Ultem - internal polishing, tubling

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zimbie

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Olney, MD
I just completed the machining of my 1st Ultem attempt. Simple 3-piece design with Jowo #6 nib unit. I am looking for suggestions for how to address the internal machining/drilling marks. I should have cleaned the ink completely from the pen (have been using it) but the pics still show the issue. External was finished to 320 with a slight buff after.

A) internal polishing? Sandpaper, Wooden Q-Tip, etc... improved it a bit but what is a more successful technique?

B) media tumbling? Some of the commercial Ultem pens (Kasama, Schon) have a tumbled finish which appears to address this issue along with creating an overall matte finish. Plastic media? Tumble duration?

I am using a manual Sherline lathe and carbide drills so both equipment and technique could be complicating things.
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Sandpaper wrapped around a dowel mounted in the lathe works really well to sand the inside, however I think you have a larger issue of what looks like severe burning from drilling. These marks won't sand out. I'd focus on dialing in your drilling process first (slower speeds, sharp bits, lubricant).
 
Thank you! I used oil and new carbide bits but there was indeed heat on the shavings. With my Sherline lathe, I have to move tailstock manually a couple times to get full drilling depth for body and cap so I wasn't sure if slight misalignment while backing out was making the marks. As with everything, practice and learn... I'll try again along with the other lessons-learned during this build.
 
My "pay the bills job" is sales with a major plastics manufacture. We produce Ultem 1000 (unfilled) rod and sheet. I haven't thought about making a pen out of one but I am now. Following this thread for all the good input.
 
There are several pros making pens with the material so if you web search "ultem fountain pen" you'll come across Kasama, Schon and others.
 
There is a method called something like "flame polish. I think you may be able to find it on YouTube. It takes a very small gas flame used in soldering and run it through the tube. It does an excellent job of smoothing some acrylics. Others might be able to chime in with a link.

Found the link for duck calls:
 
This is how I do it.
First I drill using automatic transmission fluid as a coolant/lubricant.
Second I sand using a dowel that has a saw split with sandpaper in the split
Third, I polish using gun bore mops. These come in all kinds of sizes. The polish is various plastic polishes. Mag wheel polish, anything and every thing.

Slow speed is your friend, from the drilling through the sanding. You want cool, do not produce heat. An old gun cleaning kit's rod will help, use them for the bore mops. Patience is a virtue.
 
bmachin said:
Using a boring bar or reamer to get to finish diameter would probably help.

I believe there is a video on the Edison Pens website showing how they finish the bore on their demonstrators.

Bill
Click to expand...
That's how you do it. Drilling only is hit or miss, even with a lot of sanding. Drill under size and achieve your final diameter with a boring bar or reamer.
 
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