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Part 05 - Heated Bed

The heated bed consists of a square of aluminium which is bolted onto the frog using spring loaded mounts - as I understand it the springs help you to both level the bed, and also protect the hot end if it should crash into the bed during operation. Seems sensible to me.

Getting the Kapton tape onto the aluminium should be an easy job, and it is...as long as you're not too anal about bubbles that is. I am. Bearing in mind the cheapest Kapton tape I could find is £17 GBP a roll, I ended up accepting there would be some bubbles, and stopped replacing strips where they were apparent. I did notice that by simply lifting the tape and smoothing it back down, the bubble itself would go away, however it would leave a little round mark on the tape. Seeing as the objective is to get it smooth, I found this acceptable.

I built the thermister for the bed as per the alternate instructions, which proved to be a good, strong solution. The eagle eyed out there will note that the PTFE sheath drifted down by about 5mm on one of the thermister legs as I taped the final Kapton cover strip, sealing the assembly. I didn't notice this until I'd left it overnight, and by then I guess the Kapton glue had set, and I couldn't get the tape off without risking damaging the extremely fragile thermister. I mitigated this in the next step, by using additional PFTE tape (from the back of the fan in case you're wondering) both under and on top of the thermister, protecting the thermister bead itself, and the leg where the sheath slipped. 

I taped the Nichrome wire to the plate while I bent it into shape for the recommended path, and then finally secured it by replacing the sticky tape with Kapton.

The final stage is to cover the whole lot with a heat shield, and tape into place with Kapton.

This shows one side of the mounted bed - the other side has two spring mounts so you can do limited X/Y adjustments to level the bed and set its height.