Centre of Effort - Part II

I was prompted to write this after replacing the handle I added to a HNT Gordon Trying Plane.

At the end of the previous article I wrote, “This is a low plane with a low C of G. By adding the handle and pushing from high up, the whole C of E changed. It is awful - - this weekend I plan to remove the handle ..”.

What changed by adding this handle? Well, it lost much of the control it had previously. The HNT Gordon Trying Plane has been one of my favourite planes – short jointer, panel plane, shooting plane. It has been extremely reliable. Using the handle disconnected one from the plane. There was little feedback.

What one should realise is that this style of Chinese-Indonesian plane design is traditionally used with a cross handle, such as here …

I used it this way, but mostly by gripping the body behind the blade in an open hand.

The HNT Gordon has a high bed angle (half pitch, or 60 degrees) for the interlocked Australian woods, and I use it on particularly hard timber. This combination of these factors made using it more fatiguing to push, and the reason I sought to add a traditional handle.

It has taken a little longer to get around to removing the handle. I spent some time using it some more, trying to understand why it felt the way it did, and what could be done to improve matters.

I found that I wanted to drop my hand and push with my palm at the base of the handle. By doing so the control returned. It seemed that the Bailey-style handle was completely wrong, and that it should be replaced by something Krenovian, or nothing at all.

The handle in question has an angle close to that of the common Stanley handle. My reasoning for this at the time was that the plane would be used on a low-ish bench and I did not want my wrist to cock at too much of an angle.

Below is a Stanley #3 for comparison …

Grasping the handle really felt comfortable. It was placed at a distance from the blade that was as close as I could get it and that still enabled a hammer to adjust the blade.

The problem was that it was completely unbalanced in use. What worked better was holding the handle at its base, as below …

I concentrated on how I grasp a Stanley when taking light-moderate thick shavings in softer woods. Let me know if this is the same for you?

The top of my hand snuggles under the horn. I can feel pressure on this area when pushing the plane. In other words, the effort is high on the handle.

However, with thick shavings or when the wood was hard, my hand would drop down the handle and push forward with the heel of the hand – the same way I preferred with Gordon. Looking at the result of this grip (below) a gap between my palm is left at the top of the handle.

My thought was to fill the gap at the top to provide even support over the palm.

This meant that the handle would need to be more vertical. What a minute – this is beginning to resemble the Veritas handle!

I decided to go along with this logic (well, it made sense to me). The proof of the pudding lies in the eating. So off came the handle …

Below you can see the amount that the handle needed to be straightened up to mimic the angle of the Veritas (the lower edge of the blue tape) …

Below is the new handle (unattached) alongside the Stanley for comparison of angles …

Incidentally, it did occur to try a Krenov-type grip …

This was essentially the same as using the plane without any support for the hand across the plane. The problem is that the plane body is too wide to spread the hand comfortably. So it was discarded.

Here is the plane with the new handle now attached …

More importantly, how does it feel in use? Is there a difference?

The difference is quite large. Gone is the squirrelly feeling. The control I was wanting is back. It just feels comfortable and easy to use.

Some constructional features: A screw was used to connect the handle …

A single screw was drilled through the handle. It locks into a metal insert in the body. A steel rod (aka nail) prevents twisting …

The base is scalloped out to ensure that it lies flush with the body …

Here is a comparison of three handle angles that work well on three different planes.

At the front is the HNT Gordon Trying Plane (18” long) with the centre-located mouth. The handle is the most vertical of all these planes.

In the middle is a 15” long jack plane with a 45 degree bed and a more traditional mouth location (about one-third back). The handle has the same forward angle as a Stanley plane.

At the rear is a 28” jointer with a 55 degree bed and a mouth placed about 40% back from the toe. The handle here is close to the trying plane. It is a heavy plane and pushed forward with the heel of the hand.

Summing up

The choosing of a handle angle, and its placement, appears to be a combination of several factors and how these function as a system. A corollary is that altering the angle of the handle, and how one pushes a plane, affects the way the plane performs.

Regards from Perth

Derek

March 2014