Pen Mandrel/Brass Tubes

[THOMASB]

Hi all felt better today so to the shed to finish a pen. Tuned it down on the mandrel finished it off went to take blanks off the mandrel OH DEAR STUCK, twisted and turned did get one off, but the other one had to twist off with a pair of pliers, I did not use CA glue.
Any ideas how this happened??
:x :wink:

 

[CHJ]

How tight were the brass tubes on the mandrel when you started?
How tight did you do up the clamping nut, did you by any chance crush the tubes so that they clamped onto the mandrel?

Did you use to much sealer so that it wicked into the tube/mandrel gap, this will show up if you can sand off surplus finish off the mandrel.

Was there any glue inside the brass tubes that has reformed with the heat of sanding?

 

[THOMASB]

Hi CHJ
1) Had to twist them on they did not slide.
2) don't think that happened.
3) Could be the cause, but have done this before with no problem.
4) Did use a barrel trimmer to clear the glue, trim ends.
I do use Titebond Poly which foams and expands, could this crush and make the tube smaller!!!!?
Thanks for the reply

 

[CHJ]

1) Had to twist them on they did not slide.

I would suggest this is too tight, ensure that the tube is clear of adhesive *, check mandrel diameter, best if it is about 0.247" diam, some so called 7mm outer diameter tubes are a little small on the bore diameter.

I do use Titebond Poly which foams and expands, could this crush and make the tube smaller!!!!?

I doubt it would generate enough pressure to influence a tube that diameter.


* Try rasping glued tubes with a length of threaded rod.

 

[THOMASB]

Hi CHJ thanks for the tips have just glued up a Yew blank, will try your tips tomorrow.
:roll:

 

[stevebuk]

Also be careful when trimming the ends that you dont over trim and flatten the tube ends resulting in having to force them on the tube, if you do use a round file inside the tube to remove the burr.