Paul Harris 5 Posted August 9, 2015 Share Posted August 9, 2015 Hi all I am going to make myself a hot wire foam cutter to have a go at making my own wings, I have most things sorted but have a question regarding the wire used. I understand it needs to nichrome wire but a quick search on eBay brings up a biwildering selection of thickness's The power supply I was going to use is from an old computer and gives both 5 & 12 volts at a minimum of around 30 amps. So what thickness of wire should I be looking for. I have small commercial unit but it only cuts upto 6 inch wide and the wire supplied with that is around 0.24mm would that be suitable for a cutter wide enough for 3 to 4 foot or do I need a thicker wire. Thanks for any help with this. Paul Quote Link to comment Share on other sites More sharing options...
Rick Tee Posted August 10, 2015 Share Posted August 10, 2015 I use .5mm stainless wire on a 914mm bow. Rene 41 is probably the best wire to use if you can get any. You may need something to control the current from your power supply. Edited By Rick Tee on 10/08/2015 12:37:52 Quote Link to comment Share on other sites More sharing options...
Pete B Posted August 10, 2015 Share Posted August 10, 2015 Put 'foam cutter' in the search box - there are several threads which may help... Pete Quote Link to comment Share on other sites More sharing options...
Paul Harris 5 Posted August 10, 2015 Author Share Posted August 10, 2015 Thanks for the replies What would be a good practical way of controlling the current. Thanks Paul Quote Link to comment Share on other sites More sharing options...
GONZO Posted August 10, 2015 Share Posted August 10, 2015 I've used wire salvaged from a 1kW electric fire element for a bow 39" long(total cutting length). Wire was tensioned by 'bungy cord'. Power was from a 30V 6A variable bench power supply. Trial and error test cuts on spare foam before the proper job. Only used it on EPS foam years back, although I still have it. Made foam Watt 4 wings(lots) and foam RC combat wings(lots, short life expectancy) amongst others. HTH Quote Link to comment Share on other sites More sharing options...
MattyB Posted August 10, 2015 Share Posted August 10, 2015 I second the stainless wire - we had terrible provlems with nichrome when we started which were only fixed when we moved to stainless. This may be of interest - I made these videos for our club members when we bought our foam cutter from the US... Edited By MattyB on 10/08/2015 17:26:22 Quote Link to comment Share on other sites More sharing options...
Mike Chantler Posted August 10, 2015 Share Posted August 10, 2015 Paul, I do use nichrome wire and found it to work fine - I must be doing something from MattyB so I'll give details: I use 1.3m of 26 guage wire that I got from Maplins (found 28 guage too thin). I use a 5A adjustable power suply (a replacement laptop powersupply) on 20v (its selectable from 12 to 22v in 1v steps and this seems to provide me with enough control over the heat in the wire. I use a really cheap and chearful setup for the swing arm cutter - it uses monofillament fishing linean eye hooks (the type for you use for hanging pictures on walls). The monofillament line is virtually frictionless going through the eyehooks (i.e. no need for wheels). When you want to change the cutting ratio (tapper of the wing) you just unscrew the eye hook and screw back into new position. One issue - my wire looks thicker (.45 mmOD) than MattyB's stainless steel, so you might have to allow for a slightly wider cut. For the bow I use about 2m of 25mm OD white water waste pipe which I bend into a curve and tension when I attach the nichrome. Usual warnings about protective gear (especially eye protection) apply. Pics at https://pssmodels.wordpress.com/foam-wings/foam-cutter-setup/ I suspect the nice looking stuff that MattyB has cuts more consistently. Mike Quote Link to comment Share on other sites More sharing options...
willhappy Posted August 10, 2016 Share Posted August 10, 2016 hi matty B what power supply were you using in the youtube clip? Quote Link to comment Share on other sites More sharing options...
MattyB Posted August 10, 2016 Share Posted August 10, 2016 This one... Quote Link to comment Share on other sites More sharing options...
ben goodfellow 1 Posted August 10, 2016 Share Posted August 10, 2016 i used the fusion 20v 20a adjustable psu in the clip with my cutter and had great results Quote Link to comment Share on other sites More sharing options...
John Timmis Posted August 10, 2016 Share Posted August 10, 2016 I made a cutter using a car battery charger & a guitar string. Worked well Quote Link to comment Share on other sites More sharing options...
John Timmis Posted August 10, 2016 Share Posted August 10, 2016 I made a cutter using a car battery charger & a guitar string. Worked well Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted August 10, 2016 Share Posted August 10, 2016 1st things 1st Paul, 30 Amps will melt flesh and readjust a heartbeat, maybe to zero, so be careful as any junk power supply is unauthorised, etc etc Nickel Chrome wire of minimal thickness will glow cherry red without breaking And the heat required for foam cutting is no where near this heat, in fact, is barely detectable by eye I am waffling, hoping you consider casing up the 30 amps properly Quote Link to comment Share on other sites More sharing options...
Erfolg Posted August 10, 2016 Share Posted August 10, 2016 I have been told of a way that might interest some that does not require a PSU etc. The wire used is from Maplin. The equipment is a Brushed ESC, together with a Rx and Tx and a 3s Lipo. The temperature of the wire being controlled by throttle control via the Rx and ESC. I have never tried it, although apparently others in the club use the set up. Quote Link to comment Share on other sites More sharing options...
Shaunie Posted August 10, 2016 Share Posted August 10, 2016 The last one I made ( many years ago) used 0.8mm stainless MIG. Welding wire and worked a treat. The biggest thing for me is keeping the wire taught as it goes baggy when heated up. I've been working toward making another (a divorce lost me the old one). I intend to put a bellcrank on one end and tension the wire with a spring so the tension remains reasonably constant. Otherwise you need to have the tension absurdly high when cold to keep a reasonable tension when hot. Temperature is colder than you think as the foam, being a good insulator, causes the wire to heat up when you enter the cut. The frame I have made is 20mm steel conduit, like a large hacksaw frame. Shaunie. Quote Link to comment Share on other sites More sharing options...
Ben B Posted August 10, 2016 Share Posted August 10, 2016 Whilst it's true that cardiac damage in electrocution is measured in amps it's a function of volts. . And it therefore depends on resistance or impedence. A spanner across a car battery at 12v will glow cherry red. Me holding the terminals of a psu at 30v will supply zero amps. Quote Link to comment Share on other sites More sharing options...
Mastercrashman Posted August 11, 2016 Share Posted August 11, 2016 Hello Paul, I've used a car battery and car battery charger and varied the amperage by using different nichrome wire thicknesses. I now use my iCharger which has a hot wire cutting mode and this sorts the voltage and amperage out. For sheer simplicity, however, have a look at this video from Andrew Newton. **LINK** Quote Link to comment Share on other sites More sharing options...
Erfolg Posted August 11, 2016 Share Posted August 11, 2016 The link that Master Crash Man has provided is very good in my opinion. I particularly like the additional video on how to drill for a spar. The reasons being the simplicity, combined with effectiveness. Although the bow shown is simple, I have seen a simpler bow, which does work. This bow was made simply from a broom/brush stave or handle. The stave was made longer than the wings to be cut. A hole drilled at each end, along the central axis for a short distance. Into each end a length of Piano wire was pushed/driven in. Each end was then bent through something less than 90 degrees. It is the natural spring of the piano wire that is used for tensioning. However I have forgotten how the Maplin wire was attached. Again crocodile clips were used to supply the power. In that case a battery charger was used. I am seriously considering making a device for myself, again using a Lipo and probably a old 35 Rx and Tx, as I am sure that somewhere I will have a brushed motor controller. It seems that it is simpler than ever to have a go. Edited By Erfolg on 11/08/2016 10:58:12 Quote Link to comment Share on other sites More sharing options...
willhappy Posted May 9, 2017 Share Posted May 9, 2017 hi there all Been looking at Matty B vid. i have been looking at power supply for a hot wire cutter and saw this power supply the Fusion 200w twin adjustable at sussex model center would this be any good say for a 1 meter bow. will Quote Link to comment Share on other sites More sharing options...
Cuban8 Posted May 10, 2017 Share Posted May 10, 2017 Did some hot wire cutting many years ago and had really good results. The only caveat was the very unpleasant fumes that came from the white foam that I was using and initially made me feel very ill until I improved ventilation in my work room. Quote Link to comment Share on other sites More sharing options...
MattyB Posted May 10, 2017 Share Posted May 10, 2017 Posted by willhappy on 09/05/2017 22:21:13: hi there all Been looking at Matty B vid. i have been looking at power supply for a hot wire cutter and saw this power supply the Fusion 200w twin adjustable at sussex model center would this be any good say for a 1 meter bow. will Yes, that will be fine. As others have posted though there are cheaper ways to do this that avoid you purchasing a new PSU (some chargers have a foam wire cutting output, and you can also use a brushed ESC plus 3 lipo setup too). Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 10, 2017 Share Posted May 10, 2017 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
MattyB Posted May 10, 2017 Share Posted May 10, 2017 In our mass build it was the quality of the (wood) templates that were the defining factor - they started off great, but the more wings we cut the more damaged they became and the more rippled the wings were. Getting the right (synthetic) material for them is key - I now hav some of the propoer stuff, but it's so long since I bought any I can't remember what it is called! Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 10, 2017 Share Posted May 10, 2017 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
MattyB Posted May 10, 2017 Share Posted May 10, 2017 Interesting. I like your second idea of the foil tape - we did retrospectively try some aluminium sheet, but found it acted as a heatsink and cooled the wire at each end of the cut. Quote Link to comment Share on other sites More sharing options...
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