Cutting Memory foam for camera backpack

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prfcdoc

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I've always had a back pack with foam for carrying my camera equipment but the foam was always shedding and I decided, when we got a new mattress topper, to cut the old one into my camera protection for my pack. Has anyone ever cut Memory Foam? How do you do it? I've tried a serrated knife, an ultra sharp kitchen knife and scissors. None of them make very smooth cutting. The scissors might be the best but are very hard to use, especially in the cutouts.
Bob
 

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Tom

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An electric bread carving knife works fine. For really thick foam, you might need one with a longer blade.
 

Larry N.

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Have you tried a utility knife (box cutter, etc.)? That's what I usually use, though the foam I cut isn't memory foam, just electronic packing foam, or the same stuff you get in a pre-made case for electronics. It does take several passes to get a smooth cut and get to the right depth for the cutouts for holding gear. I actually have both the large utility knife which works for so many things, and also a very small pocket size one that improves accuracy for the depth and final shaping. Of course both do best with a new blade.

Or perhaps a razor blade...???
 

prfcdoc

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It's 3 inches thick and I don't have an electric carving knife. Had one 30 or 40 years ago but it must have died from boredom. Didn't see it when we downsized a couple of years ago.
I'll ask a few friends. Don't suppose I could rent one? Maybe at a party rental place.
Bob
 

Pugapooh

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If you are near a Goodwill you might find one cheap.  Otherwise,a serrated knife pulled rather than a sawing motion seems to work ok. 

Tom,I knew what you meant but was trying to clarify.
 

Tom

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If you are near a Goodwill you might find one cheap.  Otherwise,a serrated knife pulled rather than a sawing motion seems to work ok.

Both good suggestions. 

Tom,I knew what you meant

Me too, but sometimes my fingers don't type what my brain is saying ;D

but was trying to clarify.

Thanks!
 

hedhunter9

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Northern Indiana
Build your own 12volt electric hot wire cutting tool to melt it like butter...  I dont have one now, But I built one 5 years ago to cut a ton of
foam sheets we put in our pole barn walls..  Faster and no mess... You can google it..

Bob
 

prfcdoc

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I put a piece of regular foam in the bottom of the pack to protect my back from the camera parts. I poked a hole with the serrated knife, cut the foam with scissors. It's much like cutting human tissue, fat or, more accurately, fascia. Tougher than fat but similar due to the lack of planes to dissect. It came out ok. I gave up on the electric carving knife due to the time and complexity of obtaining it. The electric hot wire is a good idea. Since I have a king size memory foam topper to cut up I can try that as well in my spare time.
Bob
 

Punomatic

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Tom said:
An electric bread carving knife works fine. For really thick foam, you might need one with a longer blade.
X2 I found one at a thrift store. They work great for cutting foam.
 

simonhard

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Probably most often in connection with memory foam mattresses. If you are skeptical about the properties of viscoelastic foam, read some of the truths and myths circulating about this innovative material. And when I go somewhere on trips with a big backpack from Compare Drawstring Backpack Specs & Features | Backpacks Global, I also fit the memory foam there. I usually sleep on this because I have back pain, but I don't feel anything with this foam, and my body seems to float when I sleep. Do you sleep on a simple mattress?
 

NSRV

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Maybe try a box cutter if a electric carving knife is out of the question. You'll have to be steady and take your time, just cut little by little until you've achieved your shape. Don't press down too hard, let the blade do the work, by doing many incisions in the foam to get deeper as you go.

I've got a carving blade set that has multiple style blades with a scalpel-type handle that I've used to cut foam, gaskets, wire insulation and various other things. Definitely want something razor-sharp. Scissors or serrated knives will only make it harder to cut, I'd imagine, due to the nature of memory foam.

Memory foam is a good foam, but if you want something easier to cut you may have to look into a more rigid foam.

P.S. maybe a wire saw? Might take two people to do this, (one to hold the foam the other to work the saw), but if you can bore a hole thru the foam and stick the wire saw thru there, it may make cutting easy and quick.
 
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