Depron Cutting and Shaping

Depron Foam
  • Depron (a brand name) is a closed cell  styrofoam foam in sheet form, it is a fantastic medium for building model aircraft, and also a popular medium for architectural model building, as well as model boats and prototype design, available in white and grey colour
  • Thickness available, normally - 2mm, 3mm, 6mm
  • Sheets from - 95mm to 1mtr Sqr
  • There are cheaper forms of foam available but genuine DEPRON far exceeds in quality and consistency and most model builders insist on genuine DEPRON foam light and strong enough for light electric motor battery set ups, the secret to strengthening depron is carbon and light wood rods and strips, light weight push rods & Horns are now available.
  • So this kind of quick and easy model flying is within everybody's reach
  • Depron was successfully used in the 2005 M.A.V. world challenge in Seoul, Korea, and now is the preferred material, depron is the future of ultra lightweight flying model aircraft. 
  • The only limit is your imagination.
  • Developed primarily for use as thermal and sound insulation Depron is very common medium for use in the food industry.
  • Food trays are quite useful if you can find large unused ones to make light weight model parts from.
  • Depron is actually polystyrene (EPS/XPS) plastic and the (EPS) means expanded while (XPS) means extruded.
  • For our purposes, we’re only interested in the stronger, denser XPS Depron which also happens to be closed-cell foam.
  • Open or Closed cell refers to its structure and because open cell (sponge type) foam soaks up all fluids (water & glue) it’s just not suitable for a model plane. 
  • The superior closed cell foam takes much less glue and is easier to waterproof.
  • Its sealed surface adds considerable strength as well as making it very easy to apply non-solvent depron friendly paint or ink finishes.
  • You don't have to worry about grain direction and splitting like with balsa wood, although depron can show a sort of grain on the surface, this is not consistent as this forms as the styrene cures in the manufacturing process, within the core of the sheet the cell formation is consistent,  like balsa wood the inertia effect is quite low and at only 20 grams per square foot, it is considerably lighter than the equivalent 95g psf of balsa.
  • You can paint your depron masterpiece with foam friendly water colour paints, or non-solvent marker pens, always do a test on a scrap piece before committing to your model.
  • With depron the name of the game is experimentation, build yourself established designs, or reach out with your own designs and above all enjoy your modelling.
Color:

  • Originally shiny white. I have seen black Depron in pictures, but it does not seem to be available here in India.
Thickness and dimensions

            White Depron -
           6mm Sheets 100cm x 70cm $22/sheet
           3mm Sheets 100cm x 70cm $15/sheet
           2mm Sheets 125cm x 80cm $12/sheet.
           Grey Depron- 
           6mm Sheets 100cm x 70cm $20/sheet
           3mm Sheets 100cm x 70cm $15/sheet
           2mm Sheets 125cm x 80cm $12/sheet -                                           
  • Here in India, Depron is available in 6mm sheets.
  • Suppliers in India.
         1. Kwality Products © 2012-14, Bangalore (INDIA), http://www.kwalityproducts.in/Depron-                  Foam-14.html,  info@kwalityproducts.in,  ismail@kwalityproducts.in, Mobile : +91 80951                  68552, +91 98450 39850
         Product Specifications
         1 - Brand (Depron) Made In Germany (Without Paper Laminated),
               Minimum Qty to Purchased 2 sheets, Width 400 mm / 15.74 Inch,
               Length 625 mm / 24.60 Inch, Thickness 6 MM, Format Size 625 mm X 400 mm X 6 mm, 
               Density 32 KG Density Per Meter Cube, Color White,
               Format Sheet Form - Rs. 350.00  /  per Sheet
         2 - Minimum Qty to Purchase 1 Sheet, Width 800 MM ( 31.48'' Inch ),
               Length 1250 MM ( 49.2'' Inch ), Thickness 6 MM, Format Size 1250 MM x 800 mm x 6                      mm, Density 32 kg Density Per Meter Cube, Color White,
               Format Sheet Foam - Rs. 800.00  /  per Sheet.
     2.  RcBazaar - Bangalore, 1193, 26th main Jayanagar 9th block, Bangalore 560069
          Karnataka, India, Tel: (+91) 80 41738892.
          LANDMARK - OPPOSITE TO RAGI GUDDA TEMPLE AND CLOSE TO BIG BAZAAR               AND BANGALORE CENTRAL MALL - JAYANAGAR 9TH BLOCK
          RcBazaar - Pune, Shriram yashoda building, Baner road, baner-balewadi phata Pune-45
          Tel: (+91) 020 65006575, LANDMARK: NEAR ORCHID SCHOOL AND NEAR TO                       PANCARD CLUB.
          EMAILS- For Technical assistance please write to support@rcbazaar.com
          For Shipping queries please write to helpdesk@rcbazaar.com
          For Payment related queries / issues please write to payments@rcbazaar.com
          Product Specifications - http://www.rcbazaar.com/category.aspx?categoryid=149
          1. Depron Sheet 4ft x 2ft (for in-store pick up only)SKU: RZ00574
              Please note that this product is for in-store pick up only. Depron Sheet used in building                       planes, Thickness: 5mm (double side laminate), Size: 122 cms x 62 cms (4ft x 2 ft), Qty: 1                   number, Weight 322 gms - India Warehouse Rs 250.00/ sheet
          2. Depron Sheet 4ft x 4ft (for in-store pick up only)SKU: RZ00575,
              Please note that this product is for in-store pick up only. Depron Sheet used in building                       planes, Thickness: 5mm (double side laminate), Size: 122 cms x 122 cms (4ft x 4 ft), 
              Qty: 1 number, Weight: 625 gms, Density: 90kg/m3 - India Warehouse Rs 400.00.
          3. Depron Sheet 8ft x 4ft (for in-store pick up only)SKU: RZ00576,
              Please note that this product is for in-store pick up only. Depron Sheet used in building                       planes, Thickness: 5mm (double side laminate), Size: 244 cms x 122 cms (8ft x 4 ft), 
              Qty: 1 number, Weight: 1250 gms, Density: 90kg/m3  - India Warehouse Rs 690.00


  • I have heard of 1mm Depron being available in Taiwan. I also read that 2mm Depron exists, but have never seen it.
  • Thickness varies slightly (+/- 5%) between sheets of different lots, and even in different parts of a single sheet.
  • The edges seem to be thicker and have a stronger skin i.e. cut your ailerons along the edges.
  • Weight - 3mm Depron sheet (1m2): 120g +/- 10g,  6mm Depron sheet (1m2): 220g +/- 10g.

Glues

  • Depron to Depron and Depron to wood (i.e. balsa): - Gorilla Glue (polyurethane wood glue) works wonders as it fills gaps and has a moderate cure time.
  • "Sader Colle Bois Polyuréthane Intérieur Extérieur", has the same properties as GG but foams slightly less.
  • Parts should be pressed or held together for some time.
  • Polyurethane glue reacts with water, producing a mild amount of foam, filling gaps.
  • Working time is about 5~10 minutes, after a couple of hours it's sufficiently hard for the parts to hold together without further pressure.
  • It becomes really hard after 8 hours or so, and can be sanded together with the Depron.
  • You cannot use generic cyano. I have read good things about Depron-safe cyano with accelerator.
  • Epoxy works well but it's expensive and bothersome to use.
  • Fevicol SH, Synthetic Resin adhesive can be used.

Cutting

  • Depron is easy to cut, but for a neat cut you need a sharp blade.
  • Use a cutter with disposable blades and change blades often, somehow cutting Depron seems to dull blades very fast.

Sanding

  • Depron can easily be sanded.
  • However, sanding Depron removes its skin and weakens it.

Sides

  • Depron sheets have two sides with slightly different properties.
  • One side is shinier and has a slightly tougher skin. This is for example the side that should be used for the outside of a fuselage.

Laminating

  • Two layers of 3mm Depron can be laminated to get a 6mm thick part, using thinly spread GG. 
  • I haven't compared the strength.
  • You can also laminate a mix of 6mm and 3mm Depron to obtain a desired thickness.
Amorphous

  • Depron is amorphous, it does not have "fibers" and will not crack along any specific direction. 
  • But it can easily develop failure lines perpendicular to any repeated bending forces. 
  • It then becomes soft and has poor mechanical properties.

Forming

 
 
 
 

 











Painting

  •  There are some fantastic pictures of what you can do with an airbrush and Depron in some threads in the 3D forum here at RCGroups.
  • I use acrylic (water-based) paint, colored masking tape, sticker cutting coloured sheets and brushes, and results are acceptable, but don't compare.
  • Careful with some spray paints, they'll melt the Depron!   If in doubt, test on a piece of scrap first.
Acrylic Paint
 Colored Tapes and Sticker cutting paper.
Only sticker cutting tape.


Building specific parts

  • Depron wheelpants - http://www.rcgroups.com/forums/showthread.php?t=912271
  • Use Spars for Depron wings using carbon fiber rods or reinforcing Depron parts with CF rods.
  • Embed a CF rod in a Depron wing.
  • The same technique can be used to reinforce stab, elevator, fin, rudder, fuselage, etc.
  • Landing gears can be made with two CF rods and Depron "sandwich". Kaos2 has a post where he describes how to do a "sandwich" of Depron/FFF, GG and CF rods that results in a very strong landing gear. http://www.rcgroups.com/forums/showp...&postcount=534

More on sanding Depron

  • The attached picture is a leading edge of a wing, made of two pieces of 6mm Depron glued using polyurethane glue, and sanded.



  • One can clearly see the glue line, and the different texture between the rounded leading edge that has been sanded and lost its skin, and the shinier Depron skin that has not been sanded.
  • Sanded Depron is very easy to puncture and very soft. Just pressing your fingernail will mark it.
  • So this leading edge will be covered with packing tape, to protect it and give it a smoother surface to reduce drag.

Glue:

  • UHU Creativ or (UHU Por) is working great.It is like a thinner foam friendly version of goop. sticks like mad but stays a bit flexy.
  • To laminate large surface areas together blob some on and rub it around as fast as you can with your finger, you do not need much.I wish there was an easier way to get a really thin full coat other than a finger..maybe use a glove?. 
  • Repeat this process on the other surface and let it dry for about 10 min then press them together with as much force as you can without hurting something.
  • Keep in mind there is not much wiggle room to move the parts around so get them lined up before bonding. 
  • You can use it as a regular glue but you need to hold the part in place and then give it much more time to cure.
  • I like to use foam safe CA WITH accelerator for parts. I need to get just right first then want to freeze them in place. Example: top fuse to wing to make sure it is 90deg.
  • If you do not use accelerator the glue takes forever to cure. Even with the accelerator you need to give the glue more time to fully cure.
  • The accelerator forms a kind of skin and will hold parts in place enough to handle but give it some time before flying.
  • Another method is to put the glue on one side and spray the other with accelerator then mate..that is pretty instant bond then.
  • I have also used 3m 77 spray for gluing plans to the foam and laminating foam together.
  • Light coats from farher away works nicely so the foam does not melt. Let it dry for 5 or 10 min then mate the parts. Coat one side for a temp bond (plans) and both sides for strong bond. Again, there is no wiggle room with this stuff as when you put them together they stick.
  • Low Temp hot glue also works well and I use it for holding in servos mostly but try not to use it as much since it can easily get soft sitting in a hot sun.
  • I have seen quickly fixed parts fall off, But then again that is not an issue unless you leave the plane in the sun....etc..

Carbon ribbon spars:

  • I really like the ribbon spar method. I use 1mm by 5 or 6mm for 6mm Depron and the 1mm by 3mm for the 3mm thick Depron. 
  • If you get unidirectional carbon ribbon they will split nicely in half or 3rds.
  • Just get a blade started at one end and pull the ribbon through...Beware the splinters though! 
  • They do not break down in skin and can hide on the floor easily.
  • I recommend just buying the right size if you can. 
  • UHU one side then the leading edge let dry 10 min then mate.
  • I like to hold the wing down on a flat table with weight then place the ribbon on from one side and work to the other. Since they are straight you can also eyeball hitting the center of the foam edge.
  • I found that Depron can snap easily during a rough landing (section of fuse behind the wing from the whipping action of the tail after catching a wing tip) so I also install a spar on the fuse sides.
  • I can make the same crappy landings without the damage now   This makes for a robust plane without adding much weight.

Hinging:

  • I love single sided taped hinges with a bevel on one side and a straight edge on the other.
  • On a pull pull setup the hinge has to stay put or you get slack or more tension where you do not desire it.
  • This was happening because there is such a small surface area on the bottom .
  • Lay the hinge so it is right where it needs to be (on top of the taped hinge) and then you trace out the hinge with your exacto where you just break the skin of the Depron. 
  • Now slide the knife under the skin Just so you can still see it through the depron and fillet it out. 
  • Check the depth with the hinge and trim off more as you need.
  • You want the hinge sitting right on and in the existing taped hing line.
  • Now you can put some vasalene right around the pins and the parts that move so CA does not get in there and glue it right into the pocket you carved out.
  • Now all the stress on the taped joint is gone and the pinned hinge takes all the heat.
  • Now your hinge line is perfectly lined up and your lines stay at the correct tension.
  • They are sweet and easy to install.
  • Don't throw away the piece that comes off after you cut the 45 deg angle on your control surface..That will come in really handy at times.






 




Bend your depron.
  • You can bend the depron by scoring lines with a blend tool along the length were you want to bend.
  • Use 2" wide tape on top to stiffen depron and avoid cracking.
  • Keep it on the edge of the working table and apply pressure with a flat wooden/iron plate or strip (long wooden ruler will work fine).














  • You can use a hot air gun (hair dryer will do) for bending depron.
  • This Heat It Up method works very well.
  • Be careful, it will damage your depron if you keep it in one place for a while too long.
  • Watch this video - https://www.youtube.com/watch?v=2FJ67LbNFy0


Depron model building tips

The following will help you to get the best from your model building and flying.

  • Always cut the edge of the foam at 90 degrees to the sheet, in order to give a maximum glue contact area, and to keep your joints square.
  • You can buy compresed card board flooring underlay sheets these make great cutting boards
  • You can cut depron with any sharp blade, scalpels and razor blades are best, you can use a fine toothed modelling saw (32tpi or finer) but has a tendency to crumble at the edges.
  • Sanding and shaping depron can be achieved by using fine grit sponge sanding blocks, without rouging up the surface.
  • Increase the strength and rigidity of your fuselage and wing by using carbon fibre rods and tubes, spruce stripwood and ramin dowel.
  • Although 95% of manufactured depron models come with a flat plate wing, it is simple to build a profile section depron wing.
  • Depron can be folded and shaped with the careful application of heat, great success has been enjoyed by using hard wood moulds in warm kitchen ovens to create under cambered and jadelski type wings.
  • The rigidity is not lost in its length, building conventional box section shapes gives good structural rigidity, but the weight is an ongoing factor to remember.
  • Many modelers have discovered Foamboard a graphics and display product that is available at art shops, this is a Styrofoam sheet laminated between white card, although quite strong, but it is also very heavy.
  • Depron can be laminated between thin balsa sheets with glue to form strong yet light sheeting.
  • Depron can also be laminated between fine glass cloth, and wetted through with water based (none solvent) floor varnish or foam friendly 2 part epoxy.
  • For flat sheets make sure all excess varnish has been squeezed out of the work piece with an old credit card or suitable tool, and sandwich between two sheets of glass that has been coated with a release agent (spray the glass hair lacquer works well) what you have is a glow fuel proof sheet of string.
Depron Foam RC Planes.