Slimline using a Zebra f-301 refill

[RunnerVince]

I recently made a Cigar pen for a client who wanted it to use a zebra refill. I puzzled over this for a bit, but ultimately found a simple way to "convert" the pen. The client loved the look of the pen and how it wrote, but realized he really wanted something thinner. I went over options, and he decided he wanted a slimline. But again, with the zebra refill.

I have to admit I'm stumped on this one. You can turn the transmission around so that it seats into the clip end of the pen, but that messes up the visual balance of the pen because the top tube must be shortened to about an inch, and the bottom tube must be lengthened accordingly. It just won't look right.

The only thing I've thought of to overcome this is to drill out the threaded portion of the inverted transmission so the zebra refill will fit farther in. I've tried this on two transmissions -- one had a plastic mechanism, the other had a metal mechanism. From what I can tell, the transmission doesn't "engage" or "lock into" the normal refill. It's just a flat surface that pushes the refill up. I "aggressively dissected" one of them after I'd ruined it, and found that there's a spring in there as well, which is what pushes the refill back up into the pen when you close it.

I saw a post from 2012 that discussed this, and no one ever came up with a visually appealing solution. I'm wondering if anyone has any new insight into how to do this?

I've attached a photo of the f-301 cartridge. These are common pens, and they have a cult following. If I can figure out a good way to do this, I think they could be a great seller, but the main thing is to get this one done for my uncle.

ANY help or ideas would be appreciated -- even if someone knows of a different "slim" pen kit that might work better for this application.

Thanks,

Vince

 

[Mr Vic]

disassemble a 301 and use it's tubes, cheaper the a kit.

 

[RunnerVince]

disassemble a 301 and use it's tubes, cheaper the a kit.

It's not the tubes that are the issue. It's the transmission itself. The refill basically won't fit into the transmission past where the threads for the intended refill start.

 

[Mr Vic]

It's not the tubes that are the issue. It's the transmission itself. The refill basically won't fit into the transmission past where the threads for the intended refill start.

What i meant is cover it's components with wood and re-assemble.

 

[RunnerVince]

What i meant is cover it's components with wood and re-assemble.

That would increase the overall diameter of the pen, which puts me outside my customer's parameters.

I think simply pressing the inverted transmission further into the upper barrel will do the job. I ruined all my transmissions trying to drill them out and am waiting for new ones to arrive, but I'll report back. My only concern is that there won't be enough of the non-brass end of the transmission showing to keep the pen together and/or provide enough grip to advance/retract the tip. As I said, I'll report back.

 

[Jarod888]

If you could turn extremely tight tolerances and bore perfectly round holes, you might be able to do it this way:

1.drill a 7 mm hole all the way through the top portion of the blank. You may want to completely round your blank first and use a collet chuck to hold the round stock for drilling.
2. Acquire a piece of tubing which just slips over the 7mm tube. It needs to be tight, but able to rotate around the 7mm tube.
3. From the center of the upper tube enlarge the 7mm hole just enough to allow the other brass tube to slide in. Essentially a stepped hole.
4. Repeat for the bottom blank.
5. Now you should have two blanks. Each should appear as follows:
On the nib end there is a 7mm hole for a brass tube, probably about 10 mm deep. From the center of that tube to the nib is a slightly larger hole, with a brass tube that has a slip fit over a 7mm tube. This brass tube needs to be extend out from the center approximately 1.5 inches or so, but leave it longer than needed and sand to final tolerance later upon final fit.. Glue in the 7mm tube, it should be small, maybe 10 mm or so, use dental wax or playdough to prevent glue from entering the tube. Glue in the larger tube, again using playdough or wax to keep the glue out of the tube.
On the upper blank glue in the 7mm tube (this 7mm tube needs to extend all the way from the upper portion to the center, but the upper portion should not be flush with the top. It needs to be inset, but only glue the very upper portion, use the slightly larger tube to center the 7mm tube. The 7mm tube needs to sit below the top surface, because you need room to glue in a cap. Essentially you are creating a sleaving system.

Then turn the blanks, I would suggest tbc bushings, but you would have to have ones that fit the tubes. A mandrel might work, you would just need to shim the center where the larger tube is so that you don't have center wobble. Finish as you see fit.

Now for assembly. You would press in the nib. Then press in the transmission, from the top of the upper blank. Then you would insert your refill, then you would need to "size" the enlarged tube which protrudes from the lower blank so that as you rotate your upper in, it pushes out the refill and retracts it when turned the other way. Glue in your cap. Finish by buffing, etc.

I think this will work. It will take a lot of extremely precise measurements, boring operations and assembly, but it should be a good exercise in creativity.

 

[RunnerVince]

That would increase the overall diameter of the pen, which puts me outside my customer's parameters.

I think simply pressing the inverted transmission further into the upper barrel will do the job. I ruined all my transmissions trying to drill them out and am waiting for new ones to arrive, but I'll report back. My only concern is that there won't be enough of the non-brass end of the transmission showing to keep the pen together and/or provide enough grip to advance/retract the tip. As I said, I'll report back.

Reporting back as I said I would. The final product ended up being a combination of three things:

1. Drilling out about a half inch of the transmission: If you look into the transmission, you'll see that there's the metal bit that has the threads for the ink refill, and then a second part of the transmission (in my trials, they were metal in some transmissions and plastic in others). You want to drill down until just before you reach the second part of the mechanism. I ended up using the largest bit that would fit into the transmission, holding it in my hand, and drilling slowly. It took about 15 minutes even with a high-quality metal-drilling bit. I could have mounted it between pin jaws, but I think doing so on my previous attempts jammed the two parts of the mechanism together, so I think by hand it the best option.
2. Installing the transmission into the upper barrel instead of the lower barrel and pressing it in until only about a half inch of the transmission protrudes.
3. Shortening the pen refill: I really didn't want to do this, because I wanted refill replacements to be easy for the customer. But it was the only way without actually shortening the upper barrel and affecting the external look of the pen. The "cap" of the refill pops right off using your fingers. Then I just used scissors to cut the tube (no sanding because you don't want plastic debris to end up in the ink) to sneak up on the fit. I ultimately decided that it's not too onerous to ask the customer to pull out a pair of scissors to get the ink refill they want.

My customer has received the pen and is very happy. He's talking to his partners about having me do 20 or so normal slimlines for them to give to their clients, so in the end it was worth it. But next time someone wants one of these modifications, I'm charging double!

 

[RunnerVince]

If you could turn extremely tight tolerances and bore perfectly round holes, you might be able to do it this way:

1.drill a 7 mm hole all the way through the top portion of the blank. You may want to completely round your blank first and use a collet chuck to hold the round stock for drilling.
2. Acquire a piece of tubing which just slips over the 7mm tube. It needs to be tight, but able to rotate around the 7mm tube.
3. From the center of the upper tube enlarge the 7mm hole just enough to allow the other brass tube to slide in. Essentially a stepped hole.
4. Repeat for the bottom blank.
5. Now you should have two blanks. Each should appear as follows:
On the nib end there is a 7mm hole for a brass tube, probably about 10 mm deep. From the center of that tube to the nib is a slightly larger hole, with a brass tube that has a slip fit over a 7mm tube. This brass tube needs to be extend out from the center approximately 1.5 inches or so, but leave it longer than needed and sand to final tolerance later upon final fit.. Glue in the 7mm tube, it should be small, maybe 10 mm or so, use dental wax or playdough to prevent glue from entering the tube. Glue in the larger tube, again using playdough or wax to keep the glue out of the tube.
On the upper blank glue in the 7mm tube (this 7mm tube needs to extend all the way from the upper portion to the center, but the upper portion should not be flush with the top. It needs to be inset, but only glue the very upper portion, use the slightly larger tube to center the 7mm tube. The 7mm tube needs to sit below the top surface, because you need room to glue in a cap. Essentially you are creating a sleaving system.

Then turn the blanks, I would suggest tbc bushings, but you would have to have ones that fit the tubes. A mandrel might work, you would just need to shim the center where the larger tube is so that you don't have center wobble. Finish as you see fit.

Now for assembly. You would press in the nib. Then press in the transmission, from the top of the upper blank. Then you would insert your refill, then you would need to "size" the enlarged tube which protrudes from the lower blank so that as you rotate your upper in, it pushes out the refill and retracts it when turned the other way. Glue in your cap. Finish by buffing, etc.

I think this will work. It will take a lot of extremely precise measurements, boring operations and assembly, but it should be a good exercise in creativity.

Hi Jarod,
I already finished my prototype, but I'm intrigued. If the "sleeve" tubes turn out to be a standard pen tube size, this could make things way easier. However, I'm having a really hard time visualizing this. Do you think you could post a simple drawing? I'm unclear as to what actually advances the refill.

 

[Jarod888]

Hi Jarod,
I already finished my prototype, but I'm intrigued. If the "sleeve" tubes turn out to be a standard pen tube size, this could make things way easier. However, I'm having a really hard time visualizing this. Do you think you could post a simple drawing? I'm unclear as to what actually advances the refill.

So I think I was to hasty in my response. I forgot that the way slimline transmissions work is by having a threaded cross refill. The transmissions are held in the bottom tube and the cross refill threads in from the top. When you twist it, it extends via the internal mechanism of the transmission.
What I was think was that the "slimmer" part of the transmission would press against the top of the refill, thereby extending it.

It might still work, but you would have to make a piston which screwed into the transmission and pushed out the zebra refill as you turned it. I'm still not even convinced that would work, but it might be fun to experiment with.

Crude drawing attached.
I used different colors to represent the different parts.

 

[RunnerVince]

So I think I was to hasty in my response. I forgot that the way slimline transmissions work is by having a threaded cross refill. The transmissions are held in the bottom tube and the cross refill threads in from the top. When you twist it, it extends via the internal mechanism of the transmission.
What I was think was that the "slimmer" part of the transmission would press against the top of the refill, thereby extending it.

It might still work, but you would have to make a piston which screwed into the transmission and pushed out the zebra refill as you turned it. I'm still not even convinced that would work, but it might be fun to experiment with.

Crude drawing attached.
I used different colors to represent the different parts.

View attachment 317366

Thanks! Your design makes sense now. However, you can dispense with the larger tube by drilling out the transmission, trimming the refill, and pressing the transmission as far as you can (leaving about 1/2" protruding) into the upper tube. In the end, I think that's the simplest solution.