Proximity sensor for glass beds?

Hi,

is there any non physical proximity sensor available that works on pure glass or needs so little resistance that aluminium foil would work?

Cheers

Yes, I have a sensor that uses 2 infrared beams to detect height above a glass surface. See [miscsolutions.wordpress.com]. It's designed for the Ormerod, but some people are using them on other printers including Prusa i3 and delta. I am about to build a fresh batch. More details in the Ormerod forum.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I use capacitive proximity sensors, they work on glass. Some people said they are not reliable, but I have used them for several months now without any problems.

Aha did have to write your own voltage table or did you set it up like the capacitative ones?

Did you meant inductive? Or the question was for dc42?

I powered from main supply (12 volts ) and signal wire goes to an LM7805 regulator and from there to the ramps board. No tables or offsets needed so far. Print with PLA and ABS, PCB heated bed with glass on top.

Yes sry i meant inductive ones.

The capacitative ones seem more expensive did you tinker that all yourself or did you find a kit?

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sungod3k
Aha did have to write your own voltage table or did you set it up like the capacitative ones?

Is this question is addressed to me? If so...

My differential IR probe has an on-board microcontroller, so it can process the signal in various ways. With the standard firmware, it produces two digital outputs, which are normally mixed on the board to produce a single analog output. This is good for feeding into the Z probe input of Duet electronics. The analog output rises from 0 to about 465 (out of 1023) when the probe is slightly above the trigger height, to signal the printer controller to slow down the descent rate. At the trigger height, the reading increases to 565 and a LED on the board illuminates. The trigger height is about 3mm above the bed.

Most 3D printer electronics other than the Duet expect the Z probe to be (or to simulate) a normally-closed switch. My board can simulate such a Z probe by removing one resistor, so that the output changes from low when above trigger height, to high when at/below trigger height.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

The printer it's of my own creation based on a Prusa i3.

Yes the capacitive sensors cost a little more and they are heavy, better suited for bowden than direct drive but I print slow so it doesn't bother me. The sensing distance and able to measure the top of the glass and not metal under is what it gets me to try, use and pay extra for them.

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ggherbaz
Yes the capacitive sensors cost a little more and they are heavy, better suited for bowden than direct drive but I print slow so it doesn't bother me. The sensing distance and able to measure the top of the glass and not metal under is what it gets me to try, use and pay extra for them.

If you do some tests, I think you will find that you are not actually measuring the distance to the top surface of the glass, but measuring distance to the bed plate underneath modified by the dielectric constant of the glass. So if you change the thickness of the glass, the trigger height will alter; unless you have the glass covered with Kapton tape or something else that is slightly conductive.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

dc42,

Haven't have any problems with it. Haven't change the offset for about 2 months now, and I haven't lost any prints to bed adhesion nor my prints are deformed in any way (Plain glass from Lowe's).

Yes I know that might be some better systems, but this one is working fine for me.

Thanks for the info.

@ggherbaz, can you share the sensor that you're using?

Pibot sell an IR reflection endstop that might work on glass. [www.pibot.com]

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

Oh nice, that looks like a perfect solution

This one:

[www.amazon.com]

But what 3DKarma posted looks really nice, cheaper, smaller and pretty advance........ I will give it a try on my next printer.

I ordered one of the pibot sensors and they also told me that they will have a video up soon where they set up the sensor for autoleveling.

Those look cool.
Any idea on the precision compared to the normal switches?

Hi,
How did you get on with the Pibot sensor?
Thinking about getting one but need to know weather they work with a glass bed and also how acurate?

Regards
Kevin

Hi,
How did you get on with the Pibot sensor?
Thinking about getting one but need to know weather they work with a glass bed and also how acurate?

Regards
Kevin