Topics created by Tpmoses

@Tpmoses I assume you were using

Can you please describe a step by step process to reproduce the error?

@Tpmoses said in parallel thermistor programing:

I am building a multi heater print bed because of size. I've got the wiring I need, and there are four NTC 100K 3950 (one in each heater) wired in parallel. I know that I will need to reduce the T value, but I have also seen that for the 3950 I will need to put in specific heat parameters in the RRF config tool.

If you connect identical thermistors in parallel, the R25 value (which is the RRF T parameter) of the combination reduces in proportion, but the B value is unchanged.

If the thermal coupling between the different parts of the bed is good (e.g. because all 4 heaters are heating the same thick aluminium bed plate), then it should be sufficient to connect the thermistors in parallel and the heaters in parallel, and drive them as one. Otherwise, the four heater/thermistor pairs should be controlled independently.

@Phaedrux That's the plan long term, however in the meantime (waiting on parts that are on backorder) I was going to use the built in ones as a stopgap to be able to print until then.

@hamel The problem is time, this machine is used to make parts that are then used to make molds for fiberglass parts. A custom replacement wouldn't be here till May.... I already checked. Four smaller ones can be here by Monday. Ultimately its not my decision to make, bosses liked the faster option.

@Tpmoses do you still get the lights flashing on the IR board on startup as expecting? If so, it suggests the chip on the IR board is fine and the power surge itself hasn't damaged the board. Most likely the damage has come from the sensor hitting something, so as the the others have said swapping to a BLTOUCH won't solve your issue.

I'd suggest going through your wiring, but maybe also look at the failed prints to see what went wrong with them. I'm guessing thrbdamage came from the board hitting the print? In which case, either there is a printing issue that has caused the print to lift up, or there is a config/slicing/hardware issue that has caused the nozzle to drop down.

@engikeneer said in Dual Z motors and compensation programing questions:

@Tpmoses just to contradict @fcwilt here... I just run homeZ (G28 Z) at the end of my bed.g. in my case my homeZ just uses a z probe at a set point, so it means I can make sure I always probe the same point to reset the Z datum. If you use an endstop in your homeZ (e.g. in a delta printer), then this won't work and you'll have to use fcwilt's method (or something similar).

Good point.

While I have a Z probe I also always install a Z end stop sensor, one per Z stepper.

The normal probing speed for one of my probes is 300 or less - depending on type of probe.

Homing using the end stop sensors is much quicker since the normal homing speed is 1200 or more.

My apologies for failing to mention this.

I should also point out that the formula I posted for probing the center of the bed...

G1 X{0 - sensors.probes[0].offsets[0]}, Y{0 - sensors.probes[0].offsets[1]}, F6000

...is based on my printers co-ordinates for bed center - which are X=0 and Y=0

The formula will work regardless if you change each 0 before the minus sign to the correct value for your bed center.

I only showed the formula there by way of demonstration. I don't actually do that but wanted to keep things simple. I actually have a macro that I call to set the Z=0 datum as needed and it does use the formula. But since I always call the macro I always use the same XY co-ordinates.

Again my apologies - I keep forgetting that not everyone uses 0,0 as bed center.

Thanks.

Frederick

Ordered the connectors, Thank you!

not enough information
please see
https://forum.duet3d.com/topic/5909/guide-for-posting-requests-for-help/2

@Tpmoses said in Z drop on board reset:

I was struggling with was when the board resets, the z motors let the gantry lower on the side..

I made a similar transition from a dual stepper single driver to a dual stepper dual driver Z configuration and it works well.

With the single driver approach, I had a macro that lowered the bed using a reduced stepper current. That causes both sides to get to their mechanical bottom which I used a standard position for stating the Z homing process.

https://duet3d.dozuki.com/Wiki/Tuning_the_heater_temperature_control

@Tpmoses
Once you've set those, the majority of your issues should go.
Just remember that you need to consider the offset in M557 as its not taken into account.
e.g. if your probe is 50mm to the left of your nozzle, it won't be able to reach the last 50mm of your bed on the right unless nozzle can go off by 50mm (and the M208 maxima reflects this)

@Phaedrux Thank you, I will apply to the program!