Crescent Filler Inking system

I’ve been wanting to make a pen with a crescent filler inking system for quite a while. But what always held me back from attempting it was the fact that I’m not a metalsmith. The crescent filler pens, from the original all the way up to the present use brass crescent bars. And for some reason I never thought of using anything else. But then one day it hit me: why can’t I use acrylic? After all, the crescent filler was patented way back in 1901 when acrylic wasn’t widely available. So back then brass was used for a variety of items. So I figured that was why they started out using brass. Then they just never tried using anything else. So I wondered, why can’t I use something else? I set out to see if I could…

The main advantage of using acrylic rather than brass is workability. In order to work with brass you need special metalworking equipment. But an advantage acrylic would have over brass is weight. Acrylic is much lighter, so besides the acrylic being much easier to work, it will allow the pen to be lighter.

I used some green tinted clear acrylic because it was what I had on hand in what I thought would be the right thickness. But doing an internet search, I found other tinted transparent as well as solid colors of sheet acrylic are available in the same thickness.

Making the crescent:

I didn’t have a physical sample to work with, so first I needed to determine some dimensions. The crescent had to be sized accordingly for the barrel, as well as keeping under consideration that the height of the ‘crescent bar assembly’ (crescent and attached pressure bar) had to be short enough to install it through the front of the barrel.

After working out the dimensions, I determined I needed at least a 1″ diameter blank for turning the crescent. Most pen blanks though are only 3/4″ (or 16-18mm) diameter. So a regular pen blank wouldn’t work. However I could glue up a blank to make a larger piece if necessary. But for the inital sample I decided to use a scrap piece of sheet acrylic. Looking through my scraps, I found a piece of clear with a little bit of green tint that I thought would work perfectly.

I cut a small piece from the scrap that was a little over 1″ square. Then I mounted the square to a flat waste block on the lathe with double-sided tape. I first shaped the acrylic into a large round washer (or a circle with a hole in it). Next, after removing from the waste block, I cut a section from the washer to create the crescent shape.

Pressure bar… An advantage of using the sheet acrylic was that it made it much easier to cut out the thin strip needed for the pressure bar that attaches to the bottom of the crescent. After cutting out the pressure bar, I glued it onto the bottom of the crescent, creating the crescent bar assembly.

Prepping the barrel:

The crescent filler works very similar to a lever filler, so like a lever filler the barrel needs a slot cut for the crescent to fit into. The only difference from a lever filler is that here it doesn’t require the little groove at the far end (used to lift the lever). So the slot gets cut the same. But the barrel also needs a recess to capture the locking ring. This is sort of a chicken and egg thing. Which do you do first: cut the capture tenon first and size the ring to fit; or make the locking ring, THEN size the tenon. I decided to wait and prep the barrel last after all the other parts were made.

Locking ring:

The hardest part in this project was making the locking ring. If you’re not familar with how a crescent filler works, it uses a locking ring on the barrel that rotates to lock the crescent in the up position so you can’t accidently press it and force ink out to the nib. So the locking ring has to fit under the crescent. And in order for it to work, it has to have a specific size and shape.

The shape of the locking ring is complex. It looks like a donut with an off-center hole. Plus it has a crosswise slot at the thin area that frees the crescent. To unlock the crescent, you rotate the ring around until the slot is in-line with the crescent. Then to lock, you rotate the ring again until the thicker area is under the crescent so it can’t move. So my challenge was to figure out how I was going to make it.

I decided the best way to make the ring was with an offset jig that allowed me to shape the ring on the lathe. An offset jig is just as it implies. It allows you to turn something off-center. So first, I prep a small piece of acrylic by drilling a center hole, then cut it to the width of the ring making a ‘ring blank’.

Next, I set out to make the offset jig. Afterwards I mounted the ring blank onto it. First I set the offset jig in centering position for turning the maximum diameter of the thick part of the ring. One more time I had to guess at a size. Then after turning the overall diameter, I adjusted the jig to the offset position, which would size the smaller thickness at the crescent access slot. It took a few attempts to find just the right shape and diameters that worked. But eventually I hit on the right dimensions. The last step was to cut the slot for the crescent access, which I did at the bandsaw.

Installing the locking ring:

Installing the locking ring was the next hurdle. I determined the ring was set into a wide flat tenon approximately in the center of the barrel, and the diameter had to be slightly larger the I.D. of the locking ring. Also the slot for the crescent had to be cut before the ring was put in place.

The ring is installed by sliding it up into place from the closed end of the barrel. And because the ring snaps into the tenon, installing it will be a ONE SHOT deal. So installing the ring is the most critical part. Because if it doesn’t fit, or it’ss too loose, it’s very hard to get it back off. Because of the shape and small size, it’s hard to get a good grip on the ring to pry it open enough to slip it back out (and my big fingers don’t help). Luckily though I haven’t had one yet that didn’t fit.

The other internal parts used for a crescent filling system are the same as those used in button and lever fillers. So the rest of the pen came together easily.

The Crescent filler was fun to make, and I’m glad I finally got around to making one. If you’d like a pen with one of these unique ink fillers, send a message through the Contact Us page, or send an email directly using the email address on the contact page. I’d be glad to hear from you!

Looking for another type of inking systems? I also offer button, lever, bulb and vaumatic filler systems. Click this link to view information about those systems: Alternate Inking Systems.