Splitting or cracking of acrylic

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denaucoin

Member
Joined
Nov 17, 2007
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147
Location
West Warwick, Rhode Island, USA.
I am having a lot of trouble with acrylic. When I try to assemble the acrylic pens, as soon as I use the pen press to insert the nib or the clip and cap, a crack occurs in the acrylic and it makes the pen unable to be sold. This occurs when all the polishing and finishing is done. I am careful to clean the tubes before assembly, I make sure the nib or cap is going in straight and still the crack.
This only occurs on the real nice pens and has not occured on the slim line and comfort pens. The cigar and the ellegant pens seems to be the problem. Any suggestions would be appreciated.
 
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My first thought is the acrylic hasn't been milled all the way to the tube so when you press your pressing agianst the acrylic.
 
Originally posted by OKLAHOMAN

My first thought is the acrylic hasn't been milled all the way to the tube so when you press your pressing agianst the acrylic.
Click to expand...

My thoughts too. But even a hint of glue inside the tubes can cause this. What glue are you using to glue in the tubes?
 
The press fit is to tight and when the brass expands it breaks the acrylic. Why this happens to you and not everyone else is the mystery. Could be your drilling the hole for the tube to small, your not cleaning either the burr or glue out of the tube before assembly. Or your not putting the parts in straight and they get cocked and crack the ends. The bottom line is there is something you are doing wrong otherwise everyone else would have this problem.
 
I am using ca glue thick, and I clean the inside of the tube, and I may be a little off with the pen press. thanks for all your help, I will go back to the drawing boards and try to be a little more careful.
 
Originally posted by denaucoin

I am using ca glue thick, and I clean the inside of the tube, and I may be a little off with the pen press. thanks for all your help, I will go back to the drawing boards and try to be a little more careful.
Click to expand...

<center>WARNING: PERSONAL OPINION COMING!!!</center>

If it's a horizontal pen press, cast it aside and buy a vertical arbor press. HOW can you keep your parts straight, when gravity keeps trying to PULL them down. When I teach, I am asked to use these presses -- I find them a general NUISANCE!!!!!

<center>YOU MAY NOW RETURN TO REGULAR, VANILLA PROGRAMMING</center>

<center>click</center>
 
All of the above are good suggestions.

IF you have a caliper, measure the inside of your brass tube and the outside of the piece you are installing. Couple thousandths, not much more or it will crack.

Drill a larger hole and use THICK CA, your chances of cracking will be reduced. IF the pens are Jr. Gents, be careful doing this, there is NOT a lot of material LEFT at the centerband and you may "see through" your acrylic as a result of solving your cracking (If it ain't one thing,,,,,,, it's another!!!):D:D:D:D
 
Originally posted by denaucoin

I am having a lot of trouble with acrylic. When I try to assemble the acrylic pens, as soon as I use the pen press to insert the nib or the clip and cap, a crack occurs in the acrylic and it makes the pen unable to be sold.
Click to expand...

The other suggestions are good ones.

Even a tiny bit of glue in the tube ends will cause cracking. Campher the tube ends, and use an exacto knife to clean out any traces of glue.

Some acrylics and Corian do not give even a little. I made corian pens and always expanded the tube ends until the fittings would slip fit into the tube ends. You may need to use a slightly larger drill bit. Check after drilling to make sure the tube fits. Use polyurethane glue on the tubes and then CA glue the fittings to the tubes. Put a drop of thick CA inside the tube, and insert the fitting. Twist the fitting to distribute the glue. Watch out because CA will cause the metal finish to "fog up" or corrode. Allow it to rest open to the air for a day or two.
 
If the tubes don't slide in easily, the hole is too small. The tube has to expand a bit to accept the fittings so if the hole is too small, the material will crack.
 
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