Ceramic(?) board

I have an old Gallenkamp muffle furnace. The outer casing is made of a dense manufactured board, which contains glistening material, possibly mica. (Hope it's not densely compressed asbestos...). I'm sure the name of the stuff is somewhere in the back of my head, but it's rather cluttered in there, and finding things keeps getting harder...

Several ventilation holes, approx 1' dia., have been machined through the board, showing that it machines well. It seems that various fittings are secured to the casing by screws, apparently tapped into the board. I now want to remove some of the screws. Some come out OK, others are reluctant. I suppose, if they are in tapped holes, the hole's thread will strip. Well, that's if I'm lucky - one screw sheared off...

The questions are 1) Any idea what this stuff is called? 2) Does it destroy taps, because of abrasive content? 3) Might Helicoils work?

I used a hard insulation board that sounds like yours you could drill and tap it was tough on hi speed steel cutters it was called sindanyo not sure about the spelling.

Yes it's probably Sindanyo, could very well contain asbestos is it's old enough, it's still made under the same name but now asbestos free.

John

Edited By Sandgrounder on 14/03/2017 10:59:09

It could be "Vermiculite" board as used on brazing hearths and fireplaces etc.

Phil

If it looks like mica it could be compressed vermiculite, also sold as skamolex.

Neil

Sindanyo now has a 700 C limit so not suitable for a muffle furnace. Ceramic fibre boards go to 1400 C.

Edited By KWIL on 14/03/2017 15:12:25

Isn't it just for the outer casing? The muffles I worked with in the late '50s and early '60s were wirewound running at 900C and globar ones at 1250C, these had Syndanyo outer casing which you could touch without burning yourself ( but not for long though, a few seconds at the most ) at a guess there was about 6" of insulation between the muffle itself and the casing.

John

Syndanyo  is an asbestos free insulation board made from a fiberglass and polymer matrix. It can be machined (with dust extraction) drilled taped and comes in various thickness it is supplied by DME mould tool suppliers. I used it in toolmaking plastic injection tools. It is abrasive to cut and used a diamond saw in a jigsaw to cut  sheet to size and carbide cutter to drill and machine. 

David

Edited By David George 1 on 14/03/2017 22:45:43

Edited By David George 1 on 14/03/2017 22:46:52

Kiwibloke, have a look at some outfit selling parts for log burners and pellet fires.

Ian S C

Thanks for all the information folks.

I've just looked at my copy of Tubal Cain's Hardening, Tempering & Heat Treatment, No.1 in the Workshop Practice series (pub. Argus Books, 1984) and lo and behold, Sindanyo is mentioned. So that's where I heard about it... Wish my mental filing system was more reliable...

Currently-produced Sindanyo is asbestos-free, but I'll assume that the casing of my elderly furnace contains asbestos.

The furnace's electrical plate says 240V, 23A, so it should cook breakfast OK. Here in the land of the Kiwi, electrickery is harder to come by - domestic wall sockets are rated at 10A, although 15A sockets are sometimes fitted in garages, etc. Wiring regs are different from UK - power circuits are radial, and most houses have many power circuits, each fed from a fuse or circuit-breaker. Joe public isn't allowed to do much in the way of wiring, unless it's 'signed off' by a professional sparkie. I'll probably have to arrange a dedicated feed from the fuse board for the thing. Oh well, if life were simple, we wouldn't mess around with this sort of stuff, would we?