Flite Test - Hot Wire Foam Cutting

Hot wire foam cutting using a homemade hot wire cutter and custom made balsa templates.
More details and links available in the article here:
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Watch the JA 37 Viggen Review here:
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Watch the Skywalker X8 Review here:
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[@BJbear2001]

Thank you for interviewing David! He seemed shy to begin, but near the end his wisdom shown through like something out of this world! David seems very experienced beyond his years! Great interview!

[@TactiColt]

Thank you so much for this video, guys. My father used to build balsa gliders way back when he was in the Navy. He and I are beginning to explore the RC hobby together, but so much has changed since his day. It would be a tragedy to build a big balsa craft and wreck it on first flight, but building is what he loves. Showing how to use foam core as a medium lets him build a much more durable aircraft. This makes a big difference for both of us getting into things.

[@wx9dx]

BTW I use a number 10 Dulcimer string " like a guitar string" hooked to my Weller Soldering gun as a transformer " tip removed and wires hook there" and run the gun from a light dimmer. Has always worked on projects for me. The biggest foam we can get around here is from Lowes or Menards for house walls. 73 Jimmy, ARRL TS, WX9DX

They are to scale. Just downloaded them of the site and they are still correct. The wingspan says 700mm so that's a scale you can use.

[@RCHobbyist463]

That is just plane epic. I have never seen a solution that simple but sophisticated enough to replace a professional soldering jig. You could literally save $100 just by choosing this simplistic yet sturdy design. I could see a whole new revolution in DIY!

[@vince38curious2]

The good thing about the templates is if you are like me and hopeless with all things electrical you can make your templates out of thin steel or aluminium and use a sanding block / Blocks to sand down to the template after cutting the excess foam away with a small saw or knife.. Thanks Dave and Josh this gives me more confidence to try new shapes that I wouln't have thought possible before.. Regards Vince.

[@frogsoda]

I have a hot foam cutter that is configured like a bandsaw. It has a table, the wire comes out of the table vertically to a frame that goes back to the table. I haven't used it but I loaned it to a friend who uses a handheld cutter and she liked it a whole lot better. Also, we have no trouble getting foam in Miami. In fact we're 30 miles from Miami and that's where we go to get foam.

[@thebunkreport]

You can buy a whole hot wire cutting set for around $25. However, the one that you made works great as well!

[@jezjezman9487]

Health and safety bit: **Wear an M3 Vapor mask**, Gloves, Goggles

[@wutangclams3203]

and do it outside! i was thinking the same thing, boy i bet those vapors have all kinds of carcinogens in them

[@TheStonehammerFiles]

Cutting it is safe, burning it is not.

[@sato4kaiba]

For those who don't know: I squared R is the power P that is produce and is not necessarily the amount of heat. There is a formula to calculate the amount heat that will be produced.

[@mnovo]

Ohm's Law is V=I*R (Voltage=Current*Resistance) Joule's Law is P=V*I (Watts=Voltage*Current) Nichrome wire with a diameter of .010 is roughly sitting at 7 Ohms resistance per linear foot. You can measure the 2 contact points on the bow with a DMM or use this as a rough calculation entry point for your R value. What current value are you attempting to achieve while you vary the voltage? Great video btw! M~

[@mnovo]

hotwirefoamcutterinfo.com/__SupplyCalc.html Nevermind. I found it. 6.2v @ .92A = 5.7watts and 400F and 8.0v @ 1.19A = 9.52 watts and 600F

[@shotintel]

Mmm, brings back my unregulated vape mod days. I would turn my own coils.

[@AndrewWorkshop]

You could also use an AC transformer and a light dimmer to control the heat of the wire.

[@eastcarolinadroneshelispla6635]

Building one of these now. Can not wait to try it out. HUGE THANKS TO FLITE TEST GUYS!!

[@user-ik7bl4yg2t]

"what was it, Vegan?" "Viggen" "Alright, the Vegan..."

[@nilsolsson880]

its a swedish plane

[@nilsolsson880]

David is from Sweden i things

[@afrog2666]

Saab 37 Viggen ;) Saab also made a car called Viggen.. Little factoid for ya ;)

[@johnlight5388]

Jan Christian Frodahl m

[@fenderstratguy]

He kept saying vegan lol

[@azgarogly]

Great! Actually, I was expecting a long time, when David'd share the knowledge on hotwire foam cutting. I have some (working) idea on how to power hotwire with simple components from electric store. Now, I guess, I have to write an article for flitetest

[@daveroche689]

I have have miles of Nicrome wire if you would like some. However you can use fine piano wire but unlike Davids bow you need more tension to get a good cut. Use a high current transformer and a light dimer or you will just get a fire. The best bows are made of wood and Aluminium, and have an H shape. You use 2 pieces Aluminium at the ends and timber to separate and insulate. Tension with shock cord or a spring & cord/rope. $20 and your cutting. Don't use PVC and don't burn the house down.

[@carmatic]

also, how about adding mirrors to the sides of the bow so you can see how far along you are cutting on both sides without having to turn the piece over the awesome thing about having the plans made in foam sections is that each of these sections are small enough to be 3d printed ... you could add pins and holes, or slots and tabs, and make it much easier to assemble and give it some added structural rigidity as well

[@masoncayaban9790]

Add Springs to tension the wire. You'll get a better finish and you can turn up the voltage, which will produce more heat and will also allow you to cut faster.

[@lululock]

If you put more voltage, more heat, yes. But the heat will "melt" more foam than your template. With a friend, we made that mistake while cutting foam cores for our glider's wings.

[@Mad-Duk_Machine_Werkes]

We need a laser-cut set of the plywood templates avail in the FT Store right away!! (for this and OTHER planes)

[@mattivirta]

and if have laser who can cut plywood can cut laser all foam too easy.

[@ballwizz23]

I just made one today. I didn't use the esc or the dimmer. Just some nichrome, wood, and screws. I used a simple 9 volt on 12 inches of 28 guage wire. I plan to step it up to 12 volt as 9 was a little slow. Idk about the AC/DC part though. You can buy Nichrome on Amazon for a few dollars.

[@MrROTD]

If you have any experience with 3-d modelling on computers this is a piece of cake, its a similar concept to skinning between two polygons, in fact I've modelled planes in 3-d doing exactly that

[@itsgr82bl8]

Thanks for the info guys, I built a foam cutter using a computer power supply which had WAY more than enough power. I will have to revisit that adventure and see if I can't refine it a little bit!

[@poobertop]

You can also use an adjustable light dimmer to have control over the current to the wire.

[@RCHobbyist463]

One of my favourite channels, other than Flite Test, did that and it was amazing.

[@Kerberosfish]

the guy in the red woodsman shirt is mad smart

[@colinmaguire3273]

David windestal?

[@colinmaguire3273]

David windestal?

[@danbeale6818]

You could use a turnbuckle half way up the arms to keep the wire taught,

[@whatelseison8970]

It's usually better to just use the flex of the bow or a tension spring.

[@hyzenthlay7151]

What amperage is the brushed ESC you are using in this video? As you say, they are getting hard to get your hands on, and I wanted to know what would be the minimum needed.

[@robinbeckford]

3M77 works, too. Spray both faces, leave until it's only just tacky then press together. Holds well, and the wire goes through the joint no problem. (I learnt that from Phil Barnes dvd on vacuum bagging.)

[@maxfig4167]

good places to find good foam, craft stores, they have a foam that is excellent for hot wire cutting and it's also very light.

[@3duckit]

Miss this young man. Great video.

[@antecboy]

It's when you're cutting the foam and the wire isn't hot enough to cut it with proper speed, so you push it a little harder and the wire starts to flex a little. That is bowing. Like when you pull back the string of a bow, bowing.

[@h78i23jjy]

Hobby King still sells Brushed ESCs. But they only have two of them. A 20a and a 30a. You have to search "brushed" if you want to find them quickly.

[@MAYERMAKES]

If you construct the bow like a spanend woodworking saw and use a string spring between the hotwire and frame you will get much better tension.

[@XxXAUTOXxX]

You shouldn't need more than 10amp I use a PWM controller instead of an esc, it has a rheostat and will take up to 40V. I use 28gauge nichrome wire (stainless fishing leader also works) and up to 24v (2 car batteries in series) for wings up to 10 feet long. Any longer than that and you have to go really slow or your wire will bend too much (but that can be useful for adding reflex).

[@carmatic]

2:53 you can use a 3 phase brushless ESC if you make a rectifier out of diodes ... you will need to hook up a motor in parallel so that it gives a feedback voltage so that the ESC will work

[@Brian_Boxtruck]

You can get big blocks of the blue foam from aircraft spruce and other aircraft/fibeglass supply places. It's not expensive but can be to ship due to size.

[@britblad]

I am not into planes anymore but making a smaller ver of you wire former would save me alot of time with my model Railroad!

[@josephmolinari1]

please please please do a flite tip episode about how to extend the flight time of an existing air frame. thanks and keep the episodes coming!

[@robfrydryck127]

Crazy good cutting skills for hand held

[@rtonce]

Found out I am very allergic to the off gassing of that foam when i used it around a window installed air conditioner years ago. When home, I had non-stop runny nose. We tested our suspicion of the foam being the cause, confirmed it was, and removed it. I have no other known allergies, so can only conclude the chemicals coming off that foam, cannot be good. The takeaway is: Use natural materials and hone your skills of workmanship with other building methods whenever possible. Enjoy lasting health.

[@NarcizoJE]

Electronic Dimmer used to control lights do the same job and is cheaper. Thumbs up for the great idea of PVC tubes for the bow.

[@WCPAGEL]

The pink foam in made by Owens Corning witch is in Toledo, OH.

[@ytubesucksazznow]

I don't even do this hobby, probably due to the fact my first real plane blew up on maiden voyage as a kid lol, that's another story all in itself haha, yet I learn a lot of tricks for other things and strangely I keep watching your vids anyway knowing I could never build the awesomeness you guys do ^^ i love watching you guys and keep up good work.

[@laynehip]

I got the plans printed off for this on 54 pages using a titled PDF. Going to get foam tommorow and start building this thing. I have never even flown a Rc plane before in my life but I don't even care!

[@VictorHugoRC1111]

You can get it from an old heater heating element. Usually it comes in a coil shape.

[@JustinBerke]

"If you live in Miami, you're gonna have a really hard time finding foam." I live in Key West. Dang it.

[@VictorHugoRC1111]

Go to the Flitetest site and they have the templates there, Thanks guys!

[@christophbader3713]

I miss David Windestål. He should have been there, when you got 1.000.000 subscribers...

[@handblitz4408]

What happened to him

[@FPVav8tr]

1:20 JOSH: "My bow is huge, you're bow is little" Remember Josh it's not the size of the bow, it's how you use it. :)

[@davidkelly4598]

I've done this w a dimmer switch wired upstream of a 12 volt car charger. Great temp control.

[@theartofflying3108]

Dimmer switch from room light switch?? And how did you force car battery charger to flow current if it is with electronic processor prevents from overload and so..??

[@jeffv2074]

Excellent 👍 video, it is a great help since it will be my first time working with a foam cutter. I'm into RC cars and drones so I am very familiar with the components utilized, the heat for the wire was my biggest concern and you guys clarified that for me, thanks

[@robopony]

I could listen to David say "glue" all day.

[@ARob16x]

im building the hot wire foam cutter from grant thomsons video. With the templates that flite test showed me how to make in their how to make templates video i can make professional scratch built planes like the ft 3d and other planes built by them.

[@chrisleech1565]

You can still get a brushed ESC at Hobby King. Check it out. Just type in search for them at the top of page and you'll find 20 and 30A there.

[@DLPlanes]

Awesome video! I live just by Miami and they always have foam at Home Depot or Lowe's. I too did a hot wire foam cutter but never thought of making it portal like this one. Great job.

[@chrisleech1565]

I think you can use a guitar string Try the smaller ones like high E or B strings if they are long enough. Easy to get in any music store or from a from a friend who has old ones. Give her a shot!

[@sirbow2]

i was gonna built one of these a while back, but im gonna use the 30A Brushed ESC for a RC Power Wheels :D

[@mtdarus]

hye!guys im using cheap guitar string and a power supply source of 3 amp and 12v to 14v of voltage. i cant get nice surface finish.it is due to the wire type i used or the technique?please help me.

[@JordnFtGuetta]

I love this idea, i just thinking about how to cut the foam, and its just awsome (: !

[@brett8090]

I would really like to see these formers and other formers like them on the store. A C-130 would turn out crazy sharp with this technique.

[@muskokamike127]

I just want to add a voice of reason to this practice: make sure you are well ventilated. The fumes from melting foam are carcinogenic. I'm not sure what the exact chemical composition of the various foams being used are, but I know that melting Styrofoam is INSANELY carcinogenic.

[@stevezvada313]

the wings and canards are just dollar tree foam core board cut with a xacto blade.

[@sparkstyl]

light weight glass and minwax polycrylic works wonders and much lighter then epoxy.

[@TristanPenson]

Its the wire not being basically flat or straight, but ending back a bit.

[@XxXAUTOXxX]

Any decent hardware store should have it in north america. I'm actually getting a new type of foam that is 12X as dense but only 25% more weight. Should be here tomorrow but you can't even mark this stuff with your fingernail. A little fiberglass and it should be bombproof!

[@hieraco]

A good cheap source for wire is your local music store. I picked up a NP017 string (guitar second string) for 10Kr (about $1.20USD) works great with a 4A 12VDC transformer to supply power (wired to a rheostat/potentiometer to adjust the wire temperature.) Also I'd like to ask David if he can recommend any Blue foam core suppliers in Sweden.

[@Mrdaddydaze1]

Thank u guys I always wanted to see a edf jet on your channel

[@johnlandbeckjr3736]

What an amazing young man!!! Very well done. John in MD

[@azgarogly]

Ok, article's submitted for approval on flitetest. "Powering a hotwire cutter" is a title.

[@calebsmedia]

You guys should sell the templates for the Viggen. That would cut down the build time a lot. Thanks!

[@MarcStollmeyer]

I'd like to see a 200% Viggen. 140mm EDF!

[@joerandolph7806]

I use a screw attached between the wire and the holder to tighten the wire

[@guloguloguy]

THANK YOU, FOR THIS GREAT DEMO!!

[@DefekCs]

Hey, guys! While David is still there and while You are on topic of blue core foam, maybe make some BEGINNER'S TUTORIAL IN FIBERGLASSING on this plane! You mentioned that it needs reenforcement for air intakes. Nothing major, just tips & tricks in basic fiberglassing - tools, compounds, methods, safety things e.t.c.

[@davidh1187]

A PWM controller will do the job of powering the circuit and is readily available (or just as easy to make)

[@heaanlasai866]

Thank you for your great video! Will you be making a video about fibreglass coating the foam?

[@chrisleech1565]

Thanks for the heads-up VH, that's what I call team work. Now that I have sorted my first Tricopter build and the associated Firm Ware issues.Whew! I can now try my hand at making an airframe from inexpensive, readily available, easy to cut Foam. BTW I am looking for the "How To Make Inexpensive Hot Wire Templates" ? Or is there another link you found with actual template designs that I can print and cut out?

[@hiram072088]

I don't think it was nonsense. There were witty comments that added entertainment to the show. I do agree that he doesn't seem to be a enthusiastic as he use to be. At the beginning I thought he was sick (a cold or something similar) and that they recorded a bunch of episodes while he was sick, but now it seems like he is indifferent towards flying.

[@alaskaboy14]

Speaking of Alaska, it would be awesome to do a flite test in alaska. we have more planes and pilots than you would know what to do with!

[@Femmpaws]

I'm from Alaska and Dad was raised in Alaska and in his many years of flying up there he had flown over most of the country up there. He learned to fly in the late 30s in SE. I'm just getting back into flying both RC and full sized aircraft.

[@cowcar87]

did you guys think about keeping the wire cutter stationary and moving the form only. it may be easier with these small pieces.

[@desidudes78]

The viggin is incredible

[@MrROTD]

A plain guitar string is working for me, I don't think you need special wire as long as you have the wire just hot enough

[@gasparreis303]

Great video, congratulations, but what are the measurements in centimeters of the saw and Nichrome wire ?

[@HuylerBrooks]

Hey, sorry for the completely unrelated comment, but could y'all do an episode/walk-around of David's "Quadrone"?? I was looking at it on David's website, and by golly, that design is wonderful! Would love to hear the designer comments on how he came up with the design and how it performs! Thanks!

[@MrJoseJasso]

did you laser cut the formers? what if i don't have a laser cutter? how do i cut formers? Great plane!!!

[@raoulcuban]

Nice work guys, thanks for the help.

[@RussellDeMussel]

The sound cuts out about a quarter of the way and comes back on approximately three quarters of the way thru.

[@heaanlasai866]

What diameter should the nichrome wire be?

[@whatelseison8970]

That depends on 2 things: The type and density of the foam, and the power you want from your wire at a given voltage. If you intend to cut thin sheets of low density foam you can use thin wire, but if you need to cut the sort of stuff they are cutting here then your best bet is to just hit the thrift store and find yourself an old hair dryer, bust it open and use the coarsest heating wire in the thing. The most important practical consideration once you're ready to string a bow with wire is how you're planning on powering it. I like the ease of use of a cordless setup so I recommend powering the setup with a lithium ion battery. Preferably 1 or 2 18650 cells. Using a speed controller like this is a nice touch but not strictly necessary. You want to be dissipating about 0.6 - 1 W/cm of wire so if you have a ~40 cm bow like David you'll need your wire to have a resistance of 0.4 ohm if you want to run it from a single 18650. Ni-chrome would actually have to be excessively coarse to get such a resistance over 40 cm but a good alternative is stainless steel or piano or guitar strings.

[@1985cjjeeper]

NiChrome wire is the stuff you need for this. It's the same stuff they put in hair driers and heaters. Get it from a hair drier without breaking it and a few sticks from the yard later you have a foam cutter if you plug it in to a rheostat like a light dimmer.

[@Harlanmote]

+1985cjjeeper Nicrome wire brakes to easy i use stainless steal or a guitar string.... Even mig welding wire works good.

[@davidb4557]

what size mig wire and what kind? SS or Fluxcore?

[@1985cjjeeper]

David B, you'd want to use SS not flux core. Probably any thickness since it doesn't get very hot. I used Nicrome in a textile mill to cut 5 10 inch rolls of 150 denier polyester at a time on a machine we built. I can't remember the gauge but you can buy it at supply shops. I can see how stainless or a guitar string would work fine on foam though. Our wire had to be a higher temperature or it would melt the tube ends of the rolls together. In that application other wires would sag/break. I admit we only used a hair dryer wire to prove the concept them moved on to thicker stuff. I still have a roll somewhere, maybe 12 gauge or 14.

[@davidb4557]

Thank you for the reply. I have plenty of SS .025in Dia. wire I can try first. I will give that a try first. If it works, I'll let you know. Once again, Thanks.

[@1985cjjeeper]

That should be fine as it won't need to be very hot for most things. Just make sure you never touch it when it's plugged in and you won't die.

[@nicholasn.2883]

Just built this. Awesome!

[@FPVREVIEWS]

i know those are not, but why cut the whole plane out of blue foam with very close to ideal shapes, and then just use flat wings? that only works well for small park flyers. i like to use real naca 4 digit foils for low reynolds numbers. would love to see a good tutorial on how to cut real airfoil wing sections from foam.

[@john3Lee]

David is a genius....

[@alcoxy]

Yes!!! Would love to build one of these too

[@simon-gabrielgervais7262]

a foot pedal like a tig welder would be great for start and restart and speed control

[@MaxImagination]

Hey guys! Super cool

[@benshapiro2wt298]

id pay a lot of money for that EA-6B prowler... if i had a lot of money

[@razor7177]

prowler/intruder or the De Havilland's vampire

[@Frifler888]

Oh WOW, That's a Great Idea man. I live in DK, and i have to say we forroners love Swedish much more than dk, mostly because most of them are Hunest, good and pure and they make good friends. So i say Go Sweedan, we love you guys...:-)

[@rwprime1]

2018 I just did a little research and the Nikrothal 80 .4mm he mentions is 26 Gauge www.fasttech.com/products/3033/10016555/3385503-ltq-vaper-nikrothal-80-heating-wire-for and that ESC is still available, but not that Turnigy Servo Driver, although they do have a servo tester as do many others. Also, looking at his cutting mat in his write-up, the length between the inside of the two pieces of PVC appears to be 15 inches. Myself, the shorter the wire, the more control you have, so I would make it just a little wider / longer than the largest piece of foam I would have to cut. Anyway, great job guys and good information and demo.

[@rajmulay4062]

You can get foam from Hydroponic shop .great video 👌👍

[@fazalrehman7441]

You can find this foam, at store called Rona hardware, search for styrofoam Or u can try other HARDWARE STORE OR BUILDING CENTRE