Smaller Diameter Holes

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TonyL

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I am sure many of you know this (and already practice this) and this may be published somewhere else. After buying drill set with letter, Imperial, and decimal drills (cheap set from Amazon), I started experimenting with making holes slightly smaller than the kit instructions. I have even reverse painted the blanks and tubes (very light coat of paint - Krylon brand). I only use epoxy to glue..acts as a lubricant. Here is what I started drilling:

Instructions state = left justified measurement. Smaller diameter on the right.

8mm ------> 5/16
3/8 ------> Letter U
10mm -----> 13/32
27/64 ------> Letter Z
12.5mm ----> 31/64

That is as far as I got. Did this with wood, acrylic, and hybrid. The best thing is you can always test fit the tube in the smaller hole. I have found there to be less slop going this route.

For what it is worth.
 
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pianomanpj

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I try not to go too small. If the fit is too tight then you won't have enough adhesive left in the hole, which could potentially lead to failure. I would also be concerned about using CA with a tight fit; may not have enough time to get the tube in before it hardens. Thanks for the conversions, though. I will keep that list handy!
 

magpens

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Good for you, Tony !! .

I also like using smaller-than-recommended holes whenever I can. . But what you can get away with sometimes depends on the material you are drilling. . Holes in some woods have a tendency to shrink after removal of the drill bit. . Plastics don't do that nearly so much.

And, yes, I prefer epoxy over other glues when gluing in the tubes.
 

Curly

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You could also look into metric drill bits. They come in 0.1mm increments, that being close to .004". So a 9.9mm and a 9.8mm would be .004" and .008" smaller than the 10mm bit. The reduction in sizes being more predictable and easier to figure out in your head. Mine at least. ;)
Victor have them and the $25 order minimum would likely set you up nicely for a few sizes.
 

Woodchipper

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I made a HDPE gizzy to insert the tubes. Glues don't stick and I can wipe it off and use again.
FWIW, I had tube go in partway and stop. Ruined a wood blank! Evidently there was a place that caught the tube. Now...I insert the tube before gluing it and inserting into the blank. Insert and let it come out the other end, JIC.
 

dogcatcher

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I turned most blanks between centers to 3/4" or 5/8" diameter drill my blanks. Then the next day I would drill using my collet chuck using a smaller sized bit, let them sit over night, then test for the tube fit. If too small, I used the next size up. Wood changes when you drill it, the heat, and the relief of internal pressures causes wood movement, and it gets worse as you remove the outside down to bushing size. I also scuffed up the brass tubes with sandpaper before gluing them. It took me 3 days to get a brass tube glued in. Glue??? I used either CA or epoxy.
 

ed4copies

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Remember with wood, when it gets warmer, the brass will expand and the wood (if the moisture is reduced) will contract. The result is a crack.

I agree with your premise, but I use it only on "dimensionally stable" materials.
 

TonyL

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You could also look into metric drill bits. They come in 0.1mm increments, that being close to .004". So a 9.9mm and a 9.8mm would be .004" and .008" smaller than the 10mm bit. The reduction in sizes being more predictable and easier to figure out in your head. Mine at least. ;)
Victor have them and the $25 order minimum would likely set you up nicely for a few sizes.
Good point...my set has those too. I think I bought these..not nearly the best. https://www.amazon.com/Piece-Cobalt-Indexed-Storage-135-Degree/dp/B00678HM6E/ref=sr_1_9?keywords=drill+bit+set+115&qid=1567727881&s=gateway&sr=8-9

I usually buy Norseman.
 

TonyL

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Remember with wood, when it gets warmer, the brass will expand and the wood (if the moisture is reduced) will contract. The result is a crack.

I agree with your premise, but I use it only on "dimensionally stable" materials.
I didn't think of that. Thank you.
 

Curly

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Sorry Tony but I think you missed a detail in my post. The 115 piece set you have does not have metric bits in it. It has fractional in 64ths, number and letter sized bits. They cover a lot of ground, even a little overlap, but they aren’t evenly spaced. Metric bits with the 0.1mm increments are evenly spaced making them easier to work with.

In a few hundred years when the US adopts the metric system you’ll get it. Okay your descendants will. ;)
 

TonyL

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Sorry Tony but I think you missed a detail in my post. The 115 piece set you have does not have metric bits in it. It has fractional in 64ths, number and letter sized bits. They cover a lot of ground, even a little overlap, but they aren’t evenly spaced. Metric bits with the 0.1mm increments are evenly spaced making them easier to work with.

In a few hundred years when the US adopts the metric system you’ll get it. Okay your descendants will. ;)
You are right. My set does not have bits in mm sizes. Only a few hundred years.....there is hope. :) Thx for clarifying on the set.
 
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I stopped using cheap drill bits from Amazon and Harbor Freight, and others, a while back. I'm not implying that all the bits on Amazon are cheap, I'm just saying you pay for what you get. I was having trouble with undersized blank holes, drift and a host of other problems. I talked with another turner, who doesn't do pens, and he told me about some bits he uses without problems. They're American made in Wisconsin and they refer to them as ICS bits (https://www.icscuttingtools.com/). The entire bit is HSS not just the tip and I've never had a problem with drift or wasting wood having to oversize it due to drift. I buy just what I need and have great results. They're not cheap but it's worth spending a bit more and not having the frustration of bad tube holes or wasting wood. And the finished tube hole doesn't leave a lot of slop in it, nice tight fits. Plus, they're American made which is a big plus in my eyes. In their on-line catalog the bits I use are on page 170. I buy mine from a small business in Great Falls but unless you're willing to drive to Montana you might want to check out your local tool supply store to see if they carry them.
 

leehljp

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Here is a link to a chart that lists diameters by mm by "tenths" and fractional inches, numbers and letters. And the diameter of each is listed in tenths and half tenths of a mm and decimals to 1/10,000ths.


With this, you should be able to find what is aviailable and pick up a few for your particular preferences.

I keep a chart on my phone and printed out (& laminated) in my shop.
 
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