Precision Piezo Z-probe Now available.

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Moriquendi
I think, but I'm not sure, that in marlin a positive offset will increase the distance between the nozzle and the bed. If you do a series of G30 probes do you get consistent results?

Idris

My understanding is:
A higher negative number will make it go closer to the bed.
A lower negative number will make it go further away from the bed.

Hope that's right.

Apologies if this is answered before, but what's the current thinking on under bed mounts?

I'm now putting piezo on my 3rd machine a wanhao i3 (already on my x5s and a kossel mini). I don't want to do a lot with the carriage as I have a titan aero mount i really like on there.

Are leadinglights simple mounts working for people (https://www.thingiverse.com/thing:2580078) I only see 1 make or should I go with the older lever style ones?

Thanks

I have the under bed piezo mounted at the x intersection of the bed carriage. Printer is the black widow piezo is 20mm with the plunger type.

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Chowa
I have the under bed piezo mounted at the x intersection of the bed carriage. Printer is the black widow piezo is 20mm with the plunger type.

I'm not sure I can picture that. You mean it's mounted on the cross piece supporting the bit of extrusion the carriage runs on? Interesting you get flex there, but unfortunately mine is a more traditional i3 style (2linear rods)

I've got a product in development for under bed piezos, Chowa, are you interested in trying it out?

Idris

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

Just curious, what material are the plastic parts that are provided in the kits made from?

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FA-MAS
Just curious, what material are the plastic parts that are provided in the kits made from?

The site says ABS, although I printed one in PETG and it works although I don't use it anymore.

Idris would love to try it out. What diameter disk? I can do the four that are produced.


Jebk
The build plate sits on the carriage held in place with screws, springs wing nuts on four corners. I will try and dig up a foto. The motor drives a belt attached to the carriage
Stef

@ FA-MAS, I print all production parts in ABS though I have printed prototype parts in PETG without any issue.

@Chowa, I'll email you.

Idris

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

I printed the Orion groovemount V2 part in PETG and it's been fine.

So I have uploaded a mount for Anycubic Kossel on Myminifactory

[www.myminifactory.com]

The 4020 fan is a little weak so go for the 5015


edit:
By the way where can I find the screwmount stl:s???

Edited 1 time(s). Last edit at 08/28/2018 06:27AM by Nitram.

STLs are on thingiverse here.

Idris

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

My google fu doesn't work it seems..


Thanks

Got my Orion Groovemount Kit and I was wondering how the Bowden Collet liner is installed, is it heat insert too?

Heat is how I install them but if you're careful you can use a vice or clamp to force it in. Make sure you get it in the right way round, the larger chamfer goes in first and be sure to remove any excess plastic from the hole after you're done otherwise it can interfere with the collet.

Idris

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

Ok, my Piezo20 with E3D V6 on Anet A8 work if someone need i can share my bowden mount and show movie with working piezo. If you need got too Marlin 1.1.9 Configuration for A8 - my friend work.

Edited 1 time(s). Last edit at 08/31/2018 01:22AM by krakow2000.

I don't know if anyone else has discovered this but I thought I would share it.
I wanted to drill a 27mm piezo but was nervous about drilling it. I remembered I have a cd-punch, the type used for making CD/DVDs unreadable.
It works quite well (see attached images). The hole is about 5.8mm diameter with minimal distortion of the disc.

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tekkydave
I don't know if anyone else has discovered this but I thought I would share it.
I wanted to drill a 27mm piezo but was nervous about drilling it. I remembered I have a cd-punch, the type used for making CD/DVDs unreadable.
It works quite well (see attached images). The hole is about 5.8mm diameter with minimal distortion of the disc.

That's pretty clever.

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[www.wildbot3d.com]

Do you have a link of where I can source the bowden collet liners? I had to remodel the screw mount as my mount holes were 18x9 but cant seem to find the bodwen liners (or maybe I just dont know what to search for).

E3D sell them here, you need the 1.75mm version.

Idris

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

Perfect. Thank you!

I'm having a hell of a time debugging my underbed sensors. I have the Universal kit with 3 undrilled 20mm sensors, I believe that this is a V2 board. (As in it looks like the one in the on-line documentation for V2, and not the one for the V1 or the V2.75 boards.)

I dialled in the sensors themselves separately. They're held in place in little "cups" which are on the Y axis rods, with plungers connected to the bed carriage. They're under a small amount of pre-load, and respond quite reliably when tapped or squeezed. I've verified that they trigger when squeezed, and not when pressure is released, so I'm certain that the polarity of the connection is correct.

I have not done any adjustment of VR1, as a tiny (Less than 1/8 of a turn) adjustment of VR2 is enough to move the range from "triggers as soon as anything moves" to "does not trigger until after the nozzle has crashed into the bed, and the Z nuts have been forced out past the springs." Neither of these produces results that I desire in any way, shape or form.

I'm a bit stalled on debugging this at the moment since my power supply let out some of it's magic smoke, and is no longer something that I want connected to my household power. I was supposed to have guaranteed delivery of my replacement power supply last night. (I was somewhat surprised to get the real-time notice that a delivery attempt had been made when there had obviously been nobody anywhere near my door in several hours (I have motion activated lights in the yard.)

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MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

The first thing to check is that you don't have VR2 180 degrees out of position. There is a position for VR2 that produces very abrupt tuning as you describe with the same blue led/red led behaviour as described in the manual, the flat of the potentiometer should roughly face the connector. If yours is very different from that, try turning it back to face the pins and retuning from there.

Another possibility is that the piezo disks are experiencing too much vibration and hence triggering early. You might try putting them on something slightly soft rather than directly into cups.

Idris

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

Hmmm. There's a downside to my design. It's a royal pain to pull those sensors to adjust how they're sitting.

I've got it so that it at least needs to hit the bed, but... It's not great.


I'm about as certain that I can be that the centre line of the bed is parallel to the X axis. It's an aluminum heated bed (Measured cold, with no glass) just to get a baseline. I'm fairly certain that it doesn't have more than 1mm of warp to it.

I'll try taking the mounts apart. I've got to disassemble a lot of the Y axis to do it though. Like I said, it's (apparently) a downside to my design for the mounts. Otherwise, they seem fairly nice.

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MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

Well, I didn't put anything soft in the cups, because that would make putting the lead screw nut onto the bed tricky. I have some adjustment leeway, but not much. It's much better now. Still a little slow on the front right corner, so that shows lower than it should. (The whole bed is sloped slightly front to back.)


Edited 1 time(s). Last edit at 09/07/2018 01:21AM by SupraGuy.

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MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

What is the mechanical arrangement of the bed? Is there any chance that the bed mount is deflecting more at one end than the other?

Idris

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

I've got a huge dead spot on the bed in the front right. I can't seem to make that corner trigger reliably at all, it is always late and heavy. I've tried the 180 degree thing on VR2, and while it's better, I still seem to have issues with it either triggering more or less at random or else missing contract entirely.

The bed is mounted on 3 bearing mounts, located front right, rear right, and centre left. The shafts are 150mm centre to centre, and the mounts are 110mm front to back. These mount a platform 220mm square to which the actual heated bed is mounted by 4 screws at 209mm centres. I have a 2mm sheet of silicone between the platform and the heated build platform.

That does make for a relatively small triangle, but there are no springs or other non-rigid parts in the mounts. A light tap with a finger almost anywhere on the bed is plenty to get a response from the piezo board, but it ends up taking quite the press from the nozzle in that corner before anything triggers. There isn't much difference in deflection of the bed at any of the corners. There is more at the corners

My current theory is that it happens on the right side (Where there are 2 sensors) because pressing on the one lifts the other. In effect the rear sensor cancels out the front sensor. I can't explain why it doesn't happen on the other side though. I will reiterate that I've very carefully evaluated the polarity of the sensors, and all 3 are very quick to react to squeezing pressure, and do not react when pressure is released. (When I squeeze the sensor between thumb and forefinger, the blue light comes on briefly. I wait for the light to go out while maintaining light pressure, and then release. At that point the red light stays on, and the blue light does not come on. This is consistent across all 3 sensors.)

It is clear to me that I will have to change how I use this, as in its current state, it is almost useless. The only thing that I'm able to use the sensors for at this point is as a Z endstop. It works in that capacity, and to determine if the 2 motor lead screws are at least level with respect to the centre line of the bed.

This leaves me with a few possible strategies:

1. Move the mounts from the bearings, and put them between the platform and the heated bed. I don't really like this idea, as it will definitely expose the piezo discs to more heat, which may bring its own host of issues with it, but at present, it's difficult to adjust the pre-load on the discs without disassembling the heated bed. Also, because of the 4 screw configuration of the heated bed mount, it might mean having to go with 4 piezo discs. (I have an order in for some bare discs, which I'd like to experiment with, but they'll be a month or so out of China. ($2 for 40 discs - 20 each of 20mm and 27mm) That is, assuming that they ever get here. My experience with ordering stuff from China has a pretty low batting average of ever arriving. I have a long Paypal history of making payments to some Chinese eBay vendor, followed by a refund a few months later for "item never arrived." this is much worse with the really low dollar items that get shipped with no tracking.

2. Move the sensors to the Z lead screws. The nuts that raise and lower the gantry are spring-loaded into place. The idea is that if the head is driven into the bed, the screws can still turn, but will pull the nuts down against the springs. If they come down about 5mm or so, they are then able to spin. I could add a plunger to the assembly which would move if the nuts are not fully seated, The plunger could flex the piezo disc, resulting in a signal. Of course the plunger could also trigger a microswitch, which might be easier in this implementation, and certainly cheaper. I don't want to go this direction, as I feel that there's a number of things that could go wrong, particularly since there will be an inherent pressure imbalance between left and right towers die to differing weights, as well as the fact that the probe will typically be off-centre.

3. Go to a hot-end probe. This really seems to be the best use of the piezo discs. If I'd thought through this properly int he first place, this is probably what I'd have done. I'm becoming of the opinion that the under-bed sensors are not as appropriate for larger beds. Even working with a theoretical model, I can see all kinds of issues with getting consistent triggering on any spot on the bed, and when variations of 0.2mm cause such large problems, real-world materials just don't seem up to the task over spans of 200mm or more. Moving the probe to the hot end at least reduces the variability so that the same amount of pressure is required at any point of contact with the bed. I suppose that it also gives me the possibility to include a noise cancelling piezo disc. The universal kit seems less suited to this purpose, however that's acceptable to me.

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MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

I've got a new product in development that might solve your problem but I've held off offering it because I'm having such a nightmare with Canadian customs at the moment. Drop me a PM if you'd be interested in trying out something new and willing to wait for it to arrive.

Idris

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

Well, all in all, I have to say that I am very interested in trying something new.

I've been playing with a force gauge and checking the bed for compliance with solid mounts, and I've found that overall, with the area that I have under the triangle of the 3 mount points, it's really difficult to make the bed equally resistant to motion with the sensors as I have them configured. With the solid mounts, it's much better, but there is still some flex and change in compliance. It looks like in order to improve response, I'm going to need to push the sensors out towards the corners, as I will require unreasonable sensitivity in order to get motion readings from the smaller area.

I could very possibly still use 3 sensor discs, but given the results of my force testing, I would feel much better with 4 sensors at the mount screw locations. Placing the sensors at the perimeters of the bed seems to be how the underbed sensors work well for the delta printers, so I believe that using 4 for the corners of a cartesian printer will yield superior results.

I still have a bit of a doubt that will have to wait until I can manage field testing. The bed that I have is 220mm by 275mm, with the mounting holes on a 209mm square. On the 220mm axis, this puts them very close to the edge, but less so on the 275mm axis, which still leaves significant area outside of the mounting points. I think that I'm good with the mesh leveling all being inside of the 209mm square, and let the firmware assume that the bed continues flat for the extra 27mm to a side, I think that I'm okay with that.

I had hoped that there would be less of a slope to the bed without the adjustable mounts (It's still about as good as I think that I've managed to make my other printer which does have an adjustable bed) so I would like to allow for some adjustment to the bed mounts, and I'd like to be able to do it without needing to take anything apart. I can see that this wasn't so great of a design decision.

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MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

Sorry for the slow responses, I'm on holiday at the moment. I'll send you some pictures of what I'm working on and you can have a think about how to integrate it into your printer.

Idris

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