Introducing 14k Gold, read more on the blog.
Home » Community » Post Production Techniques » Molding and Casting
Search Search  
Show: Today's Messages    Show Polls    Message Navigator
Molding and Casting [message #65364] Tue, 02 April 2013 17:06 UTC Go to next message
avatar HMPoweredMan  is currently offline HMPoweredMan
Messages: 10
Registered: February 2013
Go to my shop
Junior Member
I plan on making molds of my 3d models and casting them with resin.
Does anyone have any suggestions or tips for a first time mold maker?

My main concern is air bubbles trapped in my molds. Specifically on my companion cube model.
Also what paints would be best for a plastic model?
Re: Molding and Casting [message #65473 is a reply to message #65364 ] Thu, 04 April 2013 11:41 UTC Go to previous messageGo to next message
avatar Innovo  is currently offline Innovo
Messages: 165
Registered: November 2010
Go to my shop
Senior Member
HMPoweredMan wrote on Tue, 02 April 2013 17:06


My main concern is air bubbles trapped in my molds.


I am not an expert but you can never be certain of the outcome unless you have a vacuum chamber to remove the bubbles.





Innovation & Design

http://www.etsy.com/shop/InnovoDesign
http://www.zazzle.com/innovodesign*
Re: Molding and Casting [message #65515 is a reply to message #65364 ] Fri, 05 April 2013 02:40 UTC Go to previous messageGo to next message
avatar GregP  is currently offline GregP
Messages: 3
Registered: October 2012
Go to all my models
Junior Member
Hi, two main ways to avoid bubbles other than picking them out of your resin with a needle: (been there, bought the tee-shirt Smile
- mount your resin mold on a rigid board on foam rubber. Screw down a small 12 volt electric motor with an excentric weight on the shaft and power it up immediately after pouring. (small 1/4" or 6mm bolt with a cross hole drilled through it to fit the motor shaft. Tighten nut onto bolt/shart and superglue)
- As Innovo suggests, vacuum your mold etc in a wooden box using a cheap 12v tyre pump inside the box with the hose comming out through a tight hole.
- both the above.
The wooden box will need sealing with varnish etc.
Greg,P.
Re: Molding and Casting [message #65532 is a reply to message #65515 ] Fri, 05 April 2013 12:29 UTC Go to previous messageGo to next message
avatar BillBedford  is currently offline BillBedford
Messages: 346
Registered: November 2008
Go to all my models
Senior Member
Just use low viscosity resins.


Bill Bedford
Re: Molding and Casting [message #65538 is a reply to message #65532 ] Fri, 05 April 2013 14:11 UTC Go to previous messageGo to next message
avatar HMPoweredMan  is currently offline HMPoweredMan
Messages: 10
Registered: February 2013
Go to my shop
Junior Member
Thanks food the responses. I don't mean bubbles in the resin. I am talking about bubbles trapped in the mold that might not escape from air vents.
Re: Molding and Casting [message #65567 is a reply to message #65538 ] Fri, 05 April 2013 21:24 UTC Go to previous messageGo to next message
avatar GregP  is currently offline GregP
Messages: 3
Registered: October 2012
Go to all my models
Junior Member
Hi, I assume your problem is that you can't see the bubbles until after the 'rubber' is set. In that case you need to be careful in mixing and pouring it so as to avoid creating bubbles, experiment with pouring at different air temperatures and also vibrate/vacuum to draw any bubbles out. Air temperature might well be your problem - I haven't had that problem to any great extent but then I only work in warm surroundings.
Greg.P.
Re: Molding and Casting [message #65591 is a reply to message #65538 ] Sat, 06 April 2013 00:18 UTC Go to previous messageGo to next message
avatar BillBedford  is currently offline BillBedford
Messages: 346
Registered: November 2008
Go to all my models
Senior Member
HMPoweredMan wrote on Fri, 05 April 2013 14:11

Thanks food the responses. I don't mean bubbles in the resin. I am talking about bubbles trapped in the mold that might not escape from air vents.


You can paint a thin layer of mould material over your pattern to ensure that all the nooks and crannies are filled before you pour the main body of the mould.


Bill Bedford
Re: Molding and Casting [message #65599 is a reply to message #65591 ] Sat, 06 April 2013 02:42 UTC Go to previous messageGo to next message
avatar GregP  is currently offline GregP
Messages: 3
Registered: October 2012
Go to all my models
Junior Member
Hi Bill, 35+ years of casting and I never thought of that - Duhh!
Greg.P.
Re: Molding and Casting [message #65605 is a reply to message #65599 ] Sat, 06 April 2013 04:53 UTC Go to previous messageGo to next message
avatar UniverseBecoming  is currently offline UniverseBecoming
Messages: 791
Registered: March 2012
Go to my shop
Senior Member
All of the above, and one method not mentioned yet is to use air pressure. This is where you put the entire mold in a pressure chamber after it has been filled with resin. This then causes the entrapped air at atmospheric pressure to become highly compressed to the point of not being visible to the unaided eye.

Smooth-On is a good place to go to learn all about materials and methods.




I prefer to know nothing about everything rather than everything about nothing.  

James
Re: Molding and Casting [message #65740 is a reply to message #65605 ] Mon, 08 April 2013 15:53 UTC Go to previous messageGo to next message
avatar HMPoweredMan  is currently offline HMPoweredMan
Messages: 10
Registered: February 2013
Go to my shop
Junior Member
Awesome advice. Thanks again. Smooth-On is where I got my mold materials. Can't wait for my print to arrive to try this out!
Re: Molding and Casting [message #66661 is a reply to message #65740 ] Mon, 22 April 2013 20:04 UTC Go to previous messageGo to next message
avatar Sophie Kahn  is currently offline Sophie Kahn
Messages: 14
Registered: February 2011
Go to my shop
Junior Member
If you are using silicone mold materials (like Mold Max 30, 40 etc from Reynolds) a technique that has always worked for me is to mix up a small amount of your moldmaking material, and 'stipple' on a very thin coat , all over the model. You can use a chip brush that has been cut off about half way. If you apply the stuff thinly enough you will actually see any bubbles that form, and pop them with a fine tool or a skewer. Let that coating set up for a while before mixing and applying the rest of the material.

This should work for both brushed-on glove molds, or poured molds. Hope this helps! I make glove molds from 3d printed parts and have never had a bubble with this method. (I recommend the glove mold technique over poured molds if your object is complex, or has a lot of undercuts.) It should work for urethane also.


http://www.sophiekahn.net
Re: Molding and Casting [message #66752 is a reply to message #66661 ] Tue, 23 April 2013 23:06 UTC Go to previous message
avatar GWMT  is currently offline GWMT
Messages: 196
Registered: February 2011
Go to my shop
Senior Member
There's lots of good advice and help on the Casting List on YahooGroups: http://groups.yahoo.com/group/casting/

 
   
Previous Topic:Best glue, spackle and sandpaper for WSF?
Next Topic:Thorn Dice - Painted