New Products Flash Sale
Thread Tools
Old Dec 30, 2008, 08:07 PM
Psionic001 is offline
Find More Posts by Psionic001
Psionic001's Avatar
Australia, NSW, Sydney
Joined Apr 2006
2,406 Posts
Discussion
How would I mold my own EPP on the cheap...

Just wondering if anyone has tried to mold their own EPP wing on the cheap using cement or other form of mold with epp beads and steam.

If so, how is it done?

Thanx

Matt
Psionic001 is offline Find More Posts by Psionic001
RCG Plus Member
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 31, 2008, 08:26 PM
rudes is offline
Find More Posts by rudes
Registered User
Australia Sunshine Coast
Joined Sep 2007
456 Posts
So many planes should be made of EPP

If I win Gold Lotto Matt your the first person on the pay roll.

I already have the Company name picked out.

http://www.rcgroups.com/forums/showthread.php?t=849430

Rudes
rudes is offline Find More Posts by rudes
Reply With Quote
Old Dec 31, 2008, 10:02 PM
dayhead is offline
Find More Posts by dayhead
SlingWinger
San Bernardino, California, United States
Joined Oct 2004
1,856 Posts
If you want to try molding a foam plane you might consider using either spray can insulating foam or the two-part type.
You could use cement or plaster of paris to make a mold from an existing wing, or use a hot wire cut foam core. You could line the inside of a mold with poster paper and inject either the two-part foam or use the spray can stuff. The spray can stuff needs humidity to cure. The trick is injecting the right amount.

I was thinking along these same lines a couple years ago, but all I did was some experimenting with the spray can stuff. I found you can vary the density of the stuff, If you want higher density, squirt a plastic bag or a box or bucket about 1/3 full and then stir it up as it foams. If you stir it once then let it foam you'll get a higher density, If you stir it again after it foams up again then it will be more dense yet.

I had a balsa fuselage that I used for some experiments. I removed the top of the fuse and put foam straight from the can in it, and as it foamed up I just kept scraping the excess foam off the aft fuselage so that section of it ended up with the lowest density fill.
But in the nose section I kept stirring the foam, getting rid of the gas it makes and increasing the density. When I was done the front half was filled with a very hard and tough plastic that was not very "foamy". I was very impressed with how solid it was. I did no weight measurements. I was working on another project at the time, I would go over to this fuse about every 15 minutes or so and work the foam. It took a lot of time and was rather messy, but overall I enjoyed learning about the stuff.
I always thought about making a female mold of a wing and using the technique to make a wing with varying densities, high density at the front for ding resistance and keeping the cg fwd.

I think if a guy committed to the idea he could make some cool stuff, but you'd have to shop around and try to get a deal on buying at least several cans of it because some will be wasted while you experiment and learn how to work with it. You gotta want to do it just to do it, because you're likely better off just building a good hot wire and going that route.
dayhead is offline Find More Posts by dayhead
Reply With Quote
Old Dec 31, 2008, 10:07 PM
Psionic001 is offline
Find More Posts by Psionic001
Psionic001's Avatar
Australia, NSW, Sydney
Joined Apr 2006
2,406 Posts
Have played around with all this stuff, and while it's easily do-able, I'm looking for a way to DIY EPP.

Why? Because EPP ROCKS!




Quote:
Originally Posted by dayhead
If you want to try molding a foam plane you might consider using either spray can insulating foam or the two-part type.
You could use cement or plaster of paris to make a mold from an existing wing, or use a hot wire cut foam core. You could line the inside of a mold with poster paper and inject either the two-part foam or use the spray can stuff. The spray can stuff needs humidity to cure. The trick is injecting the right amount.
Psionic001 is offline Find More Posts by Psionic001
RCG Plus Member
Reply With Quote
Old Jan 01, 2009, 03:31 AM
rudes is offline
Find More Posts by rudes
Registered User
Australia Sunshine Coast
Joined Sep 2007
456 Posts
Psionic001 these guys are just down the road from me. http://www.sbrcmodels.com/store/agor...ency=currency2
Everyone I know that has bought a plane from them say they are a good bunch of blokes. Will try and get down to see them while I am on holidays and ask a few questions.

There is a guy that lives near me that molds EPP but when it comes to how he clams up (alien technology)

These people are terrific when it comes to buying sheets of EPP 100mm thick or cut into 10mm sheets http://www.polyfoam.com.au/ Brian is the guys name but the rest of the staff couldn't be more helpful.

Will try the pressure pack for fun.

Hooked again
Rudes
rudes is offline Find More Posts by rudes
Reply With Quote
Old Jan 01, 2009, 03:47 AM
Harpye is offline
Find More Posts by Harpye
Build it again, Sam!
Harpye's Avatar
Germany
Joined Oct 2004
4,095 Posts
As you probably know ... EPP is in need of a special kind of mold ... with a steam chamber allaround you could try to make this of several resines but
result is that the form will degenerate within few molds - TOO EXPENSIVE...

Check out the FAQ on the JSP ( Manufacturer) EPP Pages!!!

The other way I you could use is to 3D CNC mill it from the block ... Much effort but it should work.... but... NO mass production in respect to the effort!

OR YOU SHRINK YOUR DESIGN TO DISCRETE ELEMENTS AND STACK THEM FOR HWC...

This is what I did!!



MIG 3 Maidenflight (1 min 9 sec)
Harpye is offline Find More Posts by Harpye
Reply With Quote
Old Jan 02, 2009, 05:55 AM
DaOldGuy is offline
Find More Posts by DaOldGuy
BANG IT!!!
DaOldGuy's Avatar
United States, PA, Bellefonte
Joined Dec 2007
13,036 Posts
The Company I work for uses Polypropylene to make our products, at several of our plants. The Polypropylene pellets are delivered by Train and stored in 50+ foot silos. If I had the machine to make EPP, I think I could come up with a supplier for the raw product.

I think the equipment cost is prolly worst then the tight lipped industry of not sharing the information.

Ron
DaOldGuy is offline Find More Posts by DaOldGuy
Reply With Quote
Old Jan 02, 2009, 04:28 PM
Gene Bond is offline
Find More Posts by Gene Bond
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
The plastics industry in general is paranoid about manufacturing secrets. I have signed non-disclosure agreements with dozens...

There's not any real magic, except maybe in the formulation process. The extrusion, moulding, etc, is all pretty much the same.

Yes, equipment is expensive. But, somewhere a few years back, there was a video floating around, I swear from Multiplex or Robbe (German, anyway, I believe) of an Elapor or somesuch part being formed, and it looked like pretty simple molds. Since the material we desire is relatively low density, you'd think the pressures would be fairly low. Maybe wood would hold it?
Gene Bond is offline Find More Posts by Gene Bond
Reply With Quote
Old Jan 02, 2009, 05:45 PM
DaOldGuy is offline
Find More Posts by DaOldGuy
BANG IT!!!
DaOldGuy's Avatar
United States, PA, Bellefonte
Joined Dec 2007
13,036 Posts
Quote:
Originally Posted by Gene Bond
Since the material we desire is relatively low density, you'd think the pressures would be fairly low. Maybe wood would hold it?
I some how thing the steam process, if I understand correctly is used in this process, would have to be some really good wood and have some mold resistance. things like that may come into play. I am in the Security Group <computer side> and from a facilities stand point, visitors and cameras and such are banned from the manufacturing areas, the machines our company uses can be purchased <german made> all day, it is the technique, mixes, pressure and such that you mentioned Gene, that is very tightly protected.

This is bound to be why most hobby foam sellers just buy in block and slice to order, way too much overhead. Unless you have been in the buisness enough to know those dirty little secrets, you may end up spending tons of money, and tons of bad product.
DaOldGuy is offline Find More Posts by DaOldGuy
Reply With Quote
Old Jan 02, 2009, 06:23 PM
Psionic001 is offline
Find More Posts by Psionic001
Psionic001's Avatar
Australia, NSW, Sydney
Joined Apr 2006
2,406 Posts
I have spoken to some manufacturers in the past about mold set-up.

They use aluminum moulds and prefer to make the moulds themselves.
They drill them out with many holes throughout the surface and insert brass steam injectors. If you have a look at any epp moulded products you'll see them on the surface. Ming from windrider here at RCG is the expert in this process.
I'm unsure of the "pre-expander" process.
The raw beads need to be injected into the empty cavity and they are blasted with steam. I believe the heat activates/melts the surface of the beads and as they expand they stick to eachother.

I understand that there are limitations to the thickness of a part and that's why sheets are "generally" 50-60mm thick. I've seen sheets at 100mm thick, but apparently there are density issues between the surface and the centre of those sheets and sometimes the centre material does not get activated adequately.

I would also assume that for high turnover applications, the aluminium molds would have to be embedded with some form of water cooling like copper tubing glued into a routed channel.

I think the steam would kill a wood mold very quickly, no matter how it was surface finished. A viable alternative to wood and aluminium could be aluminum impregnated resin. This could be reinforced with steel beam for larger surface applications like wings.

If someone has access to some raw material, it would be fun to experiment with it.

Here's a page with mold pictures:
http://www.groupe-empreinte.fr/mmi/eps-epp-epe-en.php

Matt
Psionic001 is offline Find More Posts by Psionic001
RCG Plus Member
Reply With Quote
Old Jan 02, 2009, 06:45 PM
DaOldGuy is offline
Find More Posts by DaOldGuy
BANG IT!!!
DaOldGuy's Avatar
United States, PA, Bellefonte
Joined Dec 2007
13,036 Posts
Some 12 years ago I owned an Autobody shop, I knew nothing of foamie airplanes then. I literally threw away large amounts of EPP foam. The Auto industry started using Molded EPP fillers between the Structured ABS Plastic bumper and the molded, painted, exterior bumper fascia. This offer them the 5mph bumper requirement, while they had a very light weight filler to hold the bumper fascia in its correct shape.

Some of these were 10 to 12 inches wide, 6 to 8 inches deep, and 60+ inches across. I have to think a guy could get a few wing core and a fuse or 2 out of each. If I only knew them.

Those molds are very impressive and I am sure their cost is almost as grand. If you think about it, steam is an easy thing to reach, controlling it safely and suppling it on demand in the right scales could be a process in its self in both cost and use. Historically I think these threads pop up every few months, it doesn't seem to ever make it to a project that has shown any fails or wins.
DaOldGuy is offline Find More Posts by DaOldGuy
Reply With Quote
Old Jan 02, 2009, 08:27 PM
tymbrewolf is offline
Find More Posts by tymbrewolf
Registered User
Joined Feb 2007
3,657 Posts
Lots of info to wade thru here http://answers.google.com/answers/th....html#comments
tymbrewolf is offline Find More Posts by tymbrewolf
Reply With Quote
Old Jan 03, 2009, 08:06 AM
grouchy1 is offline
Find More Posts by grouchy1
Registered User
grouchy1's Avatar
Edison, NJ
Joined Mar 2005
1,044 Posts
Anyone know if EPP can be cut with a hot wire?
grouchy1 is offline Find More Posts by grouchy1
Reply With Quote
Old Jan 03, 2009, 08:14 AM
DaOldGuy is offline
Find More Posts by DaOldGuy
BANG IT!!!
DaOldGuy's Avatar
United States, PA, Bellefonte
Joined Dec 2007
13,036 Posts
Quote:
Originally Posted by grouchy1
Anyone know if EPP can be cut with a hot wire?
It can be Saw Cut or Hotwire cut.
DaOldGuy is offline Find More Posts by DaOldGuy
Reply With Quote
Old Oct 19, 2010, 06:50 PM
hoozee is offline
Find More Posts by hoozee
Registered User
Joined Oct 2010
2 Posts
hello dear , could you succeed in injecting EPP ?
hoozee is offline Find More Posts by hoozee
Reply With Quote


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
How do I get my pinion gear on my razor? Fiasco Power Systems 7 Nov 26, 2003 04:29 AM
How do I make my own decals? PDX Slope Pilot Electric Plane Talk 11 Apr 13, 2003 12:28 PM
How do i build my own Jet neophyte Electric Ducted Fan Jet Talk 1 Feb 19, 2003 10:55 PM
How do i make my own hot wire rig? PunkerTFC Electric Plane Talk 21 Apr 22, 2001 09:50 PM