Turning the blanks

The last entry in this series closed with the blanks setting overnight for the epoxy to cure. After this is complete, the ends of the blanks need to be squared to the same axis as the brass ferrules. This is achieved using a drill that is sized to the inside diameter of the ferrules, which is topped with a 4 winged cutter head. The drill is square to the cutter head, and the ferrule aligns the bit to the axis. Don't overdo the drilling here. You can inadvertently erode the ID of the ferrules and the compnents of the pen won't seat well.

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Once the faces are square, they will sit tighly to the bushings that determine the diameter at the end of each blank. Square faces ensure that the fitting will press in tight, and seat evenly at the faces. This is critical in showing off a good fit and finish on the final product. On small pieces of work it is IMPOSSIBLE to hide flaws.

Now the blanks are aligned with respect to grain, and placed on the mandrel with the bushings. Follow the instructions carefully to ensure the bushings go onto the mandrel in the right order relative to the length of the blanks. Some of the bushings can vary by less that 10 thou.

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Initial turning is done at around 2000 RPM, with a 1" roughing gouge. Some folks will say that you need a dedicated set of minature tools for turning pens. This is not the case. Good tool postion, and sharp tools will get the job done. Besindes, in more than 10 years of tunring, I've yet to see a quality set of minature tools. With acetate, you definately want a razors edge on your tools or the blank will melt and gall.

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Once the blank is round, move to a sharp detail gouge. I prefer a fingernail profile, but that's personal preference. This is where the inital shape is applied. Think smooth, flowing curves.

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I perform the final smoothing and small changes in shape with a skew. Most turners are terrified of the skew because catches can be cataclysmic and violent. Practicing on smaller diameter work is a great way to refine your skills. I've increased the speed on the lathe to about 2500RPM here. The skew helps me smooth out the ridges left by the gouge since it cuts by "following the contour" behind itself.

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This is the shape I've ended up with.

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It is very important to leave a bit of extra diameter near the bushings. If you don't you will not have enough material to sand and polish. The trick is knowing how much. I do it by feel, by leaving the smallest ridge that will still catch my fingernail. I'd guess it 15 to 20 thou. In softer materials, I'd leave more, in harder materials, less might be fine.

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Next time, we'll sand and polish the pen. Until then… write on.

 

Sanding and Polishing

Last we left our intrepid turner, he had completed the major shaping operations. The skew leaves a decent finish, and one can generally move to a relatively fine abrasive such as P240 grit as shown here.

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To ensure a near perfect surface, it's critically important to move through the grits of abrasive without missing any grits. Be certain that all the scratches from the previous grit have been removed before moving on, and wipe the pen after each grit to remove loose sanding particles. Sanding through the courser grits can be considered a final, fine shaping process, and it is for this reason that we left the small additional amount of diameter near the bushings. You will waste off this diameter during the sanding process.

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I generally sand without water, using cloth backed sandpaper until galling appears. Galling will show as small dark streaks perpendicular to the axis of rotation. These streaks are signs of melting, and indicate that a lubricant must be used to remove the swarf. Time to switch to a wet abrasive. In this case, it's P600 grit.

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Wet sanding has an additional advantage. It shows the swarf (cuttings) as a coloured paste, or as on finer grits, as a dull film on the surface of the water. That's a good indication that it's time to move to the next finer grit.

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Moving through the grits systematically will start to bring up the shine in your workpice.

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With acetate pens, and other hard surface products - natural or synthetic, you can sand all the way to 12000 grit, but with softer materials, one encounters diminishing returns. Here, the last sanding step is performed 12000 grit.

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After sanding, I give acetate pens a high gloss finish by polishing with an automotive product called "Mirror Glaze". It's a non-abrasive solvent based product that yields astonishing results.

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The blanks can now be removed from the mandrel for assembly, but first, be certain to clean the ends. Some grit from the sanding process can get caught at the interface between the blanks and the bushings. Here are the finished blanks, ready for assembly.

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Next entry, we'll assemble the pen, and pass it on to the recipient.

 

Cool, Thanks

 

Assembly

We are nearing the end of our journey, but we're not home yet. Assembly of the blank, while not difficult, has at least one critical step. Here are the parts laid out for assembly:

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A pen press can help oreint the parts so they press together squarely, ensuring all interfaces are seamless. Here, the point is pressed into the lower blank.

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The most important step of the whole process happens here. The transmission advances the ball of the pen for writing, and retracts it for storage. Seating it too deeply will not allow the pen to retract. To remove a transmission, it often must be destroyed. Before pressing the transmission into place, wrap some tape around it to it does not seat too deeply.

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The finished product:

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Beautiful pen. If my wife ever gets a hold of a small lathe, I'm done for. She has a pen fetish (sickness). She buys them everytime she sees one she doesn't have. Making your own must be an endless source of unique pens. Do you mind sharing the cost of the innards so I can do some retirement planning? ;-)