Pen blank hole oversized problem

[Novicewoodworker]

I am a newbie at pen turning and am in the process of getting my pen blanks drilled on my drill press. I purchased a starter kit from Amazon.com which included a 7mm drill bit for use on the blanks. I placed the bit in my drill press and ensured that it was square and drilled out several blanks. When I put the tubes in the blanks, it seems as if the holes are slightly oversized and I am concerned about the CA glue will not properly adhere the tube to the blank due to the slight space around the tube. I'm not sure if I'm doing something wrong to cause the hole to be slightly oversized. It's a 7mm bit and the kits I bought are 7mm kits. Thanks.

 

[David M]

what are you drilling / wood or acrlic. if plastic it could be getting to hot , melting . drill at slower speed and clear bit often. if wood is the hold bigger at one end ( Exit end ) ? could it have been tightened off center ? how are you holding the blank ?

 

[ed4copies]

If you use thick or medium CA, it will fill pretty good size gaps.

Welcome to IAP and welcome to pen-turning!!

Ed

 

[randyrls]

Scott; While the instructions may call for a 7mm bit, often the best fit will be slightly smaller. A 115 piece drill bit set is a good investment. I often drill 7mm blanks with an "I" letter bit. It is just a few thousandths smaller. Clamp the blank solidly to the drill press table and drill, then try the tube. If too small, use the next size larger.

The drill bits specified on instruction pages are the closest commonly available sizes, not the best fit. I have a 12.3mm drill bit for one of my most used size pen kits.

There are several drill size charts in the IAP library.

 

[Novicewoodworker]

Thanks for the responses. It is a wood blank and I will try a slightly smaller bit just to see, but I've already drilled out several and glued them. I do not want to waste them so I'll try them on the lathe see how they work out.

 

[Carl Fisher]

Could also be runout in the drill bit or quill on your drill press.

 

[Ulises Victoria]

When I feel the holes are a bit larger than the tube, (my test is if the tube slides out freely, it's too loose.) I use Gorilla Glue. It expands and fills any voids. It's a bit messy though...

 

[nativewooder]

Make sure the drill bit is running true in the drill press. If you do not have it correctly centered you will never drill the size hole you think you are drilling.

 

[Novicewoodworker]

Just out of curiousity, how would I verify the trueness of the bit? I'm not sure how that would be done.

 

[plantman]

Just out of curiousity, how would I verify the trueness of the bit? I'm not sure how that would be done.

Get two pieces of drill rod. put one in the drill press, the other in your blank holder. Run the drill press down so the rods are side by side and see if the rods are even from top to bottom. May be your table needs to be adjusted to 90* Also make sure your blank holder is clamped tight to your table. If this looks good, slide the blank holder away from the top rod and turn on the drill to see if there is any play or wobble in the drill itself. Jim S

 

[Donovan]

You have to start with getting the drill press table square. Place a small metal square on the drill pres table, lower the drill bit and get the square as close as possible to the drill. Now turn the drill chuck with your hand (and we assume that the drill is straight you) you should see no gap between the square and the drill. No mater how hard you try to get a round or straight hole if the base that you put your blank holder on is not square it will not happen. Make sure that the drill pres is not plugged in at the wall socket when you do this

 

[oldstoker]

I use a 6.9mm drill bit, a nice snug fit. I found that on some blanks that the holes were a bit larger using the 7mm drill bit.

 

[NotURMailman]

I quickly got tired of trying to drill good holes in pens with my table top drill press and got the equipment to drill them on the lathe.

Epoxy will fill gaps too, but it is also messy and takes a while to really set up.

 

[nava1uni]

There could be many reasons. One of the most common besides you blank not being square is if you are drilling the hole in one complete drill through. If you are not backing the bit out and clearing the chips the bit can drift from the build up in the hole. Carefully back your bit out and then drill a little more. I usually do this 3-4 times depending on the material and the length of the blank. Doing this will make quite a difference in how out of round or large your hole ends up when finished drilling.