Piezoelectric disks for Z contact detect and bed levelling
Posted by leadinglights
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Re: Piezoelectric disks for Z contact detect and bed levelling February 12, 2017 11:27AM |
OK, DJ, this is going to get complicated.
I was working on the effector for Doug, to mount the Nimble on the peizo sensor with a larger effector.
This is the overall look.
I reverted to 3 acetal posts to guide it all, seems enough and the whole effector is set up in 120 deg anyway.
The original design of the clamp worried me a little. 2 pins in one half of the clamp and 2 pins in the other. So if the clamp is a little off, like too big, the pin position is never consistent. So now the pins are all in 1 piece of the clamp.
This made for pretty funky clamping system. With angled screws to provide the clamping force.
Bolting all this together makes for a pretty sandwich. Finding places to put all the bolts and keeping the areas free. Tricky.
But it is do-able, by the look of it.
There is one little twist in the whole assembly. I feel it is important for the sensor to be pressing against a smooth and flat surface, but you did want a little recess for it. But since I need the lock-in shapes on top, By slicing 2 parts, this is solved. By printing the bottom part upside down, you can print the recess without supports. This way we can get the smoothest surfaces where needed.
All in all, it is a little more complex than I would have liked but all the bits are in there and it all seems to fit well. The proof of the pudding...
Any comments?
Edited 1 time(s). Last edit at 02/12/2017 11:29AM by Lykle.
Lykle
________________________________________________
Co-creator of the Zesty Nimble, worlds lightest Direct Drive extruder.
[zesty.tech]
I was working on the effector for Doug, to mount the Nimble on the peizo sensor with a larger effector.
This is the overall look.
I reverted to 3 acetal posts to guide it all, seems enough and the whole effector is set up in 120 deg anyway.
The original design of the clamp worried me a little. 2 pins in one half of the clamp and 2 pins in the other. So if the clamp is a little off, like too big, the pin position is never consistent. So now the pins are all in 1 piece of the clamp.
This made for pretty funky clamping system. With angled screws to provide the clamping force.
Bolting all this together makes for a pretty sandwich. Finding places to put all the bolts and keeping the areas free. Tricky.
But it is do-able, by the look of it.
There is one little twist in the whole assembly. I feel it is important for the sensor to be pressing against a smooth and flat surface, but you did want a little recess for it. But since I need the lock-in shapes on top, By slicing 2 parts, this is solved. By printing the bottom part upside down, you can print the recess without supports. This way we can get the smoothest surfaces where needed.
All in all, it is a little more complex than I would have liked but all the bits are in there and it all seems to fit well. The proof of the pudding...
Any comments?
Edited 1 time(s). Last edit at 02/12/2017 11:29AM by Lykle.
Lykle
________________________________________________
Co-creator of the Zesty Nimble, worlds lightest Direct Drive extruder.
[zesty.tech]
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Re: Piezoelectric disks for Z contact detect and bed levelling February 12, 2017 01:11PM |
Quote
DjDemonD
The signal generated by a sensor squeezed between two flat surfaces is 100 times smaller than when you bend it.
That isn't necessarily an issue, provide there's still enough signal to reliably detect it against the noise. A smaller signal and more gain on the detector might be a reasonable trade-off for a simpler physical design. The original tests I did were with a piezo element squeezed between two flats, and it didn't look like there would be a problem picking out the signal. To be fair, I never got as far as you have with putting it into an actual printer though
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Re: Piezoelectric disks for Z contact detect and bed levelling February 13, 2017 10:50AM |
Thinking about it, this thing works on bending forces, right.
So where is the bend? Inside the gray area, not in the brass. So the recesses could be something like this:
The disc is bending in the small area between the 20 mm diameter recess edge and the 18 mm pressure pad.
To make it even more stable, we could the raise the middle of the 20 mm recess up again, so it falls inside the 10 mm hole in the clamp. Say a raised area of 8 mm diameter in the center.
(just thought of that while writing this so it is not in the image, sorry)
That way you can double the bending output. And make for a much more stable nozzle.
Comments?
So where is the bend? Inside the gray area, not in the brass. So the recesses could be something like this:
The disc is bending in the small area between the 20 mm diameter recess edge and the 18 mm pressure pad.
To make it even more stable, we could the raise the middle of the 20 mm recess up again, so it falls inside the 10 mm hole in the clamp. Say a raised area of 8 mm diameter in the center.
(just thought of that while writing this so it is not in the image, sorry)
That way you can double the bending output. And make for a much more stable nozzle.
Comments?
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Re: Piezoelectric disks for Z contact detect and bed levelling February 13, 2017 11:24AM |
This is where theory is all well and good but you'll have to try it to see if it works. I would estimate that the piezo disc bends more like this (apologies for back of fag-packet diagram):
This is obviously exaggerated to demonstrate the point, the amount it bends is only 0.15mm.
The entire disc bends, the grey area (the piezo-electric material) bends with it.
So its not just the zone indicated on your diagram above which is the area that bends.
So it might work but you'll have to make it and try it. My two pence worth is that it will be harder to see the signal above the noise, but I will be happy to be proved wrong.
Edited 2 time(s). Last edit at 02/13/2017 11:33AM by DjDemonD.
Simon Khoury
Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
This is obviously exaggerated to demonstrate the point, the amount it bends is only 0.15mm.
The entire disc bends, the grey area (the piezo-electric material) bends with it.
So its not just the zone indicated on your diagram above which is the area that bends.
So it might work but you'll have to make it and try it. My two pence worth is that it will be harder to see the signal above the noise, but I will be happy to be proved wrong.
Edited 2 time(s). Last edit at 02/13/2017 11:33AM by DjDemonD.
Simon Khoury
Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
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Re: Piezoelectric disks for Z contact detect and bed levelling February 16, 2017 11:52AM |
Hi Guys,
Just made some eye candy for you all.
Most nuts and bolts are sorted out and it all seems to fit nice and tidy. Next challenge is to make it work on a Chimera.
I have added holes to pass tubing through in case you want to use Bard-air type cooling.
Lykle
Just made some eye candy for you all.
Most nuts and bolts are sorted out and it all seems to fit nice and tidy. Next challenge is to make it work on a Chimera.
I have added holes to pass tubing through in case you want to use Bard-air type cooling.
Lykle
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