Urethane Molds
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Published on February 25, 2012
Description
Specialty Molds for One-Off Urethane Parts. Made with PLA so parts can be demolded by dissolving the PLA. PLA wall thickness prevents sagging from the heat generated by the Urethane (180degF). Also making PLA molds to make Silicone Molds for more than one Urethane part. Silicone cures at room temperature and molds for molds can be thin walled. PLA dissolving makes life very easy and complex designs can be made.
Instructions
For Urethane parts, build PLA molds with part as space . . .
For Silicone Molds, build part in PLA with outer skin of PLA to support Silicone . . .
PLA selected because can dissolve away, especially for hollow parts as flanges and elbows . . .
For Silicone Molds, build part in PLA with outer skin of PLA to support Silicone . . .
PLA selected because can dissolve away, especially for hollow parts as flanges and elbows . . .
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ronthomp
on
February 26, 2012
said:
What do you use to disolve PLA?
joeserdynski
on
February 27, 2012
said:
Hi, have an old Crock Pot that I heat water to 180degF and just put the part in for about 8 hours (basically overnight while I sleep). It will then crumble to various degrees depending on thickness. Just wanting to stay away from heavy Caustics, Acids and chemicals (Urethane is bad enough). Have to take the time to say that is one excellent looking Dremel Router you made! Will be making one!
imitation
on
February 26, 2012
said:
How do you dissolve the PLA parts?
By the way, ABS can be dissolved, too. Commonly available acetone takes a while and needs some agitation while the nasty dichloromethane is fairly quick about it. Both would work for thin-walled objects, though, and do not attack silicone or PU.
License
More from joeserdynski
Where does one get urethane or pourable silicon?
You can get some hobbyist-quality stuff at smooth-on.com. The more industrial grade materials, you have to call someone or get quotes for.
Hi, Pourable Silicone is available on the web from several different suppiers (there is a cottage industry based on Silicone). You may have a local Polymer Distributor who would gladly offer Silicone and Urethane. Even large companies such as Wanker and Basf will offer polymers in small containers (1 and 5 gallon). Search Goggle and it will provide many sources. We use a local guy here in Florida and he can get the most common to the most exotic materials. Remember you will need an oven for Urethane for post cure and build up wall thickness to prevent sagging for the mold (also exposed mold walls do better than internal mold wall (which have to be the thickest)) . . .