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Thread: A second attempt

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    Default A second attempt

    Dear pen makers and lovers,

    I am stunned. The quality of the pens you show is extraordinary. Beautiful finishes.

    Recently, I published my first go at building a pen : An-attempt-at-building-a-better-pen

    It is a sorry thing, wonky threads, half broken parts, but as a proof of concept, it works, and rather well.

    I want to make a pen, designed entirely to function. A pen with a large, easy to fill reservoir. One that is comfortable to hold along the length of the barrel. With a cap that closes fast and securely, and posts confidently.

    The n° 6 nib and feed, I sourced from FPR. Apart from those, the pen has five parts : the section and the barrel come in one piece, then there is the piston, a ring to retain the piston in the barrel, the back cap and the cap. And an O-ring, and a little tube to push air from the piston through the feed, when filling the pen.

    I thought it might amuse you to watch my sorry attempt at building a better pen.



    This is when I put in the wrong gear for thread cutting, and ended up with 2,25 mm pitch, instead of the 3 required.



    Inside and outside screw threads cut on the barrel. The inside turned out not to be quite deep enough; I had to lap them with 'universal cleaning cream'.



    Cutting 0,25 mm, about 200 turns per minute, feeding at 0,01 mm per turn.



    This is what happens when the tailstock is not perfectly aligned, and when you drill after shaping the outside.



    Do it all over again.



    More knurling. Not very even, but I don't have a dividing head.



    Fitting parts.

    Quite a way to go yet, but I do have fitting parts.

    Please do not hesitate to shower me with critique and advice; I am quite the novice at this endeavour.

    Cheers!

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  3. #2
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    Default Re: A second attempt

    This is amazing work!


    Frank
    "When, in the course of writing events, it becomes self-evident that not all pens are created equal" (Federalist Frank)

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    Default Re: A second attempt

    I adore your photography.

    Sent from my E2303 using Tapatalk

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    Default Re: A second attempt

    Quote Originally Posted by carlc View Post
    I adore your photography.

    Sent from my E2303 using Tapatalk
    Lukas is an excellent photographer, he and I frequent the same photography forum called Rangefinderforum.com
    - Will
    Unique and restored vintage pens: Redeem Pens

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    Default Re: A second attempt

    As with anything new, you learn a lot along the way, even if instructions seem straightforward. Despithe setbacks yoy have a nice pen body in the works and some exceptional photography skills. I think it will turn out fine, awaiting updates

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    Default Re: A second attempt

    Thank you all for your kind remarks.

    Yes it is a learning experience.
    I had to fight my tailstock repeatedly. Someone had the Bright Idea to put one of the 2 set screws for aligning the angle right in the middle of the stock, making it very hard to adjust.
    And I've just found out that it is possible to chuck a drill slightly off, producing the same result as an off-centre tailstock. A slightly deeper cut, less than 0,01 mm, helicoidal in shape, turning once in about the length of the bore, making four evenly spaced bulges along the wall.

    But I'll show more pictures soon.

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    Senior Member Woody's Avatar
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    Default Re: A second attempt

    Above my pay grade but the photos are excellent. Going to be a great pen 😊

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    Default Re: A second attempt

    Yes, it is going yo be a great pen. The design is decent :



    this is the sketch: Capped, it is about half a centimetre longer than a 149, and the same width : 16 mm. Uncapped, it is one and a half centimetres longer. The section tapers from 11 mm to 16 mm over a 1/19 ratio, which puts the fattest part of the pen rather far back. The feel in the hand is very comfortable, even when held up high, near the threads (I like to do that for drawing, or signatures, when i like more freedom to move the point).
    It holds about 4 ml of ink, more than the famed 'Bulkfiller' made by my compatriot.
    I've decided to omit the o-ring, that was going to render the pen watertight when capped : as the tapers on the section and inside the cap have the same angle, just screwing the pen shut creates a mechanical seal, much like the Morse tapers used in machining. The back cap has the same taper, it posts firmly.

    But it is a lot of work, and fiddling, and learning. Here's a picture of the problem I tried to describe yesterday :



    There is a scratchy zone, forming a screw thread, turning twice along the length. The interesting part is, that this hole, drilled with an 8,5 mm drill, is too small for the 8,4 mm piston.
    That, combined with the fact that threads cut with nominally 0,15 mm clearance on both sides doesn't fit, suggests the material fights back under the cut : I think it compresses under pressure, and then springs back when the tool has passed.
    I'm using Dial indicators on both axes of movement, and when cutting inside thread, the compound pushes back 2 or 3 hundredths, even though both cross-slide and compound are tuned quite tightly.

    A lot of thinking and trying left to do...

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    Default Re: A second attempt



    The blind cap is screwed onto the prototype, to give it some support in the four claw.



    Roughing out the taper. The blind cap starts at the threads : only two of the jaws teeth hold onto the cap itself, the taper stopping about a millimetre from the chuck. Having the blind cap screwed to the body proved to be a life saver : when trying to part the end, the part kicked, and I couldn't get it securely back into alignment. But as the steps are only a quarter of a mm apart, filing to shape was quick work, and remarkably precise : I could judge my progress by the shiny rings at the deep end of the cuts.

    I omitted to take a picture of the 'finished' blind cap, But i used it to mount the body, together with the piston and its retaining ring, to provide some structural strength. The body has to stick out rather far, for cutting the taper.
    Here it is mounted as deep in the chuck as possible, while still allowing to indicate on the turned portion. For cutting the thread at the end of the section, I want as little bending as possible.
    That decision may end up biting me in the behind : I may have a hard time getting the piece centered, when I pull it out to cut the taper. This perspex-plexiglass-acrylic is a lot bendier than I expected : the relatively light pressure of the chuck compresses the barrel enough to grip firmly on the piston, which has 0,05 mm clearance all around.



    Onward and upward.

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    Default Re: A second attempt



    These are the gearings I use : on the left, a 16 to 1 reduction, for the slowest feed possible. On the right is the set for cutting thread of 3mm pitch. It is a chore, changing out the gears for different operations, but it beats rechucking.



    The section roughed out. I cut the steps to 1 in 18, half a millimetre every 4,5 mm. Not quite the 1 in 19 taper, but close enough to leave very little material to cut.



    Nearly a pen.
    Last edited by lukitas; September 10th, 2016 at 02:50 PM.

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    Default Re: A second attempt

    Looking good

    Sent from my E2303 using Tapatalk

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    Default Re: A second attempt



    The cap, ready for turning threads.

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    Default Re: A second attempt

    Love seeing the pictures. Thank you for sharing. I am very impressed.

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    Default Re: A second attempt

    Thank you for your kind comments!



    The threads in the cap are still too tight, even though I cut it to have a tenth of a mm clearance on both crown and cut : there should be 2 tenths of slop, and more, as I cut the inside thread to be a tenth wider than nominal.
    But I am growing blisters on my fingers trying to lap the threads with a very fine liquid abrasive.
    And wondering what is wrong with my threads. Inside and outside diameters should be fine : the male threads are a tenth smaller than nominal, and the female ones a tenth larger : the tops of one set shouldn't touch the bottoms of the other. I guess that it must be the sloped sides that cause the tightness, so I'll have to cut a little more slop on the width, rather than the depth of my threads.

    There you go, I haven't finished this one yet, and already I have to make a better one. hm.

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    Default Re: A second attempt



    The cap, freshly turned.



    Here you can see the effect of an imperfectly aligned drill bit, tool marks screwig around inside the barrel. They aren't out more than a few thousandths of a millimetre, functionally it makes no difference, but it keeps me awake.

    Have to try and polish them out.

    cheers!
    Last edited by lukitas; September 17th, 2016 at 04:03 PM.

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    Default Re: A second attempt

    Catastrophe!

    While patiently polishing out the tooling marks in the barrel, I quite entirely stripped out the threads for the piston-retaining-ring. I felt rather despondent.
    That will teach me to watch what I am doing.
    This time, I decided to cut the insides with a boring bar. Drill bits give me holes that look like Bernini's pillars in Saint Peters, and it has to do with how the bit is seated in the chuck. And that is when I am being careful.



    To fill in the gap till new parts are ready, a shot of the prototype :



    It has the new cap on, with a neat little deposit of ink int he corner of the bore. And I put some 'invisible' tape around the threads : they are loose, and the blind cap has 3 cracks in them.

    For me, it is a pleasure to use, comfortable in any position along the barrel, so that i can write as small or as large as I like. It holds a serious amount of ink, and it is generous with it.
    But I can see it is not a 'universal' pen. The cap-threads at the end of the barrel get inky. A #6 (or#35) flex nib, on a 6,3 mm feed, just fits in a round 6,7 mm hole : there are 0,2 mm wide gaps under the nib. It doesn't drip, but it tends to have some ink ready for you, that can amount to a drop in your first loop. I like a really inky pen, but I can see it is not for everybody. The cap is ugly. But it has to be chunky, so it doesn't break when it is pulled onto the cone of the barrel. And it has to be half a millimetre wider than the barrel, so I can file in a little flat to stop it from rolling off the table. It looks a little better on the back, if rather long, but the pen looks its best without it. A pen that looks best in use...

    more and better is coming.

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    Default Re: A second attempt


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    Default Re: A second attempt



    More wreckage. While turning a chamfer on the end of the blind cap. After turning the taper, It sticks out 5 cm, and is chucked on 8 mm. A very precarious set-up.
    I think the most fragile part of this pen is its manufacture. Once made, ti is rather solid. But it's shape demands a machining process that is accident prone : To cut the tapers, three parts have to be held on (very) short straight sections, leaving a long stick-out.
    This makes the turning laborious : to avoid stressing the end, cuts have to be light. Going in 0,1 mm at a time takes twice as long as 0,2mm, but I wouldn't dare.

    I 'll just have to slog on, I guess. At least my holes are straight now, and close to shiny. And my threads fit.

    Cheers!

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    Default Re: A second attempt

    labor of love, I guess

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    Default Re: A second attempt

    WOW - a terrific thread OP!

    Thanks for taking the time...

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