Setting a knot isn't an exact science and much depends on the knot type, shape and height and handle socket diameter and depth. I always aim for a socket diameter 2mm larger than the base of the knot plug. The depth of most handle sockets is between 15-20mm so if you have a 67mm knot set in a 15mm deep socket the final loft will be 52mm. This can raised by adding a coin or a nylon washer. Generally a final loft of between 52 and 57mm is ideal for most users but much depends on your personal preference.
Badger hair requires room to bloom. If the knot is set too deep in a tight socket pass-through may be hindered.
Look at the pic below... both knots have a base plug of 26mm but vary in shape and height.
Notice how the knots fan out just above the 10mm glue plug. When setting a knot the diameter of your socket needs to accommodate that extra width which is another reason I aim for a socket diameter 2mm larger than the knot diameter. For successful setting the base of your knot will always have to touch the base of your socket.
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Here's another example. Both knots have a base of 26mm but vary in loft height
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These handles have a socket diameter of 30mm and depth of 18mm. They'll be set with a 28mm knot with the final loft height to be determined depending on the chosen knot. Some knots require a lift some don't. For my personal preference I'll aim for a final loft of between 55-57mm
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Hope this helps
James
Thanks, James. Perhaps I formulated this poorly. I wasn’t really after the instructions, as I’ve set a few myself before, more the effects of different parameters, changing one or more variables, how it/they interact and impact on the performance and feel of a brush. In essence I was asking specifically about this from a scientific or systematic perspective, cf your first point about it not being exact science. It could be if we were able to control all variables such as protrusion above plug, amount of centre glue bump, numbers of hair, what hairs, diameter, height, etc, but there surely should be some general findings nevertheless.
Most of my favourite brushes have a rather tight fit and gives little when pressing against the hairs just where they exit the handle, I thus suspect 2mm wider socket than knot is too much for me. I prefer less bloom and splay, and also less loft than you, but enough not to impact on flowthrough and latherability. In principle when ordering separate knot and handle, I’ll get the knot first and measure it at the widest point usually just above the plug. Knot specs inform handle socket specs in depth and diameter. I’ll go for a rather deep drill to be able to set it deep if need be, and fill with epoxy or flat items if it needs more loft.
Going back to the systematic approach, I guess that giving a little more socket space will allow better flowthrough while keeping it deep for backbone, relative to a tight fit and a deep setting (which yields less latherability). So perhaps that is a general finding or fact. Say that a knot set with specs xxx hairs, y loft, socket diameter a, plug diameter b, and it yields too little backbone. One may try making the exact same knot only with 10% more hairs, set to exact same specs, and it would likely increase backbone. But how many hairs would be too much, and would it be good to keep adding hairs while also widening socket diameter? There must be a max density for knots, as need for flowthrough dictates a certain loft, higher the denser, and at some point it will go floppy. And the relatively denser knot presumably requires more socket diameter space, but when using an above the plug measure, that should sort itself out.
Things like these were what I was after. (Though we can do little about the knots lest we make them ourselves.)