Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

What is the most accurate way to cut 2 inch foam?

2133 views
33 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    December 2015
  • From: Shenandoah Valley
  • 7,654 posts
What is the most accurate way to cut 2 inch foam?
Posted by BigDaddy on Wednesday, December 23, 2020 5:51 PM

I was going to title it best just because I dislike "What is the best boxcar?" threads but the forum won't let me strike thru on the title.  Can't use quotes either.

My experience is with building two rectangular modules 2' wide and 5 and 7 feet long. I didn't know how deep to score the foam so (don't tell my wife) I used a big french chef's knife. Either my layout wasn't accurate enough or the snapping of the foam didn't happen exactly perpendicular, but I had areas

I am expanding the layout and I want to avoid foam extending beyond the bench work, that will require sanding to fit the fascia or back drop. I have sanded the previous modules and it is a holy mess, even if you simultaneously use a shopvac, particles of foam stick to the vacuum hose and to me.

The bench work is light enough that I can turn it upside down and trace it on the foam, or I have a craft paper 1:1 drawing of the layout that I could transfer to the foam.

I have a Hot Wire with the bow and the thing that looks like an ice pick. In my limited experience, I don't think either is stiff enough to cut a straight vertical cut.    At this point someone will demand to see a track plan. 

Here it is.   I thought I might leave the hard angles, my thought being it would be a quick and dirty job with the fascia, but am open to suggestion on doing otherwise.  I wasn't looking forward to taping seams and drywall mud, but a recent photo thread, hard angles on the backdrop look like vertical lines.

How do I cut the curves and the straight lines to have minimum touch up work?  You guys that think I should use homosote, spline, plywood or hockey pucks, I love you, but start your own thread.

 

Henry

COB Potomac & Northern

Shenandoah Valley

  • Member since
    March 2017
  • 4,830 posts
Posted by Track fiddler on Wednesday, December 23, 2020 6:08 PM

I have found the smoothest most accurate way to cut foam is a fine-tooth blade in a jigsaw Henry.

This was one inch foam but they do sell long jigsaw blades.

 

 

TF

  • Member since
    December 2009
  • 52 posts
Posted by Carolina Northern on Wednesday, December 23, 2020 6:10 PM

TF,

 

Those are beautiful looking cuts, but that must have made one heck of a mess of pink dust.

 

Don

  • Member since
    December 2009
  • 52 posts
Posted by Carolina Northern on Wednesday, December 23, 2020 6:14 PM

For the OP, I've been told that these do a really good job, but cannot tell you from experience. 

https://www.amazon.com/Festool-493656-Foam-cutting-Jigsaw-3-pack/dp/B0033LBOJY/ref=sr_1_22?dchild=1&keywords=foam+cutting+blade&qid=1608768662&sr=8-22

 

I'm a ways from the foam cutting stage on the current layout (past ones have used several different messy methods), but have a set on order. Always trying better ways to do things.

 

Don

  • Member since
    March 2017
  • 4,830 posts
Posted by Track fiddler on Wednesday, December 23, 2020 6:23 PM

Carolina Northern

TF,

 

Those are beautiful looking cuts, but that must have made one heck of a mess of pink dust.

 

Don

 

Nah, not really.  I live in a condo and cut it out in the living room with two saw horses.  Nothing too serious the vacuum cleaner didn't take care of.  But then again I'm not too scared of messes.  I've been making messes and cleaning them up all my lifeStick out tongue

 

The finer the better jigsaw blade you can get makes less mess than you think

 

 

TF

  • Member since
    January 2014
  • 1,286 posts
Posted by ROBERT PETRICK on Wednesday, December 23, 2020 6:23 PM

Band saw. Some "sawdust", but not as much as you might think. Still, a good idea to have an assistant stand by running a vacuum nozzle.

Robert 

LINK to SNSR Blog


  • Member since
    June 2020
  • 1,261 posts
Posted by Lastspikemike on Wednesday, December 23, 2020 8:53 PM

Woodland Scenics sells a foam knife which has a long blade Xacto style blade. 

This works well. Use a drawing cut like slicing bread.

Styrofoam may be "extruded" but it's pretty grainy in reality. Unless you draw the knife blade through as you cut you will break out lumps.

Hot wire works really well but freehanding a hot wire cutter is very difficult to do.

I got fairly good straight edges  using a steel rule, framers square or similar. A wooden straight edge also works because the Hotwire isn't all that hot.

The main challenge is holding the wire square to the edge if you want a straight 90 degree edge. I also use a long surform tool to square up a cut edge. 

Alyth Yard

Canada

  • Member since
    July 2007
  • From: Yorkton, Sk, Cnd
  • 441 posts
Posted by wvg_ca on Wednesday, December 23, 2020 9:43 PM

i made a hot wire cutter that would cut to a foot high, and maybe a foot deep.. it was on a laminate table that held 90 degrees quite well ... het adjustment was through a light bulb dimmer to a transformer ..

i got the nichrome wire off ebay and just spring ensioned it ... the guide was adjustable and / or  removeable ..

i cut all the foam needed fr a layout 15 feet by 16 feet, and up to 9 inches high, and it was glued together with dap alex plus clear adhesive caulking ..

ps.. NO dust !

  • Member since
    July 2006
  • From: 4610 Metre's North of the Fortyninth on the left coast of Canada
  • 7,223 posts
Posted by BATMAN on Wednesday, December 23, 2020 9:55 PM

I have glued foam on the benchwork leaving a little overhang and cut it off to shape with a pistol grip hacksaw that worked great. When I put the hardboard fascia on a little spray foam or tape or something else fills the cracks depending on the place and size of the crack.

Brent

It's not the age honey, it's the mileage.

  • Member since
    June 2020
  • 1,261 posts
Posted by Lastspikemike on Thursday, December 24, 2020 8:03 AM

wvg_ca

i made a hot wire cutter that would cut to a foot high, and maybe a foot deep.. it was on a laminate table that held 90 degrees quite well ... het adjustment was through a light bulb dimmer to a transformer ..

i got the nichrome wire off ebay and just spring ensioned it ... the guide was adjustable and / or  removeable ..

i cut all the foam needed fr a layout 15 feet by 16 feet, and up to 9 inches high, and it was glued together with dap alex plus clear adhesive caulking ..

ps.. NO dust !

 

Did you set up the wire like a band saw blade and move the foam through the stationary wire?

Alyth Yard

Canada

  • Member since
    July 2007
  • From: Yorkton, Sk, Cnd
  • 441 posts
Posted by wvg_ca on Thursday, December 24, 2020 8:42 AM

Lastspikemike

Did you set up the wire like a band saw blade and move the foam through the stationary wire?

yup, exactly ...

  • Member since
    December 2015
  • From: Shenandoah Valley
  • 7,654 posts
Posted by BigDaddy on Thursday, December 24, 2020 10:53 AM

Thanks for the ideas.  I wish I had a bandsaw, but don't.

Bosch makes a wavy edge blade for less than those Festoon blades and I recall a video of someon grinding the teeth off a blade to make a knive edge.  Knife edge jig saw blades used to come in the assortment packs, but don't anymore.

I also saw a video were a guy made a horizontal cutter with nichrome? wire so he could make thin pieces of foam for tunnel portals.

I'll give the fine tooth blade I have a try and see what kind of mess it creates.

Henry

COB Potomac & Northern

Shenandoah Valley

  • Member since
    March 2017
  • 4,830 posts
Posted by Track fiddler on Thursday, December 24, 2020 11:24 AM

Here ya go Henry

Hope this helps

 

 

TF

 

  • Member since
    July 2006
  • From: west coast
  • 5,756 posts
Posted by rrebell on Thursday, December 24, 2020 11:25 AM

I clamp a straight edge to the foam and hot wire it, if you put in the work, it can look like a factory cut if that is needed.

  • Member since
    June 2020
  • 1,261 posts
Posted by Lastspikemike on Thursday, December 24, 2020 2:01 PM

rrebell

I clamp a straight edge to the foam and hot wire it, if you put in the work, it can look like a factory cut if that is needed.

 

When I do this I notice it is easy to tilt the wire away from 90 degrees. You get a straight but beveled cut.

Ideally, you need a device to hold the wire frame at 90 degrees as well as a straight edge to guide the cut.

Setting up the hot wire at 90 degrees to a flat table and pushing the foam through would work better.  Freehanding a hot wire cutter is just not easy to do. 

I wonder if adding the guide from the bow and guide accessory pack would enable easier 90 degree cuts since it is intended to assist in making angled cuts.

Woodland Scenics video guide for the hot wire foam cutter illustrates how hard it is to make just a straight cut, let alone straight and square. 

Alyth Yard

Canada

  • Member since
    June 2020
  • 1,261 posts
Posted by Lastspikemike on Thursday, December 24, 2020 2:13 PM

For knife cuts there is a hot knife type foam cutter.

For non heated blades I would guess a thin serrated blade like a bread knife would work better than a chef's knife which is deliberately made with a spine making it wedge shaped. That would make for tough going trying to slice into foam. Foam is relatively incompressible  and a thick blade would tend to split and crack the foam rather than slice it.

A non-serrated blade should be thin like a slicing blade. These are thin, very sharp, round tipped blades designed for cutting ham and the like.

Styrofoam is surprisingly abrasive when cutting with a blade. Sharpen often. Don't use your wife's cooking blades. 

Teeth on the blade are not useful for cutting foam. That's what makes the foam crumbs that go everywhere. 

Alyth Yard

Canada

  • Member since
    May 2010
  • 7,430 posts
Posted by mbinsewi on Friday, December 25, 2020 9:16 AM

I've used the fine tooth saw blade, works fine, not that much of a mess.  I've also used a serrated knife for carving and shaping.  Also works great.  A little less mess than the saw blade.

Merry Christmas!

Mike.

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 19,557 posts
Posted by MisterBeasley on Friday, December 25, 2020 11:36 AM

Not terribly tidy or clean, but I used a drywall saw to cut a round hole for a turntable.  The edges were all hidden anyway.  Maybe it's not the right tool in this case, but if it's what you've got and you don't feel like going out, it's something to remember.

It takes an iron man to play with a toy iron horse. 

  • Member since
    March 2017
  • 4,830 posts
Posted by Track fiddler on Friday, December 25, 2020 12:04 PM

Respectfully speaking no matter what you do there's always a mess.  Even when you eat you have to do the dishes. 

Where did this big fuss and phobia come from about the static and mess from foam?  Does foam have radiation in it or something I don't know about?

It's never nothing a vacuum cleaner can't take care of.  When you cut the stuff with an ultra fine-tooth jigsaw blade you can barely even see the micro particles of pink dust in the carpet fibers or on the floor.  I've even cut the stuff on the kitchen counter as a work bench and probably had some in my sandwichLaugh

 

Please read and follow these simple directions:

Dish soap for the dishes - vacuum cleaner for the foam.  Lather-rinse-repeat.  Kids Don't Try This At Home!  Follow directions with adult supervision onlyLaughWhistling

 

I'm just hoping everyone can find some humor today, after all it is Christmas!

 

 

WinkTF

 

 

 

  • Member since
    December 2015
  • From: Shenandoah Valley
  • 7,654 posts
Posted by BigDaddy on Friday, December 25, 2020 5:47 PM

Track fiddler
Where did this big fuss and phobia come from about the static and mess from foam?

Experience.  If you sand foam outside, not only are you and the shop vac hose covered by small blue or pink particles, the grass and mulch is too.  And the later doesn't vacuum up easily.

It also give me flashbacks to my drywall hanging adventures. 

Henry

COB Potomac & Northern

Shenandoah Valley

  • Member since
    February 2001
  • From: Wyoming, where men are men, and sheep are nervous!
  • 2,592 posts
Posted by Pruitt on Friday, December 25, 2020 5:55 PM

I use a serrated knife to cut the foam. Not as neat as TrackFiddler's work by a long shot, but it does the job well enough, and any gaps or holes (and the occasional blob of foam does rip out) can be filled with Celluclay or Sculptamold during the scenery building process.

  • Member since
    March 2017
  • 4,830 posts
Posted by Track fiddler on Friday, December 25, 2020 6:33 PM

BigDaddy

Experience.  If you sand foam outside, not only are you and the shop vac hose covered by small blue or pink particles, the grass and mulch is too.  And the later doesn't vacuum up easily.

It also give me flashbacks to my drywall hanging adventures. 

 

Okay I got this Henry!

Never mind the grass and the mulch.  That can stay outside.

It's a wet-dry Shop-Vac isn't it?  Spray it off with the hose. 

Run inside quick.  Throw your clothes in the laundry Basket and your wife will wash them for you.

Jump in the shower as the same principle as the Shop-Vac, same after hanging or sanding drywall.

 

Lather rinse repeat.  Kids don't try this at home and only follow directions with adult supervisionStick out tongue

 

 

LaughI'm sorry but I just had to, ...TF

 

S.O.S.  You're probably right!  I've been working with pink foam for so many years I probably don't even sense that it is there anymore.  I hope it isn't toxic because I was cutting it on the kitchen counter again today before I made Christmas Dinner.

For all I know, ...Perhaps it is like pepper and ads a distinctive flavor to the foodLaughWhistlingWink

  • Member since
    July 2007
  • From: Yorkton, Sk, Cnd
  • 441 posts
Posted by wvg_ca on Friday, December 25, 2020 9:17 PM

freehanding the hot wire cutter is not really a problem at all... i just use two straight edges bedide each other ,     one on each side of the workpiece, that way i can wiggle the hot wire cutter and i still get 90 degress, as long as i run the wire against the guides , 

it takes longer to type this than making the actual cut, lol                                          

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 10,941 posts
Posted by SeeYou190 on Saturday, December 26, 2020 11:05 AM

BigDaddy
How do I cut the curves and the straight lines to have minimum touch up work?

Track fiddler
I have found the smoothest most accurate way to cut foam is a fine-tooth blade in a jigsaw Henry.

I went through a lot of foam with the girls making CosPlay props.

The method described by Track Fiddler is the best way we found. We used a drywall square clamped to the foam to guide the jigsaw for straight cuts. Use a fine tooth blade intended for metal cutting. I think the one we used most was 28 teeth per inch. Go slow so you do not melt the foam.

It makes less dust than you will expect. This was a welcome surprise. Do not have a ceiling fan turned on while you cut, and wear an N95 mask and safety GOGGLES!

We also used a detail sander to polish the cut foam, but there is no need to do this for model railroading purposes.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

  • Member since
    December 2015
  • From: Shenandoah Valley
  • 7,654 posts
Posted by BigDaddy on Saturday, December 26, 2020 11:30 AM

9 moving boxes later, my Hot Wire is still MIA, unless it at the very bottom of one of the boxes.  I found my electric kitchen knife but no cord and similar cords I have don't fit.

I guess it will be the jig saw. 

Henry

COB Potomac & Northern

Shenandoah Valley

  • Member since
    December 2015
  • From: Shenandoah Valley
  • 7,654 posts
Posted by BigDaddy on Sunday, December 27, 2020 5:32 PM

Found my Foam Factory Hot Wire.  The thing that looks like a skinny ice pick is of no use at all cutting 2" foam. 

The local foam has a half lap joint on the sides.  The ice pick bogs down and bends after about 6"  In retrospect I didn't need to trim this 1" half lap, but it proved it wouldn't cut 2" if it wouldn't do 1"

Henry

COB Potomac & Northern

Shenandoah Valley

  • Member since
    July 2007
  • From: Yorkton, Sk, Cnd
  • 441 posts
Posted by wvg_ca on Sunday, December 27, 2020 9:46 PM

BigDaddy

Found my Foam Factory Hot Wire.  The thing that looks like a skinny ice pick is of no use at all cutting 2" foam. The ice pick bogs down and bends after about 6"  In retrospect I didn't need to trim this 1" half lap, but it proved it wouldn't cut 2" if it wouldn't do 1"

 

can you turn up the heat a little, or is it preset ??

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 10,941 posts
Posted by SeeYou190 on Sunday, December 27, 2020 10:38 PM

BigDaddy
Found my Foam Factory Hot Wire.  The thing that looks like a skinny ice pick is of no use at all cutting 2" foam. 

My youngest daughter "stole" my Hot Wire Foam Factory when she moved out.

I bought a foam knife on Amazon from China, but I seriously doubt it would cut 2 inch foam any better. It was a lot less expensive.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

  • Member since
    February 2002
  • From: Reading, PA
  • 29,455 posts
Posted by rrinker on Monday, December 28, 2020 2:22 PM

 For cutting the long way for my previous layouts (I had sections less than 2' wide), I used a long straightedge to hold a straight line, and I used a large putty knofe (like a 6" one) that I sharpened on one side and corner to score the foam. Multiple passes, not pressing hard, so I could follow the straight edge, until it was almost through along the entire length, then it snapped off cleanly. No foam dust - which was important, since I was working inside, in an apartment.

                                     --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    June 2020
  • 1,261 posts
Posted by Lastspikemike on Monday, December 28, 2020 2:34 PM

Score and snap works well, no bits. 

Alyth Yard

Canada

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!