mixing epoxy

samuraistuart

samuraistuart

Joined
Dec 21, 2006
Messages
3,158
I'm in a funny mood today, and while I was mixing up some epoxy for a current knife build I thought I would share this tip with you.

If you're in the northern hemisphere, then mix your epoxy with a counter-clockwise motion. If you begin to use a clockwise motion AFTER you've started mixing it counter-clockwise, the hardener will lose it's bond with the resin!

Likewise, if you're in the southern hemisphere, be sure to use a clockwise motion! If you change to CC, then the epoxy will never set.

I hope that tip comes in handy.

Have a great weekend, fellas.

:rolleyes:
 
Texans get bored when there isn't a big storm to deal with. Don't worry, he'll be fine soon.

FWIW, when mixing epoxy, mix it in a cup that allows the resin height to be as much or more than the cup width. Ten, after mixing, pour into a wide flat bottom bowl or wider cup. The depth of the mixed resin controls the cure rate. Mixing in a tall thin container and leaving it there as the work pot will have it set up much faster than desired. It will also get a lot hotter in that type container.
 
Oh it certainly will set fast, as I found out last spring when I was fixing my canoe. The resin set in about 25 minutes and melted a hole in the container.. very annoying.
 
I've recently cut a large hole in the roof of my house and set up a sixty-five foot tall tower with a forty pound precision ground iron ball mounted to a cable with a frictionless carbide ball and socket to use as my own Foucault pendulum. This way, I can make certain that I'm following the appropriate direction of stir. My greatest problem now is making certain to compensate for the Coriolis effect... Any help on this would be greatly appreciated.
 
Every moving object in the Northern hemisphere that is not connected to the ground moves to the right. So as long as you've got your epoxy stationary on the table, you're good to go. But if you're mixing your epoxy in mid air, then you'll need to compensate for the right direction movement. That pendulum sounds like a wicked epoxy mixing machine in it's own right.

Waiting on that storm to get here. Stacy's right....the weather here will drive you mad(der).
 
Samuraistuart's epoxy mixing problem is the result of a little understood physics effect called the Coriolis effect. When in the Northern hemisphere, an unrestrained object will move to the right, or clockwise. Therefore, to insure complete mixing of the epoxy, stir it in a counterclockwise direction.

Matthew, you are on the right track with a Foucault pendulum but you need a magnetized steel ball and a magnetized ductile iron socket. Place the ball in the socket with the magnetic North end of the ball facing the magnetic North end of the socket. The N to N forces will repel each other so you will have a true frictionless bearing. To compensate for the Coriolis effect, simply stir in a counterclockwise direction.

If you have any questions, please ask Stacy. Joke.
 
Matthew Gregory said:
I've recently cut a large hole in the roof of my house and set up a sixty-five foot tall tower with a forty pound precision ground iron ball mounted to a cable with a frictionless carbide ball and socket to use as my own Foucault pendulum. This way, I can make certain that I'm following the appropriate direction of stir. My greatest problem now is making certain to compensate for the Coriolis effect... Any help on this would be greatly appreciated.
Click to expand...

Matthew,
What a great idea. If you get a mixing bowl with an 32.5' arc angle bottom and put a rubber squeegee on the end of the pendulum, it will completely mix all the resin as well as scrape down the sides. Using 65 feet as the length and 40 pounds as the end mass, you get a period of 8.95 seconds. In one full circuit of the Foucault pendulum it would make 9653 mixing strokes. Since it takes 24 hours for the pendulum to complete a full 360° circuit you would either need a special 48 hour cure resin or a lazy Susan to place the mixing bowl on. I would go with the lazy Susan table, as it will add to the complexity of the mixing machine. I would say to motorize the table for 10 RPM and mix for 60 minutes, which would give the mix pot 400 strokes ... which should be more than sufficient .
 
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