Friday, 27 November 2015

Fraternal twins?

A few years ago a friend expressed interest in stopped by to try a few planes. He was pretty taken with the K9, and over the course of the next several months, we talked about a few changes to the specs. What was interesting to me was that he really, really liked the Boxwood. Not so much because of the way it looked - more because of how it felt. Boxwood is one of the few infill woods that I do not french polish. I soak it in double boiled Linseed oil, let it dry, and then give it a coat of paste wax. I like the way it looks, but also the way it feels, and I think he connected with that feeling right away.

There were a few changes he was interested in. The biggest issue was to further reduce the physical weight. He wanted to increase the bed angle to 55 degrees (mine is 50 degrees), and to make the blade a little narrower - 2" wide as opposed to 2-1/8" like my K9.

Narrowing the blade would obviously reduce the weight, but so would increasing the bed angle. It allows the handle to be moved further forward because the blade is more upright. Pushing the blade forward allows for the footprint of the sole to be shortened - something else he was hoping for.

These were not minor changes, so it took some time to re-think and re-draw sidewall profiles and make new jigs and fixtures. I was really curious to see how these changes would affect the feel of the plane.

I have taken several photos so you can see how they differ. I have them placed on a 1/8" wide ‘beam’ to see where their respective balance points are.

The sole footprint of the K9-55 (55 degree bed angle), is 7-15/16" long, while my K9 is 8-3/16". A full 1/4" difference in length. As shown below, the position of the mouth changed, but not by the full 1/4". 

The photos above and below show the difference in handle position, almost the full 1/4" is reflected here.

The different bed angles are very obvious.

The front pad is almost the same size on both planes - the K9-55 is less than 1/16" shorter front to back. 

The moment of truth was weighing both planes. I was a little surprised by how different they are. My K9 is 4.28 lbs and the K9-55 is 3.99 lbs - a full quarter pound different.

In use, they feel somewhat similar - the Boxwood handles certainly help, but the reduced length of the K9-55 and the handle being pushed in further makes it feel more compact (which it is). More compact feels a little more nimble, and on the return stroke, it feels like there is less weight in the toe. This is always a good thing - less weight in the toe means less strain on your wrist. This happens because the hand holding the handle is supporting a higher percentage of the planes weight.

There is a trade off with the higher bed angle. The heavier the shaving, the more resistance you will feel. When taking sub 0.001" shavings though, the feeling is pretty minimal, and I suspect sharpness of the blade will be more perceptible than the higher bed angle. The blade will wear faster with the higher bed angle, but if the work you are doing benefits from the higher angle, the trade-off will be worth the additional time at the sharpening station.

I have always preferred a No.4 to a No.4-1/2, and in some cases - even a No.3 size. I like small smoothers. They are more nimble and much easier to use for an extended period of time. These two planes do not represent a massive jump like a 4 to a 4-1/2, but they feel different enough that I am tempted to see if I can justify making myself another K9. Or maybe I will explore the K8 instead.


Blogger Kevin Brehon said...

Your idea of comparing the two planes using the centre of balance as the reference point is interesting. Does the balance point change much for larger/smaller planes or does it stay consistent with the handle and cutting edge?

28 November 2015 at 10:00  
Blogger Konrad said...

Hi Kevin,

Good question. The longer the plane, the harder it is to control or change the balance point. But there are ways to do it - curved sided planes allow for the front to taper and reduce weight. Having the handle as close to the cutting action as possible also helps. Pick up an longer bench plane and see if it feels like it is hanging heavy in the toe. Some planes are more balanced than others - it is a fun experiment.


30 November 2015 at 13:49  
Blogger John said...

I suppose it would also be interesting to see the center of balance with the planes on their sides rotated 90 degrees. this would tell you whether there is any difference in the height of the weight. if most or all of the weight savings was down low towards the sole, then wouldn't that be a mitigating factor? this question comes more from my sailing background than experience with planes. with a boat, you want the weight as low as possible for a smooth ride. i imagine that would also be true of a plane.

8 December 2015 at 22:57  
Blogger Chris Bame said...

Hi Konrad,
Nice plane. Really like the boxwood look myself and never thought about the feel. I'm with you on the 4 VS. 4 1/2 thing and my 3 was my go to until I purchased your K7!! Interesting question from John also, I share his same passion for sailing and get the idea is thinking about.

9 December 2015 at 12:20  
Blogger Konrad said...

Great question John. If I still had the plane, I would surely test this. I suspect they had similar balance points on the side, but who knows. What would be really interesting would be to compare my 50 degree bed angle K9 with my 50 degree bed angle A5. I will conduct this one in the next little while and post the results.


13 December 2015 at 13:48  
Blogger Konrad said...

Hi Chris,

how do you find the unhandled K7 compared with the handled No.3? Very different planes in use, but I wonder how the lack of handle feels. Did it take a while to get used to?


13 December 2015 at 13:49  
Anonymous Anonymous said...

Hi Konrad,

please keep the drawings for this one. Off all your beautiful planes this would be the one I'd like. Box goes so well with stainless stell and the curves are just perfect!

The smoother I loke the most is a ulmia 44mm.


18 December 2015 at 06:19  
Blogger Konrad said...

Thanks Pedder,

The drawings, jigs and fixtures are all saved - don't worry! Making a revision to an existing plane is always a fun exercise and a great opportunity to see what happens with changes to the design.


18 December 2015 at 06:48  
Blogger John said...

Hey Pedder,

Still waiting for my saw! Don't forget your customers on the other side of the Atlantic.

John Koten

22 December 2015 at 23:36  

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