Duet 3 Scanning Z probe

[A Former User]

@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

[A Former User]

@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

[A Former User]

@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.

[A Former User]

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.

[zapta]

@Herve_Smith, what the scanner provides is similar to what the inductive probe provides with Voron 2.4 but at an order of magnitude faster. That is, height measurement relative to a known zero, which is provided by the 'tap' end switch or similar.

In other words, it takes a z=0 point at a given (x,y) and quickly provide zero points on the entire bed surface. The alternative is to use an absolute Z probe (e.g. BL Touch or Cliky) and slowly probe the entire bed, or wait until a fast absolute Z probe will be invented.

Wether this product has value to your application it's up to you.

[fcwilt]

@Notepad said in Duet 3 Scanning Z probe:

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.

And the speed would allow creating a new height map for every print which would be nice for me since I use a variety of printing surfaces.

For me the speed is the real benefit. The 8mm inductive sensors I use take up very little space.

Frederick

[Notepad]

@fcwilt said in Duet 3 Scanning Z probe:

The 8mm inductive sensors I use take up very little space.

I predominantly use 12mm inductive probes, and while the size is bigger its not a massive issue. But the time to probe the bed is just soo slow. On a regular bed it takes ~3 minutes and on a larger bed at least 6 minutes.

Even If I have to mix both, The extra speed this probe will have is going to be well worth it.

[fcwilt]

@Notepad said in Duet 3 Scanning Z probe:

I predominantly use 12mm inductive probes, and while the size is bigger its not a massive issue. But the time to probe the bed is just soo slow. On a regular bed it takes ~3 minutes and on a larger bed at least 6 minutes.

Yes it takes a while but how often do you currently do it?

With the hours and hours spent printing things what is the "cost" of a few minutes creating a height map every once in a while?

Frederick

[Notepad]

@fcwilt said in Duet 3 Scanning Z probe:

With the hours and hours spent printing things what is the "cost" of a few minutes creating a height map every once in a while?

Before every print, but the over all time cost vs printing time is so negligible so im happy to do it.

I'm known to not treat my printers very well (as they are built to be absolute tanks) so probing for every print just gives me peace of mind that its perfect every time.

[droftarts]

@fcwilt @Herve_Smith When we say we haven’t used it, or don’t recommend it (currently) for use as a Z probe, we mean that we haven’t tested it to do that yet. We haven’t calibrated it against temperature, we haven’t tested repeatability, we haven’t written macros or implemented firmware changes, written documentation or whatever else is required, to enable its use as a conventional Z probe. So we don’t recommend it, at the moment.

Temperature affects inductive probes. But inductive probes have been used successfully as Z probes, eg Prusa Pinda, and the SZP board had its own thermistor on board. As far as I’m aware there is no technical reason why it couldn’t be used as a Z probe; it’s obviously very accurate and repeatable, at least under the conditions of the show, where I watched it scanning the bed for 4 days straight. We just haven’t had them for long enough to work out the best method to make it reliable and repeatable in that role, in a wide range of situations, when the focus was on bed scanning.

Ian