RepRap: Blog

Rather than blow bits of firebrick and soot onto the slide with a blowtorch, I've got an old carbon steel wok set up over a gas burner - if you do something similar, burn out the steel surface thoroughly before putting the slide on it like I didn't. The FLIR camera that lets me accurately measure the temperature of the slide before spraying on the tin without being distracted by the furnace heat reflecting everywhere.

Short story, I do need 450C to decompose the tin chloride. I did several runs starting at 300C and they didn't start to conduct until I reached 450C (tin oxide melts at around 1,600C). This being a rough test, I reused the slide. The final slide gave a reading of 2.2M from one edge to the other, but nothing across the other way due to a, uh, significant air gap:

This is probably due to repeated heating/cooling, and the sheer volume of spray that suddenly cools it down to about 250C. To fix that, I'll make a new batch of tin chloride and double the concentration. Less squirts, less temperature drop.

Note: Antimony does not dissolve in hydrochloric acid, so I won't be picking much up when dissolving Britannia Metal in HCl.

I'm allowing the finished slide to cool gently by simply sticking the lid on and gradually turning the flame out. As I reused it a few times the finish on that slide is well grainy.

I've made a new slide holder for the Block Stage with a connection probe built-in, and all I need now is an intact conductive slide to put on it.

# posted by vik-olliver @ 1:46 AM