KC10Chief

I am wanting to cut out some foam wing cores. What exactly will I need to make a cutter. I'd like to have it at LEAST 48" wide. 55" would be better. What kind of wire would I need? What do you use for a bow? What exactly do I use to heat it? I'd prefer not to use electricity. Something like a car battery would be better for me. Thanks for any info! If anybody has pictures of their cutters, please post them! Thanks! Matt

Balsageek

Matt,
Earlier this year I had the same delimma. Couldn't find any good plans or anything for cutters. I just had to take bits and pieces from what others had told me and I experimented until I got things to where they worked. Here's what I found:

First: DO NOT USE NICROME WIRE!!! It gets hotter with less power but it stretches way too much for a 55" run!!! It would sag in the middle and make a terrible core. It also has a tendancy to break in the middle of things! Use only stainless steel. Fishing leader works well. I have also found stainless wire at automotive stores that works better. .020 is a good size to start with. That number can change depending on the application. On my 72" bow I ran .025 I think. I'm in class so I will update the sizes if they are wrong.

Second: you have to use electricity and dc is perferable to ac. A car battery is okay, but an adjustable charger is better! With a straight battery you would have to run it through a resistance circuit to achieve a good power range. Despite the fact that DC is technically better I like AC because it's easier to find parts for.
Ideally you want to run a low voltage at a high amperage. I've found that a range from 13-18 volts at 4-6 amps is prime. I like a little overkill in case I need a really long cutter, then I have the power to power it.

As far as a power supply there are two options. The best one consists of a 10Amp variac and a stepdown transformer (110vac donw to 20vac- 30vac & 10 amp rated)
A cheap system is a dimmer switch and the stepdown transformer.
Last tip: Use an amp meter!!! It'll tell you alot about your wire temp..

I apologize for the long post.

Good Luck!
Matt K.
4 State R/c Club

RAMFlyer

My Feedback: (65)

Chief:

Try this web site; Lots of good info. If you are interested I will post some other sites I have come across in my foam cutting research.

http://www.charlesriverrc.org/articles_foam_vac.htm

Ed Smith

I am not disputing what has been written before. I will describe what I use. I made my bow 20 years ago and am still using the same one. It is a 45" bow, It does have nichrome wire and I run it directly from a 10amp car battery charger. It draws about 5amp in use. The wire stretching is not an issue. The bow "legs" Are 3/16 dia music wire in tension. They keep the cutting wire tight. Nothing could be simpler to use. I plug the charger in to the household circuit an cut foam.

Ed S

tomr-RCU

Here is a simple, easy to make Foam Cutter. I made mine from scrap in my garage in 15 minutes and it only cost me $1.95. First decide on how big a foam cutter you want. Around 40 inches is a comfortable size. You can make the foam cutter any size you want by adjusting the length of the bow spreader. The bow spreader is made from a piece of 1x4 pine. I used a 36" piece to make my spreader. This makes a bow a little wider than 40". Drill two 2 to 3 inch deep 7/16" diameter holes into the spreader bar about ½"; from the ends at approximately a 60 degree angle. The cutting wire is supported on the ends of two 1 foot long 3/8" dowels. Screw a small eye or hook into the end of each dowel. Place the dowels in the spreader bar and measure the distance between the hooks.

Put two small loops at the ends of your cutting wire. The wire should be a little more than an inch shorter than the distance between the hooks. Attach the wire to the hooks in the dowels. You will have to compress the dowels together. This provides the tension necessary to keep the wire tight and holds the dowels firmly in the spreader bar. Hook your power source (car battery or 10 amp charger works fine) with alligator clips to the cutting wire and your ready to cut foam.

I used the Sig nichrome foam cutting wire I got from my hobby shop for $1.95 for my first cutter. It works great but needs a little more power than my 10 amp 12 volt battery charger for working with foam wider than 36". Using the replacement wire for the Wing Mfg. 42" Pro-Bow works the best. It costs about $4 from Wing Mfg. and works with a 12 volt source for making wing cores great.

To make your cutting wire last longer disconnect it from the bow when not in use this will keep the wire from being streched and the dowels from being permanently bent.

See attached drawing.

Tom

[email protected]

this is my watsapp number:9490962430.
bro pls text me to dis ..i want to do dis heat foam cutter pls suggest me,,,