FSR with heavy heat spreader?

My delta currently uses a 8mm thick aluminum tooling plate with a circumference of 300mm. It's a big, heavy, very flat surface that my glass bed sits on. I'm going to be experimenting with the FSR kit from ultibots later this week, which includes the silicone pads and I have recessed mounts and all ready to go, but most people are using much lighter heat spreaders with them. Anyone have experience with them? My hunch is that they monitor the change in pressure, not the presence of it at all, and so if I can set the baseline to represent the heavy heat spreader, I'm hoping it'll detect the relative increase of the nozzle touching it, but I don't know if they work this way, or if they are as accurate measuring from 99 to 100 as they would be measuring from 30-31. Thoughts? Experiences?

I had an ultibots fsr kit on my now-sold kossel mini. Much lighter alu plate just 4mm x 200mm so I can't comment on whether it will definitely work with 8mm x 300mm. However they do (the JohnSL board supplied) detect change in resistance not absolute resistance. I think they have quite a good range so they should accurately detect 50-100g pressure onto the bed. I found they do work warm, mine almost got conditioned 9ver time and were more sensitive warmer than colder.

Have you seen there is a hotend mount for fsrs on thingiverse? I'm working on a Piezo mounted in the hotend (well technically the cold end) which eliminates the need to have the fsr/Piezo near any heat and suspend the bed etc.. . It's whether it can be built to work and not result in a wobbly nozzle. Piezo wins here as they are quite stiff and yet very sensitive so I'm hoping I can tighten one between two parts and it still registers when it receives a tap.

Edited 3 time(s). Last edit at 01/09/2017 03:24PM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions