Drill Bits & Glue Joints ??

[Randy_]

There is a current IAP thread that asks for help finding a substitute size drill bit for a missing 7mm bit. After taking measurements on a couple of slimline tubes, there appeared to be several candidates that could be used. The largest was 0.014" oversize and the smallest 0.005" oversize. There is also a bit (H) that is 0.001" undersize and might be used with some gentle reaming.

I am aware of the fact that different types of glue require different joint gaps to develop their maximum strength; but I have no idea what the ideal gap sizes should be. I wonder if some of the problems that folks are having with blanks coming off their tubes is the result of less than optimum joint strength? Anyone out there know what the ideal joint gaps are for the CA, epoxy and poly glues that we use.

As I write this, I have a vague remembrance of an old post by someone.....an engineer, I think.....who was going to do some controlled tests on glue strength specifically as related to pen crafting. The post may have been made on the Yahoo Pen Group site?? I don't remember ever seeing the results of those tests. Anyone recall that post or what the results might have been??

 

[ctEaglesc]

I deally you would want the tube centered in the tube with the most amount of "meat" between the tube and the outer diameter.
In that instance I see where polyurehane has its' UP side.
I think more important is the method used for gluing the tube in the blank.
About a year and a hlaf ago I had the experience of having 3 glued up blanks blow out off the the tubes on the mandrel in one afternoon.
Aftter doing a little investigation I discovered there was no glue on the tubes under the areas where the blow out occurred.
I might have blamed it on the glue joints in the pattern,I am not perfect.
Lou and I discussed these failures on the phone and we came up with method that I now use on just about every blank I turn.It is a little more time consuming but after all the time I put into gluing up a blank I want to do everyting I can to make sure the body of the pen is solid and soound.
Ca has at times gotten bad press about its' strength.What is never mentioned it its' ability to "wick" into the surrounding wood.(Something that other adhesives don't do.)
After drilling a blank I drizzle thin CA into the hole.My theory is if we use CA to harden the blank while turning it( such as aburl with voids or a punky piece of spalted wood, doesn't it make just as much sence to insure the wood inside the blank surrounding the hole for the tube is solid also?)
After I Drizzle the hole with CA I "bore" it out with the same drill bit.I usually turn the DP on and holding teh blank in my hand run it up the bit.
Scuffing tubes.The rougher the surface on the tube the more surface area the adhesive has to bond to.
I hate to scuff tubes.
I now use a method that makes the ROUGH not just makes them shiny.
I use a blet sander to ROUGH up the tubes.I put both tubes on a long handled electricians screw driver.(I have found it needs to be a very sloppy fit)I turn on the belt sander and angle the screwdriver into the dirstion of the belt(if you have it in the wrong direction you will spend some time looking for the tubes DAMHIKT) They will literally "bounce" on the shaft of the screw driver.I reverse the tubes on the shaft and repeat.The whole process takes 15 seconds a set.
<u><b>ALWAYS DRY FIT THE TUBE IN THE BLANK BEFORE GLUING IT IN</b></u>
The last area is glue coverage on the tube.
When I first started turning pens the amount of CA that was wasted on the end of the blank I inserted the tube from would pi$$ me off.
It finally occurred to me that if the glue was on the end of the blank it wasn't IN the the blank.
To circumvent this I now plug the end of the tube with paraffin and put a bead of glue INSIDE the hole.I put less on the tube but I do put some.Now as I insert the tube into the blank I am forcing it IN the hole instead of squeegeeing off the tube.
I cannot remember the last time I had a blow out on a wooden glue up using this meathod.
(Plexiglass and metal? thats another issue)
In answer to your question.
I really don't believe the size of the bit is all tht critical as long as there is enough adhesive on the joint and the surface of the wood is enough to be turned to the proper diameter of the component it is going to mate with.
This aint Rocket science.I will measure my inlays to .000000something or other , but a hole for a glue joint? nope.[^]

 

[Thumbs]

Geez!? That sounded like a tutorial........ And just for you, Randy!..........???????? [][][}][]

 

[Randy_]

 

[Paul in OKC]

This aint Rocket science.

Darn, I guess I need a different hobby then. I thought I was building projecton tubes to launch with[]

 

[ctEaglesc]

Originally posted by Thumbs
<br />Geez!? That sounded like a tutorial........ And just for you, Randy!..........???????? [][][}][]

Not at all.I wanted to go on record that I laugh when I read the extremes some people go to when they are trying to make a little tube stay in a little hole and are concerned witha couple of thousands on a drill bit.It is a kin to how many angels can dance on the head of a pen[]
There are those who turn pens with out the tubes at all, or w/tubes but glue them in after it is turned and finished. I just feel that with my style of pencrafting the tubes make the pen structually sound.
It is just a friggin hole in a friggin piece of solid material for a friggin tube for a friggin pen!
Buy thicker glue and figure out how to make sure it stays where you put it.What is so difficult about that?
No it wasn't a tutorial Thumbs it is common sense.
(I would get off my soap box now but it seems I have CA'd my shoes to it)[]

 

[Randy_]

Originally posted by ctEaglesc.....and are concerned witha couple of thousands on a drill bit......it's not rocket science.....

Off a few thousandths and your hardware won't match up with your wood.....

Off a few thousandths and your pen transmissions won't work.....

Off a few thousandths and you will have gaps at the centerbands.....

Off a few thousandths and you will see the tubes through the acrylic....

Off a few thousandths and the refills will stick in the pen tips.....

Off a few thousandths....I could go on; but you get the idea.........


Pen crafting may not be rocket science; but without reasonable precision the pens you make won't be worth much. The range of drill sizes I was talking about was 14/1000.....enough to cause big probems in other areas of pen crafting. I don'tknow the answer to this question and was just asking for some other thinking on the subject. Not sure why eagle is getting so defensive about the issue??

 

[loglugger]

When I used ca I wanted a pretty tight fit. On slimlines I use a 7 mm bit. Now I use Ultimate Glue Polyurethane and I still want a pretty tight fit. On slimlines I use a 7 mm bit.
Bob

 

[ctEaglesc]

Originally posted by Randy_
<br />

Originally posted by ctEaglesc.....and are concerned witha <b>couple of thousands on a <b>drill bit</b></b>......it's not rocket science.....

Off a few thousandths and your hardware won't match up with your wood.....

Off a few thousandths and your pen transmissions won't work.....

Off a few thousandths and you will have gaps at the centerbands.....

Off a few thousandths and you will see the tubes through the acrylic....

Off a few thousandths and the refills will stick in the pen tips.....

Off a few thousandths....I could go on; but you get the idea.........


Pen crafting may not be rocket science; but without reasonable precision the pens you make won't be worth much. The range of drill sizes I was talking about was 14/1000.....enough to cause big probems in other areas of pen crafting. I don'tknow the answer to this question and was just asking for some other thinking on the subject. Not sure why eagle is getting so defensive about the issue??

Randy I wasn't defensive at all.
As far as the pens not being worth much, the issues I brought up are concerned with the mechanical iussue of glueing in a tube.
If you are concerned with a tube showing the tolerance you are speaking of won't make or break it, if in doubt color the tube.
Tranny not working?
Once the tube is in place it has no bearing on whether the pen functions or not.
The tips sticking out? has no bearing on gluing in the tube,
Perhaps you misunderstood the intention of my reply.
I was referring to being anal about what dimension to drill for a component that is unseen.
Common sense should prevail but the instructions from the manufacturers are not written in stone.
I paid $12.00 for a recommended bit from a supplier.It has a fancy name but not worth a dam.
I have yet to get a tube to fit in a hole drilled with it.
I believe I have enough experience to trust my ability to drill a hole.Heck I can presonally attest to the fact that every pen in my album has a tube in a hole in it that was drilled by me.I am quite certain my information is credible and based on experience.The finished pens I have posted prove it.[]

 

[Randy_]

Originally posted by ctEaglesc
<br />.....Perhaps you misunderstood the intention of my reply.....

Always a possibility.

But just to remind everyone, my original question asked for a specific piece of information....what the optimal joint gaps were for the glues we commonly use and if any one remembered seeing the result of an earlier proposed glue test. So far, we have just been dancing around those two questions.

 

[wdcav1952]

I'm a bit confused. Has drill size for a kit ever proven to be a problem for anyone? Theoretical questions can be an entertaining mental gymnastics problem, but do they have a practical application in actual penturning? I used the drills recommended for different kits, and have not had a problem that I am aware of in three years. Now if I use a 10 mm drill for a slimline, that certainly is a problem, but one caused by the operator, not the size of the drill hole.

Perhaps we need a forum for nit-picking questions?

 

[gerryr]

The only time I ever had a problem with the recommended drill bit was on the Sierra. The recommended bit is 27/64" or 0.4219", but the tube is only 0.410". If the tube is not glued dead center in the hole, you can easily end up with one side paper thin. DAMHIKT After one bad experience, I switched to a "Z" bit which is 0.413".

 

[Rifleman1776]

Use a 7mm bit in a 7mm hole and get on with it.
I know you lost yours, find something else to do until a new one arrives.
Like the man said, "It ain't rocket science."

 

[gerryr]

Originally posted by Rifleman1776
<br />Use a 7mm bit in a 7mm hole and get on with it.
I know you lost yours, find something else to do until a new one arrives.
Like the man said, "It ain't rocket science."

Or use an "I" bit, it's a better fit anyway.

 

[woodmanplus]

I am not fond of CA,personally, as I have had better results with two part apoxy. I use a small screw driver to apply and there is no dribble and squeezout is easy to remove after drying over night.
Just my opinion.