Duet 0.8.5 z probe connector

Ok, I have the Z=0 issue resolved. The z probe section in config.g had a 5mm offset defined for the probe. I changed that to 0 since with FSRs the probe touches the bed to trigger it. However, I am still "over probing" - I have to add a -.3mm offset to get in the ballpark (I haven't checked the actual first layer thickness yet but I can get the layer down), I've not had this issue with any of my other (5) deltas with FSRs. However, I did design a different FSR/bed mount system for this printer and it's possible it is taking more force (i.e. deflection) to trigger. But, it seems to be consistent from the center to the edge of the build plate

No, the homed height set by the H parameter in the M665 command is the height when the homing switch3es are triggered. The G1 Z-5 in homedelta.g doesn't affect the homed height, I added it so that the head can be centred at the end of homedelta.g.

Are you sure that you have the probe Z offset set correctly in the G31 command in config.g, to the Z height at which the FSRs trigger? For FSRs it should be slightly negative.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

It turned out to be the G31 command had a 5mm offset. However, see my post above, with the FSRs I'm finding I need a -.3mm offset in G31. I've not had to do that on any of my other FSR equipped deltas.

I believe it is entirely normal to need a slightly negative Z probe offset when using FSRs. The nozzle needs to push down on the bed, and because the system has some elasticity instead of being perfectly rigid, this requires a small movement. Also, if the probing speed is too fast, probing may overshoot slightly.

To calibrate the Z probe offset, I suggest the following approach:

1. Use the paper technique, or whatever other method you prefer, to place the nozzle at Z=0.

2. Send G92 Z0.

3. Raise the nozzle a few mm.

4. Send G30 S-1, then read off the Z height from the web interface.

You can repeat (3) and (4) using different values of the M558 F parameter to determine whether the probing speed is high enough to cause much overshoot and needs to be reduced. There is a averaging filter in the Z probe reading firmware, so a small amount of overshoot is normal. If you want the averaging filter to respond faster, change the P parameter in the G31 command from 500 to e.g. 50. Your FSR electronics may also include an averaging filter.

Edited 3 time(s). Last edit at 10/14/2015 09:24AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Yes, it seems that there is a .18mm trigger deflection on tis setup. On my other deltas I have a 8mm melamine backer/snowflake insulator, 2mm PCB heater, 3mm aluminum heat dissipator, 2.5mm borosilicate glass and .8mm PEI build surface. The melamine, PCB heater and aluminum are screwed together at the periphery and very rigid.

On this new machine I have a Kapton heater attached to a thin 1.5mm aluminum dissipator clipped to the borosilicate/PEI. So there is indeed more deflection.

Now a question on thermistor calibration! I'm using E3D V6 hotends and stock thermistors they supply. I have 4.7K ohm resistors on the Duet 8.5 so my M305 in config.g is setup for that. What sorts of values should I expect for H? I have -125 currently and it seems correct at room temperature but a bit (10°C) low at 190°C.

Edited 1 time(s). Last edit at 10/14/2015 04:19PM by mhackney.

An H value of -125 is outside the normal range. With 4.7K resistors, you should get a good reading at room temperature without any H correction. It won't be perfect because of the tolerance of the thermistor.

How are you measuring the hot end temperature, and what B value have you put in the M305 P1 command for the E3Dv6 thermistor? E3D suggests 4267 AFAIR, however I looked at the resistance data for that thermistor and worked out that 4388 would give a more accurate temperature reading at typical printing temperatures (i.e. around 220C).

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I measure temp with a direct contact thermocouple (K-type). I have modified the probe by replacing the sheath with very thin small diameter PTFE so I can insert it into theft end and push up against the nozzle tip from the inside. I have to make sure the nozzle is new or clean before doing this. I've found it gives a reasonable temp and it is repeatable across all of my printers (with various firmwares but all using the same thermistors). If I hold the thermocouple up to the junction of the tip with the heater block, I typically get an 8°C lower temp reading.

The B value may have been an issue - I was using the default B in the existing config file (3974). I reset H to 0 and set B to 4388 and will remeasure. It is reading a bit warm at RT. I'm looking at 4 other printers and they all read between 20.0 and 20.3. The Duet printer is reading 25.6°C with the H and B set as above. I'll remeasure the hot target (typically 190°C for the PLA filaments I use) and see what I get now.

I'm also looking at the L parameter to adjust the low end, it doesn't seem to have any effect even with large values (100 or -100). Am I misunderstanding it's usage/purpose? Adjusting the high end parameter H does have an effect on the measured room temperature value.

The H parameter adjusts the high end ADC correction, which has most effect on the reading at low temperature. And vice versa.

I am surprised that your room temperature reading is as much as 5C out. That suggests to me that either the thermistor resistance or the series resistance on the Duet is a long way off its nominal value. If you have a multimeter, you could try measuring them.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Yes, I can measure the thermistor resistance. Where do I measure the series resistance on Duet? In the middle of a test print now. Other than the temp calibration the printer is working like a champ on Duet 0.8.5 and our firmware. Calibration is really easy.

Well, the resistor measures 143.7K. But, I measured 5 other E3D hotend resistors on my other printers and 2 spares that I have and they were all in that range ~143K

You can try measuring the value of the series resistor between the thermistor non-ground side input and the +3.3V pin on the expansion connector, with the thermistor disconnected.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

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dc42
Yes I would like to wrap the messages to at least 2 lines, but I have more pressing work on the PanelDue firmware, in particular I have two users who need support for more than two extruders.

I migrated from Smoothie to the Duet platform because it has hardware support for 3+ extruders. Is that not working yet, and if not, do you have a rough ETA?

626Pilot, I'm considering a similar migration. How has the Duet and DC42 firmware branch been working for you?

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626Pilot

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dc42
Yes I would like to wrap the messages to at least 2 lines, but I have more pressing work on the PanelDue firmware, in particular I have two users who need support for more than two extruders.

I migrated from Smoothie to the Duet platform because it has hardware support for 3+ extruders. Is that not working yet, and if not, do you have a rough ETA?

The Duet has support for multiple extruders (both software and hardware) but as I understand it the paneldue does not yet.

PanelDue currently provides controls and status for only the first 2 hot ends. The next PanelDue firmware version will support 4 hot ends on a 4.3 inch screen, and 6 hot ends on a 5 or 7 inch screen.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

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WZ9V
626Pilot, I'm considering a similar migration. How has the Duet and DC42 firmware branch been working for you?

I did a comprehensive Duet vs. Smoothie comparison here, earlier today: here

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dc42
PanelDue currently provides controls and status for only the first 2 hot ends. The next PanelDue firmware version will support 4 hot ends on a 4.3 inch screen, and 6 hot ends on a 5 or 7 inch screen.

Ah, I can live with that as long as RepRapFirmware itself supports at least 3.

Edited 1 time(s). Last edit at 10/24/2015 06:22AM by 626Pilot.

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626Pilot

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WZ9V
626Pilot, I'm considering a similar migration. How has the Duet and DC42 firmware branch been working for you?

I did a comprehensive Duet vs. Smoothie comparison here, earlier today: here

Nice writeup!

Thought I could comment on a few things.

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If you want to drive a big CNC machine with its own high-torque stepper drivers, Smoothie has pin connectors that you can use to bypass the built-in drivers, so you can use Gecko drives or whatever you want. Duet lacks this feature - but again, if you're here, you probably only care about running a low-current delta printer such as the Rostock MAX.

You can do the same with the duet using the expansion header and then use an M-code (don't remember which) to relocate the desired axis there.

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You can get the Duet 0.8.5, DueX4, and PanelDue from a single vendor in the UK that will ship to the US reasonably quick. I got mine in about a week. Since all three parts can be had from the same vendor, I consider this a fully-integrated hardware solution.

The duet 0.6 is also available from two other vendors, replikeo and reprappro and is still a good option if you are planning to run one or three to five extruders, the 0.85 is the better choice if you plan to run two or six extruders.

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Duet doesn't allow you to mount the SD card over USB at all, which is an inconvenience. However, you can edit over FTP, or upload over the web interface. I don't know whether it's faster than USB transfers to Smoothie. Someone else can chime in on that.

I can only chime in about the speed of the duet.
Seems most user get upload speeds around 200-300kB/s when uploading via the WEB-interface, I read someone getting much higher speeds but he used an "overkill" SD-card if I remember correctly.
Myself I get ~240kB/s when uploading via the WEB-interface, haven't tried the ftp-function as of yet.