Drilling insulated firebrick

[jwmelvin]

Keep in mind that metal and ceramic have differing thermal expansion. You need some way to hold the ceramic that can account for this. If they are rigidly attached the metal will stretch the ceramic and crack it. Of course some cracking may be inevitable.
Robert

Thanks. My plan was to have the metal extend into the ceramic from the outside, just a planar interface parallel to the front of the burner. Perhaps it would be good to use some mold release or paper coating on the metal?

 

[rwm]

That sounds like a great plan. I don't think mold release would be necessary. I was going to suggest several smooth pins sticking into the ceramic from the edge. A lot of furnace lids are done that way. That might be technically easier?
Robert

 

[jwmelvin]

That might be technically easier?

I like that idea thank you.

 

[jwmelvin]

I printed a mold with integral cores for the nozzles and cast a first burner today. It will be a while before I can fire it to burn the core out but the casting went pretty well. Easier than drilling I think.

For retention of the refractory I bent four tabs in on the front edge of the metal shell.

 

[jwmelvin]

Today I got my forge working (fired the refractory lining and installed a burner), so I was able to burn out the PLA core of my casting. Part of installing the burner involved drilling an insulated fire brick, which I figured I would take a picture of in case someone searches this thread some day. It was super easy on the drill press with a hole saw (no pilot) and a shop vac:

The forge appears to be a success so far:

And here is the burned-out casting for the ribbon burner (the approach I am taking instead of drilling as I initial though about), ready to finish integrating with a plenum and try in the forge:

 

[jwmelvin]

I know this is out of band for this forum and even off topic for this thread but I am happy to report that my ribbon-burner prototype (what motivated this thread) appears to work. It will benefit from some tuning but I’m excited. I made a sheet metal diffuser to expand the inducer flow to the nozzle bock:

And I’m getting a pretty reasonable flame:

 

[bfd]

instead of compressed air hold a reduced dia vacuum as you drill each hole bill