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Blue Foam Models


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#31 Guest_gonzo_ID_*

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Posted 03 May 2009 - 10:13 AM

Here's how to make a hot wire cutter for cheap:
http://www.instructa...re-foam-cutter/
and here,
http://www.instructa...-parts-availab/

My bluefoam process is:
  • sketch out rough shape and cut near the lines with either a saw or foam cutter
  • take out the chunks and form the shape with rasps
  • sand down with 200 and 400 wet and dry

on some models to take forward or show a client I usually cover in a couple of layers of filler, some more sanding, colour spraying and then lacquer.

#32 Guest_chris albanese_*

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Posted 13 June 2009 - 10:23 AM

You could always try tooling foam, just light weight polyurethane foam. The particles that make the foam are much smaller than non tooling foams, such as insulation foam, so your surfaces will be smooth and the particles "rub" off much easier than "Blue" foam so shaping is painless. Saying that you do need to paint/seal it when your done, to harden the surface, otherwise it could abrade, and mush your surface.

Freeman carries it, I don't think its all that expensive either.

http://www.freemansu...e5020Polyur.htm

#33 Guest_Buff_*

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Posted 13 June 2009 - 12:17 PM

In the UK try John Burn Ltd.

The foam to use is polyurethane based. Ridgid boards by Sika and Ciba Geigy and flexable foams from Plastazote.

Use a VERY sharp knife... VERY SHARP

typical knifes to use are simple and cheap utility knife with a carbon steel blade with a 10 -12 cm blade about 2.5cm wide and 2mm thick

Sharpen the new supposedly sharp knife on a 600 grit diamond based whetstine, these can be bought quite cheap nowadays.

Then between working sharpen you knife about every 30 mins of working, for this iin between sharpening I use a plank of 18mm plywood 2 inches wide and have glued with thin and even film evostick contact adhesive a pice of 600 grit carborundum paper to one side and 1200 grit to the other.

your knife edge should look like chrome electroplating.

On average it take about two to three months to get a knife sharp using it about 4 hours a day, thats a good 5 minuet sharpening every half hour 8 times a day, five days a week for about 10 weeks.... then its sharp.

Such a knife can with practice be used to "chop" off large lumps with a "new knife" for rough shape, a month old knife used to "peel" strips of foam for rough shaping and a 3 month old knife for "shaving" to near net shape.

use old (two or three years old) knives that have been sharpend down to pencil width for shaing small holes and such like (you can grind down a new one if you dont have old ones)

Final finishing before paint can be done with 240/320 grit garnet paper.

Prime with a Tekaloid (Alkyd based) filler primer and leave to dry for at least 3 days (sooner and your sand paper will clog up rapidly) repeat theis process untill you are happy you have zero defects, note, use wet or dry paper with warm water and a tad of washing up liquid, rinse regularly.

undercoat the paint again with alky based undercoat chosen to suit your top coat, eg, blue shade use a blue undercoat, greenshades, green undercoat, light coulors such as white, silver, yellow, use a white undercoat, dark colour such as grey black, brown, use grey undercoat, and reds, use red... simples

Wet sand with wet or dry paper, again use soap and warm water, rinse regularly.

then final coat with a top coat, you can ask the paint supplier to make the paint to your chosen colour RAL, BS, Pantone etc, and you can also specify the amount of gloss.

I would recomend using a nairbrush for all but the largest models,

I plan on making some tutorials and posting them on my blog or perhaps a jamoola site.

I'll post to let you know about them if there is any interest

#34 Guest_angela1983_*

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Posted 29 June 2010 - 12:42 PM

As a prototype maker, for foam part, plastic part and metal parts, we use two differernt ways to smooth surface.
One is sand blasting, second is sand paper with different density.

Just as above guy said, if you hot wire machine to cut foam, the edge will be quite smooth than normal knife.

Hope it is helpful.

#35 Guest_Bowl of Soup_*

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Posted 01 July 2010 - 03:12 PM

That is a great foam link above, thanks for that.

I have used some commercial blue in the past, I recommend a hot wire (hand or CNC). A hand wire is about 40$, replacement wires are about 3$. for the hand wire, the issue is that you need 2 electrical contacts and this limits the size of the tool and the piece you can work with.

Most CNC hot wires are not really restricted this way, and can do larger pieces. There may be hand tools that do not heat with electricity and would be better for larger pieces, but I have no experience with them.

So, for larger pieces, you may be limited to "knives" or larger CNC rigs.

For coatings,

I would seal and spray paint, use an air brush though as the propellant in cans will melt most foams. I would use different paints for different finishes, don't forget that many products on the market have clear hard-coats as well. The more reflective the finish the finer the surface finish needs to be, you can achieve this with super fine grit sanding and layered paint coats.

Don't forget that some Ferrari models have up to 40 coats of paint, don't be scared to layer a bit to get your desired end effect, I would recommend getting an air brush (not a gun).

Hope this helps.

#36 Guest_cubuilt.com_*

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Posted 23 August 2010 - 08:11 AM

A sharp Stanley knife will allow you to cut off some of the smaller bits. Don't try to cut in one stroke, use a sawing motion, very slowly

#37 Guest_ekelrock_*

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Posted 24 August 2010 - 01:16 AM

Sanding certainly takes the longest and often yields the best results in blue foam. I think someone mentioned it before, but it's worth repeating: blue foam has something of a grain. Lightly sanding in one direction will help avoid chunks getting ripped out.

I usually leave the blue foam rough and give it a few solid coats of spackle, then sand that down to a nice smooth finish and paint as desired. I find the spackle is faster and more forgiving to sand...

#38 Guest_porcelain_*

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Posted 25 November 2010 - 03:24 PM

Sanding certainly takes the longest and often yields the best results in blue foam. I think someone mentioned it before, but it's worth repeating: blue foam has something of a grain. Lightly sanding in one direction will help avoid chunks getting ripped out.

I usually leave the blue foam rough and give it a few solid coats of spackle, then sand that down to a nice smooth finish and paint as desired. I find the spackle is faster and more forgiving to sand...


fully agreed

#39 MichelHaussi

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Posted 24 March 2011 - 07:15 AM

Use blue foam dude. Sape with utility nives and files. Finish with finer sand paper. fill gaps with spakle. It will look mint. To glue pieces together, use Super77 spray adhesive, it doesnt melt the foam. Plus, blue foam makes dust thats doesnt get airborne as bad as yellow foam.

Plastic Container, Foam Cups




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