Reducing technique (the Shrink-Ray!)

The place to discuss all aspects of building models from scratch.

Moderators: Joseph C. Brown, Moderators

Post Reply
User avatar
Alex Dumas
Posts: 750
Joined: Thu May 01, 2003 6:02 pm
Location: Montreal, Canada
Contact:

Reducing technique (the Shrink-Ray!)

Post by Alex Dumas »

I have been reducing kit parts for my current project (the Swift from Space 1999) and some of you have asked for my recipy so I wrote a quick article, here it is :8)

http://scihighmodels.com/howto_shrink.html
Last edited by Alex Dumas on Sat Nov 07, 2009 10:13 pm, edited 1 time in total.
Alex
scihighmodels.com
DennisH
Posts: 2015
Joined: Fri Jul 12, 2002 9:34 pm
Location: location, location!
Contact:

Post by DennisH »

Thank You! :D

I recall someone had a series of formulas posted here a while ago, but the thread must have dropped off the boards, 'cuz I couldn't find it when I went looking for it recently.

Mighty fine of you!



Dennis
Winners don't use question marks!
User avatar
Migmaker
Posts: 990
Joined: Mon Aug 26, 2002 4:53 am
Location: Florida
Contact:

Post by Migmaker »

I see these are open cavity molds, same work for 2 part molds?
Will
If you can dream it, I can build it, and probably already have......:) William
User avatar
Alex Dumas
Posts: 750
Joined: Thu May 01, 2003 6:02 pm
Location: Montreal, Canada
Contact:

Post by Alex Dumas »

Migmaker wrote:I see these are open cavity molds, same work for 2 part molds?
Will
I haven't tried 2 parts molds but it should work.
Alex
scihighmodels.com
Wug
Posts: 2226
Joined: Sun Sep 05, 2004 8:52 pm
Location: Kentucky

Post by Wug »

Thanks,

That's remarkable.
User avatar
Migmaker
Posts: 990
Joined: Mon Aug 26, 2002 4:53 am
Location: Florida
Contact:

Post by Migmaker »

honestly, I've been thinking about this and come to the conclusion that I don't think it will work. This is mainly because in a two part mold, you will have a different volume of RTV back side verses the front, So with that in mind, my best estimate is this will only work for single open cavity molds.
I could be wrong, but I think you will end up with different mold shrinkage rates because of this. I hope I'm wrong though...
Will
If you can dream it, I can build it, and probably already have......:) William
DennisH
Posts: 2015
Joined: Fri Jul 12, 2002 9:34 pm
Location: location, location!
Contact:

Post by DennisH »

Will wrote:
honestly, I've been thinking about this and come to the conclusion that I don't think it will work. This is mainly because in a two part mold, you will have a different volume of RTV back side verses the front, So with that in mind, my best estimate is this will only work for single open cavity molds.
I could be wrong, but I think you will end up with different mold shrinkage rates because of this. I hope I'm wrong though...



What if the mold was poured as one piece and opened using the jeweler's cut method? It would take some skill and patience and might not work for everything, but could have some possibilities???

Just thinking out loud.




Dennis
Winners don't use question marks!
User avatar
Migmaker
Posts: 990
Joined: Mon Aug 26, 2002 4:53 am
Location: Florida
Contact:

Post by Migmaker »

worth a try!...guess I can run some small tests... I've always only done the single pours though myself....I have however, used this little trick for many years so know the process well..
Cheers,
Will
If you can dream it, I can build it, and probably already have......:) William
User avatar
Alex Dumas
Posts: 750
Joined: Thu May 01, 2003 6:02 pm
Location: Montreal, Canada
Contact:

Post by Alex Dumas »

Migmaker wrote:honestly, I've been thinking about this and come to the conclusion that I don't think it will work. This is mainly because in a two part mold, you will have a different volume of RTV back side verses the front, So with that in mind, my best estimate is this will only work for single open cavity molds.
I could be wrong, but I think you will end up with different mold shrinkage rates because of this. I hope I'm wrong though...
Will
I don't think volume matters here. Both mold parts will shrink evenly (loose the same mass ratio) so if they fitted together before shrinking they should still fit correctly after. Still, I haven't tried it myself so I may be wrong...
Alex
scihighmodels.com
User avatar
Migmaker
Posts: 990
Joined: Mon Aug 26, 2002 4:53 am
Location: Florida
Contact:

Post by Migmaker »

right i just meant that there could be issues since the front may contain mor rtv then the back, hope I am wrong though...
Will
If you can dream it, I can build it, and probably already have......:) William
User avatar
Chacal
Posts: 3654
Joined: Fri Jul 12, 2002 3:09 pm
Location: Rio. Always unseasonably warm, even in the Winter, when we'll host the Summer Olympic Games of 2016

Post by Chacal »

This is one of those things that can only be settled by practical experiments.
Sheer elegance in its simplicity.

Political unrest in dictatorships is rather like a round of rock-paper-scissors: The oposition goes on denouncing the regime on the papers, the regime censors the papers, rock-throwing ensues.
Post Reply