Micro crack

[Brumar72]

Hi all,
It happens to me to have micro cracks when mounting the pen parts on the tubes. I make the operation with the lathe so to keep pen parts perfectly aligned, I slightly sand the inside of the brass tube, once taken off the late, to remove any dirt. But the unusual thing is that It only happens (90% of the times) when I use ebony or grenadilla, as terminal parts of a segmentation (like in the photo attached), never happens with other woods. Are those woods too brittle to hold on the minimal expansion of the brass tube when inserting the pen terminal?
Any suggestion how to avoid that? I have a customer asking for a segmented pen like the one in the photo and I'm sure I'll have the same troubles.
Thanks a lot.

Marco

 

[jttheclockman]

I use Gabon ebony all the time and never had a problem with cracking wood. I use epoxy to glue my tubes in so it does have some flex to it. If you are having problems you may want to use a small round file and file the inside of the tube so the components are slip fit. Then use some blue locktite to adhere the parts in tube. This works for most people when they are using woods that are prone to crack.

 

[magpens]

Marco, the suggestion just expressed by jttheclockman is a very good one .......
Namely, before pressing the hardware parts into the finished tube/barrel, enlarge the inside of the brass tube just a little bit, then glue in the parts.

I do things a little different from John, but the purpose and the result are the same .... no cracking even with delicate barrel materials.

I enlarge the interior of the brass tube at both ends so that the parts go in, almost all the way, with hand pressure only.

I do the enlarging with a small reamer. . It is a straight-sided reamer, and it is adjustable ( usable for a variety of brass tubes , and expandable in order to take off more brass as the enlargement progresses ). . A good tool store that caters to metal working should have such reamers.

Then, before inserting the parts, I put a little epoxy glue on the inside of the brass tube in the last 6 mm of the brass tube at each end. . Just a little glue.
The parts slide in and a little tap seats them. . Let the glue harden before doing anything else.

 

[Brumar72]

I use Gabon ebony all the time and never had a problem with cracking wood. I use epoxy to glue my tubes in so it does have some flex to it. If you are having problems you may want to use a small round file and file the inside of the tube so the components are slip fit. Then use some blue locktite to adhere the parts in tube. This works for most people when they are using woods that are prone to crack.

Thanks a lot, nice hint.

 

[Jans husband]

I've had this problem in the past, and I discovered that the end of the blank had not been squared off right up to the end of the tube, and I thought that the wood was taking all the pressure of the assembly process rather than the tube.
Hope that helps
Mike

 

[mark james]

You can also stabilize your end caps before gluing on. Drill your hole, then flood the inside of the blank with thin CA, re drill to maintain the fit. I also would as noted, sand the inside of the tubes for an easier fit. For fussy timbers I also use CA on the outside after a few passes with my gouge - stabilize it as you turn it.

Nice pen!

 

[Brumar72]

Thank you all for the hints. I'll try soon and let you know.