Best saw to cut blue foam

[NevinW]

I would like to cut some blue foam to be used as benchwork. I would like to cut it and get a sharp straight smooth edge with 90 degree angle. Would a jig saw with a fine blade work? I have always used a sabre saw in the past, fast but messy and not with the clean edge I desire. Opinons? - Nevin

[ARTHILL]

Score it, break it, smooth it with a sureform rasp.

Table saw will give the edge, and a first class mess.

Band saw will work but only the width of the throat.

I could never get a smooth edge with the hot knife.

Let us know what you learn

 

[SpaceMouse]

I use a drywall saw. I find I can cut about any shape I need--even the straight line. I don't cut faom indoors no matter what--well maybe a little after it's glued and I want a better shape. Mostly I don't bring it in until after I have shaped it and covered it in a layer of drywall mud.

[loathar]

I use those cheap box cutters with the long retractable blades. Any kind of saw is going to make a mess that you'll be finding pieces of years down the road.

[JON168]

 Only saw I can think of that won't make a huge mess and might give you a smooth edge is a coping saw. I use a razor knife, works good on the thin sheets of foam,  never tried it on the thick ones.

[Anonymous]

A knife is best. No dust and smooth cut. None of the razor blade knifes have long enough blades. I used a good pocket and sharpened it frequently.

As for saws. A small hobby saw and a keyhole saw is what I use when I need them. They make rough cuts and leave a lot of sawdust, but do work.

[Lillen]

I use those cheap box cutters with the long retractable blades. Any kind of saw is going to make a mess that you'll be finding pieces of years down the road.

 

This is exactly what I use, you can even cut the white stuff and get it smooth.

When I do large chunks I sometimes just use a regular saw.

 

Magnus

[tomikawaTT]

The Japanese pull-saw I use has a very thin blade and small crosscut teeth that cut clean and make a minimum of mess, whether the foam be blue, pink or white.  The downside is, it was a gift from my sister-in-law in Osaka; I don't have the faintest idea where I could find an equivalent in North America.

Chuck (modeling Central Japan in September, 1964 - with Japanese hand tools) 

[Bob W]

Here is a link to the pull saws.

http://www.garrettwade.com/jump.jsp?itemID=102120&itemType=PRODUCT

 

[jktrains]

For a long, straight edge use a table saw, radial arm saw or a circular saw with a cutting fence.  Will it make a mess - yes, a lot less than homasote though.  Just have someone follow you with a shopvac.  The saw will give you a good smooth edge with a straight edge and a 90 deg square edge.

Almost any power tool you use for woodworking can be used with foam.  Saws, router etc.  If you need sand the edge use drywall sanding screen for a nice smooth finish.

 

[jbinkley60]

An electric knife, like you cut turkeys with, will work well too.   It makes a nice clean cut.

 

[nof]

I use a hot wire. I built a "table saw" with a hot wire instead of a saw. I have used it for cutting both big and small pieces of foam. You can see a picture at my webpage.

[dgraham]

I tried a hacksaw blade, hot wire, box knife etc. but had the best results with a sharp pocket knife.

[selector]

I have used several items, but for getting a clean straight cut, if you use a straightedge to make sure it really is straight, the cleanest and quickest is with the utility knife or carpet cutter style you get for peanuts at the hardware store...the ones with the replaceable and snap-off sectional blades that retract or fold...you know the kind.  Align the straightedge, place blade deep into the foam, swipe in a controlled way, and then snap the rest of the way through by bending the foam.  Change the blade when you begin to generate feathering on the edges and the blade won't swipe cleanly any more.  Happens sooner than later.

[Bill54]

I'm with loather, lillan & selector, 

I use either my pocket knife which has a very thin, sharp blade or one of the cheap utility knives that have break off sections every 1/4".  It will extend about 3" or more.  I place either a 4' or 6' straight edge, gently clamped down to hold it in place then cut the foam with the utility knife. 

It usually makes a perfect 90 degree angle and is straight. 

I have also cut curves using a plywood template and carefully cut the circle with my pocket knife.

Bill

[selector]

While we are at it, the blade should be held at a relatively shallow angle to the foam surface.  That means 45 deg or less.  That way, the blade slices as opposed to trying to merely separate the foam.  Come to think of it, I usually do a slow sawing action to help this slicing process, but being careful to keep the blade angled low.  When I lift the blade and try to speed things up, that is when I get more feathered and torn edges.  I'm pretty sure the others have found that as well.

Later, for generating curved surfaces, such as slopes and gulleys or reentrants, a wire brush does a quick and rough job, but it is very messy.  For a finer finish, sand paper or a surform file.

[LD357]

 I was helping out a buddy today and needed to cut some blue foam, I didn't have the long blade razor knife I usually use, and I was looking for something suitable and got my Fiskars filet knife out of the tackle box....it worked great!  its thin ,sharp and the blade will bend a bit.....I used it to cut a beveled edge on the foam and it made a nice clean cut.  Not what the manufacturers intended for their knife to be used for,  but if it works....why not!?

[johncolley]

I have no trouble getting a good foamboard edge with several passes of a serrated bread knife against a metal straightedge. I have also had good results in scenery with foamboard. Like any new medium there is a learning curve, so practice a few cuts on scrap.                                jc5729 John Colley, Port Townsend, WA

[jktrains]

I guess the first question is how thick is the foam?  1", 2" ???  The problem you can run into using a any kind of knife to cut the 2" foam is that it will want to bend and flex.  You'll be left with a straight on top were the straight edge was but a wavey edge in the middle.  I've built foam topped modules for 6 years and the best way to cut foam for benchwork of with a table saw or radial arm saw.  Sure, you'll create a small mess but it can be minimized by point the nozzle of the shopvac right were the saw cuts.  You'll get a nice straight edge that is square to the top.

jktrains

[jbinkley60]

Don't dismiss my suggestion of an electric carving knife.  They are cheap, don't make a mess and make a clean cut. I was surprised how well they work.  I've cut 2" and thicker foam with no problem.

 

[AZdivider]

I use a hacksaw blade (32tpi), Just the blade without the frame, when necessary to saw. For most cuts and shaping I use a Swiss Army knife that I keep VERY SHARP. When using a saw to cut, rub off the loose stuff with your palm before getting it test-fit on the layout. And keep a good strong vacuum close for the massive amount of blue dust.

Roger Eyrich 

[steamnut]

I use a knife blade in my jigsaw. This is a blade with no teeth, just a moderately sharp knife edge. These are easy to find at good hardware stores although the "big box" ones don't always carry them. It makes a very clean cut with NO mess and NO fumes. Goes through the stuff like the proverbial hot knife through butter. Doesn't seem to wear out from cutting foam (that's all I've used it for); I've had this blade for over ten years and it cuts foam just as well as the day I bought it.