yoderjac
5 year old buck +
Since I'm sure there are folks reading this that are new to grafting, I think we should discuss why knives designed for bench grafting are single bevel. A double bevel knife (sharpened on both sides) wants to change directions when cutting through wood based on resistance (wood density). As the knife slices thorough the wood, slight movement will create a wavy. Consider the first cut of either rootstock or scion for a whip and tongue graft. If both sides are not completely flat, bumps or waves in the wood will reduce cambium contact even if you have good diameter alignment. A single beveled knife (sharpened on one side only) tends to resist this to some degree. Because one side of the knife is flat, the single cutting edge tends to lead. The same thing is happening in that the blade wants to turn slightly based on differing wood density (resistance), but the knife design tends to resist this and the cut tends to be flatter.
Now consider the second cut on a W&T graft, the tongue. We want this to be straight, parallel with the rootstock and scion and the same distance on both so the tongue holds the cambium layers together when assembled. It is much easier to make this cut straight rather than at an angle with a single beveled knife. The flat side is easy to keep parallel.
One more thing to keep in mind. Regardless of the type of knife, a dull knife is much more subject to having its path altered by the density changes in the wood than a sharp knife. Sharpness, in my opinion is more important.
Does this really matter?
I would guess in the hands of an experienced grafter, just about any sharp knife will do just fine. They know exactly what is important about each cut and are skilled at creating those features. In the hands of use novices, every advantage can be helpful. Consider the rest of the grafting process. You can have gaps in cambium contact and still get a successful graft. Things like grafting rubbers can force some gaps to close if the alignment is good. So, if you experienced with the whole process, good practices on one step can mitigate less than perfection in another.
Finally, consider the kind of tree you are grafting. Apples, for example are very forgiving. I've had success (and I'm not highly experienced), doing W&T grafts on apples with only one side of the cambium aligned. Apples have a thick cambium layer and the wood is relatively soft. You can move a sharp knife slowly and delicately with little pressure through the wood. By contrast, a tree like Jujube is very hard wood. They are often no round so alignment can be difficult. The cambium layer is very thin by comparison. I have had success bench grafting Jujube, but I've really got to do everything right, and even then, some will fail.
The knife is only one factor. The less experienced you are, and the more difficult the tree species you are grafting, the more important it is. I personally spent more on good sharpening stones than I did on a knife. I ended up buying one like this: https://www.amazon.com/Victorinox-B...ocphy=9008141&hvtargid=pla-380729511332&psc=1 It was not expensive and holds an edge well. I spent a lot of time figuring out what sharpening stones to get.
Thanks,
jack
Now consider the second cut on a W&T graft, the tongue. We want this to be straight, parallel with the rootstock and scion and the same distance on both so the tongue holds the cambium layers together when assembled. It is much easier to make this cut straight rather than at an angle with a single beveled knife. The flat side is easy to keep parallel.
One more thing to keep in mind. Regardless of the type of knife, a dull knife is much more subject to having its path altered by the density changes in the wood than a sharp knife. Sharpness, in my opinion is more important.
Does this really matter?
I would guess in the hands of an experienced grafter, just about any sharp knife will do just fine. They know exactly what is important about each cut and are skilled at creating those features. In the hands of use novices, every advantage can be helpful. Consider the rest of the grafting process. You can have gaps in cambium contact and still get a successful graft. Things like grafting rubbers can force some gaps to close if the alignment is good. So, if you experienced with the whole process, good practices on one step can mitigate less than perfection in another.
Finally, consider the kind of tree you are grafting. Apples, for example are very forgiving. I've had success (and I'm not highly experienced), doing W&T grafts on apples with only one side of the cambium aligned. Apples have a thick cambium layer and the wood is relatively soft. You can move a sharp knife slowly and delicately with little pressure through the wood. By contrast, a tree like Jujube is very hard wood. They are often no round so alignment can be difficult. The cambium layer is very thin by comparison. I have had success bench grafting Jujube, but I've really got to do everything right, and even then, some will fail.
The knife is only one factor. The less experienced you are, and the more difficult the tree species you are grafting, the more important it is. I personally spent more on good sharpening stones than I did on a knife. I ended up buying one like this: https://www.amazon.com/Victorinox-B...ocphy=9008141&hvtargid=pla-380729511332&psc=1 It was not expensive and holds an edge well. I spent a lot of time figuring out what sharpening stones to get.
Thanks,
jack
