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Old 11-16-2010, 12:56 AM   #1
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Question Hot Wire Foam Cutter

I have looked all over this site and others trying to find out what wire and gauge size is being used in the home made foam cutters.. And what wire gauge and temps are used for what foam and thickness.
Going back to 1970 we used nichrome wire 20-22 gauge and used a old or new model train transformer for power on are manual bow cutters..
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Old 11-16-2010, 01:07 AM   #2
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Originally Posted by Tin Man View Post
I have looked all over this site and others trying to find out what wire and gauge size is being used in the home made foam cutters.. And what wire gauge and temps are used for what foam and thickness.
Going back to 1970 we used nichrome wire 20-22 gauge and used or new model train transformer for power on are manual bow cutters.. I
Back in the 1960's, I used steel music wire, right out of the hobby shop. If memory is correct, wire was something like 0.010 or 0.012 inches or so.

It takes a little more power to heat up the steel wire, but on the other hand, you can place far more tension on that steel wire. That tension results in less "Sagging" of the wire while cutting the sharp curve of the leading edge of the wing.

Power was something like a 10 or 15 Amp lead acid battery charger. The amount of heat was varied by using 10 or 20 feet of standard #18 gauge lamp cord. Just make the lamp cord shorter until you get the correct amount of heat. You will need a digital multimeter with a 10 Amp DC range to make certain you don't overheat your charger. (Or, you could just use a deep cycle battery!)

I made a lot of wings with that bow. (The bow was made out of a piece of 1 X 2 inch oak from the lumber store, with two 3/16 inch by 8 inch long pieces of music wire inserted into each end of the piece of oak. A real short spring from the hardware store connects to one of the 3/16 inch diameter music wire to provide tension for the music wire. I used something like 10 or 15 pounds tension.)
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Old 11-16-2010, 02:15 AM   #3
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Originally Posted by kyleservicetech View Post
Back in the 1960's, I used steel music wire, right out of the hobby shop. If memory is correct, wire was something like 0.010 or 0.012 inches or so.

It takes a little more power to heat up the steel wire, but on the other hand, you can place far more tension on that steel wire. That tension results in less "Sagging" of the wire while cutting the sharp curve of the leading edge of the wing.

Power was something like a 10 or 15 Amp lead acid battery charger. The amount of heat was varied by using 10 or 20 feet of standard #18 gauge lamp cord. Just make the lamp cord shorter until you get the correct amount of heat. You will need a digital multimeter with a 10 Amp DC range to make certain you don't overheat your charger. (Or, you could just use a deep cycle battery!)

I made a lot of wings with that bow. (The bow was made out of a piece of 1 X 2 inch oak from the lumber store, with two 3/16 inch by 8 inch long pieces of music wire inserted into each end of the piece of oak. A real short spring from the hardware store connects to one of the 3/16 inch diameter music wire to provide tension for the music wire. I used something like 10 or 15 pounds tension.)
We made the bows out of 3/8 ply wood cut "D" shape... the good ole days !
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Old 11-16-2010, 02:23 AM   #4
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Check this out: http://www.aircraftspruce.com/menus/cm/hotwire.html Good stuff, good prices, GREAT SERVICE.


Possum

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Old 11-16-2010, 03:11 AM   #5
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Originally Posted by hillbillynamedpossum View Post
Check this out: http://www.aircraftspruce.com/menus/cm/hotwire.html Good stuff, good prices, GREAT SERVICE.


Possum
Interesting:
BUT, that variac, being used as a power supply for the foam cutting system is dangerous. The variac output is directly connected to the 120 VAC power line, no isolation. (They do make isolated variacs, but their price sky rockets!)

PS, I've used variacs thousands of times over the past 40 years, and have several 5 ampere variacs in my home. Company I worked for before retiring, had a monster 220 Volt 600 ampere three phase variac used in their testing equipment. You need a fork lift to move it.
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Old 11-16-2010, 03:23 AM   #6
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Originally Posted by Tin Man View Post
I have looked all over this site and others trying to find out what wire and gauge size is being used in the home made foam cutters.. And what wire gauge and temps are used for what foam and thickness.
Going back to 1970 we used nichrome wire 20-22 gauge and used a old or new model train transformer for power on are manual bow cutters..
Hi Tin Man, I made a hot wire cutter from a toy transformer, i bought the ni chrome wire from hobby people i belive, lots of good input from others on this thread.

http://www.wattflyer.com/forums/showthread.php?t=58627





I may be getting Older, But I Refuse to grow Up I am Having to much Fun to Grow Up LOL
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Old 11-16-2010, 03:31 AM   #7
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http://www.hhhh.org/~joeboy/resource...am_cutter.html



I think you can use from .008 to .030 wire nichrome wire. or .030 stainless steel fishing line
0.008 to 0.015-inch (thickness) single-wire steel guitar strings (available at your local music store)

I may be getting Older, But I Refuse to grow Up I am Having to much Fun to Grow Up LOL
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Old 11-16-2010, 04:25 AM   #8
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Originally Posted by hillbillynamedpossum View Post
Check this out: http://www.aircraftspruce.com/menus/cm/hotwire.html Good stuff, good prices, GREAT SERVICE.


Possum

Thanks...
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Old 11-16-2010, 04:26 AM   #9
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Originally Posted by CHELLIE View Post
http://www.hhhh.org/~joeboy/resource...am_cutter.html



I think you can use from .008 to .030 wire nichrome wire. or .030 stainless steel fishing line
0.008 to 0.015-inch (thickness) single-wire steel guitar strings (available at your local music store)
Thanks !
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Old 01-16-2011, 09:28 PM   #10
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Originally Posted by Tin Man View Post
I have looked all over this site and others trying to find out what wire and gauge size is being used in the home made foam cutters.. And what wire gauge and temps are used for what foam and thickness.
Going back to 1970 we used nichrome wire 20-22 gauge and used a old or new model train transformer for power on are manual bow cutters..

Hi so I just made myself one of these and I took apart a hair dryer and took the wire out of it ( there are enough in it for 3-4) just don't over heat it and it is plenty strong. For heat control just wire a dimer switch with a 24 volt transformer and whala. Works great! Hope this works good for you.
Foam
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Old 01-20-2011, 11:43 AM   #11
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Been cutting for a while , my hotwire setup is pretty decent.

H bow made from scraps
Wire is from an old electric bar heater
Power source is a 3 cell lipo
Brushed esc
receiver or servo tester
Transmitter.

Cuts very well and allows you to easily adjust the voltage.
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Old 01-20-2011, 10:19 PM   #12
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Originally Posted by scouse View Post
Been cutting for a while , my hotwire setup is pretty decent.

H bow made from scraps
Wire is from an old electric bar heater
Power source is a 3 cell lipo
Brushed esc
receiver or servo tester
Transmitter.

Cuts very well and allows you to easily adjust the voltage.
Neet Idea

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Old 01-22-2011, 02:25 AM   #13
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I built my hot wire power supply from an article on the 'Garage of Evil' web site. Won't let me post a link here, but its the 'garage of evil network dot com'. You can get the whole thing a Home Despot...


I use 1/2 inch plastic electical conduit for a bow. It all works great up to about a 3 ft span with 22 gauge steel wire. Its better with nichrome 26 gauge.
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Old 01-22-2011, 04:19 AM   #14
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Originally Posted by deadeye51224 View Post
I built my hot wire power supply from an article on the 'Garage of Evil' web site. Won't let me post a link here, but its the 'garage of evil network dot com'. You can get the whole thing a Home Despot...


I use 1/2 inch plastic electical conduit for a bow. It all works great up to about a 3 ft span with 22 gauge steel wire. Its better with nichrome 26 gauge.
Cool Thank you for Sharing and Welcome to Wattflyers Take care, Chellie

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Old 02-13-2011, 01:20 PM   #15
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DIY Foam cutter bow :

Get hold of a wire wound electric heater element - this has NiChrome wire fitted usually round a heat proof glass rod. Extract the wire and fasten one end to a fence post. Now lean back and stretch it to take out the coils ...

You will find you have a l ooooooooooo nnnnnnnn gggggg length of it - and all you need is 1.5m .....

Construct a tensioning bow that is shaped like a H .... the bottom of the H being the hot wire legs ... the top of the H being the tension part where you spanish windlass rope. The legs pivot on the middle part.

Now setting the legs straight ... you wind fasten the wire to legs and then run last lengths up the legs toward middle. Staple to legs with a small loop proud.
Fit rope to tension and tension up.

A 12v battery will provide all the heat you need across that wire ... or you could be fancy and use a hobby 12v controller to regulate the power ... the power being croc-clipped to the small loops of the wire you made.

NOTE : when you heat the wire - you will need to take up tension again ... and is reason for the spanish windlass system. Not forgetting that when you disconnect power - you will need to release tension ...

easy to make ... little cost ..... I used one for foam core wing cutting for years ...

If you really need to - you can buy same NiChrome in DIY shop or via ebay.

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Old 02-13-2011, 07:46 PM   #16
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Built mine just like that about six years ago and it's worked well for me.
High power 12 volt tractor battery charger and steel fishing trace wire.


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Old 05-18-2011, 09:14 PM   #17
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Default Hot wire cutter....

I did a lot of searching and made a bow with 1 1/4 PVC pipe about 34" long. I tried steel wire, but the cutting was terrible. I found some stainless steel .021 OD wire online and it worked great. I can cut 30" pink foam with great quality using a 35 amp car charger.
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Old 05-18-2011, 09:44 PM   #18
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0.051 mm (020) guitar strings works well and is really inexpensive at the local music store.

All of my landings are three point landings if you count the spinner, too
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Old 05-26-2011, 11:56 AM   #19
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maybe too late to help but recently bought a foam cutter from #http://www.hotwirefoamcutter.co.uk as spec'ing out the correct wire gauge/length/amp requirement was a nightmare especially as the power suppliers were looking very expensive the higher you go

they sell cutters both with/without the power supply so gives a choice

another helpful info source was http://www.hotwirefoamcutterinfo.com who look like they know their stuff and have calculators which look helpful......i guess if building your own 'bow' cutter you can build to exact size you want but the other site may help if you want a 'good to go' solution

,.......hope that may have been some help
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Old 05-30-2011, 07:21 PM   #20
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I started out with guitar strings, I heard they work. They only worked sort of. I was trying to cut 3 feet and my wire is about 40 inches, some strings are longer than others. I tried different gauges. I found the wire about half way through the cut was glowing red at the exposed ends. It got brittle and broke. It may have worked if it was a lot longer than the cut.

I then took apart a hair dryer. For that length 24 volts wasn't enough, I need just over 30, so I had to go to 120 volt power. The hair dryer was wired so the length I used had 60 volts on it, I used half a coil. If I had matched transformers I would have done 2 for 48 volts. I am using a dimmed household halogen lamp for a ballast to give me about an amp and a half.

I am just getting started and my cuts are not smooth at all. I need more experimentation and practice.
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Old 06-11-2011, 08:20 PM   #21
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Staineless worked for me as has good ol nichrome.
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Old 07-16-2011, 04:27 AM   #22
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dont know if anyone knows about SIG but they still sell 36in. real nichrome wire

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Old 03-24-2013, 11:32 PM   #23
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I've been doing some experimenting this afternoon. I've got a 10 amp Pyramid power supply (had it for years). It can heat up a 30" piece of .014" music wire quite nicely . I've made a plywood frame with geared guitar tuners on both ends so I can keep the wire nice and tight. Preliminary tests are going great - it just falls through 3/4" panel foam, leaving a very nice surface finish. This opens up all kinds of possibilities .

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Old 03-25-2013, 02:14 AM   #24
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Originally Posted by dgjessing View Post
I've been doing some experimenting this afternoon. I've got a 10 amp Pyramid power supply (had it for years). It can heat up a 30" piece of .014" music wire quite nicely . I've made a plywood frame with geared guitar tuners on both ends so I can keep the wire nice and tight. Preliminary tests are going great - it just falls through 3/4" panel foam, leaving a very nice surface finish. This opens up all kinds of possibilities .
Yeah, I did that using music wire back in the mid 1960's. Cut a lot of foam wings with it to. As for wire tension, my cutting bow used a spring from the local hardware store that worked well.

Something like 10 pounds tension, maybe 20-30% of the breaking strength of the music wire. Nice thing about the spring, as the wire heats up and expands, the wire tension is held fairly constant by the spring.

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Old 03-25-2013, 04:15 AM   #25
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started out back in the 80s with a 36in. woodin u shaped bow used for tapered symmetrical type u-control wings then made a jig and droped a hot-rod down the center for the lines. then for the last 2 yrs had an old sears jig saw sitting around so took the blade out and ran some nichrome wire between where the blade attaches and used a 45 watt train transformer for power. you can get wire on ebay for cheap, think I got 6 ft. for $4 shipped.......will post a pic if someone wants to see it


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