how deep should the knot cup be?

Title pretty much says it all. Let's say I was going to try making a brush. how deep should the cup for the knot be? Does it matter from one manufacturer to the next? In other words, if I ordered from TGN, will they give some sort of specification of the dimensions for the cup? Watching YouTube videos, I've seen several people do the tape-on-the-bit thing as a depth gauge, but I'm still not clear how they determined what that depth should be. Thanks!

Between 5 and 25 mm, depending on the the knot and the handle. Knots come in a variety of hair types, diameters and lofts. If I have an old brush, with a 20 mm opening, I would order a 20mm 2 band finest from the Golden Nib. I would then use a dremel w/ sanding drum to open the handle to about 22 mm, (a 20 mm knot will not fit into a 20mm hole) and deep enough so that 44-46 mm sticks out of the handle ( I like more backbone than some). The 20 mm knot from TGN is 65 mm tall, so I would drill down to 18-20 mm. If I temporarily set the knot and it looks too deep, I would raise the knot up using cork, coins, or build it back up with epoxy before setting the knot permanently.

what he said.i never set the knot base above the cup but after that its as your desired backbone.deeper = more good luck and we like pics.

Great information, thanks Mike!

Welcome to Badger and Blade geoffvsjeff!

Thanks for the info. If you want more backbone and go for a deeper cup, would you also use more epoxy when putting the knot in? In other words, would you use the same adhesive technique regardless of depth, or do you use more for a deeper cup? Also, for deeper cups, is there any worry about water being retained in the brush and doing damage?

Yes, use the same amount of epoxy, regardless of depth, and do not use very much. It only takes a drop. If you put too much in, when you set the knot it will squeeze out and get on the hair and around the edge and look awful. Don't ask...

In my experience, water will not stay in the bottom, the capillary action of the hair will pull moisture up, and the bush will dry normally.

Mike H said:

Yes, use the same amount of epoxy, regardless of depth, and do not use very much. It only takes a drop. If you put too much in, when you set the knot it will squeeze out and get on the hair and around the edge and look awful. Don't ask...

In my experience, water will not stay in the bottom, the capillary action of the hair will pull moisture up, and the bush will dry normally.

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+1even on the dont asksee the glue at the base.it was my first reknot.brush still works well,but it could've been better.

geoffvsjeff said:

Title pretty much says it all. Let's say I was going to try making a brush. how deep should the cup for the knot be? Does it matter from one manufacturer to the next?

Click to expand...

Depends
Synthetics and Boar knots don't need to "toss" them below the top of the handle.
Some very soft badgers will over-bloom so few mm's down will help a lot.