Duet 3 Scanning Z probe

T3P3Tony

We have been working on a Scanning Z probe for Duet 3 / RepRapfirmware, I am happy to announce the details now:

https://www.duet3d.com/blog/Duet3d-Scanning-Z-Probe

https://docs.duet3d.com/en/Duet3D_hardware/Duet_3_family/Duet_3_Scanning_Z_Probe

We are aiming to get supplies to our resellers by the 22 of November

https://youtu.be/k-wD0_l69SQ

fcwilt

@T3P3Tony

I am going to have to give that a try.

Thanks.

Frederick

oozeBot

@T3P3Tony what's the upper temp limitations on this initial version and is there any opportunity to use the build plate's temp within RRF to average at higher temps? Or will that only be available on future versions with a built-in thermistor to the probe? Also, is it possible to set actual z-height with the probe? Or just scan the surface once z-height has been set. Thanks!

jens55

@T3P3Tony , just to confirm - this probe does not work with a glass surface ? .... and presumably doesn't work with any other non-metal surface such as PEI, gerolite etc etc?
Thank you for mentioning the increased number of probing points available for the 6HC, I was unaware.

fcwilt

@T3P3Tony

And if it works like I hope I have printers running on v2 hardware that will need to be updated.

So clearly this is a clever plan to sell more v3 hardware.

Thanks.

Frederick

R4ffers

I definitely want to give this a go

@fcwilt I'll wait a bit and see if they combine this with the tool board. A 1LC+ would be awesome!

fcwilt

@KenW

That would be good.

I have a few 1LC boards but have never gotten around to trying them out on one of my existing printers.

Though I have re-designed my E3D Hemera XS mount that I have on my E3D MS/TC printer with the idea of trying them.

Too much to do and too little time.

Thanks.

Frederick

@fcwilt Figure since they included the accelerometer and it has the CAN-FD hardware adding it to a toolboard would seem to be an option.
Replace the JST-ZH with a larger connector and keep the 3 and 4 pin fans and other IO and I would definitely reduce the wire count on my printers.

o_lampe

@KenW said in Duet 3 Scanning Z probe:

@fcwilt I'll wait a bit and see if they combine this with the tool board. A 1LC+ would be awesome!

Didn't take long to fulfill your wish

@o_lampe

Now I get to wait until some make it across the ocean blue.
Documentation to make sure it can be made to work is needed too.

I see it has 3 pin fans so the 4 pin 12v 4010's I finally found are not usable but the 3 pin 12v blowers might be. The ZH connector is history, several others are beefier and all appear to be easier for an old dude to crimp.

I'll pause my work on the rebuild of the printer and the eventual updating of the other 2 to see . The Roto looks interesting too. And might solve the width issue I am having with the IDEX conversion idea. As well as weight.

zapta

Duet3D keeps innovating. This is very good.

I guess that with this fast scanner, it's more feasible to run bed mesh before each print.

Notepad

Really excited to try this. If it can do the auto calibration for sensitivity, it may be able to remove the issue that plagues regular inductive probes because of ambient temperature drift.

droftarts

@Notepad yes, it does an auto-calibration before scanning. The probe board also has a thermistor, an accelerometer and CAN connector. It should be possible to compensate for temperature using the thermistor, or use the thermistor to check that the temperature is the same for each scan. So it could theoretically be used as a Z probe, but we currently recommend a more reliable bed surface probe; our demo machine uses Voron tap, but any other Z probe should be fine.

The probe scans the top-most metal surface, in the case of the Voron Tridex at the show, this is the spring steel backing of the PEI sheet. We found we could put a business card between the PEI sheet and the aluminium bed, and it would show as a large deviation in the bed! If it was in the right place you could see the rectangular outline of the card. I forgot to take a picture of it, but it showed the bed mesh was being updated each time it was scanned, ie not a faked show display!

Ian

dc42

@Notepad the auto calibration is only possible if you have another way of establishing Z=0 first. This could be another type of Z probe such as a BLTouch, or manual probing.

We haven't yet tried using the scanning probe as the only Z probe. To do this you would need to do the following:

Set an accurate Z=0 reference, run the calibration command, and save the results in config.g
At several different temperatures, measure the Z height that produces the reference output value from the probe, and use these measurements to set up suitable temperature compensation in the M558 command.

Notepad

@dc42 said in Duet 3 Scanning Z probe:

the auto calibration is only possible if you have another way of establishing Z=0 first

Ahh, so reference point first, then it can scan the entire bed.

We haven't yet tried using the scanning probe as the only Z probe. To do this you would need to do the following:

Ill definitely be testing this out once I get mine, as a bit of pain calibrating it initially will mean I don't have to constantly carry a inductive/BLTouch on the toolhead.

fcwilt

@dc42 said in Duet 3 Scanning Z probe:

We haven't yet tried using the scanning probe as the only Z probe.

That is a bit of bad news.

It makes the product less appealing.

I need to think on this a bit.

Frederick

zapta

If I got it correctly, this is the third Duet3D Z sensor, each with a very different technology. The quest for the ultimate Z sensor continues.

This post is deleted!

Notepad

@fcwilt said in reference to @dc42 Duet 3 Scanning Z probe:

We haven't yet tried using the scanning probe as the only Z probe.

It definitely makes the switch over not as simple of a choice. Hopefully if I can figure out a test cycle or homing regime to use it as the only Z probe, Ill share that to everyone.

If it cant be used stand alone. The main selling point of fast and compact bed scanning looses the compact aspect as there would need to be a redundant probe just for initial offset measurements.