CA crack on a stamp pen

[george]

Hello everyone !

I thought I had CA finished all worked up, since it works great on my wood pens. Never had a crack, no white spots or other problems ..... but recently I have completed 3 or 4 stamp pens.
I have glued stamps with "non-colour" (??? what would be the right word for that) glue, another layer of this glue and then build up quite thick CA finish (6 or 7 layers of thick CA to hide bumps where stamps lay over eachother).

And I have just disovered a crack on the bottom of one of the pen (it is missing a piece 2x2 mm of CA layer). All other pens are Ok, but it got me worried.

Has any of you experienced similar problems on stamp pens ? Could this be because the CA is applyed to the glue instead of the wood ? Thank you for any advice in advance.

 

[ldb2000]

You say it's at the end of the blank ? any chance you might have done it during assembly ? That is a thick layer of CA and it wouldn't take much stress to crack or chip . Also if you didn't trim the ends after you finished the blanks there could have been extra CA on the end of the blank and it chipped off during assembly .

 

[leehljp]

My thoughts are along with what Butch said. I have had chips, on two or three occasions - all on oily wood. The similarities is that under the stamp, the tube and stamp may not have had good adhesion. From my experience, when the adhesion is not that good, and a thick coat of CA is there, "lifting" can occur and then a chip will come out.

The chip takes place in both examples of what Butch said - during assembly or in squaring the blank with a pen mill - but particularly when the CA is either very thick or has "lifted" and is kinda floating free of the tube.

 

[hewunch]

Is it a crack or a chip? In other words, do you have just a fine line somewhere or is there a chunk missing? If it is the later, then it sounds like you took a chunk of your finish with you when you broke the bushings lose.

 

[george]

It is deffintely missing a small piece of layer. I am in process of making few more of this kind, and will be more carfull when putting them together.

I usualy sand on 400 sand paper ends of the blanks when they are finished (and mounted off the mandrell). Do you guys use a trimmer ? Is this not to agressive method for damaging the finish ? DO you turn the trimmer by hand or in the boring machine ?

My main worry is this: if I give a perfect pen to my customer and he returns after few weeks or month with chipped off CA pen. Can this happen without any "good" reason ( such as dropping on the floor) ?

Thank you all for good advices

 

[RussFairfield]

You may be experienceing one of the problems with a CA finish, and why it may not be the finish for all pens and wood species.

CA glue is a very brittle finish, and the thicker it is the more brittle it is. Pressing in the end fittings slightly expands the brass tubes which tries to enlarge the pen barrel, which puts a tensile stress on the finish. The brittle CA will not tolerate the tension, and it cracks. This is accented when there is a rigid glueline between the brass tube and the wood, and reduced if there is some "give" in the glueline.

Cracking in the wood and the finish is one of the reasons for drilling the next increment larger in diameter and filling the gap with a Gorilla tyle glue. You might try using a Gorilla type glue if this is a problem. The foam in the glueline will compress to some degree, and take the pressure off the wood and the finish.

 

[george]

Interesting .... I have glued few of the tubes with PU glue and few with CA ( I was in a hurry, and could not wait for PU glue to cure). Doe I do not know which glue is in the cracked blank, I will consider this next time.

Thank you again for advices.