Drilling for tubes- how much "slop" do you want for glue?

[BigguyZ]

OK, I was drilling a bunch of blanks for some 7mm pens I recently purchased. I was using by trusty old 7mm brad point bit, drilling on the lathe. I was finding that the holes I was getting laft a lot of room between the blank and the tube. So, I ended using like an H or an I bit to drill the blanks, and git snug holes that had little or no play between the tube and the blank.

That got me thinking- how much, if any, space do you want for glue between the tube and the blank? Assuming you're not talking a huge gap, would you rahter it be a hole sized exactly for the tube, or one just slightly oversized so there's more room for glue? In woodworking, you want no gaps in the joints you glue up. However, you don't want it to be too tight a fit, because then you have a glue-starved joint, and it may fail.

So yeah, just thought I'd ask the experts what you thought. Haven't had too many issues so far, but I'm always looking to improve.

Thanks!

 

[bkersten]

Don't forget if it's too tight a fit the wood may crack when you put in the nib, transmission, or clip. That's happened to me on the best looking grain ones and then it was too late.

 

[jedgerton]

I've seen cracking in acrylics when the fit was too tight. I also use gorilla glue in almost all cases and it expands when it cures. I like to see the hole large enough that the tube will fall through on its own (no interference). If there is enough play that the tube wobbles around, I would definitely use gorilla glue or one of the expanding polyurethane glues.

Just my thoughts.

John

 

[jkeithrussell]

Sounds to me like your drill bit is dull. You have to apply more pressure to push a dull bit through the blank and that causes a little bit of flex which creates a bigger hole.

 

[rherrell]

.015" is the limit I TRY to stick to.:wink: