Re-drilling a pen blank

[Gralli]

I got myself in a pickle and need some advice and possibly help in rectifying a situation. I have a unique pen blank from a customer. When drilling, I had the wrong specs in front of me and drilled the hole too small. What's the best way to go about fixing this situation. Right now, I'm thinking of just filling it with resin, let it sit for a few days and re-drill at the correct size. Is there a way to safely re-drill the hole bigger? I drilled 3/8 but needed 10mm (about .5mm too small).

 

[monophoto]

Interesting dilemma -

Have you tried to slip the tubes for the kit you are using into the hole? If it fits, the question is whether there is enough space for glue.

As to redrilling, my inclination would be to just chase the 3/8" hole with a 10mm bit. A standard 118 deg twist drill bit will center itself in the hole. I presume the blank is plastic, in which case drilling always presents some risk of disaster. I would think that slowly redrilling using a slightly larger bit would be less stressful on the material than drilling an entirely new hole (you only need to remove about 0.25mm. If you want to be extra cautious and if you have the bits, redrilling in two steps would be even better.

Filling the existing hole with resin creates a bunch of unknowns - what would happen if there were voids in the refilled area? How can you be certain that the refilled area has fully cured?

 

[KMCloonan]

I think you can carefully chase the 3/8" hole with the 10mm. But... make sure your tail stock is locked down. Otherwise, if you engage the larger drill bit with the smaller hole, the blank can grab the drill bit and pull it in, which can result in disaster for the blank. Don't bother asking me how I know this...

 

[Displaced Canadian]

Make sure the 10mm bit is sharp. As was mentioned, if the bit is dull it will turn into a screw and "thread" itself in and blow up the blank. I don't like to name names but new DeWalt bits are famous for this. It's not that much undersized, If you control the feed rate you shouldn't have much of a problem.

 

[boatemp]

All of the above. Just go slow and be careful!

 

[Gralli]

I think you can carefully chase the 3/8" hole with the 10mm. But... make sure your tail stock is locked down. Otherwise, if you engage the larger drill bit with the smaller hole, the blank can grab the drill bit and pull it in, which can result in disaster for the blank. Don't bother asking me how I know this...

Probably the same way I know... That's why I was asking... I chased the rabbit down the hole before without success. I might go super slow and lock it down!

 

[Gralli]

Just an update... Went to 1000rpm and slowly fed the blank. Worked out smooth with some blow out on the back end... No big deal there as I always cut the blanks larger than needed. Appreciate everyone's feedback and holding my hand! Still 10 fingers and damn proud of it!

 

[Curly]

A 1,000rpm? What speed do you normally drill your holes?

 

[Gralli]

A 1,000rpm? What speed do you normally drill your holes?

Actually I was on the 1,000 rpm wheel, but dialed down to about 1/2 speed. So probably more like 500 rpm. I usually leave the belt on the middle wheel for most of my stuff.

 

[KMCloonan]

For what it's worth, I have been routinely drilling my blanks at about 250rpm (248 on my Laguna) for years. I know I can go faster, but I am not in a hurry, and it limits heat buildup.

 

[Painfullyslow]

For what it's worth, I have been routinely drilling my blanks at about 250rpm (248 on my Laguna) for years. I know I can go faster, but I am not in a hurry, and it limits heat buildup.

Same here. 250 rpm for all drilling.