Rehair-bow plugs?

[polkat]

rehairing my bows for the first time. Should the little wooden plugs in the tip/frog be pressed in or glued in? In most of the cheaper bows I've dissembled they were glued in, but somehow this doesn't seem right.

[stradofear]

They should fit in securely without glue. Properly cut, the mortise holds the wedge without glue, given the direction of the pull of the hair, which only wedges the plug in tighter, and yet you can back the plug out of the hole easily. Many cheap bows aren't cut this way, however, but you can recut them so they are.

If you pull the illustrated wedge out diagonally in a straight line up towards the upper left, it slides out. If you try to rotate it counter-clockwise as pulling on the hair would do (the hair fitting in the space to the right of the red box), it binds. Often, though, cheap bows don't have a parallelogram-shaped hole for the wedge.

[FiddleDoug]

No glue! I always curse people who put glue in any bows that I get in to rehair. I use yellow poplar for my tip and frog plugs, and basswood for the spreader wedge.

[Josh Henry]

Yes, the head plug and frog plug should NEVER be glued in. Stradofear is correct about having to usually recut the mortises on cheaper bows due to improper manufacture. However, I hate to disagree with Stradofear (because he is usually accurate in his postings! ), but in the diagram that he drew, there is no chance whatsoever that a plug could hold without a spot of glue ACK!. In his diagram, the right side represents the back of the frog, while the left is the ferrule end. The end of the mortise at the heel end should be angled like shown, but the ferrule end of the mortise should be close to vertical. This vertical end is where the the frog bears the pressure of the hair tension, and if cut at too much of an angle (like drawn), the plug will pop out.

I don't usually make the recommendation for the Wake book on rehairing, but the following diagrams of the plugs from his book are accurate, and show the correct shape. I went ahead and left the text so that you can read the instructions.

Also check out Don Reinfelds diagrams: http://www.drbows.com/diagram.html

[stradofear]

I have always seen it explained as I drew it, but on thinking about it I see why you're right.

[Brad Dorsey]

"Should the little wooden plugs in the tip/frog be pressed in or glued in?"

They definitely sholud not be glued in, but I use a little trick from Retford's book that sticks them in a little better than using nothing. I dip the plugs in powdered rosin before inserting them. It doesn't stick the plugs in like glue would or interfere with their removal, but it increases the friction and makes them less likely to slip out. The plug surface that I put the rosin on is the one facing the other end of the bow. I moisten the plug with my tongue to get the rosin to adhere to it.

Learning to shape the mortises and fit the plugs is a major part of becoming a competent rehairer. I realize that a plug correctly fitted into a properly shaped mortise will hold without any help, but I still like to use the rosin as a little extra insurance.

[zefir68]

rehairing bows is the biggest pain in the $%^. I'm lucky to have a very good guy close by. All of you that do it, kudos to you. I'd rather do anything to help fix a violin, but rehairing? Most players are so picky I just lose patience. A loaded question: is there more tension on the hairs of the bow closer to the player or even tension throughout?

[Oded Kishony]

I apply tension differential to the hqir if the bow is whimpy and the player requests stiffer action. It causes a slight 'good warp' in the stick. Too much will make the stick unwieldly, just enough will greatly improve performance of a mediocre stick.

Oded

[~ Ben Conover]

Interesting diagrams, thanks.

[Josh Henry]

... I dip the plugs in powdered rosin before inserting them. It doesn't stick the plugs in like glue would, but it increases the friction and makes them less likely to slip out. The plug surface that I put the rosin on is the one facing the other end of the bow. ...

This is a technique that I also use. I was taught to fit the plugs properly so they fit without any additional aid, but sometimes (especially on older bows that have been rehaired many times) this little extra bit of rosin powder is the insurance to keep 'em where they belong. In addition to a small tray of powdered rosin, I also have a small tray of liquid rosin (powdered rosin dissolved in alcohol). I use this on the ends of the bowhair to 'glue' the hair together and keep my string from slipping while I tie the end knots.

In the scans that I posted, Wake mentions the use of willow or poplar for the plugs. These would be fine, bit I generally use maple for my plugs, as I find that after properly fitting them with the harder wood, I can reuse the head and frog plug several times before needing to replace them. I do use basswood when fitting the spread wedge (this gets replaced with every rehair). I like basswood for the wedge due to the compressibility in the wood. Here is the only place where glue is used in the rehair--one drop of glue (I use the liquid hide glue--in the brown bottle) on the wedge will hold it in place.

... A loaded question: is there more tension on the hairs of the bow closer to the player or even tension throughout?

If I can, this is something that I try to observe before I cut the hair out of the bow. I'll also ask new clients if they have any preference here. I was taught to spread the tension of the hair evenly across the ribbon of hair. However, I am often requested to slightly bias the tension to the player's side, and sometimes even requested to spread the hair so that there are more hairs on that side. I don't have a problem with this as long as it is not excessive. Too much, and the bow will warp and not play well. As Oded Mentions above, it can help a not-so-bow, but if overapplied, can be detrimental to the playing qualities. By the way, the tension of the hairs in the middle of the ribbon of hair are always slightly lower than the tension of the hairs at the sides.

[John Vergara]

Yes. Please do not use glue. Its really hard to get out if you're rehairing. I also use poplar for the tip and the frog. Also the the wenge.

[GlennH]

Where is a good place to purchase powdered resin to secure the thread wraps on each end of the bow hair?

Glenn

[Brad Dorsey]

Some violin trade suppliers sell powdered rosin, but you don't need to buy it.  You can crush and grind up pieces of cake rosin.  That's what I do.

[Guido]

5 hours ago, GlennH said:

Where is a good place to purchase powdered resin to secure the thread wraps on each end of the bow hair?

Glenn

A mortar and pestle makes old rosin chunks explode into dust.