advanced foam and depron tecnologies.

[clausxpf]

it does not belong here.
Claus

[clausxpf]

I am against the mowe.

[WannaFlyJets]

I think its a great idea. It would make a great resource for all. Ive been scouring rcgroups for new techniques in bending/forming depron, forming my own list in my head. If you wanted to make a thread or site about it, I'll contribute.

Perhaps the FAQ can be divided up into stages of modeling. Like cutting, forming, adhesives, sanding, finishing, etc...

Here are some from me:

CUTTING:
- I use an angle cutter or put a blade on an angled piece of wood to cut. Its great for parts that need to butt up on an angle. Its nice for formers too, so the skins line up and butt perfectly.

- find a protractor that will let you fit your xacto knife on it to cut the perfect radius.

- cut a tiny bit larger than your plan suggests, and then sand down to fit for the perfect fit. (from Airbuzz)

FORMING:

- Use 4-600 grit sandpaper on a block and sand the surface flashing off both sides of the depron. This essentially turns the depron into zepron. Alot of the stiffness is reduced, but it helps for forming. For light forming, just sanding the inside will do.

- For a large area compound curve, use a wok or something else that has a spherical shape and can hold boiling water. I bought a 12" wok for 13 dollars. Sand the surfaces to get them pliable. Roll the part over the side of a table in both directions (x and y) to soften the piece up a bit. Boil up some water in it and then place your piece inside and then with a burlap bag filled with sand or rice, press down on the part for maybe about a minute. Then flush it all out with cold water. Presto! For this method Ive found that a piece no larger than about 5" in width will work. Any larger and you'll risk creasing.

[madsci_guy]

I thnk it's a great idea. Here's a tip I use.

When bending Depron, use a curved piece of sheet metal and use your heat gun to heat the metal instead of the foam, so that just the foam in contact with the metal bends. That way the edges of the Depron don't thicken and shrink. I can easily make curved pieces of all sorts of radii. Got that one from a guitar making book ;)

-- Val

[Hawker]

Good idea here. I've been lately using Fuelsguy's method of using blue foam as a mold - after cutting it with hot wire. Then place depron sheet into it and tape it in place. Then place that piece into a dry cleaning bag and fill up the mold with boiling water. Let it sit for 10 minutes, then carefully remove it. You end up with a beautifully formed piece of depron even with compound curves. See my C-5 Galaxy thread for pics. (Still not home from vactation yet but will be back to work on my Galaxy this coming Wednesday)

[monkamarm2000]

great idea, and more of what Hawker said! Fuel has some great tricks that should be seen by all.

Barry

[power]

I just started a thread where I use just the hot water from the tap to form a fuse. So far I am very pleased with the results. Take a peek :)
I have included a few pics here as well.


http://www.rcgroups.com/forums/showthread.php?t=399547


Mike

[clausxpf]

it just not belong here

[Thomas Nelson]

Good idea for a thread, Claus. Here's a quick contribution:

You can make little "blisters" and fairings by rolling a semi-tube, and then bending it a little. Slice away the bent portion flush with the sides of the semi-tube, and you're done. Great for gun ports, cooling vents, F-15ish engine covers and the like. I used this to replicate a feature on the underside of the Su-27.

I'd think it would work fine for reproducing smaller diameter shapes like missiles and fuel tanks. One of these days I want to try a variation of this method on thick depron to see if I can make a reasonable nose "cone" ... I mean ... a nose cone that doesn't look like a simple cone ... you know what I mean. :o Might work well with the latest nanojet that Power is building.

[monkamarm2000]

cool stuff Thomas! In the old hot rodding days they called that frenching, why I dont know. For example if they wanted a neat recessed hole for a power antenna they would weld a tube into the fender and then cut the part hanging off on the outside to the shape of the fender. This would give them a pocket that looked like a gun port.

Barry

[WannaFlyJets]

That's a great technique, Thomas! thanks for sharing that one. I think maybe to do the same thing on a larger scale one would have to use something as a core to wrap around with the depron before bending the tube so you wouldnt risk collapsing it. I guess sort of like creating a "Mandrel" bend in a depron tube. Id love to see your method for creating a nosecone like you described.

Ive taken a picture of a piece Ive experimented with using boiling water and a roundbottom wok. I think multiple pieces like these over a structure would make a smooth rounded cone.

[clausxpf]

that is real nice to see...a little heat and a form can do the trick.... now I have to take it further.
Claus

[newcomer]

Hawker, where's the C-5 thread ?

[winmodels]

that is real nice to see...a little heat and a form can do the trick.... now I have to take it further.
Claus

Any more results??

Klaus

[clausxpf]

I do hope to have some results tomorrow.....
Claus

[Bryce From Nice]

the link for hawker's c-5 galaxy :

c-5 galaxy (http://www.rcgroups.com/forums/showthread.php?t=214286)

[Ed Waldrep]

As for forming nosecones or other parts with compound curves (in other words, parts that have a curve in more than one direction, like say a cereal bowl, vs a coke can which for the most part doesn't have any compound curves), you could sand a plug for the part out of a block of foam, then form the depron piece around that. But then, you might just use the block of foam to carve the piece out of and use that to save some work! You'd have to paint it of course (if you use blue foam), and depending on the foam it may be a bit soft and need some filler, but blocks of foam can be very useful in making compound curves. I just felt this needed mentioning in case the idea hadn't struck some people.

You can order 2 and 4 inch thick sheets of Dow blue styrofoam from aircraftspruce.com or local insulation suppliers. The blue comes in two weights, and the heavier one is more dent resistant.

[clausxpf]

Ed you are right..
I too use it for that perpose.
but right now the plaster of paris is "cooking" and I am to make a mold for the fist parts of the wm trainer mrk. 600
I have started with the intake/ main body part as the might be the biggest challange.
Claus

[RNAF]

Here's a nice way to fold depron succesfully.
http://members.lycos.nl/theoschoorl/Folding.htm

You all know this one: rubbing depron along a table edge to make tubes. Even cones are easely made this way.

Happy buildin',
Dave

[clausxpf]

I will come back with a new thread...Claus

[GGRN]

Hi,
A very easy and secure method to bend depron :
1/ Find right sense and face of Depron (on which it's easy to curve)
2/ Roll it between a piece of pipe and ...your belly (small parts) :D ; or a piece of pipe and a soft surface (large parts like wings extrados for ex). Diameter of pipe determinates radius of curve. And, it's done !

[GGRN]

All my models you can see on this website(Rafale, Airbus A318, Martin Marlin and Concorde) are built according this method. It works !

[clausxpf]

can we have some pictures ... please
Claus

[clausxpf]

i will not be double sending and the files do not belong here

[GGRN]

Sorry Claus, you'll not get any pics of my belly :p . Most seriously, i've been RC pilot for 27, but i'm a PC beginner aged of 42 ! I've to learn a lot before i send all pics and pdf i want... Be patient

[monkamarm2000]

I always bake my plaster moulds in the oven at about 450 for 6 hours, that way i can even glass them if I want. Also Ultracal dries out faster than straight plaster and gypsum.

Barry

[Kevin Cox]

GGRN, does some excellent depron work.

Check this one out.....
http://www.rcgroups.com/forums/showpost.php?p=4128802&postcount=11

[Ron Laden]

WOW, I see what you mean Kevin, GGRN that is amazing, you are obviously a master when it comes to forming depron, fantastic.

Ron

[clausxpf]

My compliment´s GGRN...
do you have any pictures building it?
and the "recipie for the finish " please.
Claus

[Trikster]

GGRN, does some excellent depron work.

Check this one out.....
http://www.rcgroups.com/forums/showpost.php?p=4128802&postcount=11
All I have to say... "That is Depron?! (as I look at my little 3mm sheet and wonder how in the heck?!)"

[GGRN]

Thanks for compliments.
Bending depron and "'recipie for the finish" are really easy.
"Secrets for the finish" :
1/ "Think and do simple", as we used to say in my country :)
2/ Elbow grease :p
3/ Right materials (depron, glue, filler, sand-paper, etc...)
4: Build as light as possible (a plane is always too heavy)

For example : I found a special filler for ceiling fissures, based on aqueous and micro-balls solution, adapted to stop-up little holes and -after dilution- to prime surfaces before paint, to smooth-out imperfections (orange-skin aspect of depron). This filler is very light when dry and easy to sand down with fine sand-paper.

I'll try to put some pics in this thread in a month, when i'll be back home after holidays :cool: .
Ciao :)

[chuck George]

This Thread is Great:

Found a site on how to make a wing in ten mins.

http://www.lecun.org/hobby/dzepron.html

[clausxpf]

tried to get it in the right forum .... but no reaction... so this

[clausxpf]

i shall come back in an other forum

[The Jetson's]

Wow, Claus that is excellent work... :)

Eric B.

[clausxpf]

I will make a new forum for development

[roccobro]

WOW! Is there any cracking or splitting with all that formation? Can you tell a difference in flexability after sanding, or does it just "set" better when heat is applied? Good looking stuff!

Justin

[clausxpf]

the sanding gives a little more freedom in the forming and the too much compression in the first attempt is almost gone.
it is so far not for wild 3 d forming that have to be done with several pieces still.
A little down the road I will go into infrared heating and vacum forming just to see what can be done.
But one thing for sure this is not the end of the line, much more can be done, and I will try my best to do it.
Claus

[Thomas Nelson]

Good stuff Claus! Looking forward to seeing more cool stuff too - keep it coming Claus ... and everybody!

[WannaFlyJets]

Nice results!

[clausxpf]

have to do it all over

[clausxpf]

I looked at the tailpart.
"Thats just a job for Madsci guy´s technique"
12 mm alu bar heatgun and there it was.. but one have to have a little tape at the end of the foam
But the one i got out of the process is really ok...

[clausxpf]

Now it starts looking like a fuselage.
But when I start making the model... the WM trainer mrk. 600 it will be in that Thread
Claus

[jmralves]

Claus,
From your experience, Do you think it's possible to do the curved nose cone also with this depron technic?

And what about cowlings?

Jorge

[clausxpf]

That will be on my mind too..
The nose on this model will be first step in that direktion, But I have a feeling that it would take some vacum or a male form heated, and may build up from 4 pieces of foam. But time will show.
Claus

[jmralves]

I forgot to mention "Good work Claus"

Keep us informed :)

Jorge

[clausxpf]

after covering the inside with one coat of glas ( 50 gr/m#) the form is fixed.. and it was surely nice to see that the WM 600 fan just fitted in.
Claus

[Airbuzz]

good idea claus! and that water method looks cool, I've never thought of that.. we tried a hot-air-gun, but the temperature was so uneven so we scrapped all work with heat. I allso tried to mould things in an oven but that wasn't successfull eather.

[fuelsguy]

Claus, Just came across this thread, lots of good ideas.
The boiling water idea I've been using for my pusher jets does a nice job of "setting" the depron once it is shaped to a mold. The work to get compound curves is really pushing the art along. I was thinking along the lines of a female mold with the prebent foam on top, all in a bag with a vacuum source to pull the depron into the mold but with a second bag on top which can be filled with boiling water. I think using the boiling water to soften the depron then pull the vacuum might be a good technique. Have you tried anything like this?

Ivor

[clausxpf]

Airbuzz... it is ivor (fuelsguy) that we can thank for the boiling water idea.
what the boiling water preserves the form, it actually makes it a little over-bend

Ivor.
I do have a vacum surce and I am going to try that too..
But down to the bottom... what really makes the trick is if we can stretch the depron a bit without having compression in the flanches...
I am working on another idea too...now that I can make the foam follow the form more it is simple to make a male model too. if that one is heated in the oven 100-120 degree we might be able to aply the stretch to the depron..and not have much compression.
But I will come up with a full report..
Claus

[clausxpf]

After a couple of days hardning the vernice really gives the 50 gr/#m glas a strength, it is not like depron any more, i think that it would be no problem to handle that model by hand it really fells tough.
The area ruled duct is as usual made by heatformed plastic bottles ( the thin ones) over a simple wooden plug.
It is niece when things comes together as planed...
tomorrow it will be time for the nose parts to be casted, both female and male form .. for heat pressing the depron. I will try a similar process to the heated tube/ bar
Claus

[Thomas Nelson]

Very nice work, Claus. And thanks for sharing!

Oh - I didn't quite understand your comment regarding vernice. Is this a type of epoxy?

Keep the pictures coming - I am looking forward to seeing how you tackle the nose!

tn

After a couple of days hardning the vernice really gives the 50 gr/#m glas a strength, it is not like depron any more...Claus

[gfcermak]

I think he means water based polyurethane (vernice is quite close to "varnish").

[clausxpf]

sorry Thomas..
i mis-spelled it water based varnish, for floors...
and the nose.... me too.... but I have to find a way....there must be a way and I am going to find it....
Claus

[The Jetson's]

Hi Claus,

See I am not the only one who misspells words and names... ;)
I corrected the name in the other thread.

Eric B.
AirX at Home
The Jetson's at Work

[Thomas Nelson]

Got it!

And no apologies needed, Claus. I have nothing but respect for those who post in a language other than their native tongue. A while back I tried PMing in French and got rather frustrated at how long it took to say anything even half-resembling what I had in mind, all the while knowing full well my post was still full of errors. I guess I'm just suggesting you don't get too hung up on spelling and grammar; we all speak the same 'model airplane' language anyway, and I should have caught the connection with varnish.

And I'm offering this comment for all our ESL friends. Would be a shame if fear of being caught by the grammar & spelling police kept some from sharing their methods and results.

BTW, my weekend is more than half free so I am going to have a go at a rolled nose cone too. We'll see if it is worth posting. :rolleyes:

tn

[clausxpf]

it will always be worth posting even when it goes not so good..then we can determin a different way to go... og just ajust a little..
This forum is meant to be an open door to more development, and we all know... there will be many dead ends.... but the more sweet is the good ones..
Claus

[clausxpf]

it is a little hot here at the moment ... so I got a little lazy
decided to make a male plug from the body part... It is a little rough but to show if it works it will be ok..
I have to dry it out... but tomorrow it should be able to go into the oven and be heated to a 100 degree C.
then I will try it out both on pvc foam and depron.
Claus

[clausxpf]

I have just put this plug into the depron in the form....
it was heated in the owen at 150 degree c. for one hour..
10 minutes from now we will know the result..
Claus

[clausxpf]

I just opend it.... and it works- but a bit more open than the boiling water tecniqe.
looks like we have to combine those two tecniqes.
Claus

[clausxpf]

it works...
I just let it cool down for an hour or so.... and you will see the result.
Claus

[clausxpf]

it looks like it can be done good...
Claus

[clausxpf]

a little ajustment of the male plug and it will do the job.
ok this is moderate 3 D forming but now we know that it can be done without too much throuble.
Claus

[clausxpf]

just take a look
Claus

[AirX]

Nice work Claus...:)

Eric B.

[clausxpf]

for those who would like to see the trainer come to life look at the wm trainer mrk.600 thread.
Claus

[CHEF-UK]

anyone know of a way to waterproof EPP so that water can not get inside it, I am building one of these new hydro planes at the moment and some people say that when you run it on wet grass or on the lake etc water gets in through the tiny holes in EPP and stays there. What products or way is there to stop the water being absorbed into the EPP ?


Many thanks

[clausxpf]

Water based varnish preferebly with a thin layer of woven fiberglas.
Claus
ps car wax or mold release wax can do the job too.

[CHEF-UK]

Thanks but would that add much weight, not adding much weight is the key to the holy grail

[clausxpf]

chef-uk...
then just leave it as it is an let it rest between flyings ind the sun upside down.. Then the little water it is able to absorb will disapear..
Claus

[clausxpf]

the next challenge is to get the nose done.
I have made the form a little longer than the part to have a little room for not exact cut depron, It can be hard to determin where it shall be cut in the first run.
Claus

[clausxpf]

it can be done ...
heat on a normal piece of depron...and a hot roller.
Then you can have something like this.
as a matter of fact... it is a little over bend but when aplying the coat of glass inside that can be corrected. But the best way to go is the hot male form as far as I know for now.
So my next step will be male forms for the nose.
Claus

[Thomas Nelson]

Now THAT'S what I'M talking about! I never got around to trying this myself, but a male mold is what I had in mind too. Well, not so much a mold as a former to bend the depron around. Good stuff!

tn

[AirX]

Thomas,

It does open up a chance for a much more defined F-16 doesnt it.

Eric B.

[clausxpf]

As you might be able to see .... I have tried to make the body out of a little shorter parts so it is more handy to make in a normal workshop. A model as F-16 can be "cut" tha same way.
by having both a male an a female mold.. and keep the male as the warm part the forming of the depron comes almost by itself.
and being in the female form to preserve the form while the male form cools down.
Claus

[Thomas Nelson]

Sure does Eric. I'm just not sure I'm ready to commit the time to making the molds, though. I have yet to even start my new bird, for instance, nevermind all the behind the scenes effort that goes into the molds.

Keep the pics acomming, Claus!

[clausxpf]

What do you say .... a normal piece of depron.... on top of the form, and a heated roller normally used for getting air out of laminates.
5 minutes at you have got a perfect match to the form... look at the left mold that has been done with the roller, the right one was done with boiling water and the other roller.
the next I do have to try... is a roller without grooves and do it on a male form...... That might work too...
one thing for sure I am going to make me a set of alu rollers ... that can come around.
Claus

[clausxpf]

here you can see how little the wheel makes to the foam....
But i think it might have a stabilation effect on the result.
Claus

[clausxpf]

I broke the first Male mold for the nose...
then I made a new flat roll It works but not as well as the first one.
I still have to try it on a male mold.
but a new experiment had to be done too...
the 3 mm PVC foam ( Divinycell) had to be tried... my first attempt with heat gun and a roller did not turn especially good.
I started to work with the ruller and found that preheating and the hot roller could do the work
Pvc does not collapse the same way as Depron, but needs longer time to setle in the form.. but the advantage .... by the material harder and abillity to use cheap Polyester.
Claus

[Ed Waldrep]

Have you guys thought of building a vacuum former and using male molds? Seems like it would be the easiest to make parts. I don't know how good of a vacuum you need though. Maybe a professional level production machine is needed and the shop vacuum type wont work? I wonder what fantastic models uses on their stuff?

[clausxpf]

Ed ...
that is a way to go.... but my intention was more or less to help the little guy at home to make something 3-d in forming depron.
What I know so far about Depron is that it is very sensitive to to much heat, and the hot roller shall be just undet the temperature where it sticks to the depron.
If you need a little softening af the depron the Hair dryer is better than the heat gun
the parts I have made here are made from out of the box depron.... no sanding and no pre-bend. But you have to work all over the form like en 5-7 steps to have final contact with the form...You can do a part in 15 minutes...
Claus

[gfcermak]

Claus, what is the magical temperature to keep the roller under?

[Hawker]

Claus, keep up the great work!

My C-5 used 6 pieces of depron using Fuelsguy's boiling water method and the fuselage is
so strong. It's great stuff! I like what you are doing too. Don't stop. :)

[clausxpf]

gfcermak.
temperature?? really I do not know... but on a test piece when it draws fine treads from the wheel it is too hot . and when it does not make the groowes eazy it is too cold.
Hawker ....
then try to glass it on the inside.. it is a all new ball game then ..
Claus

[fuelsguy]

Hi Claus,
Glad to see you making progress. Can you add a bit about the roller you are using? Is it electrically heated or what, brand name etc? I've continued to use the boiling water technique for several models now, F-100,Hunter, Mig 15, all work well. I would like to get to compound curves at some point. Your technique looks the best so far. Have you tried a smooth roller over a male mold?
Ivor
Ivor

[clausxpf]

Fuelsguy
#79 shows you the roller .... it is normally put into work when you make boats in glassfiber and polyster..I am sure you can find it at surplyer for boatyards.
I have not tried the plain roller on and male form.... but it will come, and I will try it on a styro form may be with some kitchen aluminium as a protection..
Claus
Ps:those of you that have started experimenting with some of thise tecnices, lets have som pictures.

[Hawker]

Claus,

It already feels incredibly strong as it is. I don't see any need to glass the inside.

[clausxpf]

hawker...
to make the depron a true construction part, even at the high loaded areas. and no or next to no formers.

I look forward to show you wings done this way...
Claus

[Hawker]

Actually with my parts that were made using this technique, there are no formers. Just a
bit of epoxy at the joints and it's rock solid. Gotta love it! Fuelsguy's method is
fantastic. :)

[Kevin Cox]

Have you guys thought of building a vacuum former and using male molds? Seems like it would be the easiest to make parts. I don't know how good of a vacuum you need though. Maybe a professional level production machine is needed and the shop vacuum type wont work? I wonder what fantastic models uses on their stuff?

Excellent work Claus!

Ed,
I have vacuum formed (but not in the normal sense) some small pieces but to do something on the size you have here, at home, doesn't sound like a whole lot of fun.

[duhaas88]

Any more progress Claus??

[clausxpf]

duhass88
The nose parts for the WM trainer is glassed inside with epoxy, It really is very stiff may bee too stiff, and the weight gain is more than doble the depron... might be me that is not too good with epoxy..
But I got some of Klaus Scharnhorst´s stuff.... the HSB system and that is very eazy to control and most of all it is more sticky than varnish the glass stays on so to speak and no air pockets. and best of all 15 minutes and you can go on working on the piece.
I have made the elevators and the ruder with glas on the inside and the HSB sealer ... and I am impressed and satisfied by the result.
Claus

It is my friend Kenneth that holds the trainer.

[duhaas88]

Looking good:) When you did the male and female mold sandwiching, is there any thign that you would do differently? I am thinking of trying this out, making the mold out of foam and then glassing it for use as the Male mold. Any suggestions?

[PlaneCrazee]

clausxpf-
those are some fancy cauls you are using to hold you wings! Isn't that curly maple?

[winmodels]

Hi Claus

for the nacelle of a biz-jet I need some nicely rounded intake lips for the engines. Here is a photo sequence how I went about it.
If you hot wire cut foam pieces without a bow, like you see in the picture, you need a strong wire which does not deform under heat. I found some nifty small flat steel wire in the car windscreen wiperblades. If you exchange the blades don't throw the old ones away - here is a use for the wire in the blades.
The drawback is that you need a regulated power supply wich can deliver around 2V and 10A min. I could imagine that a few old NiCd Cells in parallel and a speed controller does the same.
I think the rest needs no more words.

Have fun with fans

Klaus

[winmodels]

more pictures

[winmodels]

and the rest. Tomorrow I will show the fitting.

[roccobro]

That is slick! I never would have dreamed of something that clever to make the foam inlets. Excellent indeed!

Justin

[clausxpf]

Klaus... that way... if one have a support higher up even the inside of a duct like yours can be made with the right shape.
I had a similar idea for at digging out too on a stick. I wonder if one of those soldering guns would be power enough for that system of yours. It have to be tested.
Claus

[winmodels]

Klaus... that way... if one have a support higher up even the inside of a duct like yours can be made with the right shape.
I had a similar idea for at digging out too on a stick. I wonder if one of those soldering guns would be power enough for that system of yours. It have to be tested.
Claus

Hi Claus

yes, a soldering gun of the transformer type works very well. I didn't think of that last night. I have seen it done. If you buy one from Weller they even have foam cutting tools available.

Klaus