Measuring bow hair length

[polkat]

I don't normally rehair bows, but have done a few...some successful and some not. I usually install in the tip first, then comb it out and determine where to knot it for the frog. This is where I run into problems. How does one determine where to knot the hair at the frog end to end up with the right length once fully installed? I sometimes end up with the hair too long (and less often with the hair too short). With the frog installed and run up toward the tip, is there a standard place on the frog bottom to use as a guide to knot the hair? Thanks!

[alfadir]

Hello,

I was taught to take the depth of the mortise of the frog and add that length to the end of the slide slot and tie the knot there.

[Brad Dorsey]

"How does one determine where to knot the hair at the frog end to end up with the right length once fully installed?"

I make my knot so it starts about 5 millimeters past the end of the hair mortise and ends about 10 millimeters past the end of the hair mortise. The knot itself is about 5 millimeters long.

The exact length that I make the hair is somewhat variable depending on anticipated humidity changes. In the humid summer I leave the hair longer, because I know that, if I don't, when the dry winter comes, the hair will shrink to the point where it cannot be completely loosened.

I make the knot by winding the thread on the hair for about 2.5 millimeters, tying a knot, winding on another 2.5 millimeters and tying another knot. If it turns out that the hair is too short, I can undo one of the knots and let out a little more hair to lengthen it.

It's always better to err on the side of leaving the hair too long rather that cutting it too short. If it's too long, you can always shorten it by tying another knot and cutting more hair off. But if it's too short, all you can do is take the hair out and save it for a shorter bow.

A cheap bow will often have a hair mortise that is too short. If it does, I dig it out longer (and deeper, if necessary) to give myself more room to work. And with a longer mortise, I can make a longer knot, which gives me more extra hair to let out if I need to.

[Mat Roop]

If your hair is just a touch short... you can add length by slicing a bit off the top of the frog plug. I guage each job separately knowing that the knot needs to lay flat under the plug and the hair needs to ride up and over the top of the plug... so the plug dimension is key to the location of the knot....

Cheers, Mat

[Josh Henry]

Have you tried to hair the bow frog to tip? I find it much easier to gauge the correct length at the tip end. (However, this could be because this is the method that I was taught.) It seems that every time I try to hair a bow from the tip to frog, I have the same problem--inconsistent length results. Both methods work well with practice, but I definitely prefer starting at the frog.

[polkat]

Thanks guys, the responses make sense. But to make sure I understand, just a few questions more.

alfadir; in most of the frogs I've worked with the mortise is roughly some 10 to 12mm ahead of the back of the slide, so you are adding that distance, plus the depth of the mortise, right? Seems like you'd end up with the hair a tad long, no?

Brad; If the hair ends up the right length after you've done the two knots, isn't that a pretty big knot (5mm) to stuff under the plug?

Of course, I'll have to give these a try, and I'll let you know how it comes out. Thanks again!

[fiddlecollector]

Is rehairing tip first an American thing ?Most people here in Europe i know of always rehair frog first.

[Brad Dorsey]

"Brad; If the hair ends up the right length after you've done the two knots, isn't that a pretty big knot (5mm) to stuff under the plug?"

It depends on the plug length, which depends on the mortise length. Now I'm looking at a ruler, and I see that 5 mm is probably longer than most of my knots. As I said, I often cut the mortise longer to give myself lots of room. I always tie two knots to give myself the option of letting out a little hair if necessary.

[Johnmasters]

Have you tried to hair the bow frog to tip? I find it much easier to gauge the correct length at the tip end. (However, this could be because this is the method that I was taught.) It seems that every time I try to hair a bow from the tip to frog, I have the same problem--inconsistent length results. Both methods work well with practice, but I definitely prefer starting at the frog.

I taught myself to rehair from tip to frog did this for many years. The other direction has two advantages:

1.) Variations in the sizes of tip mortices varies less than those in frogs.

2.) I buy my hair in bulk and separate it into a number of smaller bunches, tied at the yellow end. Each of these can be divided into approximately the same number of individual hanks tied at the white end. This end can be as near as possible to the good end of the hair. I waste only the worse end of the hair. That is not to say that I do not adjust the amount of hair for a bow.