Hot wire foam cutter
 

Does anyone have any pictures or plans for a hot wire foam cutter that would work for cutting wings. Also what size wire and power supply do I need.

RE: Hot wire foam cutter
 

Gene, there was a thread in the last year of one a fellow made with a HOW TO. It was slick. Looked like something even I could use.

RE: Hot wire foam cutter
 

There is a Yahoo group, "CNCFoamcutters" that will make your head hurt will all the information.

A couple guys at our club wanted me to make one, but it is cheaper to buy the foam already cut unless you are going to make a big bunch of wings. There is some free software listed on the site for cutting wings and turtle decks and about anything else you can think of. While I was toying with the idea, I decided that if I were to build a CNCRouter, I could put a second Gantry on it and use it for foam also. That idea may come tofruition one of these days.

We have a guy who does some really nice foam cutting manually. For tapered wings, he projects the LE and Te out to a point and uses a long wire from there to the root pattern. It isn't quite a accurate as a CNCcutter, but it does work.

Icut my first foam core back in 1970 using patterns cut from Formica and a long bow. Itturned out so well that I've never done another. http://www.rcuniverse.com/forum/js/f...used_smile.gif

Don

RE: Hot wire foam cutter
 

Gene, here's mine. The bow is made from PVC and the power supply is made from a 24vdc transformer and dimmer switch (all from Home Depot)

The wire is .020 Stainless Steel that I bought on line.

RE: Hot wire foam cutter
 

thanks Minnflyer. How well does it work? Trying to build the wing for my gull wing Cobra and it is giving me a pain in the you know where. I think foam would be the way to go. I have to go to Home Depot today anyways so I may pick up the items I need and do some practicing and see if I can do it. I will post some resultsgood or bad.

RE: Hot wire foam cutter
 

It works great

RE: Hot wire foam cutter
 

You also need to get the correct type of foam too I've been told before.

RE: Hot wire foam cutter
 

I've accumulated these over the years:
http://www.mackrc.net/patternwings2/index.htm
http://tysplanes.com/how_to_videos
http://www.rcuniverse.com/magazine/n...roduct_id=3815
http://www.rcgroups.com/forums/showthread.php?t=462759

RE: Hot wire foam cutter
 

Here is a couple of pictures of the items that I purchased for the foam cutter. How do I wire it up. What goes where.

RE: Hot wire foam cutter
 

I use a battery charger for power, it works fine. i like Minflyers better though. More control.

RE: Hot wire foam cutter
 

Check out this link

[youtube]http://www.youtube.com/watch?v=KXWWnPIhk44[/youtube]

[youtube]http://www.youtube.com/watch?v=jM8U4WZ2klg&feature=related[/youtube]


I used a 2 amp fuse.

Jim

RE: Hot wire foam cutter
 

Like this

RE: Hot wire foam cutter
 

HUMMMMM!!!! me thinks I have a bad transformer. Won't get hot. Can't feel anything in the transformer when I plug it in. So back to Menards. Love it, when all those places are over an hour away.

RE: Hot wire foam cutter
 

You might find these links on foam cutters, power supplies. etc useful:

http://www.rcgroups.com/forums/showthread.php?t=462759
http://www.rcgroups.com/forums/showthread.php?t=558772</p>


http://www.rcuniverse.com/forum/m_58...tm.htm#5858217</p>

http://www.rcuniverse.com/forum/m_67.../tm.htm#670783</p>

http://www.rcuniverse.com/forum/m_49...tm.htm#4968914
</p>

RE: Hot wire foam cutter
 

I have seen them made with old electric train transformers.

RE: Hot wire foam cutter
 

I'd use a double pole switch and put it on the input side of the transformer, switching both black wires. Your way will have the transformer drawing current whenever the system is plugged in. Wasted money.

RE: Hot wire foam cutter
 

True, but it's only plugged in when it's in use. I like to have the switch right at the bow so I can turn it off easily before setting it down

RE: Hot wire foam cutter
 

Hoorayyyyyy!!!! Minnflyer does that foam cutter work good. thanks for the help to all. I am now in business. I made one very lite bow from a 1/4" oak dowel and one from the pvc pipe. ended up using a radio shack 25.5v transformer. Put it in a project box with a neon light and fuse holder. If ya dress the part, ya gotta look smart:D:D:D

RE: Hot wire foam cutter
 

Cool!

RE: Hot wire foam cutter
 

Now I know where to send my foam cutting work to. :D

RE: Hot wire foam cutter
 

Me too, when I try it the foam looks like Shakey Jake tried to work before his 6 pack of beer. Can't wait to see some of your work with it.

RE: Hot wire foam cutter
 

My bow was made from a 3/4 wood dowel and some 1/4 in wire(like for landing gear ) from the LHS. Drill holes in the dowel at an outward angle so when the wire is attached it will spring outward keeping the wire tight.

I've found for cutting wing cores two people is a help. One on each end of the wire. I divide up my templates into "numbered sections" The same number of sections on each template. One person is the "master" and calls out the number as you cut. The "helper" just keeps pace with the master. If you're cutting a tapered wing, the root template may have the sections spaced 1/2 inch apart. The tip template may have the sections spaced 1/4 inch apart, 10 section on each template. As I said, the key is to have the same number of sections so both of you end at the same time and the wire tracks uniformly on both templates.

I hope this makes sense.

Ken

RE: Hot wire foam cutter
 

Haaaa! will only show you the good stuff. Have been trying it out and I am surprised at how easy the wire goes through the foam. Made my wing rib profile out of formica. Did I spell that right?

RE: Hot wire foam cutter
 

kenh3497 Makes sense to me. My wife didn't understand it, but I did.:):):)

RE: Hot wire foam cutter
 

You can make your templates out of wood amd put Chrome furnice tap on the edges. Will not burn the wood and easyer to make.;)

RE: Hot wire foam cutter
 

Gene, show us some photos in use. The one I saw with the weights that ran it across a table made sense to someone like myself with hands that shake.

RE: Hot wire foam cutter
 

Goirish,
Hi. I just am finishing setting up verticle and bow type cutters and home made swing arm table. Can't add to much but a couple things I picked up on are;
stainless steel fishing leader works great .022g or close (some are coated but it burns off easily)
U control wire is the same thing or works just as well and no coating
(the ^$ wires such as tungsten are preferred by guys doing LOTS of cores)
Thinner wire lets a smaller XFMR work well
letting the wire go slowly gives better end product...smaller kerf or melt out (cleaner TEs)
The less the bowing of the hot wire while cutting the better....use just enough but not to much weight, be patient
Sliding patio door rollers from Lowes make good swing arm table pulleys (the ball bearings ones)
Wives don't like foam cutting smells[:o]

RE: Hot wire foam cutter
 

[/quote]
You can make your templates out of wood amd put Chrome furnice tap on the edges. Will not burn the wood and easyer to make.;)
[/quote]
Chrome furnace tape? What is it and where do I get it? Your method sounds like a good idea. I always dread the task of cutting my templates from Formica. RS

RE: Hot wire foam cutter
 

Great thread!

On the "Articles/Files" page at www.TailwindGliders.com there is an article on how to build an automated foam wing cutter and also an Excel or OpenOffice spreadsheet that will help with setting up where the pull clips go.

Curtis
Montana

RE: Hot wire foam cutter
 

Home Depot, Ace, Wally world, Just about any hardware store. It is made of Alum. foil to rap vent pipes and has many uses on model building.
Larry k

RE: Hot wire foam cutter
 

Curtis, many thanks for the article and build file. I will build one of them tomorrow. Gee, being retired does have its advantages. Will let you know how it turns out. Again thanks.

RE: Hot wire foam cutter
 

HI,
Some say metal patterns act as a heat sink and slow the wire down. I wonder if the tape is not as much of a heat sink and would work OK. IF so stainded glass makers use a thin (1/2") tape to edge the glass pieces then they solder over these to make it look like lead. Copper foil tape? That would be a handy size.

RE: Hot wire foam cutter
 

The Pattern is wood and only coated on the edges with the tape. Solid metal does act as a heat sink, and a coating of solder will melt by heat of the wire.

RE: Hot wire foam cutter
 

It works great??<span class="info"> </span>

RE: Hot wire foam cutter
 

Templates,

I've tried foil that is used for making stained glass but what a mess. At times the wire would actually pull up the foil and cause it to hang up during the cut ruining the core. Plus I did notice cooling near the ends. Perhaps I didn't try hard enough to perfect the process.

Here is how I make Formica template. They are quick and easy to do and they last forever.
From the video I produced called "A Beginner's Guide to Cutting and Bagging Foam Wings" I show how to make formica templates and it takes less than 30 minutes to make a set.
I print the template off of an airfoil program onto paper, I use Profili. Make two copies. I then trim the paper airfoil to size perfectly along the bottom and then just slightly outside the lines where the foam cutter will ride.
I glue this to the formica on the non-finished side with superglue by aligning the bottom edge of the template with the edge of the formica. The Superglue ensures the template doesn't move.
Then I rough cut this on the bandsaw.
I take this to the drill press and take a round dremel sanding disk and sand just right up to the lines. http://www.amazon.com/Pack-Dremel-Sa.../dp/B003NFIXDK
While at the drill press I align the bottom and top template up with the bottoms flush and drill two holes, which I will use to hold the template up against the foam.
Then I'll take hand sanders, a cardboard fingerboard sander works great, and I sand till I think the airfoil is accurate.
Now I take the two templates and hold them together with nails inserted in the holes I drilled. I lay these down flush against a straight edge and take a .007" diameter pencil and draw the airfoil on paper. I carefully pull the one template off and draw the other side of the airfoil.
Lastly I take another printed version of the airfoil and hold the drawn airfoil and the printed airfoil up against the window so I can see through them to ensure the are accurate. If not I go back and do a little more sanding till I'm happy with the accuracy.
Once I'm happy with the template I'll take a white polishing wheel on the Dremel tool and run across the template once or twice and it's smooth as a babies behind!

That's it!
Of course it's easier to see this than type how it's done, thus why I produced a video; it's like having a building clinic right in your house that you can view over and over! :-)
Hope what I wrote helps.

Curtis
Montana
[link]http://www.TailwindGliders.com[/link]

RE: Hot wire foam cutter
 

I have watched several videos of cutting foam, both manually and semi-automatic. Most of the cutting that was done was with a smooth wing, no slots for spars. I built a automatic foam cutter via plans from tailwindgliders.com. By a gentleman named Curtis. I don't understand how to do the wing with the spar cutouts in it. Looks like the hot wire will not drop down into the slots. Do you cut the slots last after the profile has been cut? I will include a picture of the wing rib profile so you will be able to see what I am talking about. Thanks`

RE: Hot wire foam cutter
 

Smooth cores then the slots or you will have a mess.:eek:

RE: Hot wire foam cutter
 

I'm glad you found the article helpful.

The foam core is cut to the planform then the airfoil shape. Make sure you cut the bottom of the airfoil first then the top or your airfoil will be thinner. Then you prep the core with spars slot, holes for servo wires, etc.... Then you apply the skin of your choice; ie. composite material, balsa using epoxy, gorilla glue etc...

I can give more details later but it's all shown and much, much more in my instructional DVD.

Curtis
Montana

RE: Hot wire foam cutter
 

Here is a picture of my foam cutter. Now I just have to figure out how to work it.

RE: Hot wire foam cutter
 

I just want to pass along my thanks to cloudyIFR (Curtis) for all the help he has given me building my automatic foam cutter. I have ask many, many questions and he has responded quickly and friendly. If ever you think of building one of these cutters I'm sure Curtis would appreciate letting him know how it is working. Thanks again CloudyIFR.