Casting Acrylic

[bandkbrooks]

I recently purchased one those kits for casting my own acrylic resin blanks. Has anyone else used this and what did you think about it?

Brandon

[oklahoma red]

Are you sure your kit is acrylic and not perhaps polyester? If the catalyst is methyl ethyl ketone peroxide then you have polyester which is very common. It goes under a variety of trade names in the crafts market such as Castolite.
Less common is methyl methacrylate (acrylic) which uses cyclohexanecaronitrile as a catalyst. (What a mouthful!)
The majority of pen blanks are polyester. There are different grades of polyester and it is widely used in the boat industry as a gel coat.
There is an informative thread running now under "Rhino blanks (polyester).
My experience with polyester (not for pipe stems) is that it has a tendency to be brittle. The amount of catalyst used seems to have an effect on this. It shrinks a bit as it cures and this most likely is inducing stresses. If you follow the Rhino thread you'll note there are some having problems with it coming apart and some that are not.
There are some top name pipe makers that are successfully casting their own stems so it can be done. It is a lot of hassle (trust me) so why not just use cast (NOT EXTRUDED!!) rod stock?
I speak from the experience of having been in the plastics fabrication business for almost 40 years. Working with this stuff is nasty and the stink of the chemicals will run you out.
Chas.

[bandkbrooks]

It does indeed stink. I will double check to see if it's poly. I cast one and it looks really good but haven't had a chance to play with it yet. If it works I have thought about making a mold of some type to cast a "pre-molded" stem just for the sake of playing around and curiosity.

I brought the first cast into the house to dry because it has been cold outside in the garage. I poured a little extra in a "mold" and left it in the garage. The one in the house did nicely. The garage one was still a little tacky after 24 hours.

Brandon

[bandkbrooks]

It does indeed stink. I will double check to see if it's poly. I cast one and it looks really good but haven't had a chance to play with it yet. If it works I have thought about making a mold of some type to cast a "pre-molded" stem just for the sake of playing around and curiosity.

I brought the first cast into the house to dry because it has been cold outside in the garage. I poured a little extra in a "mold" and left it in the garage. The one in the house did nicely. The garage one was still a little tacky after 24 hours.

Brandon

[oklahoma red]

Where would we all be today if we did not experiment and satisfy our curiosity?
Go for it.
Chas.

[DMI]

Oddly enough I have been thinking about resin/amber stems made this way, my concern was the heat generated during the curing process melting the moulding material but then I thought 'hang on they use it for lead and pewter so it should be up to the job'.

If I ever get around to it I'll let you know how it goes.

David.

[bandkbrooks]

Please do!

[bandkbrooks]

Chas, it is poly.

[oklahoma red]

Follow the mixing instructions carefully. Too much catalyst can definitely cause brittleness.
Also, mix slowly and try not to entrain air into it or you'll have fits.
Chas.

[TreverT]

Casting entails taking wads of your cash and burning it, both in the form of initial failed experiments and in the end cost of the useable stock you will eventually produce. That said, I love doing it and have enjoyed making some custom cast rod for my own pipes, because it's nice to have colors and looks that are unique to my brand. The biggest difficulty for me has been getting the mix right - Too often the result is either a rod full of micro-cracks or too many air bubbles stirred into the mix. You might want to get a paint pot - That's what I use to put the rods under pressure and force trapped air out of the mix.

[oklahoma red]

Casting entails taking wads of your cash and burning it, both in the form of initial failed experiments and in the end cost of the useable stock you will eventually produce. That said, I love doing it and have enjoyed making some custom cast rod for my own pipes, because it's nice to have colors and looks that are unique to my brand. The biggest difficulty for me has been getting the mix right - Too often the result is either a rod full of micro-cracks or too many air bubbles stirred into the mix. You might want to get a paint pot - That's what I use to put the rods under pressure and force trapped air out of the mix.

Another way of getting the bubbles out is to do the reverse and put the container in a small bell jar set-up and pull a vacuum on it. Surely everyone has a bell jar and vacuum pump laying around. If not, do like Trever says and spend another wad of cash.
Chas.

[TreverT]

Casting entails taking wads of your cash and burning it, both in the form of initial failed experiments and in the end cost of the useable stock you will eventually produce. That said, I love doing it and have enjoyed making some custom cast rod for my own pipes, because it's nice to have colors and looks that are unique to my brand. The biggest difficulty for me has been getting the mix right - Too often the result is either a rod full of micro-cracks or too many air bubbles stirred into the mix. You might want to get a paint pot - That's what I use to put the rods under pressure and force trapped air out of the mix.

Another way of getting the bubbles out is to do the reverse and put the container in a small bell jar set-up and pull a vacuum on it. Surely everyone has a bell jar and vacuum pump laying around. If not, do like Trever says and spend another wad of cash.
Chas.

I've tried this with a vacuum hand pump, one of the brake bleed kits that will pull about a .25" WC, but that wouldn't do the trick, FWIW. The mixture was too thick for the trapped air to escape under that level of vacuum. I've never had the chance to try a real, honest to gosh vacuum pump this way, though it does leave me wondering if there wouldn't be a thin line between "Too low to have any effect" and "Too high, making the liquid bubble and splatter". That was why I eventually settled on the paint pot, and pressure instead of vacuum.

[oklahoma red]

Yes, one must be careful. If there is a lot of air in the mix it will foam up and create a horrible mess. I use polyester resin as a potting compound in my business. I don't vacuum the stuff very often but when I do I tickle the vacuum slowly with a bleeder valve on the pump. If you give'er hell all at once it you WILL have some icky cleaning up to do.
Chas.