capacitive Sensor for glass bed

capacitive Sensor for glass bed

Postby festaman » 2015-Aug-Mon-18-Aug

Hey all I ordered a glass bed and what i thought was goign to be the correct sensor but i was shipping the wrong one. Is anyone out there using a capacitive sensor with a glass bed? I am about to order a LJC12A3-H-Z/BX or LJC12A3-H-Z/BY i think they are pretty much the same thing but cant tell for sure.
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capacitive Sensor for glass bed

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Re: capacitive Sensor for glass bed

Postby evanalmighty » 2015-Aug-Mon-18-Aug

These sensors only detect metal, not glass. You can still use your glass bed and place a piece of foil under the glass so that the probe can trigger. You might need to find a probe with longer detection range so that it can trigger before crashing into the glass.
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Re: capacitive Sensor for glass bed

Postby festaman » 2015-Aug-Mon-20-Aug

There are 2 kinds of sensor that you can use. Inductive that will detect metal which is what comes on the Printrbot. I ordered a capacitive one . They will detect anything near it. The reason for for the new sensor is that if it doenst detect the glass it defeats the purpose of it. If the sensor detects the aluminum underneath then it wont level off the glass surface which could be flatter then the bed under it.
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Re: capacitive Sensor for glass bed

Postby evanalmighty » 2015-Aug-Mon-20-Aug

That's why the Z offset is adjustable. You'd just increase the Z offset to compensate for the thickness of the glass.
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Re: capacitive Sensor for glass bed

Postby RetireeJay » 2015-Aug-Mon-21-Aug

Although capacitive proximity sensors can respond to dielectrics like glass, their response sensitivity is likely only 1/3 of the sensing distance for metal. Of course, for glass backed up by metal, the result will be intermediate.

I found this data sheet (not the one for the sensor you specified, but perhaps representative). Look at the graphs on page 3
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
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