Inductive probe on PCB/Aluminium foil/Glass setup

Hello, everybody!
Not too long ago I discovered that I'm much more of a maker than I initially thought and my excitement led me to buying a kit and venturing into the world of electronics and deeper (than before for me) tinkering with stuff. I'm starting the thread like this firstly because it's my first post here (despite I have been lurking for some time) and I feel a bit of introduction is in order and secondly because I'd like to clarify that until six months ago I hadn't soldered or used a multimeter ever before, so please excuse any noobish questions. This entire adventure, although it has started quite recently for me, has unveiled more than just a new world for me - its was more like a couple of dimensions - and all of this excites me to my very bones!! That being said I'm very eager to learn and should any of you venture into deeper explanations it won't go unnoticed!!



Now to the point:
I own a MakerFarm Pegasus 12 Standard edition, which I want to upgrade to inductive probe auto bed levelling. This entire project was spurred by the fact that sometimes my printer takes into account the mesh levelling I have input and sometimes it doesn't - all this couldn't be resolved by Colin which made me take it into my own hands.

I have done some research but before I go ahead I'd like to know if anyone has had good experience with PCB/Aluminium foil/Glass and inductive probe? I read it works fine which is why I lean towards it.

I don't want to mess with capacitive probes as a lot of things influence the readings of the probe. Also, as I'm a student BLTouch is beyond my budget.

Best

Have a look at piezoelectric discs. Within the budget of a student and should appeal to any tinker.
So far, and as far as I can tell, nobody who has tried piezo discs has either failed or been unimpressed - if there are any they haven't written on any forums. Be warned though, you would be one of only a handful of early adopters.

Details on [reprap.org] and [reprap.org] and most of the history in [forums.reprap.org]

Also, other types on [reprap.org]

Mike

Thanks for the suggestion, Mike, also thanks for the links!

I was aware of all the Z probing methods outlined in the article but for the piezoelectric sensors. They do appear quite fascinating and I will be ordering a set of five for testing. Hopefully I will be able to provide some kind of benefit to the community by trying those out.

I'm located outside of the UK, but ebay is my best bet for shopping, especially slightly exotic components so I'd like to order both, given the low cost.

I did some more reading in the meantime...
In this thread - [www.instructables.com] it says that some probes require voltage modification (http://www.ebay.co.uk/itm/LJ12A3-4-Z-BY-Inductive-Proximity-Sensor-Detection-Switch-PNP-DC6-36V-UK-Seller-/181919632606?hash=item2a5b414cde:g:TPUAAOSwLnBX9UqV) and some don't (http://www.ebay.co.uk/itm/ANET-A8-A6-A2-Autolevel-sensor-8mm-NPN-LJ18A3-8-Z-BX-3D-PRINTER-/122353461183?hash=item1c7cd5a7bf:g:-V8AAOSwr~lYoFf9). Not sure how to tell them apart. The guide suggests looking at the colour of the probe but I think that's not a very reliable way.

Also, in a video Tech2C states that PNP sensor should work at 5V and thus wouldn't need custom wiring.

I'm not sure what to look for in an inductive sensor so I'd like some help, please. Also I'm shooting for a probe with sensing distance of at least 8mm.

Doc

Edited 2 time(s). Last edit at 03/03/2017 12:05PM by Doc7.

You can use an "8mm sensing" inductive sensor with glass and alu foil and a heated bed. You might be pushing it with 4mm thick glass, but 3mm works. Higher voltages often increase the sensing distance. I have successfully used an lm7805 voltage regulator rather than dividers. You can also use relays, quite a nice idea as you can switch nc to no and vice versa.

There are some sensors which you can use without voltage dividers, and some do work (even though Thomas Sandladerer said they don't in his video two days ago) on 5v.

However I'm quite involved in the piezo sensor project and they are better than any of the sensors I've used so far. And cutting edge right now. There's a miniature one on my bench right now.

Edited 1 time(s). Last edit at 03/05/2017 02:19PM by DjDemonD.

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Simon Khoury

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

That being said, are there any benefits inductive/capacitative probes offer over piezo sensors? I did get keen on the idea of these little buggers but originally I considered trying both...now I'm thinking of going full-piezo sensor. Share your thoughts, please!

I can't think of any benefits, except the inductive probe is cheap, and if you get the right one, easy to get going with. But the drawbacks are numerous, x,y and z offsets, glass thickness issues, you can't probe the whole bed unless you have a big printer with a small bed, they're big/heavy and potentially the hassle of voltage dividers/regulators.

But try one first see what you think then try the piezo.

The piezo takes a tiny bit of tweaking to get going with it, and you need a signal board which in limited supply, but its fantastic once its setup.

Repeatability is about the same with piezo/IR/inductive at around 0.01mm range over 50 probes.

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Simon Khoury

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

Could you tell me more about the setup process of the piezo sensor and this signal board, which is in limited supply, please.

Start here: [reprap.org]

Then take a look at [www.thingiverse.com]

The signal conditioning board can be made, or there are some pcb versions Moriquendi made (PM him see if he has any), that you can buy.

Come back if those links don't make any sense.

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Simon Khoury

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

For your printer you might be better off with the latest version here:

[www.thingiverse.com]

But so far I've built one, it should work but I haven't a machine to fit it to to test it. You'd be the first!

It is based on a working design its just smaller than the previous design.

Edited 1 time(s). Last edit at 03/05/2017 03:39PM by DjDemonD.

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Simon Khoury

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

Thanks for your replies. I'll read what you have linked and will research it some more. Probably will get back with more questions, though, hehe.

Doc