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Precision Piezo Z-probe Now available.

Posted by DjDemonD 
Re: Precision Piezo Z-probe Now available.
July 30, 2017 07:02PM
Lowest I can get it to go is 4.4 if I turn it a tiny bit more it jumps down to 0.6
Could 4 27mm piezo's be too much for it?
vr2 measures around 46.6 that's with the blue led just going out. That's on the end stop ground but I get 0.8 on the PZ-

Edited 1 time(s). Last edit at 07/30/2017 07:05PM by Suggy.
Re: Precision Piezo Z-probe Now available.
July 30, 2017 08:00PM
Managed to get vr1 down to 2.3 and turned vr2 way down, clamped bed to mounts 1/4 turn and still false trigger. Turned front bed nuts a further 1/4 turn and


BINGO got it

Lets hope it stays that way when I fit the new control board

I'm getting .36v across the LED out connector is this going to run an LED?

Thanks ALL for your help very much appreciated

Ian

Edited 1 time(s). Last edit at 07/30/2017 08:14PM by Suggy.
Re: Precision Piezo Z-probe Now available.
July 30, 2017 08:41PM
01:41:01.008 : Bed Level Correction Matrix:
01:41:01.010 : +0.999997 +0.000000 -0.002520
01:41:01.012 : -0.000003 +0.999999 -0.001159
01:41:01.014 : +0.002520 +0.001159 +0.999996
01:41:01.015 : X:248.96 Y:148.98 Z:15.80 E:0.00 Count X: 19920 Y:11920 Z:24000
Re: Precision Piezo Z-probe Now available.
July 31, 2017 11:22AM
LED wired up
Re: Precision Piezo Z-probe Now available.
July 31, 2017 11:29AM
Glad you got it working smileys with beer

My corexy had a layer shift printing my revised underbed mounts (with adjusters in them), so haven't had chance to try it yet.


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. PT1000 cartridge sensors plug straight into duet boards and others.
Published:Inventions
Re: Precision Piezo Z-probe Now available.
July 31, 2017 01:54PM
VR1 needs to be measured with respect to PZ-, VR2 needs to me measured with respect to board ground (GND), just in case there's any confusion.

Idris


{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
Re: Precision Piezo Z-probe Now available.
July 31, 2017 02:27PM
I will also add that you check the polarity of the piezo regardless of the colour of the wire and position where they are soldered on the piezo
All mine were red inside black outside and the polarity was different
Re: Precision Piezo Z-probe Now available.
July 31, 2017 03:35PM
Bed temp at 94, temp in piezo housing 51.9 and still working finethumbs up
Re: Precision Piezo Z-probe Now available.
August 01, 2017 03:42AM
So Marlin now has probing delay for piezo sensors. Use v1.1.x bugfix [github.com] if you want this change

[github.com]

Look in configuration.h at line 635
//#define DELAY_BEFORE_PROBING 200 // (ms) To prevent vibrations from triggering piezo sensors

In other news, I finally managed to get my underbed sensors fitted to my corexy.

I had to turn down VR1 a lot to get reliable triggering and am still tuning it now. But it does work, the piezos are so very sensitive to the vibrations from the bed, I am only really noticing this now as I am getting into the underbed system, whereas I have been very focused on the hot end up until now. I will post a write up and measure the settings etc.. once I'm convinced its working well.


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. PT1000 cartridge sensors plug straight into duet boards and others.
Published:Inventions
Re: Precision Piezo Z-probe Now available.
August 01, 2017 04:03AM
I feel the pain Simon
Re: Precision Piezo Z-probe Now available.
August 01, 2017 04:24AM
I never intended to cause anyone else pain, I can accept a dose myself...

I think once we have some settings that work, it will provide a good starting point for those who come later, right now we're path-finding our way to the optimum settings. I also wonder whether using 27mm discs might be a poor choice, they're too sensitive. Perhaps 20 or even 16, 12 mm might be better as they will be less responsive to the inertia of the bed as the carriage moves.

I've got my z accel at 50, jerk at 10 (although turning it off entirely for Z might make sense), I need to measure VR1 resistance to see what it's currently set to. I'd definitely suggest using the 1.21/1.22 kit board in NC mode with the led ON when open and OFF when triggered, just to avoid head crashes. Its much better to get "probe trigger before probing move" or equivalent error.

I am also wondering whether a series resistors on the 27mm piezos for this application might help to filter some of the noise.

Edited 1 time(s). Last edit at 08/01/2017 05:05AM by DjDemonD.


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. PT1000 cartridge sensors plug straight into duet boards and others.
Published:Inventions
Re: Precision Piezo Z-probe Now available.
August 01, 2017 05:54AM
NEW STOCK ANNOUNCED

I've got 10 more kits available to buy in the shop
[www.precisionpiezo.co.uk]


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. PT1000 cartridge sensors plug straight into duet boards and others.
Published:Inventions
Re: Precision Piezo Z-probe Now available.
August 01, 2017 06:28AM
Thanks a lot DJ for implementation in Marlin!

On my old Delta I'm still on Marlin 1.1.0 RC6 - works great for me.
For my new Delta (under construction) this will make it much easier to get everything tuned for the Under-Bed-Piezos!

And if I manage to get them working properly, my old Delta will get an upgrade too.




Old Delta = Sintron Kossel Mini
New Delta = Reused parts of an Anet A2 and some self sorced parts --> Delta XL --> 1000mm high, vertical extrusions 400mm spinning smiley sticking its tongue out
Re: Precision Piezo Z-probe Now available.
August 01, 2017 08:25AM
Looking forward to the final implementation for the piezo in the bed for a CoreXY... will this work with big beds? I'm using a 300x300 one, and I'm not sure if just with 3 disks this will work...

BTW, I saw in BangGood that they're selling piezo disks, but I'm not sure about the quality... @DjDemond can you recommend a brand/place for buying additional piezo disks?

Regards
Re: Precision Piezo Z-probe Now available.
August 01, 2017 08:30AM
Large beds, a user on duet forum is planning a 550x550 printable area (700x700mm actual size) quad-idex corexy, hes designing a piezo mount, I suspect 4 corners would be needed to support this bed without it sagging. I'll ask him if he will share it if it works.

Yes I buy Murata discs from RS Components [uk.rs-online.com]
stock numbers:
871-1994 - 20mm piezo with leads
871-2029P - 27mm piezo with leads

Please note there are two packaging options on RS "retail" and "production". If you go production they are much cheaper but you waive your right to return them.

I have bought from ebay, and there are a lot available.


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. PT1000 cartridge sensors plug straight into duet boards and others.
Published:Inventions
Re: Precision Piezo Z-probe Now available.
August 01, 2017 09:35AM
Interestingly I'm finding a lot of different piezo disks (different sizes, and frequencies)... I can see in the ones that RS-Online (currently doesn't) have that the frequency is 6'3Khz... How the frequency affects?

Regards
Re: Precision Piezo Z-probe Now available.
August 01, 2017 09:44AM
On the RS page switch the packaging option to production/industry they usually have them in stock.

Try other brands, avoid those with thick leads, unless you're careful, or your installation is quite static, the thicker leads strain the solder joints too much.


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. PT1000 cartridge sensors plug straight into duet boards and others.
Published:Inventions
Re: Precision Piezo Z-probe Now available.
August 01, 2017 09:55AM
No worries, I will get some from RS-Online in Spain, just curious about the frequency smiling smiley.

Cheers
Re: Precision Piezo Z-probe Now available.
August 01, 2017 10:03AM
They are designed as buzzers/speakers so the smaller ones can do higher audible frequencies.

Mike knows more about them than I do but I don't believe it has any effect when used as sensors.

Edited 1 time(s). Last edit at 08/01/2017 10:03AM by DjDemonD.


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. PT1000 cartridge sensors plug straight into duet boards and others.
Published:Inventions
Re: Precision Piezo Z-probe Now available.
August 01, 2017 10:20AM
I am away from my normal computer at the moment so can only be brief but best bet is Murata Numbers like 7BB-27-4LO for 27MM, 7BB-20-4LO for 20mm. Frequency doesn't matter much but go for ones with leads on (LO suffix). Second hand or bulk buy piezo sounders are likely to work if you pull the element out but no promises. Most piezos can be made to work but things like temperature, change in temperature or mechanical noise can stop it being good but may be worth trying on the off chance.

Mike
Re: Precision Piezo Z-probe Now available.
August 01, 2017 10:54AM
Yup, I got some 7BB-20-6L0 ones.

Thanks!
Re: Precision Piezo Z-probe Now available.
August 02, 2017 07:28AM
Well the underbed system on the larger machine is proving to be very frustrating. Its so sensitive that I am not getting very far.

I am going to change the mounts physical design to use the disc in "squeeze" rather than bend, this should decrease the sensitivity mechanically by quite a lot. Hopefully this can be achieved (assuming I can prise them open where they are bonded together) by inserting printed washers under the discs to remove the tendency of the disc to bend when pressed.
I might have to make the plunger in the top part wider also.

It's worth saying for a smaller machine with a stationary bed it works well.

Edited 1 time(s). Last edit at 08/02/2017 08:07AM by DjDemonD.


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. PT1000 cartridge sensors plug straight into duet boards and others.
Published:Inventions
Re: Precision Piezo Z-probe Now available.
August 02, 2017 07:56AM
Just let me know if you want some QA for this, I've a CoreXY with 300x300 bed, and I'm restoring a Prusa i3 with 200x200 bed. RS just sent my piezo disks, I should get them next week.

Cheers
Re: Precision Piezo Z-probe Now available.
August 02, 2017 03:10PM
I think it would be helpful if I might ask those who are using underbed piezos to consider sharing:
-A brief description of their machine type
-Their bed size/weight
-3 or 4 point fixing (or other combination?)
-what design of piezo mounts they are using
-what resistance for VR1 on the PCB (and any additional resistors etc..)
-their z acceleration/jerk
-probing settings like probing speed, travel between probe point speed, pause before probing timing
-how well its working/any issues

I'll kick off with one
-micro delta
-120mm bed, weight 200g
-3 point fixing equilateral triangle at bed edges
-using DjDemonD 20mm underbed mounts
-0.3Mohm VR1
-z accel 200 mm/s/s Jerk 3mm/s
-probing speed 7mm/s travel 50mm/s
-working perfectly no issues at all.

Can't say the same for the corexy which is stubbornly sitting always between too sensitive, not sensitive enough, or inconsistent. But the fight continues.

Edited 1 time(s). Last edit at 08/02/2017 03:11PM by DjDemonD.


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. PT1000 cartridge sensors plug straight into duet boards and others.
Published:Inventions
Re: Precision Piezo Z-probe Now available.
August 03, 2017 02:09AM
Fight on Simon, don't give in its worth it in the end. Will upload my setting later today
Re: Precision Piezo Z-probe Now available.
August 03, 2017 04:03AM
Moriquendi did suggest and he's on the right track, that it might be a combination of the piezo vibrating or the way my current mount works causing too much bend in the piezo. So I modified the mounts by placing a printed washer below the piezo, which effectively supports it on the underside across its whole surface rather than just on its circumference.

This has improved the response quite a bit, I can now home using z-probe, and check the bed level by the 3 mounts, and the adjustable mount I have designed works well to adjust the bed. My grid height map however still has a couple of aberrant points on it so its not completely reliable yet, but its progress.

If anyone is intending to use the bed mounts (I will release an official 27mm version) I will include the printed washers, place them under the piezo discs, if you are going to sit a heavy bed on them, to dampen them down a bit.

Edited 1 time(s). Last edit at 08/03/2017 05:41AM by DjDemonD.


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. PT1000 cartridge sensors plug straight into duet boards and others.
Published:Inventions
Re: Precision Piezo Z-probe Now available.
August 03, 2017 04:40AM
Moriquendi may have a good point, certainly worth looking at. A good test may be to fit your printer up with both your Z probe and underbed sensors - the Z probe controlling the probing as normal but with the undrerbed sensors connected to an oscilloscope to check for vibrations. I have still not got back to base so can't check myself.

I will admit to finding the problems that people are having are much more instructive than anybody saying it works well. Sadly my tow attempst at getting any negative feedback have mostly come up dry.

Mike
Re: Precision Piezo Z-probe Now available.
August 03, 2017 05:21AM
Did you glue the plastic washer to the piezo? You should find that the vibration is damped even further with the piezo bonded over the whole surface.

Idris


{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
Re: Precision Piezo Z-probe Now available.
August 03, 2017 05:43AM
Thanks guys. No I didn't glue them, but I can do. I might even try fibre washers or rubber or something like that, if gluing them doesn't solve the problem, its pretty close probably a few degrees of adjustment on a potentiometer close.


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. PT1000 cartridge sensors plug straight into duet boards and others.
Published:Inventions
Re: Precision Piezo Z-probe Now available.
August 03, 2017 03:24PM
-core xyz Marlin 1.1.0 RC6
-300x200mm bed
-round holder fixed to bed carrage, piezo inside, lid then plunger (https://www.thingiverse.com/thing:2466725)
-4 point fixing around 40mm in from each end both back and front
-using DjDemonD 20mm underbed mounts
-3.6 Mohm VR1 (lowest I could get it to go) VR2 tuened until LED went out then about 1/8 turn
-z accel 3000 mm/s/s Jerk 0.4 mm/s (I think)
-probing speed ?mm/s travel ?mm/s (don't know where to find these)

Edited 2 time(s). Last edit at 08/03/2017 05:42PM by Suggy.
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