cutting upholstery foam

A ply board top and bottom, multiple bolts and compress the 6" down to 4" total. Cut around the edges and you have new nice firm cushions....<exits stage left>

pgk

As I understand it the foam ,as used in furniture, gives off cyanide fumes when set alight, would this not apply to hot wire cutting... just remembering Fire brigade videos of home safety. Play safe & spend a few shekels on new cushions.

George.

Re: " As I understand it the foam ,as used in furniture, gives off cyanide fumes when set alight, "

It's a complex issue and drifts way off topic but in essence:-
Flexible PU foam (not rigid PU foam used for insulation) when used in furniture has to comply with the tight UK Regs for flame retardancy. Smouldering (reduced O2) is very different from combustion or flaming in the presence of O2. But all organic nitrogen containing substances can produce HCN whether "natural" (e.g. feathers, rubber, wool etc) or synthetic (e.g. PU, polystyrene) in reduced O2 concentration. A definitive paper, 35 years old, explains - **LINK**

Relevance to model engineering? Very little I guess unless you insulate the loco's firebox with flex PU or feathers !

Hi Duncan,

You've two choices really. First take to a foam converter if there's one near by , probably only charge you a tenner to cut or if you've access to a band saw cut in to strips and rejoin using spray glue. when finished cover with 2oz of 4oz polyester wadding (Dacron). Remember to leave the foam 1" bigger on all dimensions than the actual cover or the cover will slip round . The foam HAS to force against the cover.

Regards,

Bob .

40 years as upholsterer

Bit late in the day to advise against hot wire cutting foam but if you do it you will be left with a horrible sticky surface. It will cut with a band saw but a band knife is better.

I worked for years as an upholsterer/ furniture restorer/ part time fisherman and radio controlled aircraft flyer, just two of us.

We cut foam of all sizes with a Russell Hobbs electric carving knife and a 14 inch long thin butchers carving knife, one that was used for slicing cooked meat.

To do what you want to do we would cut all around the block with the electric knife and then reach in to finish cutting with the long knife.

We tried using an hot wire but found it quicker for us using the knives.

If the sun was shining and the mates wife was out working we stopped work and went flying or fishing, great life.

I agree with Cyril you can cut it with a electric carving knife but its far from easy keeping the blade straight and flat and the result is far from perfect, and depending on the fabric on your furniture it will show, especially on leather.