Introduction: Urethane Rubber Molds
Urethane Rubber molds are widely used when a flexible mold material is required and a more expensive or less abrasion-resistant silicone rubber is not desired. However, their use requires careful application of release agents.
To see other mold making videos see http://www.freemansupply.com/moldmaking.htm
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8 Comments
6 years ago
The videos have been removed or moved
15 years ago on Introduction
I wonder if I could pull 29 inches of mercury with a shop vac and a 5 gallon bucket...
Reply 11 years ago on Introduction
Real vacuum pumps are actually pretty cheap on Ebay; I've seen them for under $75.
Reply 14 years ago on Introduction
I seriously doubt it, no matter what brand or model you get. You need a vacuum pump to get that high. Vacuum cleaners are made for high volume suction, not high intensity. Just like the foot bellows pump for pool toys won't inflate your car tires, high volume vs high pressure.
Reply 15 years ago on Introduction
With a big enough Shop-Vac, it might work. I have a big one, but don't have a spare vacuum gauge to test it. Most cars (at least what I consider a real car, e.g. an old V-8 Ford van), will pull about 19-23 inches of mercury. To make work vans for one of my businesses, I tap into the brake booster line and use it to pull steady vacuum on a 300-gallon tank thru standard 3/8" fuel line (other thin junk will collapse). It's enough to suck about fifteen gallons of sewage from a portable toilet in less than 5 seconds. It's enough vacuum that it'll eventually break the welds on a 7-gauge steel tank unless you beef up the ends with quarter-inch steel plate welded onto it. It's also enough to deform, inwards, a steel 55-gallon drum. Hard to believe, from that miniscule amount of "suck" we feel from the end of an auto vacuum line, but it's far more powerful than I ever imagined. Some shop air compressors can also be fiddled with a bit to act as a vacuum pump. I think there is an instructable to that effect ... I know I've read it somewhere. I believe it's especially easy with those cheap little Chinese & Korean 12v auto tire fillers, though it'd take a while to suck any AMOUNT of vacuum (as opposed to just the inches of merc. One thing I've learned about vacuum is that sometimes just the sheer AMOUNT of it is more important than the strength of the "suck."
14 years ago on Introduction
Excellent vid!
15 years ago on Introduction
oh yeah... cool video :-)
15 years ago on Introduction
wow... you sure are posting a lot of stuff.