Shrinkage in resin Saver molds

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mick

mick

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Cast my first blanks in my resin saver mold today. I noticed that there was a good bit of shrinkage end to end. That's not really a problem with the Jr series mold but the Since the lower tube of a cigar is critical I mixed up a little more PR and poured it into the mold. Anyone ever had this problem and will adding the extra PR work or will I see a dividing line where the two pours meet?
 
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Hey Mike,

The two will merge quite nicely and no seam should be visible. I've found the shrinkage to be a problem on some pens where the barrel lengths are critical such as the cigar. I thought Charlie had begun to make the slots a little longer to compensate for the shrinkage...or did I just dream that? Although I really like the resin saver molds, I still cast cigar blanks in the mold with slots so I have some control on them.

Do a good turn daily!
Don

mick said:
Cast my first blanks in my resin saver mold today. I noticed that there was a good bit of shrinkage end to end. That's not really a problem with the Jr series mold but the Since the lower tube of a cigar is critical I mixed up a little more PR and poured it into the mold. Anyone ever had this problem and will adding the extra PR work or will I see a dividing line where the two pours meet?
Click to expand...
 
The molds should be long enough to account for shrinkage in properly applied and properly mixed PR.
If you do like I have done, and followed the directions on some of the kits of pr, then you find that the pr shrinks way more than normal. I read the instructions and followed step by step my first couple of pourings, and found out by talking to others later, that you do not pour the proper amount of pr in the cavity then add the required drops of mek after. They need to be mixed beforehand, then added to the mold. I have 10 pr blanks in the basement that are both tapered and shortened:eek::redface:

So, please mix then put in mold

Jerry
 
The mold cavities are 5mm longer than the tubes and so far it's been enough extra
for me.. the original ones were the exact length. Good for alumilite, not so good for PR.

What type of resin are you using? I've been on Silmar41 for a while now and haven't
had any shrink back further than the tubes. Usually I have to sand off the extra.

But yes, you can pour again and it will work just fine.
 
NewLondon88 said:
The mold cavities are 5mm longer than the tubes and so far it's been enough extra
for me.. the original ones were the exact length. Good for alumilite, not so good for PR.

What type of resin are you using? I've been on Silmar41 for a while now and haven't
had any shrink back further than the tubes. Usually I have to sand off the extra.

But yes, you can pour again and it will work just fine.
Click to expand...

Charlie...first I love the amount of resin the mold uses! As for the shrinkage, yeah it's Silmar 41 and I noticed after stripping them out that I had the tube all the way against one wall of the cavity(the end that shrank) I'll pay special attention next time and center the tube. So that ones on me :mad: Another question. I noticed a little resin seeped into the tubes but I was casting under pressure so I'm assuming that forced the resin in? All in all I'll probably get more after our spring shows start any I'm got more "play" money
 
I know that pressure can force resin in, so when I was still using pressure I kept
it low .. maybe 20-25 psi. But after seeing Don Ward's tutorial I switched to warming
the resin and casting without pressure. No leaks or bubbles after that (except for the
labels.. sometimes ..still haven't mastered that one!)
And yes.. centering seems to take care of that. I just nudge the tube with my
fingernail to get them centered. A little oil or vaseline helps them slide easily.
 
Another thing I was wondering. Could amount of catalyst determine how much PR shrinks?
Or outside temp? ie higher temp either from more catalyst or hotter environment causes resin to set quicker thus faster reaction....more shrinkage? Just wondering
 
I haven't had any shrinkage with the temperature, or anything else for that matter. I love the fact that it's warmed up so that they can actually cure in a short time tho. I am loving these molds. will eventually get some pics up.
 
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