the MRH Forum

Foam Cutting - Soldering Gun Tips Scenery and structures
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Regular poster 438 posts GT Mills Regular poster 438 posts
GT Mills

Read somewhere that wire coat hangers work great to make foam cutting wire loops and shapes to use with a trigger soldering gun if you remove the outer layer of coating and paint.  Tain't so.  Don't ever waste your time.  Or your wire coat hangers.  Save them for when you lock your keys in your truck. 

What DOES work is solid COPPER 12 AWG ground wire, or stripped primary conductor.  I haven't found the maximum length loop yet, but it is much longer than 10", which is the first loop I made and which actually gets so hot I find the need to cool cycle it by releasing the trigger, and only using the trigger on the low stage. 

Next, I read that installing track directly on the extruded foam base is much noisier than using standard roadbed.  I have a decibel meter app on my iPhone downloaded a while back for testing how loud my Yamaha aircraft conversion engines are with various mufflers installed, and tested a single car rolling on a section of track laid on Woodland Scenics foam roadbed atop of the 2" extruded foam base, and track laid directly on bare extruded foam.  The roadbed read 72 dB, the bare foam was 74-75 dB.  Meh.

Conclusion: can hardly tell the difference in noise, so I be will laying most of my track directly on the foam, and using the hot wire loop bent in the proper shapes to cut away the "raised" roadbed and drainage ditch profiles. 

 

 

Greg

Grew up next to the Flint & Pere Marquette RR tracks originally laid 1871 through Northville, Michigan

 

 
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NCR-Boomer Frequent poster 509 posts
NCR-Boomer

Thanks for the tip

I'd seen something like that for the "foam flyers" back in the day, guess I'll try the 12 AWG in my Weller gun for spot work on the foam scenery sections where a hot wire cutter can't get in there.

Track and roadbed on foam board is problematic.  My experience with it is in two different directions: a test layout on a 4x6 sheet of 1" green, and with 1" and 2" green backed by 5mm underlayment in Free-mo modules of varying sizes, 26"x5' being the most common.  The two are dramatically different.  The 4x6 test loop is literally a drumhead, and even with cork roadbed, is so loud that I can hear a GP9 cruising along in the attic on this loop when I'm downstairs, with the intervening doors shut.  The Free-mo modules, it's more of the "wheels on rails" noise you're accustomed  to, with a much reduced background level from the structure.  With my permanent layout, I've gone with sheet foam, with 5mm ply bonded to the underside for noise dampening and an attachment layer for switch servos.  So far during the buildup phase, I'm happy enough with the noise levels I've elicited, by laying loose track on sections, and rolling box cars along the rails. 

Hot Wire Foam Factory has a free-form cutter that uses a ribbon-shaped wire.  Given what you've seen with 12 AWG in the soldering gun, I'll abandon any attempt to use that ribbon with the gun.  It sounds like the ribbon will pop like an old-style fuse element.

Cheers!

Tim B.
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ctxmf74 Super User 15,959 posts
ctxmf74

cutting with hot wire

   The thinner the wire the less smoke and smell it makes so I try to cut everything with a thin nichrome wire. The wire temperature also affects the amount of melted foam smoke. One can get cleaner cuts by adjusting the temperature to just hot enough to cut cleanly but not red hot so it melts excess foam. I power my nichrome wire cutter with an old MRC DC power pack so I can get a fine heat adjustment.When the wire temperature is ideal one can tell by the sound the wire makes while ripping thru the foam....DaveB

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Jon898 New member 23 posts
Jon898

Noise on Bare Foam

Remember that 75dB is twice as loud as 72dB due to the nature of logarithmic scales...so not really so "Meh".

Jon
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