Re: Piezoelectric disks for Z contact detect and bed levelling April 20, 2017 08:42AM |
Registered: 13 years ago Posts: 1,465 |
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ECJ
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I do not understand why you care about this question of probing with the heated nozzle. Of course there is variation with heating, but I assume it's always the same. Here I do the probing with the cold nozzle and compensated with z offset and never had problems.
Is there really any plausible reason to probe with the heated nozzle? I wonder what it is.
Re: Piezoelectric disks for Z contact detect and bed levelling April 20, 2017 11:19AM |
Registered: 8 years ago Posts: 65 |
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DjDemonD
My thoughts are probe at 130 deg C nozzle temp (below ooze temp) with bed fully heated to 1st layer temperature for the material you intend to print. You wont damage your bed at this temperature for the brief contact involved.
The hot nozzle ensures that any residual plastic at the nozzle has minimal/no effect on your probed height. Of course you should clip it with a wire cutter or whatever beforehand but we're all human and forget occasionally. The heated bed because some (probably a lot) of beds, deform when heated and therefore grid levelling or delta autocalibration will be a poor fit for the actual bed surface.
The effect of thermal expansion is minimal we did a calculation based on an e3d hotend where the nozzle, heater block and the lowest part of the heatbreak are expected to expand when heated from 130 deg C to 250 deg C it was only 0.02mm, so account for it it you want but its probably not worth it, however from 20 degrees to 250 degrees its more like 0.035 which may have more of an effect.
As for not having to have any z- offset, currently this is not realistic, as there has to be some vertical compliance in the probing module to get a reliable trigger, less so with later module designs, which pre-load the piezo more, but still in the order of 0.1-0.2mm. So I set -0.1 in firmware, and occasionally babystep up/down 0.05mm.
Perhaps referring to the earlier post by Mike about getting a probe to trigger at 1g of force, we might get a result which genuinely requires no offset except thermal if you're bothered by 20 microns error.
But sure probe with a cold nozzle (but a hot bed) if you want to and then work out the offset.
Re: Piezoelectric disks for Z contact detect and bed levelling April 20, 2017 11:38AM |
Registered: 13 years ago Posts: 1,465 |
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ECJ
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As for the question of obtaining detection with only 1 gram of pressure, how theoretically do you imagine avoiding false shots?
I'm starting a new version. Instead of the 25mm perforated disc, I will use two 10mm discs arranged side by side and connected in parallel. This should suppress most non-vertical movements. But only 1 gram I find it difficult to achieve.
Re: Piezoelectric disks for Z contact detect and bed levelling April 24, 2017 05:12AM |
Registered: 8 years ago Posts: 62 |
Re: Piezoelectric disks for Z contact detect and bed levelling April 24, 2017 05:16AM |
Registered: 9 years ago Posts: 3,525 |
Re: Piezoelectric disks for Z contact detect and bed levelling April 24, 2017 05:39AM |
Registered: 13 years ago Posts: 1,465 |
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briangilbert
Just wondering.. Is there any reason you couldn't mount the board near your control board and just run wires from the piezo back to the board?
Re: Piezoelectric disks for Z contact detect and bed levelling April 30, 2017 02:39PM |
Registered: 13 years ago Posts: 1,465 |
Re: Piezoelectric disks for Z contact detect and bed levelling April 30, 2017 03:50PM |
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Re: Piezoelectric disks for Z contact detect and bed levelling April 30, 2017 04:54PM |
Registered: 9 years ago Posts: 3,525 |
Re: Piezoelectric disks for Z contact detect and bed levelling May 03, 2017 11:34AM |
Registered: 11 years ago Posts: 65 |
Re: Piezoelectric disks for Z contact detect and bed levelling May 03, 2017 12:45PM |
Registered: 9 years ago Posts: 3,525 |
Re: Piezoelectric disks for Z contact detect and bed levelling May 04, 2017 04:21AM |
Registered: 13 years ago Posts: 1,465 |
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swoozle
BIG thanks to all you folks that did this work!
I just added a Moriquendi board and 3 piezos to my bed mounts and it works fantastically. Over the years I have tried microswitches, FSRs, proximity and IR detectors. This is by far the easiest, cheapest, least invasive and most accurate that I have used.
Which also makes me wonder: why the emphasis on incorporating it into the hot end? The bed mount scheme seems easy and performs well.
Re: Piezoelectric disks for Z contact detect and bed levelling May 04, 2017 05:22PM |
Registered: 11 years ago Posts: 65 |
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leadinglights
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swoozle
BIG thanks to all you folks that did this work!
I just added a Moriquendi board and 3 piezos to my bed mounts and it works fantastically. Over the years I have tried microswitches, FSRs, proximity and IR detectors. This is by far the easiest, cheapest, least invasive and most accurate that I have used.
Which also makes me wonder: why the emphasis on incorporating it into the hot end? The bed mount scheme seems easy and performs well.
Hi swoozle,
Can you put up some photos of how you mounted the piezos. I had to use a complete sub-frame to mount the piezos on my delta but Moriquendi has a method which is much easier. Cartesian printers are actually much easier than Deltas as long as they have a three screw bed adjustment method.
Putting a single piezo in the effector or behind the hot end comes very close to a universal solution as the RepRap community is moving towards having one or only a few informally standardized hot end mounts.
Mike
Re: Piezoelectric disks for Z contact detect and bed levelling May 05, 2017 05:01AM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 05, 2017 06:06AM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 05, 2017 07:20AM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 05, 2017 07:25AM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 05, 2017 09:24AM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 05, 2017 12:39PM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 05, 2017 04:13PM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 05, 2017 04:35PM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 05, 2017 05:06PM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 05, 2017 05:11PM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 05, 2017 05:12PM |
Registered: 9 years ago Posts: 3,525 |
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rolloo
What about 'Gravity: Flexible Piezo Film Vibration Sensor'
£4.57($5.90)+shipping
Digital/Analog output
Re: Piezoelectric disks for Z contact detect and bed levelling May 06, 2017 03:52PM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 08, 2017 04:57AM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 08, 2017 05:32AM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 08, 2017 06:12AM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 08, 2017 07:51AM |
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Re: Piezoelectric disks for Z contact detect and bed levelling May 08, 2017 09:44AM |
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