Split in ca at nib end when pressed

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Hi guys. I need help please. I make various pens both acrylic and wood. On wood I sometimes use Chestnuts melamine which gives you a satin finish. people like a ca finish though and yet. I’ve turned my wooden pen, I always clean the inside of the tube especially the ends, then apply ca. Then polish. Then assemble the component parts and here’s my problem. The nib end being the thinnest sometimes splits the ca as the nib connector goes in. It happens every now and then. Interestingly on some of the slimmest pens I’ve made it’s never happened. Has anyone got any ideas, tips? Or is this a reason to stabilise blank first. many thanks, Steve.
 
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magpens

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I just hate my beautifully polished CA finish to crack when pressing the parts in.

Stabilizing can help .... but .... remember that you are putting the wood in tension when you press in the metal nib component.

Wood does not respond well to tension and cracking is the result.

What I do is ream out the brass tube ends by about 0.003"-0.004" using an adjustable reamer, and then glue in the metal part.
This takes time and effort ... I don't like doing it but it is FAR better than seeing the CA crack, or, worse still, seeing both CA and wood crack.
 
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PatrickR

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I’m with Mal. Kits put a lot of radial pressure on the wood. Like driving a large nail into a small piece of wood.
my solution is to sand the ID of the tube. If it’s a wood known for cracking make it a slip fit and use glue.
 

monophoto

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As Mal said, when you press the nib into the brass tube, the tube wants to expand very slightly. This imposes tension across the grain of the wood surrounding the tube, and can lead to cracks.

In theory,this shouldn't be a problem - the diameter of the male portion of the nib should be sized to fit snugly into the ID of the tube without causing excessive expansion of the brass.

In my experience, there are three factors that can cause cracks to appear. One is tapering the wood too much at the nib end of the barrel. Obviously, you must turn it down to match the OD of the nib, but if you keep the body of the barrel a bit thicker, and make the taper fairly short, the wood will be stronger. And by the way, the degree to which this matters probably varies with the species/age/dryness of the timber you are using. Burls, and timbers that have a natural tendency to splinter (such as birch) are more problematic.

Another factor is getting glue inside the brass tube. That reduces the ID which means that the tube will need to expand just a tiny bit more to receive the male portion of the nib, which increases the tension across the grain of the wood. Using a plug to seal up the end of the tube before gluing it into the blank is one solution (dental wax, plasticine modeling clay, or the old standby - a slice of raw potato - make good plugs).

Finally, there is another issue that I think is even more likely. If the nib isn't aligned exactly on the axis of the tube, pressing the nib into the tube will cause the end of the tube to distort and that will increase the likelihood of a crack. DAMHIKT
 

penicillin

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I endorse everything @monophoto suggested above.

In addition, may I suggest that you consider buying an inexpensive deburring tool for the ends of the pen tubes? It creates a tiny bevel at the end of the brass tube that helps guide the parts as you insert them. You can buy one "for pens" from Penn State, or save money by buying the same deburring tool from many hardware sources.
https://www.pennstateind.com/store/MSDEBURR.html
 
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Thanks guys, these are great answers and given me plenty food for thought. What would you do now? Do I strip it and sand it back or rub a little ca over the crack, protecting the nib of course, and hand polish to blend in? Or leave it and give it away?
 

egnald

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In addition to what has already been offered above, I sort of manually press on the the parts to see how tight they "feel" before using my pen press. If they "feel" too tight, I use a chainsaw file to open up the tube a little. I also chamfer the ends and apply a light film of Renaissance Wax to the inside of the tube with a cotton swab - just to provide a little lubrication when pressing the parts in with my press. - Dave
 

leehljp

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Snakewood is notorious for cracking with the slightest stress. I have used flexible epoxy for fragile wood. Even silicone glue allows "give", but it will take a few days to cure.

These are not the best suggestions, but they are alternatives. It has been a while since I ordered any flexible epoxy (Amazon) but it works.

Louie:
Finally, there is another issue that I think is even more likely. If the nib isn't aligned exactly on the axis of the tube, pressing the nib into the tube will cause the end of the tube to distort and that will increase the likelihood of a crack. DAMHIKT
My thoughts were along the lines of Louie's last two lines.
 

jttheclockman

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You got a boat load of answers that would cover everything I would have said. Reaming the ends, trying fir by hand and if too tight file inside of tube for slip fit. I prefer to use blue loctite to adhere parts, wood does not like to be expanded forcefully. Things that come into play here is how tight is that hole compared to the tube slipping in. What type glue are you using. If using a Ca or other glue that is not flexible this will add to problem. I prefer epoxy because it will remain abit flexible and can help. I do as mentioned about reaming and I use Vaseline for slip fitting parts to help slide better. Good luck. As for what you have to me dismantle and refinish again. You will now have a tube that has been stretched so will not have a problem again.
 
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