Quote
Ralph.Hilton
My suggestions - forget the FSR and make the machine robust enough so that calibration, once done, persists for a while. I just built a Kossel mini and found quite a few things in the design that make calibration inaccurate.
Screwing bolts into plastic is a very bad idea. It means that you cannot tighten things up fully and they will loosen quite quickly with temperature fluctuations.
Electronics failures are often related to heat. Trying to cool down electronics under a heat bed is not an optimum situation especially given that many people will be using cheap boards with underrated FETs without heatsinks.
I suggest building an enclosure for the electronics out from under the heatbed. I consider auto levelling as a bit of a flavor of the month approach that really isn't needed if one designs the machine for stability of calibration in the first place and spends the time needed for accurate calibration.
Wood is not a stable material especially near heat. It contains a lot of moisture and will warp.
Thanks for the suggestion but I am determined that I need some type of auto leveling. I use an E3D and even if you try to always tighten the nozzle the same, there is bound to be slight differences. There is no way I want to re calibrate the height every time I change a nozzle. Using the FSRs is a great solution for this. As far as kossels not being accuarate due to screwing thru plastic... sure, its not perfect but there seems to be plenty of well calibrated kossels all over youtube. So it is working for a lot of people. However, it's looking likely that I will have to move the RAMPS board from under the bed.
