Sunday, April 15, 2007

Lead Advance Length

Oh dear, here I go again, off on another mad tangent. Somehow, way down deep inside, I know I’m going to regret this lead advance measurement thing, but in a couple of my reviews I have made a comment about the lead advance mechanism only advancing a short length of lead for each activation. I knew of course that eventually it would get the better of me and I would have to start investigating and measuring this. Well it happened. In a moment of weakness I grabbed all the mechanical pencils on my desk at home and started clicking away. Here’s the results.

10 Clicks of the Mechanism Advanced This Much Lead

Pentel Excalibur = 5mm
Pentel Ergotwist = 5mm
Parker Jotter = 6mm
Pilot Clicker = 6mm
Lamy Scribble = 9mm
BIC Pencil #2 = 12mm
Unbranded Cheapie Pencil = 20mm

Now this was only a quick rough test, measured with a plastic ruler, etc so it’s not terribly exact, but it shows some clear interesting differences. I’m trying to resist taking this further.


pigpogm said...

Pentel GraphGear 1000 0.5 = 5mm
Pentel GraphGear 1000 0.3 = 3mm
Staedtler Mars Micro 0.3 = 5mm
Rotring T 0.5 (looks identical to the modern Tikky II) = 8.5mm
Pentel Kerry = 5mm
Pilot The Shaker H-245 = 6.5mm (Clicked, not shaken)
Pilot Shaker-X = 8mm (Clicked)
Staedtler Mars 780, held point up = 0mm
Staedtler Mars 780, held point down = about 1m, depending if sitting or standing ;)

Interesting that the GraphGears vary depending on the width - no idea if it's just because of the smaller mechanism, or if it's done on purpose.

SomeBloggerDude said...

This is great - the principles of science (controlled experiments) applied to pencil reviews. I love it.

AdB3 said...

Dave, we hear you talk lead advance lengths, but I can't recal you expressing quantitative preferance: What's the ideal lead advance rate IYHO?
pigpogm makes an excelent observation that mechanical pencils come in about five diffrent thickness! Diffrent size leads = diffrent lengths, like advance & useable lead beyond tip... I assume you do most of your reviews on 0.5 or 0.7 pencils.

Kiwi-d said...

See, I knew I was going to regret this whole subject.

I was initially surprised at the Graphgear difference by lead diameter, however with a little more thought it does make some sense that with very thin 0.3mm (weak) leads the advance amount would be small so there’s not much lead protruding and its less likely to break. Conversely with something like 0.9mm lead you could have a much bigger advance and not risk breakage. I certainly do most of my reviews with 0.5mm or 0.7mm, which hopefully I declare somewhere in each review. So my comments about small lead advance are historically based on 0.5 / 0.7mm leads.

I suppose the pencils purpose could also make a bit of difference to the desirable lead advance amount. Some might think that a technical draughting pencil should have a different lead advance amount than a general writing pencil.

For general writing with 0.5 / 0.7mm lead, IMHO I think about 7-9mm of lead advance for 10 activations is about right. 3mm advance for 10 activations with a 0.3mm lead must mean you are continuously clicking away at the mechanism?

pigpogm said...

The 0.3mm GraphGear is even clickier than you'd imagine - I keep it filled with 2B leads, so it wears away *extra* fast. Makes for a really nice solid, thin, black line, though.

Kiwi-d said...

Man, talk about living in Clicksville, U.K. !!!!