# Electrically Conductive PEI To Level The Bed
**URL:** https://forum.lulzbot.com/t/electrically-conductive-pei-to-level-the-bed/1640
**Category:** Hardware
**Created:** [April 13, 2015, 10:50pm UTC](https://forum.lulzbot.com/t/electrically-conductive-pei-to-level-the-bed/1640 "2015-04-13T22:50:46Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@inventabuild](https://forum.lulzbot.com/u/inventabuild)
#### Post date: [April 13, 2015, 10:50pm UTC](https://forum.lulzbot.com/t/electrically-conductive-pei-to-level-the-bed/1640/1 "2015-04-13T22:50:46Z")
Currently Lulzbot is tapping electrically conductive washers with the hot end at the corners of the bed to discover the bed height at the corners.
I wonder if Lulzbot could instead use an electrically conductive PEI print bed w/ leads running to it and tap the PEI bed itself with the hot end instead of tapping corner washers?
Get that working or something like it, then hopefully we can get a Marlin upgrade that will utilize taps across the build surface to create a 3D topographical map that in turn can be utilized to navigate the hot end perfectly across the build surface to create perfect 1st layers every time.
Then we can all spend more time printing w/ our printers and much less time tuning them with failed prints as our guide. This will save money on filament too 🙂
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### Author:  [@kcchen\_00](https://forum.lulzbot.com/u/kcchen_00)
#### Post date: [April 14, 2015, 1:19am UTC](https://forum.lulzbot.com/t/electrically-conductive-pei-to-level-the-bed/1640/2 "2015-04-14T01:19:08Z")
Why use the hotend to touch anything? How about a non-touch capacitance proximity sensor?
[https://www.thingiverse.com/thing:617615](https://www.thingiverse.com/thing:617615)
Just need to confirm the version of Marlin includes support… There’s a thread about this on the forum.
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### Author:  [@inventabuild](https://forum.lulzbot.com/u/inventabuild)
#### Post date: [April 15, 2015, 2:49am UTC](https://forum.lulzbot.com/t/electrically-conductive-pei-to-level-the-bed/1640/3 "2015-04-15T02:49:02Z")
The issue w/ the G29 probe and other sensors as they are currently being implemented is that you need to go through countless iterations and test prints to find the exact position of the sensor relative to the tip of hot end.
So if you take the nozzle off to swap sizes or you need to dismount the hot end from it’s carriage to get rid of a clog it never goes back into the carriage in the exact same position that it was in before you took it out. So now we’re back at square 1 again with countless iterations and test prints to find the new z offset of the sensor relative to the tip of the hot end.
This is why Lulzbot’s technique of electrifying the nozzle tip and using the tip itself as the sensor is a great technique. Even if you change nozzle sizes the new nozzle tip becomes the probe so you don’t need to find it’s position relative to some sensor, the tip is the sensor itself.
I could see possibly developing some kind of unibody hot end that incorporated a non-touch capacitance proximity sensor and all the components always come apart and go back together again with incredible precision where even the nozzle snaps into place when fully seated.
The question is which technique is easier to develop? I think it’s easier to use Lulzbot’s current technique of turning the nozzle tip itself into a touch probe rather than developing a new unibody hot end with high precision parts that incorporates a non-touch sensor.
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### Author:  [@kcchen\_00](https://forum.lulzbot.com/u/kcchen_00)
#### Post date: [April 15, 2015, 5:02am UTC](https://forum.lulzbot.com/t/electrically-conductive-pei-to-level-the-bed/1640/4 "2015-04-15T05:02:56Z")
Valid point about changing nozzles/toolheads. The autoprobe would be part of the toolhead, so the hotend height would be consistent. I find that nozzle changes don’t affect the the z-offset much… well at least not the .3, .4 &.5 nozzles I’m rotating through. I’ll have to double check more often, though. I guess I should be tankful that the PEI is very forgiving from a adhesion perspective.
Coming from a printer that had an induction probe. It was reliable and easy enough to calibrate using a physical jig for the nozzle and probe. Then it was just a matter of adjusting the M212… No different then adjusting the end stop.
Anyway, I hope an autoprobe option is offered… regardless of which option.
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### Author:  [@Aliraza47](https://forum.lulzbot.com/u/Aliraza47)
#### Post date: [April 15, 2015, 6:32am UTC](https://forum.lulzbot.com/t/electrically-conductive-pei-to-level-the-bed/1640/5 "2015-04-15T06:32:27Z")
The printed part name is extruder\_mount\_hex.stl. I need the CAD file for it, FreeCAD, STEP, Solidworks, etc. ???