Large Scale Central

Injecting Resin

Tools and Tips
#1

I was just thinking about this. My buddy who makes fishing lures uses syringes that he cuts for funnels to pour his Alumilite resin. Normally for a larger part the resin flows everywhere it needs to go. And I don’t have any experience doing two piece molds for tiny parts. But I would like to make some smaller parts and am worried the resin won’t flow to all the small details without some force behind it. Has anyone used a syringe to inject resin into their molds. Seems if you did it this way you could use fine air relief veins of a very small diameter and force resin to every part of the pattern and the air would be forced out with the incoming pressure of the resin. Isn’t this more or less how injection molding is done but at a more rudimentary level? I don’t want fancy equipment I want simple. If it doesn’t work then I would rather buy detail parts. But seems to me this should work.

Has anyone experimented along these lines?

#2
I tried it once, but never got much out of it.
 
The reason why I didn’t like it was that the syringes didn’t last long (tons of cleanup to re-use), and I could not get everything mixed, injected, and in the pressure pot before the resin kicked.  I was trying to inject several ounces of resin at a time.  Maybe smaller parts would have better luck.
 
If you try it, your mold will need a rigid box (“mother mold”) around it to keep it from deforming under pressure.
#3

Yea, you would have to use a resin with a longer working time, and get some cheap syringes that would be one use and then toss.

#4

Burl,

You mention a pressure pot. I have never used one, but can see the advantages. Now if, in pouring smaller parts I use an extended set time resin and a pressure pot would that suck the air out enough to fill all the voids on smaller parts? That’s my concern, nothing else. If there is no need to inject then thats fine. I just want successful pours on things like brake wheels and thin parts like that.

#5

The pressure pot will eliminate most all of the bubbles, if your mold is properly designed.

#6

I have molded windows for my structures…lots of small mullions and such. my first molds didn’t work well and I had to change the orientation of the windows in the mold. with the windows set at an angle and filled from the bottom and vented at the top , I had quite good success. the angle let each mullion fill smoothly and without bubbles .

Perhaps some thought into mold design will help?

#7

Why doncha try using your vacuum to pull the resin into the mold. Instead of pushing the air out, set up a small box to hold your mold, create a vacuum around it (attach the hose and turn it on) then pour?

I await reports of 100% success, but yours will do too.(http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-laughing.gif)

John

#8

I am not sure how easy that will be to do John. I think using an extended set resin and a pressure pot pulling the air out will be my next attempt. Like Eric and Burl both mention I know proper orientation in the mold and lots of air releases at high spots are the key. After the recommendations here I will waiting on trying to inject it and use that as a next step if I do not have success.

Pouring fine detail parts I know is doable in resin. I don’t need to reinvent the wheel.