Which tool to cut seat foam ?

[WR250F]

I am doing a little upholstery work over the next week or two. Part of this will involve re-covering seats. I think since I will have it all torn down, I might as well replace seat foam while I'm doing this.

I have located the foam I want to use, but will need to cut it to fit, and probably require a little shaping/cleanup for the proper fit.

I just realized I don't have a clue how to properly and cleanly cut foam other than using a razor knife, which is slow as molasses.

I see a tool called a hot knife, but it appears to be used primarily for shaping styrofoam. I see what is termed a hot wire cutter, which looks somewhat like a coping saw that uses electric current through a strand of wire to cut the foam.

Being completely inexperienced in the nuances of proper foam cutting, I'm hoping some of you can lend your experience and suggest the right tool to use. This tool will see a lot of use on this project, but after this is complete, I probably won't have any use for it in the foreseeable future.

The foam is roughly 1½" thick, closed cell. I'd really like to make some clean cuts and not have a bunch of frayed, hacked up edges.

Suggestions ?

 

[rockwithjason]

an electric carving knife seems to be the preferred tool.

http://www.amazon.com/dp/B00004X12T/?tag=atomicindus08-20

 

[Cashed]

Electric turkey cutter.

 

[cotjocky]

And a Stanely Surform Shaver.

 

[Outlawmws]

And a Stanely Surform Shaver.

Good for Styrofoam not seat foam...

The electric knife works well, but if it is a thinner covering piece, (say under an inch) large (sharp) scissors also work well.

Do a couple of practice cuts with the Electric knife before committing to the final cuts, it does take a little practice to finesse it.

Also a vertical band saw does well on closed cell, but is again, a bit tricky to keep straight, ( a guide is probably a good idea)

 

[Givl Reggin]

And a Stanely Surform Shaver.

I think you're thinking of the hard type Styrofoam - on foam rubber that shaver won't do squat.

Another method is to squeeze the foam between two wood boards and use a butcher knife run along the edge of the board - a couple of light passes and you'll get a rather clean cut.

Most places that sell seat foam will cut and shape it for you too.

 

[G1GRANDEUR]

Hot wire.

 

[Prime320]

Dirtbike seatfoam?

 

[Walterchang]

Turkey carver, get an ac powered one. Band saw works awesome. Hot wire is good, but hard to use plus it smells, I have never used a hot knife. I cut a lot of foam for work. I have found the electric knife to work the best plus it doesnt not stink.

 

[A_Pmech]

For rough cutting, a waffled razor blade in a band saw works perfectly.

For fairing seat foam after rough cutting, the model makers I know use an angle grinder and flap wheel.

 

[up_in_the_air]

http://www.boschtools.com/Products/Tools/Pages/ItemResults.aspx?catid=1015

 

[vintagefan]

Turkey carver for rough cutting, a very high quality bread knife like this for fine cutting:

http://www.amazon.com/dp/B0019WZ7EW/?tag=atomicindus08-20




I remember an upholstrey shop I used to use had a few different bread knifes that had the blades chopped off to different lengths, like one full size, one 6", and one 4" with the top ground down to a reverse drop point (I think that's called a wharncliffe point).

 

[Auto trimmer]

do not use hot wire. turkey carving knife is best for foam. before you cut, make a small cut in foam first with shears or razorblade. this will make a smooth cut. also spray with silicon on blades for smoother cut. also band saw will work. instead of paying 500 to 600 for bosch. look up accucutter. half the price and just as good. Autotrimmer

 

[barcalo]

I have no personal knowledge of first hand use but I have always heard electric knife and also serrated bread knife if it is thin enough.

 

[Stuart in MN]

I have one of those serrated knives they sell on TV that will cut tin cans and tomatos (I think it's a 'Bionic Knife', I won it as a door prize somewhere years ago) and it works pretty well for cutting foam.

 

[jjjrmx5]

I have access to an industrial Eastman foam and fabric cutter that is a regualr in the garment industry. YOu can get them under $1000 and it looks like a big router but acts like a jigsaw with with a teflon coated 9" long VERY sharp and smooth (no teeth) verticle recipricating blade .

Since you want single use, I;d go the electric turkey carving knife route, but you might want to check with a local sewing shop to see if they carry the Eastman blades. With a quick mod. they will fit in a file or countersink wood handle and act like a really really sharp thin flexi knife (they do cut kevlar, so that gives you some idea as to how sharp).

I keep several modded blades around to do seat foam, black closed cell foam and really any foam work where a knife and a metal straight edge is needed.

I can get the blade part no;s you need if you got that route.

 

[GirlnAgarage]

I used the turkey carving knife when I worked on my motorcycle seats. I used IIRC sanding sponges to blend any lines. They couldn't be seen under the seatcover.

 

[cotjocky]

Good for Styrofoam not seat foam...

The electric knife works well, but if it is a thinner covering piece, (say under an inch) large (sharp) scissors also work well.

Do a couple of practice cuts with the Electric knife before committing to the final cuts, it does take a little practice to finesse it.

Also a vertical band saw does well on closed cell, but is again, a bit tricky to keep straight, ( a guide is probably a good idea)

I think you're thinking of the hard type Styrofoam - on foam rubber that shaver won't do squat.

Another method is to squeeze the foam between two wood boards and use a butcher knife run along the edge of the board - a couple of light passes and you'll get a rather clean cut.

Most places that sell seat foam will cut and shape it for you too.

A shaver is good for small shaping. I'm not recommending it over the electric knife, I'm saying in addition to it. Most people who are inexperienced are going to have snags and bad cuts/shaping.

A flap wheel or a DA will remove foam fast making it hard for the inexperienced to get a good shape.

A rasp like the Stanley Surform is a good tool that won't get you in trouble as quickly as a electric knife or DA/Flap wheel will.

Example of it's use:

http://knoplace.com/Gel_Pad_Installation.html

Here is a guy using a glue can lid with holes punched in it for shaping. More or less a homemade rasp. He uses it about 4 minutes into the video.

Most all seats have rounded edges and contoured shapes. A electric knife can only get you the rough shape. The finish shape has to be formed with something such as a rasp, flap wheel, DA, hand sanding, etc...

 

[kippieland]

Like the other guy, I am not sure if you are doing a bike seat. But if you are, I found this:

http://forums.dirtrider.com/70/8209635/dirt-bike-modifications/seat-shave-101/index.html

 

[GirlnAgarage]

On the stapler, use a heavy duty stapler to reattach the upholstery to the pan. That plastic pan is very tough so a wimpy stapler won't get the staple all the way through without enough power. Also, use staples that are not real long. You don't want the business end of the staple protruding from the pan as when you put your weight/legs on the seat the foam will get pressed down and you'll cut yourself on the staples.

 

[junk4dummies]

You all have missed the tool made for cutting foam.
Yes, a 2 bladed carving knife works but it does not have a flat bottom guide to run on a flat table. Doing it by had will not give you a good clean square 90 degree cut.

Bosh makes a foam cutting tool It is about $300. I got mine at the swap meet for $40. It has 2 blades. It has a nice square base the blades fit into and you can slide it along on a flat table as you cut the foam. It makes a perfect cut. You do not need to hold the whole sheet of foam and strugle with the piece you are cutting off. The electric carving knife works but there is a huge difference.

 

[jjjrmx5]

I don;t think anyone missed anything as the Bosch unit was mentioned on page 1, but outlaying $300 for a tool you'll use once to cut half a dozen to 12 pieces of seat foam is not my idea of good fiscal sense.

Before I;d do that I;d buy the foam, make dwgs showing sizes needed and haul it down to the local auto upholstery shop to cut.

$30 later you get all your cuts done by a pro machine.

Seat foam seldom needs to be trulely sq. unless extremely thick as by the time it is suffed and stiched/rolled, the sides are not truley 90 degrees in auto, boat, etc seat applications.

Electric knife will get you pro results if not doing a large production run and I;ve seen and done it first hand. No need to overthink this simple problem.

.

 

[Auto trimmer]

my suggestion is to ask your local supplier of trim supplies, if they have a foam saw. purchasing a bosch foam saw for this need is LOCO. a turkey cutter and large knife is my suggestion.

 

[Omphaloskeptic]

Just a suggestion - have you tried getting a price on the job from an upholstery shop? You might be pleasantly surprised with the cost. They have all the tools and you are pretty much guaranteed a professional result. You can buy the hand tools to do the job yourself, buy an electric carving knife from Goodwill, Salvation Army, etc., etc., and suffer the learning curve. It can be done well by the DIY'er, or you can let the pros do it and save yourself the cost of tools, materials, time and aggravation.

 

[WR250F]

The project at hand is recovering/repair of a set of buckets going in a old Chevy truck.

I picked up an electric knife and practiced a bit on some scrap foam.

It works, and works well, but like anything it is an acquired skill. The biggest problem is getting fine control on the tip in tight turns. I hacked up the test foam pretty good, but got some idea of what to expect.

I am going to use scrap foam to make a few template pieces to make sure I have an idea how much/what size is needed for a proper fit with anchoring.

Just to see if it would work, I tried a jig saw with a thin, fine tooth blade. It actually works better than I expected. This is practical when doing longer cuts, or where a tight radius is encountered, but for trimming and ripping (planing ?), the electric knife is far better.

I used a stainless rule as a fence and it really helps in keeping the knife perpendicular and the cut straight. Doing any cuts freehand makes me realize my lack of fine motor skills and experience.

I welded up the frames with a little reinforcement, and got the anchor holes and support figured out, d&t the holes and got all the hardware necessary to anchor the seat belts and servos.

I'm wondering if there is a better way to make a plunge cut and gain some fine control.

Do any of you think a roto-zip or something similar with a really thin blade might be usable with foam ? I need to cut a couple of areas around the hinge that must fit well. The foam will shred and tear if too tight, and look/fit like **** if it isn't snug.

 

[Auto trimmer]

if you set on a foam cutter at a lower price. there is a tool called EZE cutter. it is the same concept as bosch, but at a lower price. 148.00 it's meant for shops that cut only 10 to 15 foams a week. only has single blade. smaller motor. perfect for what your doing. also use silicon for blades.

 

[HubbaBubba]

I use a bread knife.

 

[kyrbz]

I use a rubber knife for straight cuts. They're a really handy item to have in the shop. There are also foam cutting blades available for jigsaws.

http://store.harryepstein.com/cp/Knives/6SQRU.html

 

[GreyOwl]

In my shop, I have always used an old angel food cake knife to cut all my foam. They are about a foot long and have real fine teeth like a hack saw blade but finer still. My original lasted about 30 years and I just picked up a couple more at the thrift store for a buck each. To get a smoother surface, I use my DA with medium grit paper on it. That part takes a light touch or you go too deep and have to add more foam.

 

[2mJps]

I use a battery charger 2 nails a length of wire and a board it works great. You can get foam on trash day on side walks. Hot wire is unbeliveable.