Rapidograph issue

[bluefooted]

I was wondering if someone could help me out with my pen problem :)

I have Koh-i-Noor rapidographs, and a couple of them leak ink sort of off and on from a point on the nib. Here's an arrow pointing to the spot where the ink comes out:

http://img511.imageshack.us/img511/6204/rap3165ue5.gif (http://imageshack.us)
Shot at 2007-08-03

Disassembling and cleaning seems to help for a little while, but the problem always returns. Is there something I'm doing wrong? Or do I just need a new nib? They're about 4 years old and get pretty heavy use.

Thanks!

[Ilaekae]

Two things cause this...

1. The entire little nib that unscrews has a "slot" or two running up its side through the screw-in threads. If this slot get filled with dry ink and plugs, the pen sometimes gets leaky. Just make sure this slot is clean. If it's blocked, air pressure can't equalize and the pen will either spit ink at the spot you indicated or it will stop working altogether.

2. The main cause of leaking is air pressure. It can be from #1 above, or the pen is either too full or nearly empty. Just watch how you fill the pen. And, if it's still a problem, when you put the plastic reservoir back on, pinch or squeeze it just a tiny bit at its center when you put it back on. This causes a negative air pressure that offsets the tendency for the pen to spit ink when the clogs and atmospheric air pressure cause it to have a higher air pressure IN the tube than outside it. But the main problem is usually that slot I mentioned above being filled with gunk. And definitely DO NOT over-fill the pen. This can cause ink to actually shoot out when you shake it a bit. Not real good if you're wearing your best prom dress at the time...

[bluefooted]

Thanks, Ilaekae, that's really helpful!

I'm guessing it's probably #1, since I rarely keep the pens very full. Will give it a good soaking in cleaner and pay special attention to the grooves.

I really didn't want to have to buy a new nib - those things are expensive!

[Seedling]

2. The main cause of leaking is air pressure.

I learned this by taking my filled pens on an airplane. Handfull of ink, yum!

[alesoun]

My first job was as a tracer/draughtswoman. Oooh, the spotty legs I had until I learned a little less is more.....

LOL! Oh, the memories....