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Thread: How to make a hot wire cutter.

  1. #1
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    Default How to make a hot wire cutter.

    ​"Life is under no obligation to give us what we expect." Irrfan Khan. RIP

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    Default Re: How to make a hot wire cutter.

    Hot wire cutters are kind of fun. You can also make hand-held versions, typically with the wire suspended on a "bow" made from plywood or PVC pipe. They can be used for jobs like cutting foam cores for composite rudders and daggerboards. I used mine to make rock formations and cliffs.

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  3. #3
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    Default Re: How to make a hot wire cutter.

    I want one for cutting fabric.
    ​"Life is under no obligation to give us what we expect." Irrfan Khan. RIP

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    Default Re: How to make a hot wire cutter.

    Quote Originally Posted by Todd Bradshaw View Post
    Hot wire cutters are kind of fun. You can also make hand-held versions, typically with the wire suspended on a "bow" made from plywood or PVC pipe. They can be used for jobs like cutting foam cores for composite rudders and daggerboards. I used mine to make rock formations and cliffs.

    Attachment 63327

    Attachment 63328
    Links don't work Todd.
    ​"Life is under no obligation to give us what we expect." Irrfan Khan. RIP

  5. #5
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    Default Re: How to make a hot wire cutter.

    Don't know why. Let me try again. What sort of fabric cutting are you trying to do?

    cliffs.jpg

    mountains-38.jpg

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    Default Re: How to make a hot wire cutter.

    image.jpg

    I used a hot wire and jig to cut the rocker and deck profile on these sailboards I was building back in the early 90's. Might still be a ride or two left in them given the right circumstances. / Jim

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    Default Re: How to make a hot wire cutter.

    What kind of foam can be wire cut, have useful mechanical properties and donít soak up water?

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    Default Re: How to make a hot wire cutter.

    Or.......you could just use a cheapo soldering iron.
    What is it that someone on the forum has said “ Simple is alway s better except when complicated is really cool!” LOL!

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    Default Re: How to make a hot wire cutter.

    This is the product I used for the sailboards, in the 1.1 lb/cu.' density. / Jim

    http://www.truefoam.com/about-eps

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    Default Re: How to make a hot wire cutter.

    Quote Originally Posted by JimConlin View Post
    What kind of foam can be wire cut, have useful mechanical properties and don’t soak up water?
    I use "building insulation"...pink or blue, both have the same properties ( it cuts well- only produces a small amount of "hair" strands on the cut foam and wire, that wipes away easily ( other insulation types produce a mess)...cheap and easy to source ... this foam doesn't glue ,all that well well if subject to stresses/shock. usually needs an over lay of fiberglass to create a good bond. it won't " soak up water. it's easy to cut and shapes easily
    Last edited by the_gr8t_waldo; 07-04-2020 at 10:45 AM.

  11. #11
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    Default Re: How to make a hot wire cutter.

    Quote Originally Posted by Todd Bradshaw View Post
    Don't know why. Let me try again. What sort of fabric cutting are you trying to do?

    cliffs.jpg

    mountains-38.jpg
    At the moment nothing but I've been given a good bit of Sunbrella that I want to turn into a cockpit cover at some stage. A hot knife would be handy.
    ​"Life is under no obligation to give us what we expect." Irrfan Khan. RIP

  12. #12
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    Default Re: How to make a hot wire cutter.

    Quote Originally Posted by Todd Bradshaw View Post
    Don't know why. Let me try again. What sort of fabric cutting are you trying to do?

    cliffs.jpg

    mountains-38.jpg
    Nice rocks by the way.
    ​"Life is under no obligation to give us what we expect." Irrfan Khan. RIP

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    Default Re: How to make a hot wire cutter.

    The industry standard for cutting Sunbrella has always been the Engel hot knife, but only if you plan on doing a lot of it because they're damned expensive. They do, however work very well. These days there are quite a few knock offs of the same basic type at lower prices, though I have only used my old real Engel and can't say how well they work. Before the Engel, I had a knife blade mounted into a soldering iron tip, which didn't cost much and did a decent job, but slowly and only one layer at a time. I think I originally paid about $20 for the iron and tip.

    https://www.amazon.com/Engel-HSGM-11.../dp/B01HN6YVHQ

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    Default Re: How to make a hot wire cutter.

    Quote Originally Posted by Todd Bradshaw View Post
    The industry standard for cutting Sunbrella has always been the Engel hot knife, but only if you plan on doing a lot of it because they're damned expensive. They do, however work very well. These days there are quite a few knock offs of the same basic type at lower prices, though I have only used my old real Engel and can't say how well they work. Before the Engel, I had a knife blade mounted into a soldering iron tip, which didn't cost much and did a decent job, but slowly and only one layer at a time. I think I originally paid about $20 for the iron and tip.

    https://www.amazon.com/Engel-HSGM-11.../dp/B01HN6YVHQ
    Seattle Fabrics carries those. A bit rich unless you're in the business

    Weller makes soldering irons that come with hot knife tips. And Solder-It makes butane soldering irons and hot k ice tips. https://solder-it.com

    Street price in those is about $80: https://www.wirecare.com/interest/in...tane-hot-knife

    Though I think the Engels is better for fabric because of the length of the blade: I suspect it makes it a lot easier to cut a straight line or a fair curve.
    You would not enjoy Nietzsche, sir. He is fundamentally unsound. ó P.G. Wodehouse (Carry On, Jeeves)

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    Default Re: How to make a hot wire cutter.

    My original hot knife from Sailrite in 1980 was essentially a fairly small Weller soldering iron with a flat spade-shaped knife blade (not really sharp, but ground down to an edge of sorts). It worked fine back when I was working on balloons made from ripstop nylon, but was pretty slow on Sunbrella or Dacron sailcloth. Slow cuts with a hot knife tend to be somewhat ragged and uneven if it matters cosmetically to that particular job. An old industrial thread cone makes a pretty decent stand. Since it takes a few minutes to initially heat up, you usually leave it plugged in for the entire cutting job. The Engel, on the other hand, only takes about three seconds to heat up.

    hot-knife.jpg

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    Default Re: How to make a hot wire cutter.

    I've seen hot knives on EBay for around $128, I should have another look.
    ​"Life is under no obligation to give us what we expect." Irrfan Khan. RIP

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    Default Re: How to make a hot wire cutter.

    You can buy nichrome wire from an educational supply company like Flynn Scientific, or take apart an old toaster. Once you have the nichrome wire its basically a trade-off between your power supply, the gauge of the wire and the length of the wire. You can chuck wire into a regular electric soldering gun, a salvaged computer power supply, a car battery, an old-style stupid battery charger, (not the auto-sensing kind) etc, etc. Just be careful, don't use line voltage, start with longer wire and lower voltage than you think you might need and go for "successive approximation." And USE LOTS OF VENTILATION. I built theatre scenery in a past life, we sculpted a lot of foam

    Ken

  18. #18
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    Default Re: How to make a hot wire cutter.

    I'm glad you mentioned ventilation. The one thing I'm very sensitive to is burning plastic, to the point where even one whiff can ruin my day. if I use a hot knife, it's in front of a powerful exhaust fan, but even that kind of ventilation won't let me use a hot wire cutter. I guess outside on a windy day might work, but I'd rather use the bandsaw and glue multiple pieces together instead of using a hot wire.

  19. #19
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    Default Re: How to make a hot wire cutter.

    One of the nice things about being able to cut Styrofoam with a hot wire is that you don't generate all that horrible, static-laden "sawdust" that sawing and sanding foam creates. That stuff is horrible to try to clean up and get rid of. It is also worth noting that there are some non-styrene (urethane) foams that you don't want to mess with with a hot wire, as they give off seriously toxic fumes (not that breathing melted styrene is good for you, but this stuff is seriously worse).

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    Default Re: How to make a hot wire cutter.

    Quote Originally Posted by WX View Post
    I want one for cutting fabric.
    This is the best way I found to cut fabric...a rotary cutter

    download.jpg


    But for foam a hot knife works great
    Russell

  21. #21
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    Default Re: How to make a hot wire cutter.

    I've never used nichrome wire, but s.s. fishing leader ( solid, NOT stranded) it works well but I never turn on the current, unless everything is in position and I'm ready to cut. once the wire starts to exit the foam I turn it off. . never allow the wire to heat up, without foam being cut. in open air it heats up VERY fast and the cut wire will break/melt
    Last edited by the_gr8t_waldo; 07-14-2020 at 04:15 PM.

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