12" dia circular 'former' for casting required - any ideas?

[julianf]

Ive got the burner working on my furnace now, so time to put the dense castable in.

I need a former for the inside, of 12" dia - but it has to be somthing i can get (or burn) out again.


Any ideas?

A 300mm (d) x 420mm (l) tube would be perfect, but there must be a number of other things that would do also.

 

[mpats]

I've seen someone use a reasonably thick walled cardboard tube as a former to pour their castable refractory round. Seemed to burn out ok, you could probably peel half of it out then use the burner to get the rest out.

 

[julianf]

Collapsing is certainly an issue - i was planning on filling the inside with dry sand to equalize the pressure some.

Im wondering where i should try and scrounge some 12" card tube?

 

[500e]

How big do carpet tubes go

 

[slim_boy_fat]

Tube from the inside of a carpet roll? They seem fairly substantial and readily available.

Edit: Ignore this, they'd not be big enough in diam.

 

[julianf]

How big do carpet tubes go

I used to pick them up from a couple of fitters (for making sawdust logs for the burner)

In all the time i was doing it, i did not see one larger than about 150mm

 

[Screwdriver]

Plastic bucket or paint can and you can do the base at the same time. Bit of polish or a light oiling and it should pull straight out.

 

[rikrobson]

i'd get a sheet of 2" polystyrene (I've already got some though) and make up a 6 layer sandwich and make that round.
That should be easy enough with a hot wire or a knife and sand paper

then it can be disolved/melted/burned out of the centre.

 

[awemawson]

Sheet of thin aluminium or steel sheet, rolled by hand and pop riveted. Then when the refractory is set cut the heads off the rivets with a chisel and peel out the sheet. Old lithographic printers sheets would be ideal.

 

[bonepyro]

Have you got a firework display company locally, cardboard tubes are used as mortar tubes usually increasing in 1" increments. Maybe a local operator would have an old one they would let you have.

Alternatively http://www.essextubes.com/ supply cardboard tubes in various diameters and thicknesses. If wet casting, they do come with a waxed finish which should keep them dry long enough for the fill to set.

 

[WorkshopChris]

Bendy mdf pinned around a couple of former's would be strong and easy to remove after, if well waxed. or just let it burn.

 

[slim_boy_fat]

Short length of plastic drain pipe? They come in all sizes, but are probably corrugated - simple enough to wrap cardboard round it though......

 

[sardine]

Oversize printing firms have big diameter cardboard tubes off the materiels they use, there is one near me but I won't be down there for a while.

Like has been mentioned you can use them as ersatz logs if you don't mind the amount of ash they produce.

 

[8ob]

The 18kg ish calor gas bottles are exactly 12" OD, they are lying about all over the place. The one on our forklift is 600mm long.

Bob

 

[gaz1]

oh thats easy use wood and masking tape for the former

from my rocket burner former

http://www.mig-welding.co.uk/forum/threads/first-build-rocket-burner.45497/#post-778101

the other stuff you can use a cement tube

http://www.homedepot.com/b/Building...e-Forming-Products-Forming-Tubes/N-5yc1vZbv35

forget cardboard tubes they fail

you can use thin metal and wood for externals note this is 6" casting equals 8-9" on external size but see for yourself