Seeking two materials - ideas?

A spring that can be straitend out is not a spring. Perhaps you should be looking for some type of plastic that has a memory effect at certain temps. some sort of thermoset set stuff.

The moulding stuff you want is :-

Such springs are used in a wide variety of domestic machines - the first of which springs ( ho ho ) to mind is a clock...though for the dimensions you require it would have to be a reasonably large clock.

Vacuum cleaners with retractable mains leads also use such springs, as do petrol mowers ( on the starter pulley ), though I think these come in at just under 1cm wide...but can be picked up at your local tip for barely a couple of quid.

Sitting here on my workbench is a clock spring...some 16mm wide, at least 20 cm long.

BUT....

....although I can indeed straighten it out with two finger's worth of pressure, I wouldn't want to be on the other end of it when the spring is released! If fingers are going to be involved in the equation then I'd seriously recommend going for a nylon spring. One wrong move and you'd either cop a whack from the returning spring or it'd slice a neat hole in your finger.

Depends what the purpose is. If you can be more specific I think people will come up with some suggestions. There's a 'dip' available that some toolmakers use to coat handles with...it sets as a sort of plastic sleeve.

Regards,

Er, yes it is...got one right here...

Regards,

The guts from an old tape measure perhaps?

We used to use something called 'metrology casting rubber' which would set up into a shape within about 5 minutes of mixing 2 liquid components together and pouring it into/over a form to be measured, and which was reasonably soft and gel like. However, I don't think it had a long shelf life after this. There is something similar here under the title of Reprorubber :

HTH

Peter

what I meant is "if it" stayed straitened out once uncoiled. there are loads of so called clock springs ..... cheapest ones are in them retractable dog leads or old vacuum cleaners to retract the flex....tape measures.or even an old clock. all the best.mark

On 20 Dec 2005 09:44:25 -0800, "Peter Neill"

Silicon Rubber or PCB conformal coating resin?

Peter

-- Peter A Forbes Prepair Ltd, Luton, UK snipped-for-privacy@easynet.co.uk

Try Tirranti's, they do a range of RTV (room temperature vulcanising) rubber and silicone based compounds. These are easliy cast at room temperature (just mix the compound and a hardener). They come in a variety of hardnesses and they sell it quite small quantities.

Regards Kevin

Ah yes...IF it stays straightened out...what you have there is a piece of string! ;)

Regards,

Silicone (aka bath sealant) might be fine, but some types release acetic acid whilst curing. This might not matter if you're coating plastic, fabric or plant material but it's a disaster if you apply it to metals. There is a non-acidic version that's used for conformal coating of elctronic circuits which is much safer.

-adrian