# Pen Kit requires 8mm . . . Can I use a "O" drill bit?



## Weymouta (Nov 22, 2021)

I have someone who would like me to make a "Faith Hope Love" pen (from Penn State Industries}.  This requires the 8mm drill bit.  I have a "O" drill bit.  I have a Pen Reamer that says it fits 8mm and O . . . so does anyone have any experience using a O drill bit for a pen kit that says to use 8mm?  I did print the wonderful conversion chart posted but curious if I need to do anything to make this work.  I know the 8mm drill bit is only $6.95 but curious???  Thanks!


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## KenB259 (Nov 22, 2021)

Yes, there's only about a thou difference between the two. If you want to verify, just drill a hole on a piece of scrap and slide the tube in.


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## Weymouta (Nov 22, 2021)

KenB259 said:


> Yes, there's only about a thou difference between the two. If you want to verify, just drill a hole on a piece of scrap and slide the tube in.


Thank Ken . . . great idea!


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## monophoto (Nov 22, 2021)

According to the iEngineer app on my phone, an O bit is 0.001 inches larger than an 8mm bit.  

The only thing you might want to worry about a little is whether the glue that you use to fix the tube in place is able to bridge the slightly larger gap.  The normal choices of glues are CA (good), polyurethane (better) and epoxy (best) -  since there is nothing better than epoxy for this application, I would probably take that option.


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## Joebobber (Nov 22, 2021)

A 5/16 will work too


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## SabertoothBunny (Nov 22, 2021)

Just get an 8mm drill bit


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## its_virgil (Nov 22, 2021)

I use the letter O bit for 8mm with no problems using two part epoxy. 
Do a good turn daily!
Don


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## Jarod888 (Dec 12, 2021)

If the hole is slightly a larger than the tube and the tube has a sloppy fit, I would use gorilla glue to glue it in. The glue will expand, filling the gap and have the added benefit of centering the tube in the hole.


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## Woodchipper (Dec 12, 2021)

One of the handiest things I have over my workbench is a chart with fractional/decimal equivalents, thread sizes and appropriate drill sizes, drill sizes in metric and English dimensions, etc.
I used Gorilla glue on one pen blank. Never again. It does expand but makes a big mess on the ends of the blank. I'm saving it if I have to glue any gorillas back together.


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