Over the years I've used a variety of mandrels and release types. Today it
depends on the size of the grain/mandrel that determines what I use.
For small 38/54 mm grains that I don't do much of, I use latex rubber surgical
tubing with a solid pin inside to help it stay straight but loose inside the
tubing. When the propellant 'cures', I simply remove the solid pin and pull on
the latex tubing...it stretches and peels itself off the propellant.
For 75/99 mm grains I use Delrin rods and a coat of PVA. If I don't have the
PVA with me I sometimes use aluminum foil wrapped loosely around the mandrel.
For 150/300 mm grains I use either Delrin rods or aluminum cases for the
mandrel...for the 300 mm grains I used 75 and 100 mm motor cases as the
mandrels covered loosely with paper followed by either plastic wrap or aluminum
foil.
One thing I can say for easy removal, make sure there are no imperfections on
the surface of the mandrel. Take care of them.
Star or Finocyl mandrels work best for removal if in pieces with a central core
that gets removed first.
On Thursday, October 4, 2018 7:56 PM, Ray Rocket
<dmarc-noreply@xxxxxxxxxxxxx> wrote:
Not sure why, but the last few attempts at casting have resulted in stuck
mandrels. I've never had this problem before. I'm using electropolished
stainless steel tubing for a mandrel, sprayed with Pam cooking spray. This has
worked just fine in the past.
What are you guys using for mandrels and release agents?
