biomechanics of planes

[Derek Cohen]

Hi George

Thanks for the info. I do recall you mentioning using the web of the hand to push. In fact, I particularly remembered you describing this when I wrote about pushing this way from low down on the jack and bailey handles.

The logic behind the offset handle still escapes me. Kees, I am not convinced by your thoughts in this regard. "Balanced" suggests that the object is in equilibrium, that is, does not require extra force to steer it straight. An offset handle would require extra force, such as in the front hand pushing laterally rather than just guiding the plane. A central handle facilitates equilibrium, especially when pushed with the heel or web of the hand (since this avoids the issue of a wrist twisting when the handle is held in a fisted grip).

Regards from Perth

Derek

[george wilson]

Surely we must realize that our ancestors had reasons for developing tools as they did. It was my job to accurately reproduce them. Early planes had offset handles. You guys can figure out why they were so made. Fact is,they were. An interesting mystery for you to solve. Hand tool methods went down hill after machines started coming into use.

[Kees Heiden]

Yes Derek you are probably right. So there is maybe another reason. Just think how you hand and under arm are positioned with the full fist gripping a central tote. To move the plane forwards, while standing to the left you must bring your underarm in line with the plane, which means leaning over a little until your ellbow is behind the plane. Now imagine the offset handle, where only the web is behind the tote and the fingers dangling of the offside of th ebody. That lets you standing straight up besides the bench. Of course this will tend to push the plane sideways, but that is easilly controlled with these dangling fingers and the left hand together.

You probably should make a plane like that and try it out. No amount of theorising will give you the answer. For inspiration I suggest this website: http://www.openluchtmuseum.nl/ontdek...n/houtschaven/

[Derek Cohen]

Hi Kees

You are right. I will have to build a plane with an offset handle. The fact that this has been a design of choice indicates that there is more to it than meets the eye. Thanks for your links. I will likely, however, make one similar to the one George built.

Regards from Perth

Derek

[Kees Heiden]

Oh yes, that plane form George is fantastic. It is somewhere high on my wishlist too, but I have too many handyman jobs around the house at the moment. I would make it 50 degree if you stick with the single blade. That was the standard for almost all planes in The Netherlands in the 17th and 18th century.

[Pat Barry]

Yes Derek you are probably right. So there is maybe another reason. Just think how you hand and under arm are positioned with the full fist gripping a central tote. To move the plane forwards, while standing to the left you must bring your underarm in line with the plane, which means leaning over a little until your ellbow is behind the plane. Now imagine the offset handle, where only the web is behind the tote and the fingers dangling of the offside of th ebody. That lets you standing straight up besides the bench. Of course this will tend to push the plane sideways, but that is easilly controlled with these dangling fingers and the left hand together.

You probably should make a plane like that and try it out. No amount of theorising will give you the answer. For inspiration I suggest this website: http://www.openluchtmuseum.nl/ontdek...n/houtschaven/

Hi Kees - thanks for the link. I find it rather interesting here that only 11 of the 55 planes pictured have rear handles and everyone of them is offset to the right. I don't read Dutch - do they somewhere provide descriptions and estimated ages for these planes?
Also interesting that eveyr one of the planes with a handle has a horn at the top of the handle whereas the old plane that David pictured has not got a horn. Wonder if that plane is older or newer than the ones in the museum pictures.

[David Weaver]

Guarantee the one in the hay cabinet shop picture doesn't predate George's employment at CW

Otherwise, they are probably similar in age in terms of design. Where the tools are old enough, they may have done a fairly significant amount of their work when wood is green, which planes more easily.

[Jim Koepke]

the old plane that David pictured has not got a horn.

The image clarity could be better. It looks like there might be a horn. It also looks like it might have suffered in an accident.

jtk

[David Weaver]

Presume he means no horn on the front like the continental planes?

[Kees Heiden]

The planes from the Openlucht museum (Free air museum) are from the 18th and early 19th century. Around 1830 the less ornate English design started to take over. The design of these planes is much older though. In the Netherlands the oldest known professional planemaker is from the late 16th century, and this was their original model. Similar shapes are known from Germany.

You can compare with the planes from the Mary Rose which have the front horn but no handle in the rear. These are from 1545. https://pfollansbee.wordpress.com/ta...ose-shipwreck/

Interesting is also the "Sign of the three plains". That one is copied a lot but was originally a shop sign from one of the earliest London planemakers. These don't seem to have offset totes. A crude image: http://threeplanes.net/

[Jim Koepke]

Interesting is also the "Sign of the three plains". That one is copied a lot but was originally a shop sign from one of the earliest London planemakers. These don't seem to have offset totes.

Kees,

Maybe my eyes are off but the "Three Planes" all seem to have their totes to one side. What is odd is two of the three seem to be left handed.

It may be that there was a left hander in the shop. It may also be the sign was made this way to cause inquisitive minds to come in and ask.

The real question would be if any left hand examples of old planes have been found.

jtk

[Kees Heiden]

Here is a beter picture from the book Britisch planemakers. To me it looks like central totes. But yous houldn't put too much faith in the artist. The irons look skewed, and they even look like double iron planes, which would be a bit too early. This business card is from early 18th century.

Threeplanes.jpg

[george wilson]

You can't rely on the illustrations. Artists likely did not use the tools,and sometimes the reversed images got confusing to the engraver.

There does seem to be some damage to Mack's plane's horn. It is exactly the same model jack that I have posted pictures of before,but here it is again. We also made a jointer with an offset handle,but those are the only models we made with handles. The rest were coffin smoothers.

The image of the cabinet shop is bad because it was taken in the low light inside the shop,apparently without flash. Maybe to not disturb the other tourists?

Mack must have used the plane a lot,because when new,the iron went over the top of the tote,clearing it by only 1/8". That is how the original was made too,with the iron barely clearing the tote. It looks like the iron is worn down nearly to the last of the steel bit.

[Tom M King]

I had a theory about the offset handle, so rather than figure it out by talking about it, which I usually find pretty unreliable, I tried it out by hands on.

I gave a guy a Primus Jointer to run on the edge of a board for ten passes. He had never operated a hand plane before. The iron was sharp, iron honed straight across, and the plane properly adjusted to take the same thickness shaving on both sides of the iron.

After ten passes, the board's planed edge rolled down to the left.

Then I did the same test over again with my Brother-in-Law, who had used a hand plane before, but didn't remember exactly on what, and got pretty much the exact same result.

My theory was that without a center knob on the front, and with a right handed users left hand on the left side of the front of the plane, that there would be more pressure put on the left side. I was thinking that the offset rear handle to the right would counter this.

I expect a lot of work was handed to the new guy/apprentice/slave to do a lot of the work like planning the larger surfaces, and planeing in general. Tool makers probably came up with a way to get better results quicker.

When those of us, who are used to using tools, do something like plane an edge, I expect we subconsciously make any small adjustments needed to get good results, so we are not the best test for such a theory.

I wished that I had had a right offset rear handle plane to put in the hands of both of these guys, but didn't.