Author Topic: shaping upholstery foam  (Read 4187 times)

Offline AlanT

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shaping upholstery foam
« on: March 13, 2015, 12:35:51 PM »
I needed two pads to get a better finish on a leather car-seat:
https://www.flickr.com/gp/90670218@N04/3Z1hY2

They are shaped like this:
https://www.flickr.com/gp/90670218@N04/y321u5

This stuff can be easily cut with a scalpel but getting a smooth round shape is hard with a blade.

Strangely you do it with a steel angle-grinder. Use a gentle touch and mind your fingers!
https://www.flickr.com/gp/90670218@N04/6C2gy3

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Offline petertheterrible

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Re: shaping upholstery foam
« Reply #1 on: March 13, 2015, 12:54:34 PM »
Probably the most useful tool in any toolbox.

There are commercial available blades that do that sort of work, they look like panel shrinking blades.

My personal favorite is the hot wire method, thanks for sharing.

Ever tried cutting a perfect circle in about anything with a baby grinder, works perfectly, no add-ons needed.
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Offline vtsteam

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Re: shaping upholstery foam
« Reply #2 on: March 13, 2015, 01:16:28 PM »
One more possible method -- I remember someone saying a few decades ago that they used an electric carving knife to cut through sponge material, like mattresses.
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Offline Sid_Vicious

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Re: shaping upholstery foam
« Reply #3 on: March 13, 2015, 02:36:33 PM »
I have used sandpaper on the grinder with good results.
Nothing is impossible, it just take more time to figure out.

Offline Arbalist

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Re: shaping upholstery foam
« Reply #4 on: March 13, 2015, 02:37:20 PM »
One more possible method -- I remember someone saying a few decades ago that they used an electric carving knife to cut through sponge material, like mattresses.

Yes I've used that method. Another is a smooth bladed band saw.

Offline steampunkpete

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Re: shaping upholstery foam
« Reply #5 on: March 13, 2015, 02:38:26 PM »
On a few occasions we machined rubber for certain strange applications (no, not what you're thinking) but putting it in the freezer overnight. I wonder if that would work, or help, with foam materiel?  :scratch:

Offline petertheterrible

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Re: shaping upholstery foam
« Reply #6 on: March 13, 2015, 04:09:03 PM »
I believe it depends on the type of foam, with some high density foams freezing them would make them a breeze to machine.  (Especially the types made from soy-bean would stiffen when friezed).

I am skeptical if it would work on the foam commonly used in the upper parts of auto seats.
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Offline petertheterrible

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Re: shaping upholstery foam
« Reply #7 on: March 13, 2015, 04:18:40 PM »
Problem solved, soak in water, then freeze and machine very quickly after freezing.

Beware, very messy!
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Offline AlanT

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Re: shaping upholstery foam
« Reply #8 on: March 13, 2015, 05:50:14 PM »
Thanks for all the replies chaps.

The carving knife method is good for big straight cuts but you really want a double-blade type.

I'd never done upholstery before and had to work out a whole load of new tricks.

Offline hopefuldave

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Re: shaping upholstery foam
« Reply #9 on: March 13, 2015, 08:49:05 PM »
For sculpting motorbike seat foam (I suffer from Jack Russel syndrome - long body, short legs) I've always used a router motor with a 150 grit abrasive flap wheel, leaves a nice smooth flat finish.
Wear goggles and a good dust mask though, first time I felt like I had Something Serious for about 3 days afterwards...
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Offline millwright

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Re: shaping upholstery foam
« Reply #10 on: March 17, 2015, 04:48:01 PM »
Electric carving Knife worked very well for me for cutting upholstery foam, and cuts tight radii or circles.

John