Hot-Wire Foam Cutting Technique

hotwire power unit for foam cutting

Hotwire Power Supply Ready To GO

People use foam to create all kinds of arts and crafts projects. Homecoming floats, replica sculptures and even building facades are made with foam. I use foam to build radio controlled airplanes. It can be a messy job cutting foam so I want to share a great technique called “HotWire” which cuts foam without making you look like the abominable snowman!

The principle is to use a very fine wire like a thin “E” guitar string and run a low electrical current through the wire.  The current heats the wire hot enough to cut through foam like a hot knife through butter.  I cut foam wing cores and formersections of the fuselage of my DC-3 project as well as the P-47D Thunderbolt. Using templates (pre-cut shapes) that I made.

hotwire bow made of pvc

PVC bow and stainless steel wire.  Use Formica or balsa templates to cut smooth, precise pieces of foam.

I did some research online and discovered it was pretty easy to make your own!  Better yet, there were step by step building instructions.  I even found a great 2 part video that I used to help put mine together.  Crash Hancock (Build Your Own Hot-Wire Power Supply) is the author of these step by step instruction videos.  The first video discusses all of the parts necessary to build it.  The second video goes into putting it all together.  There is a complete parts  list available at his YouTube video page under the description of the video.

 

Part 1

Part 2

 

PVC Speaker Wire and a nut and bolt

With the PVC bow assembled, it can be plugged in using these banana clips to the power supply.

Crash does a great job explaining how to make a hotwire cutter.  This technique can be used to help you make foam cores for wings and even fuselage parts from templates.  Whatever your favorite model scratch building techniques are, a hotwire is the tool of choice when foam is involved.  For more details of how to make your own homemade hotwire foam cutting bow, watch the videow Crash Hancock made OR see the links below.

How to build your own Hotwire Foam Cutting Wire

Foam Cutter Power Supply

Here is an example of a part that is cut using a hotwire.  I used card-stock type paper as the templates.  The hotwire could then simply follow the teplate and cut an extreemly precise part as seen here.  Once quick tip…  The cut will only be as good as the template you provide.  Make sure your tempates are smooth and strong enough for the wire to follow.

HotWire Bow made from PVC

Here is a pic of the fully assembled bow. This is a 36″ wide bow, ready to cut wing cores.

templates and foam cut with a hotwire

Finished cut part with the template still attache

3-View Drawings for the DC-3 Project
Douglas DC-3 Retractable Landing Gear
2016-10-15T19:48:00+00:00

2 Comments

  1. Steve Haynes March 19, 2014 at 4:33 pm

    Hi Mike –

    Just ran across your site today after getting an out of the blue thought to search for info on the DC-3 for my Aircraft library.

    Comment #1, I very much appreciate that right at the top of your site you share that you are a believer in Christ Jesus and have a group following reading thru the Bible in 90 days. Having read thru the bible 3-4 times since being reborn in 1990, I have a great appreciation for Bible study and how God blesses with his Holy Spirit thru a dedicated study filled with prayer. So, God bless you for leading this effort.

    #2, it’s a blessing to potentially connect with other Christians in the sport of R/C Airplanes and in general. I’ve met a lot of Good men in the past 29 years, but few Godly men, and have always enjoyed the mentoring process whether giving or receiving. As a worship leader with Calvary Chapel San Mateo CA, have wondered about being part of a Christ centered group, or attempting to start one.

    #3, one big yet simple question about the foam you use, it looks like the very dense (not beaded Styrofoam) “carvable” type of foam material that I have had problems finding for modeling. In my profession of Medical Imaging Design & Manufacturing I have seen a blue colored dens carvable type of foam used in Radiation Therapy “Block Cutting” which is also done by a “hot Wire” device.

    So what is the material called by, and where do you get it?

    God bless Mike, It’s good to meet you.

    Steve Haynes – Alameda CA.

  2. Mike March 21, 2014 at 8:34 pm

    Hi Steve,

    Thank you for your comments. Yes, my purpose for this website is to share my experiences and interests. As you can see one of them is My Christian faith. So, I purposely mix my content so visitors can land on my site, find the article they are searching for and then indirectly be exposed to the Gospel through other articles that appear along the “recent posts” sidebar or in my navigation.

    I believe that there is a group (although I have not perused it) called Fellowship of Christian Modelers that you may want to learn about. let me know if you want to talk more about this.

    Now to your question about the foam I use. If you go to a place like Home Depot, take a look at the rigid foam insulation board they have. Specifically, take a look at this stuff. It is strong and dense while lightweight. At 2 inches thick, this stuff is great for hotwire and shaping with a sanding block. Don’t go to aggressive with the sand paper or you will chunk it.

    Thanks again for your kind comments and for taking time to check out my site.

    God Bless.

    Mike

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