish system with a lot of heat capacity, so you don't notice the heater coming on at all.
I do notice the same effect with the oven light that's installed in the build chamber (which acts as its own 25W heater btw), which flickers when the duet kicks on the heater element. It's a visible flicker because I'm running the heater with 10 Hz PWM (SSR-compatible).
@dc42 Thanks for that detailed information here as well as the other thread, this is why I buy duet boards and will continue to do so for all of my machines in the future. For now, we are going to try just leaving the blower fan on at a really low subtle speed and see if that's enough to get away with using bang bang on the heating element and not cause the thermal expansion or banding in the prints. If not then we'll explore this route.
I think I'll add something that looks like an e-stop instead of using the inconspicuous switch on the side; or if e-stop is something one could resume from if accidentally triggered thats not the end of the world after all - but I feel e-stop should look like e-stop.
I guess there is also the reed or hall sensor in the front door that could be a pause button. Still lots to figure out, love it!
Yes you can use 19V power. The RepRap Huxley printer does that, so does the Fisher I think. Btw, RepRap Ltd. sells a 19V blower fan.
Last time we looked at using a USB C connector on the Duet, they were too expensive.
Any news on the DueX0?
I've got an application which it would be very helpful to have, just wondering if I can skip working on a workaround.
If the board design is ready, I could have it fabbed if needed for my purposes, or could help you out with beta testing.
i suspect that most people will either be running pt100 or normal thermistors.
there around 100 ohm will not make a big difference.
i adjusted the resistor value in the m305 and its working as expected.
@phaedrux you're a great help, I really appreciate it.
The probe ran without issue for 10 minutes before I called it. I decided to try again while moving the x axis back and forth and at almost the exact same point it failed to probe. The little blue light dimmed slightly.
I swapped in the true probe, and repeated the test and it happened again, almost the exact same spot.
With your help I'm convinced it has to be wiring related. Tomorrow it's going to get a new wiring harness that's 2 meters without any extensions
@lb said in Duet2 Stepper Driver Current Limit:
just doing research on this "old" topic: With heatsinks on top/bottom of the driver and/or active-cooling it could be experimentally increased another 0,2-0,4A up to those 2,8? (Just thinking out loud here...)
You could recompile the firmware to allow 2.8A, but it would be at your own risk.
The point to remember is that Trinamic allows a higher current when the stepper motors are moving above a certain minimum rate than it does at standstill, because when the motor is moving, the heat dissipation is shared between all 8 mosfets instead of being in just 2 of them. Also the mosfets are on separate dies from the controller chip in the TMC2660, so the over-temperature detection on the controller chip won't react instantly to an overheating mosfet.
I originally hoped to implement standstill current reduction in firmware, but that turns out to be very difficult to do in a way that is 100% reliable.
Duet 3 will allow higher currents, certainly over 3A and maybe as high as 4A.
If you have the on-board 5V regulator enabled, then the contrast on the 12864 display can be expected to change when you switch from USB power to VIN power (or provide both - the VIN power will take over). This is because the 5V rail is only about 4.6V when powered from USB alone, but a true 5V when powered from VIN. However, increasing VIN from 12V to 24V shouldn't make any difference to the contrast.
There are two places where the contrast pot may be:
Mounted on the back of the LCD PCB (the green one), so the red PCB gets in the way of adjusting it. If you orient the unit so that you are looking into the SD card socket opening with the LCD on the underside, the pot is slightly behind and to the left of the back left corner of the SD card socket. Some of these display/encoder combos have a hole close to one corner of the SD card socket, to provide access to the pot.
Mounted near the bottom left corner on the front of the red PCB. Most of the current listings on Amazon and eBay show it in this position.
The most common problem we see with older DueX boards is imperfect soldering between the SX1509B chip and the PCB. the pads are under the chip, so it's not possible to inspect the solder joints other than by using X-rays. That could explain all the problems, although the Fan 3 problem might also be caused by a blown mosfet.
Replacing the SX1509B or just reflowing the existing one using hot air rework equipment may fix the problems.
The Za and Zb connectors are internally wired in series, so they both get the same current you specify with M906. It's recommended to set the motor current in the range of 65-85% of the rated max for the motor. So in your case, 2000ma max * 85% = 1700ma.
Since the Za and Zb connector are already expected to be a single combined Z axis, you don't have to do anything else special to set up the driver. Just treat it as a single Z axis entry in all the commands.
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