Re: Cutting Polystyrene Insulation

why on earth use 4" of polystyrene ? .... you can use polyurethane, it is much better for use with underfloor heating. It is more dense, and much higher insulating value than polystyrene .

But if you want to cut it ... you could use a soldewering iron, but simpler to use a stanley knife set to correct depth of cut - cut left & right side then use a fork to scrape out the waste.

Rick

Rick Hughes wrote: >

pipework to the rads under the floor. Tony

He needs to make a polystyrene cutter

If you need a few yards of the stuff it's sort of free (you are requested to post what its worth to you in the next RAF Benevolent fund box you come across). Get in touch if you need some.

In article , Peter Parry writes

Similarly but different, the pistol grip 100/200W instant heat soldering irons that seem to be getting sold cheap all over these days have, *I think*, copper wire elements which just get hot by passing a huge current through the wire. Strip wire from some T&E and shape a new 'element' to the desired cutting profile - bingo . . . .

Flaws anyone?, are those elements really just copper?

Errm, you don't need nichrome, unwinding one strand from a steel bicycle brake cable works perfectly. If it is clamped into a fretsaw frame (suitably insulated) and fed with current from a 12V source via a rheostat it works very, very well.

"Rick Hughes" wrote Q:

In message , Rick Hughes writes

I think a craft knife at full extension might work a little better

Constantan wire from Maplins also works well.

For straight cuts I suspend a piece from a batten fixed near the garage ceiling tensioned with a weight. Croc clips supply the power (6V or

I guess for troughs you could make a "U" shape, but it wouldn't be very rigid.

Regards,

Simonm.

Thanks for all the very helpful replies - I'm sure my neighbour will be able to choose a method he can cope with from all the suggestions.

Many thanks, Tony

Yes but think of the nuisance, first you have to buy a bicycle, then dismantle the thing, then having extracted one strand of brake cable you have to go and buy a replacement brake cable. I mean it's a right hassle compared with my free offer :-).

Buy? Years of living in Manchester taught me that most DIY projects start with "First steal a bike".

and 4 times as expensive...

So do guitar strings, stainless steel fishing trace or just about anything.

Not if you buy form Seconds & Co. ... you can buy any size, thickness and style of foam - getting polyurethane for the price of polystyrene.

They have 2 outlets - but I think they are now unrelated.

I bought more than 60 sheets of foam, 50mm and 100mm ... saved a packet compared to builders merchants.

Rick

not so ... see my subsequent post on seconds & Co.

Looks good. I see Seconds (Southern) Ltd. in Kent & Seconds and Co. in Wales, shame there isn't a third branch further north. Looks like they both do deliveries - should be worth a call. Was just about to buy a floor load of polystyrene.

Toby.

In message , Peter Parry writes

G'wan then Peter, I'll have a km off you

Could you 'wobble' a circular or bench saw blade to cut a groove/slot in the foam? I've done this to cut shallow slots in the uprights for a book case, in which to fit the horizontal shelves. To wobble the saw, washers etc. were clamped in the bench saw arbor, on both sides of the blade to tilt it 'off centre'. A few experimental cuts with adjustments and it worked fine to a depth of between a quarter to half inch, in plywood cutting a three quarter inch wide slot. (So the outer edge of the blade had to be wobbling about three eighths off centre line.) In a soft material such as foam probably no trouble cutting say,

No. it chars, doesn't melt.