Drill Bit Shrinkage...

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Dutra

Dutra

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Well maybe it didn't shrink but it seems like it did...

I have a large order of pens Ive been working on. I drilled and glued the tubes into the first 10 or so pens, everything went fine.

Then after drilling more blanks, the tubes are fitting ridiculously snug in the blanks, so much that I need to file the blank out to get the tube to fit right. I was using a 7mm colt drill bit and it was fairly old so i ordered a new one. The problem still exists...

This is strange cuz the first pens I did drilled out fine, Ive been using the colt 7mm (not the pen makers bit, which I here is too long to be any good) since I first started turning, it has always worked good.

Anyone have any Ideas as to why this would happen?

I thought it could be my drill press, but wouldn't that make the tubes fit loosely, like if it was from a wobble or something? :confused:

Sorry for the long windedness...
 
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Do you have a set of Calipers to check the bit against the OD of the tubes? If the tube is larger maybe you can bump it up to a larger bit. I have gotten 3/8" tubes from PSI that were smaller than WC's 3/8" Tubes. This was an ID issue for me and I was not able to use my tubes from PSI to replace the WC tubes, had to run to WC and buy some of theirs.
 
Thanks for the idea on the bit.

Also I have tried with kits from WC and some from smitty. Both were really too snug.
 
Sounds like the bit got a little dull , one flute more than the other and then the bit starts pulling, Wandering", to one side actually putting a slight curve in the drilled hole. This makes the tube (which is straight) fit really tight if it even goes all the way. If the tube starts each end, but gets tighter as it goes, this is most likely the problem. My cure was a Darex drill sharpener.
 
If you drill at high speed, wood heats up pretty good. After you let it cool a little, it shrinks. This is especially true of wood that isn't perfectly dry. When this happens, just re-drill the cool blank and advance slowly.
 
Also, I like to use a gun cleaning brush mounted in the drill press to help those absurdly snug fits out. I have that problem with my 10mm pieces. Brand new bit. You just want to move fast to avoid over-doing it.
 
shrinkage

Robert111 said:
If you drill at high speed, wood heats up pretty good. After you let it cool a little, it shrinks. This is especially true of wood that isn't perfectly dry. When this happens, just re-drill the cool blank and advance slowly.
Click to expand...

Robert said it, so no need for me to repeat it.

Butch

p.s. He's right by the way
 
Dutra said:
Well maybe it didn't shrink but it seems like it did...

I have a large order of pens Ive been working on. I drilled and glued the tubes into the first 10 or so pens, everything went fine.

Then after drilling more blanks, the tubes are fitting ridiculously snug in the blanks, so much that I need to file the blank out to get the tube to fit right. I was using a 7mm colt drill bit and it was fairly old so i ordered a new one. The problem still exists...

This is strange cuz the first pens I did drilled out fine, Ive been using the colt 7mm (not the pen makers bit, which I here is too long to be any good) since I first started turning, it has always worked good.

Anyone have any Ideas as to why this would happen?

I thought it could be my drill press, but wouldn't that make the tubes fit loosely, like if it was from a wobble or something? :confused:

Sorry for the long windedness...
Click to expand...

Hahahah, that's not a LONG windedness, I do a much better version of those, all the time...!hahahahah:eek::biggrin::wink::smile-big:

Well, the question I would like to ask is, were the blanks the same wood as the first lot or different...!
All the suggestions given before by other members are truth and may apply, I tent to believe more in the fact that the last blanks you did are from a different wood and I'm wondering of their MC% (moisture content),as some woods do react badly with high humidity days, particularly if they are either too wet or too dry. Yes, that's right, woods that are too dry, some can give reading of 2% MC or less, in a environment that all of a certain becomes 60 to 100%MC, will make that extremely dry wood to "soak" humidity making the wood to expand.

Cheers
George
 
different wood

I have seen this kind of thing. I tend to think that it is [a] as many have said, related to moisture content and drilling speed or less likely, it could be slightly oversized tubes but you've said you had the same problem with tubes from different sources, [c] even less likely, I suppose it could be a slightly undersized bit but I believe you said you had the problem with more than one bit.

While all tubes are not created equal, the o.d. should be the same within a fairly small tolerance at slightly less than 7.000mm. Drill bits should be within a pretty tight tolerance around 7.000mm I would guess in the third decimal place.

Given all that, I would suspect [a] above.
 
No Spandex

ed4copies said:
Smitty37 said:
I usually expand (weigh more) when I get out of the pool.:biggrin::tongue:
Click to expand...


Don't DRINK the pool, SWIM in it!!!:biggrin::biggrin::biggrin:
Click to expand...
Actually it is my swim trunks, which carry at least 2 or 3 pounds of water out of the pool when I leave (I refuse to strip and ring them out to put the water back:biggrin:) - I'm thinking about getting a spandex for just that reason. I do try not to drink it and I put out of my mind what all those 3 and 4 year old preschoolers do in it, just in case I do get a mouthful:mad::mad:
 
WHOA there sparky!!!!!! Smitty in a speedo.

Smitty37 said:
ed4copies said:
Smitty37 said:
I usually expand (weigh more) when I get out of the pool.:biggrin::tongue:
Click to expand...


Don't DRINK the pool, SWIM in it!!!:biggrin::biggrin::biggrin:
Click to expand...
Actually it is my swim trunks, which carry at least 2 or 3 pounds of water out of the pool when I leave (I refuse to strip and ring them out to put the water back:biggrin:) - I'm thinking about getting a spandex for just that reason. I do try not to drink it and I put out of my mind what all those 3 and 4 year old preschoolers do in it, just in case I do get a mouthful:mad::mad:
Click to expand...
 
Haynie said:
It is cold. A certain amount of shrinkage is normal. Like when you get out of the pool.
Click to expand...

from my brain to your keyboard...

while being 44 and a rather seasoned individual in worldy events...

I am still a damn juvenile at heart and a delinquent one at that.

But to the point of the poster, I am betting that you may have wet wood? I've had a few I had to go back and re-drill...which is why I now check them ALL before putting glue on a tube.
 
Always try to drill at low speed. Just doing that solves most drilling issues. Otherwise, the tubes could certainly be slightly oversized, the drill bit could be slightly under what it says <unlikely though>, or many other things, but the highest probability is just drilling at too high a speed.
 
Drstrangefart said:
Also, I like to use a gun cleaning brush mounted in the drill press to help those absurdly snug fits out. I have that problem with my 10mm pieces. Brand new bit. You just want to move fast to avoid over-doing it.
Click to expand...

Awesome idea there Doc....I have been using a rat tail file, but you have to be very careful to not drag the file on the edges. With all the calibers of brushes available I bet you can cover a mirad of hole sizes. I am going to try that.

and to Smitty, spandex?.....really?
 
If the relief behind the cutting edge is flat, you can use a small sharpening stone, perhaps Arkansas hard, and hone just the flats. Very easy to do if that surface is flat and not inaccessible due to outer diameter cutting points.
 
I'm reminded of some cherry burl blanks that I was working with a while back. I drilled several of them and glued a few with no issues when I got called away. I returned to the job several days later and found that a number of the untubed blanks had twisted and were unusable. D'Oh!
 
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