Problem making FG molds!

Problem making FG molds!

Post by NRus78 » Mon, 03 Apr 2000 05:00:00



I just designed a new a/c and made a male cowl mold for conversion to female
mold.  Problem is everytime I attempt to make my female molds I can not get the
male mold out without tearing it up.  (I sculptured it from balsa!)  I have
used the product-PARTALL Paste #2 and PARTALL Coverall film as recommended (10
coats of wax and several coats of mold release-still eats up my male sculptured
mold.  I'm sure the products I'm using are good products-I'm the one who is
screwing them up!  Could use some comments from a fiberglass gooru (Tried
several fiberglass suppliers-don't seem to want to respond!) as to what I'm
doing wrong?  Help!  Norm (RedLead1)
 
 
 

Problem making FG molds!

Post by MGA4Ger » Mon, 03 Apr 2000 05:00:00


Norm,

What shape is the cowl?  Are you trying to make it a one-piece mold?  Be sure
the draft on the plug does not "lock-in"  the female mold.   Even on a round
cowl it is best to make a two piece mold.  There needs to be some
flexibility(either the male plug or the female mold) to get the part to
separate.  If the plug is solid balsa and the mold cures rigid, it is not
likely to release without breaking one or the other.  Although I have not used
the release system you describe,  I don't think  it is the problem.  

Gerry G.

 
 
 

Problem making FG molds!

Post by NRus78 » Mon, 03 Apr 2000 05:00:00


I started with some easy wheel pants-left overnight, balse male mold had to be
dug out?  Balsa mold had plenty of relief.  Do I need to take the male mold out
before it fully hardens?
 
 
 

Problem making FG molds!

Post by A.T. » Tue, 04 Apr 2000 04:00:00


check =
http://www.cstsales.com/fiberg0.htm
regards
Alan T.
Quote:

> I just designed a new a/c and made a male cowl mold for conversion to female
> mold.  Problem is everytime I attempt to make my female molds I can not get the
> male mold out without tearing it up.  (I sculptured it from balsa!)  I have
> used the product-PARTALL Paste #2 and PARTALL Coverall film as recommended (10
> coats of wax and several coats of mold release-still eats up my male sculptured
> mold.  I'm sure the products I'm using are good products-I'm the one who is
> screwing them up!  Could use some comments from a fiberglass gooru (Tried
> several fiberglass suppliers-don't seem to want to respond!) as to what I'm
> doing wrong?  Help!  Norm (RedLead1)

 
 
 

Problem making FG molds!

Post by pbw.. » Tue, 04 Apr 2000 04:00:00


Norm, make sure the male forms don't have any reversed angles or edges.
if they do you will need a two piece mold. Are you painting your plug or
leaveing it in raw balsa? The plug should as smooth as possible. I use
an automotive urathane paint with good results. I let the paint cure for
a couple of days, then apply 3 to 5 coats of mold release wax. Then
spray on a thin coat of release (PVA). I use partall brand on molds
from airlane parts to 400 sqft. one piece trailer bodies with no
problems.

Have fun;
Rick Mayhew

e-mail me if you have more questions.


Quote:

> I just designed a new a/c and made a male cowl mold for conversion to
female
> mold. Problem is everytime I attempt to make my female molds I can not
get the
> male mold out without tearing it up. (I sculptured it from balsa!) I
have
> used the product-PARTALL Paste #2 and PARTALL Coverall film as
recommended (10
> coats of wax and several coats of mold release-still eats up my male
sculptured
> mold. I'm sure the products I'm using are good products-I'm the one
who is
> screwing them up! Could use some comments from a fiberglass gooru
(Tried
> several fiberglass suppliers-don't seem to want to respond!) as to
what I'm
> doing wrong? Help! Norm (RedLead1)

Sent via Deja.com http://www.deja.com/
Before you buy.
 
 
 

Problem making FG molds!

Post by StarCa » Sun, 09 Apr 2000 04:00:00


Try using a garden hose with the nozzle on to force water between the
male and female parts.  Make sure you wear your swimming trunks as you
can get quite wet in the process.  Note: Works sometimes and at other
times, Well...!
--
Guy Fuller
ICQ# 26561523
AMA 667982

                +++ STARCAD PLANS +++
       National Flying Site Directory/Database
Your site on the Internet for FREE Model Airplane Plans
  Bookmark this site for the fantastic resource it is.
             http://www.starcadplans.com/

 
 
 

Problem making FG molds!

Post by Indigo New » Sun, 09 Apr 2000 04:00:00


This really sounds weird.<VBG>.

--

Cheers,
Jonathan,

and

.

Quote:
> Try using a garden hose with the nozzle on to force water between the
> male and female parts.  Make sure you wear your swimming trunks as you
> can get quite wet in the process.  Note: Works sometimes and at other
> times, Well...!
> --
> Guy Fuller
> ICQ# 26561523
> AMA 667982

>                 +++ STARCAD PLANS +++
>        National Flying Site Directory/Database
> Your site on the Internet for FREE Model Airplane Plans
>   Bookmark this site for the fantastic resource it is.
>              http://www.starcadplans.com/

 
 
 

Problem making FG molds!

Post by NRus78 » Mon, 10 Apr 2000 04:00:00


Thanks Guy!  Since I live in Fl will give it a try!  Also one of the other tips
was to use a clear polly on the balsa before waxing-will try that also!  Norm
(RedLead1)
 
 
 

Problem making FG molds!

Post by Paul Rya » Wed, 12 Apr 2000 04:00:00


I made a fuselage mold, and it ended up with tons of little pinholes-
and the male was torn up- like yours.  But I used it, and what worked
fine for getting out the finished parts was to pour some hot parrafin
wax in the mold, and wipe it out with a paper towel as it cooled to the
solidifying temp.  This filled in all the pinholes and made an
impervious anti-stick surface which parted nicely.  It's not quite the
same situation, but it might work in your case too.

--
   -Paul
   Brea, CA

++ a good crash is no accident++