Thoughts on the blTouch? I’m half tempted to add them to the #fuseboxCoreXY and my Prusas over a proximity sensor… for ~£25 it’s not bad. My issue with it is the Z offset value, that is, if it’s needed.
It’s basically a servo/microswitch combo in one package.
http://www.ebay.co.uk/itm/BLTouch-Auto-Bed-Leveling-Sensor-for-3D-Printers-To-be-a-Premium-3D-Printer-/201523795715?hash=item2eebc11703:g:yKIAAOSwa-dWsYvI
You can’t get a cheap proximity sensor for a similar price? Maybe it’s just me, but the servo-microswitch combination seems to have a lot of parts that have to retain their precision to 0.1mm or less. The machines I have with microswitches for z (not servoed) definitely change with the weather.
@paul_wallich - when it comes to printing on glass, which I do, using a proximity sensor becomes an interesting affair. My 3 Migbot Prusa i3’s have glass plates that have copper tape contact pads on using an SN04 NPN NO sensor. It’s possible to do but can be janky as hell as the pads can deteriorate over time, due to them being caught by the nozzle or me bring clumsy with a scraper. You then have to remember that it’s putting about 0.15mm on the glass plate too. This would basically negate the need for a metal contact surface, therefore being able to auto level properly on Glass.
PEI’s a bit out of the price range currently when you’re talking 4 printers to add it to, the FSR on the other hand, looks very interesting. I’m taking it that it’s a the equivalent to a NC wired microswitch, my question is, if you’re using the FSR-400 how much pressure does it need to trigger it? Definitely interested though…
For $33 ($28+$5 s/h), I’d rather buy a flat machined aluminum bed and an induction sensor. Which is basically what I did, and I LOVE IT. I also have questions about the precision/repeatability of this item.
For those using proximity sensor I’m wondering if you have seen a difference in sense distance due to heat. When I reviewed the specs it seemed like they would give different results depending on the temp. Are you having issues with this or do you have a solution?
I’m using the BLTouch and am happy with it so far.
I always have things hot when calibrating, mainly due to expansion, I’ve found with my 3 Migbots that if I don’t heat the hot end and bed the offset is too high.
Thanks for the replies! Sounds like each of you prove with the probe itself at a consistent temp. Thanks again!
Curious… I designed that Hotend a few years ago for our Polar 3D printer… I see two things that are interesting to me. One, the nozzle length appears to be long… if that is the standard barrel tube that came with it (I know China is selling all kinds of them now) then you can raise that up so that the opening is within .5 - .7mm distance from the drive gear so you can run flexible filaments and possibly gain a few mm of additional z height. And two, there are additional groves on the top side of the aluminum mount… is that something you created, as the standard mount only has the two nozzle holes and two mounting holes and is milled from flat stock?
One last thing… we’ll have a new version of that extruder with integrated Z probe on our next version of the Polar 3D printer… should be a simple modification to make when the Chinese copy it too. 
@William_Steele - Pic’s off eBay. Not my printers…
Ah… missed that!