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24th Sep 2006, 12:21 pm | #1 |
Nonode
Join Date: May 2005
Location: Godalming, Surrey, UK.
Posts: 2,593
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Cutting Sponge
Hello,
I often have to cut new bits of sponge to replace pieces in radio battery compartments which have disintegrated and I find that cutting sponge with scissors always seems to leave an untidy or crooked edge. Car upholstery restorers use a hot wire tool to cut through replacement sponges for seats etc so I've now tried heating up a piece of fusewire over a gas hob and then immediately plunging it through a piece of sponge and it leaves a perfect straight edge One has to be very quick though cos the wire cools down very quickly I guess there may be a better way of heating up the wire so that one can take one's time .......... any suggestions ? Howard |
24th Sep 2006, 12:29 pm | #2 |
Moderator
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Location: Ipswich, Suffolk, IP4, UK.
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Re: Cutting Sponge
A thin piece of wire will always lose heat quickly, so it needs to be constantly heated.
You could use a piece of wire taken from an electric fire element. Use 1/20th of the total length and a 12V car battery or pro rata. You'll need a suitable frame such as that from a plastic tilecutting saw. Pieces of metal will be needed at each end of the wire to stop it melting the frame.
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24th Sep 2006, 12:29 pm | #3 |
Dekatron
Join Date: Jan 2005
Location: Oxford, UK.
Posts: 17,863
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Re: Cutting Sponge
The classic way of doing this is by passing a controlled current through the wire to keep it hot.
Some of the "schools" suppliers [Maplin? Rapid?] used to sell a hacksaw-like frame with special wire for this very purpose. Googling is informative, e.g. this one using a soldering gun to provide the current: http://club.cycom.co.uk/hotwire/Hot_...rene_foam.html Nick. P.S. I see Graham beat me to it! |
24th Sep 2006, 6:58 pm | #4 |
Hexode
Join Date: Jan 2003
Location: Darlington (DL3) North East U.K.
Posts: 394
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Re: Cutting Sponge
Please be aware that hot cutting some plastics inc. some foams can give off unpleasant gasses.
So do it near an open window or door
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Chris C G8TJR |
24th Sep 2006, 9:38 pm | #5 |
Retired Dormant Member
Join Date: Sep 2003
Location: Wrexham, North Wales, UK.
Posts: 799
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Re: Cutting Sponge
Hi Guys, "THE" tool for cutting foam rubber is an electric carving knife I've used one for years for this purpose and it's truly excellent, if you can't persuede SWMBO to part with hers, scour the boot sales there is always plenty about
Mike |
24th Sep 2006, 10:05 pm | #6 |
Heptode
Join Date: May 2004
Location: Ellington, Northumberland, UK.
Posts: 815
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Re: Cutting Sponge
I made my own tool from a block of aluminium for cutting the round battery pads for fitment to the inside of the back covers on Hackers, I place the foam on a block of wood, then just press on the tool by hand, picture of it here, but it's obviously no use for cutting square bits!
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John. |
24th Sep 2006, 10:11 pm | #7 |
Retired Dormant Member
Join Date: Dec 2003
Location: North London, UK.
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Re: Cutting Sponge
I've used an ordinary carving knife or bread knife to cut thick sponge. Don't know if it would work so well on thin or very low low density sponge. Maybe not as easy as an electric carving knife but I don't have one so I can't really say.
Many years ago I used wire from an old heater element to cut large sheets of expanded polystyrene. Wire was about 5' long with a handle on each end. Obviously a 2 person job. We used some kind of variable power supply to heat up the wire. Worked very well though the smell was horrible. |
25th Sep 2006, 8:37 am | #8 |
Dekatron
Join Date: Nov 2003
Location: Near Leeds, West Yorkshire, UK
Posts: 4,609
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Re: Cutting Sponge
There used to be a device with a hot wire that was mounted on a large 15.v cell - the ones used as a gas lighter (remember them?)
It did look a bit like a hacksaw frame.
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Mike. |
25th Sep 2006, 11:24 am | #9 |
Dekatron
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Location: Croydon, Surrey, UK.
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Re: Cutting Sponge
I'm sure I've seen something in B&Q that was designed for cutting polystyrene foam. It was in the shape of a soldering gun with a wire between the two poles and a large battery.
Maybe these no longer comply to the current safety laws! Rich.
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25th Sep 2006, 11:50 am | #10 | |
Hexode
Join Date: Mar 2003
Location: World Heritage Village of Saltaire, Shipley, West Riding of Yorkshire.
Posts: 324
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Re: Cutting Sponge
Quote:
Paul |
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25th Sep 2006, 4:41 pm | #11 |
Dekatron
Join Date: Nov 2003
Location: Near Leeds, West Yorkshire, UK
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Re: Cutting Sponge
That, of course, should have been 1.5 volt
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Mike. |
25th Sep 2006, 4:56 pm | #12 |
Dekatron
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Re: Cutting Sponge
The cuttter was used in aero-modeling, I had one when I was a youth many years ago. I hope this link is permitted http://cgi.ebay.co.uk/Polystyrene-Fo...QQcmdZViewItem. May not be hot enough for foam.
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23rd Oct 2006, 8:43 pm | #13 |
Pentode
Join Date: Aug 2005
Location: Hemel Hempstead, Hertfordshire, UK.
Posts: 154
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Re: Cutting Sponge
I've watched professional upholsterers cut foam, and they use a gadget like an electric meat carver. No fumes, and a clean edge. then they sand the profile with a rotary disk akin to the thing you would use to prepare a bit of rusty metal for priming. But maybe a bit finer?
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