The previous discussion of grips is far from over!
One method I have used to compare grips, is to have them face off. Then I can see, as I swap hands and grips, which grip applies more force with less effort.
I followed the suggestions of a source that advised making an OK sign with your thumb and index finger to find the ideal diameter for a tool.
I think I will ignore that source from here on out, the handle is way too big. 1 3/4″ is definitely too large. My smaller fingers only get a bit more than half way around this. Not a secure grip.
So now I will evaluate another source of ergonomic data.
The study, Optimal cylindrical handle diameter for grip force tasks
by Yong-Ku Kong and Brian D. Lowe, indicates that an ideal diameter would be 19.7% of the distance from the tip of the middle finger to the crease where the wrist starts and the palm ends. If I divide this by pi, to get a diameter I get 6.27%. From middle finger tip to crease, I measure right at 8″. From their data, a 1/2″ diameter grip would be ideal for me. OK, we are back to the drawing board. I like 1/2″ for a pen, but it is way to small for a good chisel grip.
So after loosing faith in authoritative experimental data in this field, it is time to use simple logic. If the grip spreads the forces to a maximum area of the hand, this will reduce stress. If it can be spread evenly or distributed to use the strengths of the hand well, that will be even better. Having the handle function for a wide range of grips is also a must. It also seems logical that a larger grip will reduce the chance of cramping by keeping fingers less tightly curled.
Another question for me is whether an octagon puts more stress on due to micro-adjustment or less stress due to positional feedback. since the bones swivel all the way back from the elbow, I suspect that micro-adjustment is no big issue. So my guess is that the solidity of the grip and the feedback makes the octagon superior. On the other side, I have used a hexagon shaped tool handle and found the facets to be much too large. is reducing the facets from six to eight enough?
In any case I am forced to examine my hand and the grips I use and the size of handle that that grip requires.
When pounding on a chisel I use a hammer grip with the blade pointing down. Slightly over 1″ feels about right.
I want to start using the gouge grip,
But I don’t want the butt of the chisel in my palm since industrial statistics show a good deal of hand injuries are related to tools that are pushed by the palm.
When chiseling away from me I usually use a fencing grip with my index finger extended towards the blade. Again, a hair over 1″ feels pretty good.
When chiseling across relative to my body, I just grab the chisel. I may fold the thumb back if I need extra clearance. 1″ again is fine.
For detail I like to use several different pinch grips. For this, 1″ is usable but too large. I like a big pencil but if it gets too far over 1/2″ it stops being comfortable.
For cutting and whittling, my grip is pretty standard, with my thumb extended on the back of the blade. I am used to a fairly wide range of sizes for knives, so I don’t have a huge preference here.
To accommodate all of these grips, a handle that tapers from a bit larger than 1″ to about 1/2″ at the tip may be the solution. This profile seems to match with what Thomas Martin, in his, The Circle of the Mechanical Arts, London, 1813 considered a to be a chisel grip.
Since I like a fencing grip quite a bit, I want the tool to taper from a maximum diameter of about 1 1/8″ to a minimum diameter of maybe 1/2″ inch over the distance from the tip of my pointing finger on the tool, to where my pinkie wraps around the tool. I want my pinkie on the back side of a taper to give it a secure grip. After a bunch of figuring I came up with a 1 to 16 slope and made this cone.
I mostly used the methods shown by Timber Frame Tools. I figured out that if I cut a taper on the side of the V-Block, it would make a good guide for getting the angles correctly. Oddly enough this works the same even after you have cut down the tools other sides. The V-Block mounted on a board, can be both a guide for sawing, and a specialized shooting board for reproducing handles. 🙂
Then I gripped the cone to see if I even liked the thing and adjusted to where it felt snug in my hand.
The point between my pinkie and my ring finger, was where I decided to start my taper. I made a second cone so I could keep the first as a reference. The angle of the back taper was selected by feel. I kept pruning down until I liked the feel of it. The slope on the back is 1 to 4.
Then I smoothed it down. Cut off the excess on both ends and smoothed it some more. I am quite pleased with the book matched grain appearance!
The chisel is 7″ long, 1 1/4″ at the thickest and 5/8″ at the thinnest. Not quite the dimensions I was expecting, but I love this handle.
And it does it all!
Low Clearance grip for chiseling horizontally in front of you.
Regular grip for chiseling horizontally in front of you.
Fencing grip for chiseling away from your body.
Gouge Grip, which I have not used enough to know when to prefer it yet.
Mallet grip for when you are pounding a chisel. I will also put my other hand over the hand holding the tool, to add pressure while rocking the chisel side to side for deeper push cuts.
I don’t actually use this one, but I was taught to use it so that injuries would be less if I missed and hit my hand. I still think it will hurt pretty bad.
This is a grip that I use with a knife edge when whittling. I also use it for chiseling upward. When using a paring chisel, I usually use the fencing grip.
Then there are a couple of pinch grips that I use.
Brad has some amazing skills there!
After watching the video again, and getting some feedback on grips from WoodNet, It is possible that I have most of the single hand grips, but have left out the zillions of two handed variations.
Now that I have listed all the grips that I use, I would love to know if I am missing any important ones, or better ones?
Back to the octagonal grip in hand, I love it! It feels right! It is a lot of work to make right, and I fear that when I drill the end to put a bit on it, I will go crooked and make the tool look stupid after all this work. Still it is all worth it. Unless I hate it after I actually use it, this is now hands down and entirely, my favorite handle size and shape. Oddly enough, my better half loves it too, and she has tiny hands compared to me.