What am i doing wrong

[Inkpen]

When i drill the blank for a sierra tube it is either tight or goes in ok? I use a 27/64 drill size.

 

[Woody]

You may be drilling to fast and the wood getting hot and expanding making the hole to small let the wood cool down then try the tube on a dry run

 

[wm460]

I like to drill my blanks last thing in the evening, the check the fit next day before glueing it in.

 

[Neil]

Whole heap of things! Blunt drills will wobble and create a bigger hole in some woods. Drilling with too much pressure will cause a difference. The type of drill can make a difference as well.

 

[Phil Dart]

Whole heap of things! Blunt drills will wobble and create a bigger hole in some woods. Drilling with too much pressure will cause a difference. The type of drill can make a difference as well.

And for those of us who don't live under a sunlamp, Mark's routine is normally a recipe for disaster. Generally speaking, don't drill a wooden blank unless you are going to glue it up in the same session. The whole in a drilled blank if left overnight for instance, will often go elliptical, and if that is your practice, it may well be your problem

 

[Inkpen]

Thanks for the replies but not sure how fast the drill is set at to be honest, i do know it is fast so i will try it slower to see if this is the cause.

 

[Penpal]

Tim I have not changed my drilling speed for pens ever its how you hold your tongue and join the club mate. Some timbers are mongrel by nature then comes the realisation that innumerable causes have effects, now to isolate them. speed does not become the overriding factor IMHO I drill fast all the time using a variety of drills, for Slimlines Streamlines I useDeWalt Extreme 2 drills getting extraordiary numbers of drillings for each drill. How you arrive at the cause of swelling distortion all the processes have to be examined closely.

There has been a recent question re 6.9 mm drills or 7 mm drills it would appear in your case 6.9 would be horrible. Consistency will rule out variables. Mike your drills. Check your tubes.

Peter.