Expanding PU foam molding / tech from furniture making

[Mustafa Umut Sa]

I am thinking to manufacture most difficult to manufacture shape bass with fastest and replicable method.
I think this is hidden inside of polyurethane hard foam molding which comes from furniture manufacturing.
You make a tough female mold - easily openable - and fill 1/10 of the mold with polyurethane foam base mixed with hardener.
PU foam expands and fill the all mold and harden.
This is fast and extreme easy method.
One thing is important , some of the pu s are producing cyanide when hardening. I dont know how furniture factories work with this , may be there are water based , non poisonous pu. I think there might be.
Acoustically , pu is one of the closest sound producer like western cedar when mixed with carbon cloth.
There are serious research on building classical guitars with pu.

Best ,

Mustafa Umut Sarac

Istanbul

[THIRSTYGUMS]

You seem to have some progressive ideas there mustafa, the thing is handmaking basses and guitars is quite different from industrial production methods.
If you have access to these facilities we would all love to see the results of such experiments with materials and production.

good luck

[Mustafa Umut Sa]

Thirstygums , i have two good news for you. First of all , you can produce very cheap and very fast an extreme design with my method without drinking dust
second news , a good new for a black beer drinker.
there is a web site of porshinger , a glass manufacturer family who is in the business since 1568 at austria. they are the oldest company of west.
They produce beer glass for 3 liters you can tame your thirst with 45 euro glass

[pilotjones]

It seems you are producing a PU foam instrument. Correct? Or, are you lining the mold with carbon fiber cloth, then using the PU to push out the cloth to the form of the mold, then dissolving out the PU? This would be somewhat like BassLab.

[Dusty G]

You sold me, Mustafa Umut Sa! Make one right away, and post pics for us to look at.

[Mustafa Umut Sa]

i found some patents at google patents regarding manufacturing pu foam instruments.
they call the material two component rigid pu foam.
there are two specific patents , one cover 0.3 to .9 gram density pu foam for making , other less than .3 density pu foam body making.
western cedar density is .9 grams.
pilotjones , there is no removing pu at my process. i found a paper at yahoo group on luthiers and stringed instruments , it was telling there is virtually nearly no difference between wood acoustics and fiber + pu foam acoustics.

best ,

mustafa umut sarac

[pilotjones]

Originally Posted by Mustafa Umut Sa

i found a paper at yahoo group on luthiers and stringed instruments , it was telling there is virtually nearly no difference between wood acoustics and fiber + pu foam acoustics.

Have you got a link to that? Sounds interesting.

But keep in mind it probably just represents one man's opinion. Especially since "wood acoustics" is a huge range by itself, with all the different woods.

[Mustafa Umut Sa]

Paper comes from
acoustics sci & tech 23 , 3 2002
acoustic characteristics of unidirectional fiber reinforced polyurethane foam composites for musical instrument soundboards
ono , miyakoshi , watanabe

i m attaching a similar paper , original paper size 187kb and i could not attach. if you want , i can send.

best ,

mustafa umut sarac

[Mustafa Umut Sa]

I think i m wrong in a way. There is no business with foams at this attached paper but carpenter wood glue , if i m not wrong. it is pu also.