Precision Piezo Z-probe Now available.

K. I'll check those. Thanks!

Awesome. It was the crimped connector on the piezo disc. One wire wasn't stripped back enough to make a good contact. I tried to scrape it off but broke it and then lost the connector on the floor. :/ I soldered on a jst connector (it's all I have) and it seems to be working again. Thanks for the help!

Well, maybe I spoke too soon.. It worked when I had it on my desk after resoldering. After I put it back on the carriage, it wouldn't trigger like before. I took it apart again and put it on my desk and it won't trigger now as well. Maybe I did something to the disc so I ordered some.

I checked the voltage from the board connection and it's at 4.95V so no issue there.

*SIGH*

Hope you get it sorted the leads are the only weak pint really the discs are pretty robust. There is a design for a circuit which has the disc soldered onto it directly.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Quote
DjDemonD
Hope you get it sorted the leads are the only weak pint really the discs are pretty robust. There is a design for a circuit which has the disc soldered onto it directly.

Question on polarity. The wire on the outside of the disc is black and red on the inside. Is the connection to the board suppose to have the red wire (inside disc) on the bottom and black on top?

Not necessarily. The kit board has polarity marked. The positive are the "upper" row of pin headers as you view the board with the logo towards you. However the best test, as occasionally discs have reversed polarity in the piezo-electric ceramic itself, is to attach it, tune vr2 and then tap it whilst installed in the printer/module/device, to simulate normal operation. If it triggers like this when you apply the force, then its correct, if it triggers as the force is release turn the dupont/jst connector around the other way. Especially important with multiple piezos that they are all the same polarity. Or they cancel each other out.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Ah. Thanks for the info.

So we now have a PR for marlin [github.com]

which if it makes it in means that all the 4 main firmware flavours support pause before probing of some sort.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Still having trouble getting the under bed system running. Think it may be the bed leveling springs causing too much pressure. Going to try removing the springs and use some shims to level it best I can get it. Lets hope it helps

I'd go for that option. You won't need a mechanically level bed (we'll not very level anyway) once it's working.

I'm going to have a go converting my corexy to 3 point levelling with 27mm Piezos. Then I can finally try the titan aero I've had for ages.

Will share the stls and tricks to getting it working if it works.

Edited 2 time(s). Last edit at 07/30/2017 12:36PM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Cheers Simon
Already using 27mm piezo's. I have 4 as with 3 point leveling the 3 point is 15mm further away from the bed suport's than where I have places the piezos.
I like the look of the extruder with the flexi drive cable, like having a direct e3d with the motor mounted Bowden style. Carnt remember what its called

Edited 1 time(s). Last edit at 07/30/2017 12:52PM by Suggy.

It's either a flex3drive or a nimble, there are two in the market now.

I have no experience of Mike's system but the system I've setup on the micro delta works so well might as well see if it will scale-up.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Removed the springs still wont home, too much vibration. Do you recommend turning VR1 down a tiny bit or some more on VR2? Not right up there with the Marlin experts and not sure how in implement the delay before homing

Delay before probing is achieved currently by configuring and installing this version of Marlin 1.1.x

[github.com]

by Teemu. Although if they accept the PR then it will be integrated into the main branch.

This includes in configuration.h the "wait before probing" option in quiet probing section - setting something like 0.5 will help.

Make sure z accel is 200 or less (try 100).

You can turn VR1 down, measure its resistance from centre of pot to piezo pin, 0.4mohm is standard but try 0.3 or 0.2 for less sensitivity. Also turn vr2 slightly past the point where the led goes out.

On my corexy what I do is home using a mechanical switch at the bottom of the frame (Z-max) and then I can move the head to Z5 as I now have working z motion, then manually enter a pause G4 P500, then G30 to reset z=0.
This might work but does still require a mechanical homing switch. If you have one at z-min (I3 style machine) you could bend the lever of the microswitch upwards a bit, so the endstop has some give. Move the endstop (turn the screw to trigger it whatever) so it stops around 1mm above the bed. Home to Z-min conventionally G28 Z, then use the trick above to do G30 to get your fine Z-home position. You need to allow Z-2mm in "travel limits".

Edited 2 time(s). Last edit at 07/30/2017 02:39PM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Thanks Simon, will try turning down VR1 and look at Marlin


On my corexy what I do is home using a mechanical switch at the bottom of the frame (Z-max) and then I can move the head to Z5 as I now have working z motion, then manually enter a pause G4 P500, then G30 to reset z=0.
This might work but does still require a mechanical homing switch. If you have one at z-min (I3 style machine) you could bend the lever of the microswitch upwards a bit, so the endstop has some give. Move the endstop (turn the screw to trigger it whatever) so it stops around 1mm above the bed. Home to Z-min conventionally G28 Z, then use the trick above to do G30 to get your fine Z-home position. You need to allow Z-2mm in "travel limits".

Wosh straight over my head

VR1 no change in reading when turning .624

How are you measuring VR1?

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{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.

So your VR1 could be stuck at 0.624 Mohm?

that would mean its permanently set a little high on sensitivity. Put a drop of wd40 on the potentiometer and turn it one or two times to see if it frees off.

If not no matter 0.6mohm is a reasonable setting, just turn vr2 a little past the point where the led goes out.

As for what I said above what I mean is configure a mechanical endstop - a microswitch for z. Get it working and homing properly. Leave the probe for the minute. but set the microswitch so that the nozzle to bed gap when z is homed is about 1mm above the bed.
Now attach the probe but configure marlin to use the z-probe as a separate pin (marlin can have a z endstop and a z probe as separate entities, the z-endstop is used for homing, the z-probe for probing - duet/smoothie etc.. have seperate endstops and probes).
Now you can home to the microswitch. This means you have got control of the printer as it shows homed in x,y and z.
Then you can move to a position (using your start gcode) 5mm above bed centre, then pause, then send g30. This probes the bed and sets z=0 to the level you probe, overriding the position the microswitch set previously. To do this the lever on the microswitch needs to be able to give a little, past its triggered position.

As for doing autolevelling in your start gcode use M201 to set a very low jerk and acceleration, then autolevel using g29 or whatever you want to do, then return them to normal for the rest of the print.

Edited 2 time(s). Last edit at 07/30/2017 03:12PM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Quote
Moriquendi
How are you measuring VR1?

Tenma 72-1016 Multimeter set to Autorange red lead to VR1 via insulated screw driver, black lead to grd nearest pin on top of the board to VR2

Currently prototyping a generic bed mount for beds fixed using m3 screws, incorporating a thumbwheel to do some manual bed adjustment, with a piezo in each mount.

Fairly sure it will work but a few hours printing to do to try it out.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

WD added goes down to 5.90 if I turn it any lower the readings start to go up

Pics uploadad

Simon already have 1.1.0 do I just add this (https://github.com/MarlinFirmware/Marlin/pull/7365/commits/7e00f24a9357e95ddb0f26826306903a4022dd4d) to the 3 files in Marlin?

No I think you'll have to get the whole repository then configure the configuration.h and configuration_adv.h files manually then reupload to your board. Try it the quick way you suggested first but my experience with marlin is that it just doesn't work that easily.

I've not that much experience with github.

Edited 1 time(s). Last edit at 07/30/2017 04:05PM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Sounds like the vr1 pot has given up but you can turn some sensitivity down with vr2. They are only rated for about 20 turns but often last longer.

We are thinking about doing away with vr1 and setting between 0.4 and 0.8Mohm fixed resistor instead.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

We are thinking about doing away with vr1 and setting between 0.4 and 0.8Mohm fixed resistor instead. sound like a good idea
Today is the 1st time I have moved it. I have tried turning VR2 down but it then need a hard knock to trigger

If you think the board is faulty and I it might be ill send out a new one. If you want to send back the old one please do, we'll test it to see what wasn't working. You don't have to but it will help us iron out any issues.

Edited 1 time(s). Last edit at 07/30/2017 04:34PM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Give vr2 a tiny bit of adjustment you can measure resistance here from vr2 to GND on the endstop header on the piezo board. Record the resistance when the led just goes off it'll help you make finer adjustments.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Quote
Suggy
black lead to grd nearest pin on top of the board to VR2

There's your problem, board ground (GND) is not connected directly to PZ-, and therefore not connected to VR1. To measure the value of VR1 measure the resistance between any of the PZ- pins and the top of VR1 (with the screwdriver as you mention)

Idris

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{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.

My bad was supposed to say VR1 not VR2

Can get it working fine with the head mount (https://www.facebook.com/groups/1668257026779488/) just not on the under bed

Edited 1 time(s). Last edit at 07/30/2017 06:48PM by Suggy.