z Axis

Has anyone tried to put small force gauge sensors under the build plate for z-axis height sensing? Four force gauge sensors can be had for around $20.
This would automatically compensate for ANY bed material,Nozzle Length, etc. and accurately. One would have to add an op-amp comparator and tied directly to Z-axis limit switch input. The software would look for say a 1lb difference then back up 2mm and then slowly lower again (similar to the BL Touch) until the nozzle just touches the build plate. Softer materials like cork would still register but may compensate lower than harder materials but could be compensated for by Z-offset.

Hmmm! I think there are many better places to put this query than in the RepRap magazine section but I will do my best to reply.
Force sensors have been used with some success - there are some videos on YouTube where the elements from a set of kitchen scales are used for exactly that purpose. Having said that, there are many other sensor types, my own personal favorite is the cheap piezo elements used in everything from musical birthday cards to beepers, sounders and speakers for all purposes and can be had as little as £0.28 each (or less) see [forums.reprap.org] Force sensitive resistors are still popular but I confess to being perplexed as to why anybody would use them when there are better options available. An effector for delta printers which has built in strain gauge is available [duet3d.com].

Mike