CA layer diameter

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pagemcutter

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Jun 7, 2021
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Hello,
I just joined the forum and am new to pen turning. I have a question in regards to applying CA glue as a finish.

I am going to use GluBoost and try that approach after watching lots of different videos on YouTube. My question is in regards to the diameter when you turn down the pen. If you turn each end down to the diameter of the bushing and then apply a CA layer, would there be any issues with these multiple CA layers building up to the point where there is now a noticable difference in the diameter between the kit parts and the blank? The CA has to be of some thickness - I just don't know if it is sufficient enough to worry about. I guess if it was then the solution would be to sand down each end of the blank to be slightly narrower than the bushing to allow for the CA layer to build back up?

Hopefully not a dumb question.

Thank you in advance!
 
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magpens

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Definitely NOT a dumb question.

In my opinion .... and it is only my OPINION ....

It is OK to have the ends of your pen barrel just a LITTLE larger than the mating metal hardware. .
In fact, I like that look and feel much better than the other way.
Of course, if you can get a PERFECT sizing match at both ends all the time that would be ideal.

My general practice is to turn the blank ends down so that their diameter is about 0.005" or 0.006" larger than the mating metal parts.
This allows for some reduction due to sanding .... but realistically, sanding does not take off more than about 0.002" on the diam.

So after you add the layers of CA (which don't increase the diameter by very much at all .... (I would say 0.004" at the most) .... your finished pen barrel will be about 0.008" in diameter bigger than the mating metal .... that's really only barely noticeable.

All this depends on two things .... how aggressively you sand, and how much CA you put on.
But for both of these factors, the effect is usually smaller than you might think.
Of course, it would be nice to be able to point to some quantitative studies of both effects, but I don't know of any.
 
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duncsuss

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My view is that everyone applies finishes at a different rate, "my 5 coats of CA" will not be the same as another person's 5 coats.

So - do a test. Turn a barrel but not all the way to the bushings and measure with calipers. Apply as many coats of CA as you think are correct and measure again. That gives you *your* allowance.

(BTW - don't trust bushings to be exactly accurate, use calipers on the hardware and on your turned parts. All bushings get smaller as a natural consequence of sanding the pens you make.)
 

jttheclockman

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If you want your product to be some of the best on the market than yes you do not want any steps up or down with transition from components to finish. Any pen buyer that is worth their weight in salt would feel for this and check the overall fit and finish and what you would want to strive for is greatness. Yes it can be achieved but takes practice and trial and error. As mentioned above and an excellent point, everyone finishes differently. Weather it is the top coat used, thickness of application of each layer so there is no solid definite answer. I am sure others will come here and give you measurements but again how they accomplish this each and every time is amazing if they do it. Also another great point was do not trust bushings to be same size as components. Rarely are they ever. Get yourself a good set of digital calipers and measure both parts and determine what it is you need to do to meet true meeting of parts. Now there are those that will mention fancy bulbous ends and things like that but it still comes down to that exact matching point and to me is the mark of a craftsman who takes pride in his or her work. My opinion has been stated and only my opinion. :) Good luck and have fun as you enter this hobby.
 

leehljp

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I am one of those who turns .005 or so smaller than the center band, clip end or nib/nose cone end, and build back up with CA until the CA is about that much - 005 to .007 larger than the fittings. Then I do one of two things, which ever I prefer at the moment - I will turn the CA back until it is precise (measured with a good set of calipers), or on occasion I sand it down using nothing less than 800 - 1000 grit sandpaper or 8000 MicroMesh.

I don't really measure thicknesses per layer or keep track of how many layers of CA. Those are not my goals and if they were, they would be irrelevant. What matters is that I have a thickness that covers 100% of the wood after it is perfectly matching the fittings.

I occasionally meet up with people who do what John mentioned - they feel the transition and measure its worth by that. First, the pen will be attractive for them to pick it up, then they will feel for diameter transitions and inspect for flaws by looking for scratches or irregularities in the finish. Most people don't do this, but when the few do and it passes their judgment, the prices can reflect the perfection!

I am close to being obsessive compulsive when it comes to fit and finish on wood and pens. Turning down and building back up is the norm for me.
 

MPVic

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I am one of those who turns .005 or so smaller than the center band, clip end or nib/nose cone end, and build back up with CA until the CA is about that much - 005 to .007 larger than the fittings. Then I do one of two things, which ever I prefer at the moment - I will turn the CA back until it is precise (measured with a good set of calipers), or on occasion I sand it down using nothing less than 800 - 1000 grit sandpaper or 8000 MicroMesh.

I don't really measure thicknesses per layer or keep track of how many layers of CA. Those are not my goals and if they were, they would be irrelevant. What matters is that I have a thickness that covers 100% of the wood after it is perfectly matching the fittings.

I occasionally meet up with people who do what John mentioned - they feel the transition and measure its worth by that. First, the pen will be attractive for them to pick it up, then they will feel for diameter transitions and inspect for flaws by looking for scratches or irregularities in the finish. Most people don't do this, but when the few do and it passes their judgment, the prices can reflect the perfection!

I am close to being obsessive compulsive when it comes to fit and finish on wood and pens. Turning down and building back up is the norm for me.
Lee, want you to know that up until the time I read your process (few years ago now) it really changed, for the better, the fit and finish of my pens. Before then it was an extremely discouraging part of the craft for me. Thank you for taking the time to share it again.
Mark
 

pagemcutter

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Wow! Thank you all for your advice and sharing your techniques. I didn't realize there was such a level of precision after taking my one pen course. All of you use calipers it appears and don't just go by feel. I'm rather a technical person by nature so that suits me fine, but from my gem cutting I know tolerances get down to thousands of an inch.
 

leehljp

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Wow! Thank you all for your advice and sharing your techniques. I didn't realize there was such a level of precision after taking my one pen course. All of you use calipers it appears and don't just go by feel. I'm rather a technical person by nature so that suits me fine, but from my gem cutting I know tolerances get down to thousands of an inch.
Composite calipers are a no-no as they can flex. Metal calipers such as HF's and other companies within the range of $20 - $50 are good and give a measurement of .005. In order to be able to measure .001, most of the time a hand held micrometer is needed - in which most will deliver .0001 degree of accuracy.

There will be those who say this is not needed, but with your gem cutting, you could probably use a micrometer. That said, different woods will swell (even encased with CA) and contract .001 or .002 overnight with humidity swings. The finger can detect difference as small as 13 nanometers on smooth surfaces. (I can't fathom 13 nanometers.)
 

pagemcutter

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lee - I do have a micrometer but would never have thought it needed for pen making. I do have a good small digital caliper however.
 

Jans husband

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Thanks for the above everyone.
My query is however that when you are measuring (say) where the nib section of a pen enters the turned-to perfection- blank, this is usually a gradient from the nib end towards the rest of the blank. How do you ensure that the measurement is correct at the actual tip of the turned blank where the nib will sit, given that even if you measure a couple of 000s up the blank, that will be a different reading. My callipers sometimes slip off the end of the turned blank as I am trying to get an accurate measurement.
In other words, how do you correctly measure the diameter of the end of the turned blank with callipers during turning?
I hope I am not being too pedantic, but we are talking of 000s of an inch here.

Welcome David.

Please carry on with your "dumb questions" such as mine!!

Mike
 

jttheclockman

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Thanks for the above everyone.
My query is however that when you are measuring (say) where the nib section of a pen enters the turned-to perfection- blank, this is usually a gradient from the nib end towards the rest of the blank. How do you ensure that the measurement is correct at the actual tip of the turned blank where the nib will sit, given that even if you measure a couple of 000s up the blank, that will be a different reading. My callipers sometimes slip off the end of the turned blank as I am trying to get an accurate measurement.
In other words, how do you correctly measure the diameter of the end of the turned blank with callipers during turning?
I hope I am not being too pedantic, but we are talking of 000s of an inch here.

Welcome David.

Please carry on with your "dumb questions" such as mine!!

Mike
It is not that hard. Just the very end of the blank is what you want. Measure using the side of the calipers. The same when measuring the parts where the blank meets.
 
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