Using violin rosin to increase friction?

If you have a string instrument of any kind that needs fixing, a mistake you made in building a new instrument that you need to "disappear," or a question about the ethics of altering an older instrument, ask here. Please note that it will be much easier for us to help you decide on the best repair method if you post some pictures of the problem.

Using violin rosin to increase friction?

Postby Andy Birko » Mon Aug 27, 2012 11:15 am

The attached picture is that of a re-tune mechanism. The mechanism raises the pitch of the string by a semitone when engaged. Unfortunately, this style of mechanism doesn't work very well but, I'm tasked with getting it into passable condition. The problem I'm having is that on some strings, there's not enough friction between the brass part and the wood to get a good tone. If you hold the mech engaged with your fingers you get a decent tone but as soon as you let go, the string tension pushes the mech back a little bit and the tone dies.

I had a though that perhaps I could make a powder out of some violin bow rosin and coat the mech with that to increase the friction enough to hold the mech where it needs to be. Can anyone think of a major reason why I shouldn't go through with that? Any other ideas?

I had another thought of using pin-tightener for pianos but as I looked into that, it seems thats just a solution of water and PG to hopefully draw more moisture into the wood. That solution sounds temporary and irreversible so I'm going to skip that.
Attachments
mech.jpg
PMoMC
User avatar
Andy Birko
 
Posts: 125
Joined: Fri Jan 06, 2012 5:02 pm
Location: Rochester Hills, MI

Re: Using violin rosin to increase friction?

Postby Steve Senseney » Mon Aug 27, 2012 2:44 pm

When I have had a loose tuning pin on a piano, I have tightened the tuning pin with a shaving of hard wood.

Your pins don't look as if they are tapered, or knurled. Is the block that they sit in a laminate or simple hardwood?

If it is a laminate you might try a slip of wood. If it is solid piece of wood, it will most likely split if you try a shaving of wood.
Steve Senseney
 
Posts: 673
Joined: Fri Jan 06, 2012 2:45 pm

Re: Using violin rosin to increase friction?

Postby Andy Birko » Mon Aug 27, 2012 3:09 pm

It's solid wood. I thought of the shaving idea as I've done that before with loose tuning pins as well but, this is pretty tight all ready, it just needs a tiny bit more. I'm not sure a shaving will even fit as the mech isn't tapered or anything. It would probably have to be glued in.

I'm not convinced that the rosin thing will work but I'm more looking for good reasons as to why not to do it. It seems like it would be pretty benign to try it but I want to make sure I'm not missing something.
PMoMC
User avatar
Andy Birko
 
Posts: 125
Joined: Fri Jan 06, 2012 5:02 pm
Location: Rochester Hills, MI

Re: Using violin rosin to increase friction?

Postby Barry Daniels » Mon Aug 27, 2012 3:48 pm

I can't imagine that it would hurt to try it. You can always clean it off if not successful.

The fact that these pegs are not tapered is probably why they slip.
MIMF Staff
Barry Daniels
 
Posts: 2370
Joined: Thu Jan 05, 2012 10:58 am
Location: The Woodlands, Texas

Re: Using violin rosin to increase friction?

Postby Michael Lewis » Tue Aug 28, 2012 1:47 am

It is a bit unclear to me how your mechanism needs to work. For wooden pegs I use chalk dust to gain friction rather than rosin. Rosin tends to be very grabby and jerky and the chalk is smoother. Those look like a different type of sharping levers as used on harps, not like what I have seen. What is the instrument?
Michael Lewis
 
Posts: 1446
Joined: Thu Jan 12, 2012 1:22 am
Location: Northern California USA

Re: Using violin rosin to increase friction?

Postby Andy Birko » Tue Aug 28, 2012 3:12 pm

The instrument is a bandura. These aren't a cam type mechanism but rather a "pinch" type mechanism. The reason being that one mechanism is used to raise a string and the string a half step lower.

These mechanisms don't work very well period but as I mentioned, I'm tasked with getting them to a passable condition. Chalk sounds like a good idea. I was worried that the rosin might be grabby.

Is there any special chalk I should look for or will regular old black board type chalk work? I think I might even have some red chalk in the basement in powder form which would be less conspicuous.
PMoMC
User avatar
Andy Birko
 
Posts: 125
Joined: Fri Jan 06, 2012 5:02 pm
Location: Rochester Hills, MI

Re: Using violin rosin to increase friction?

Postby Andy Birko » Tue Aug 28, 2012 3:25 pm

Gotta love this forum! I tried the chalk powder and it works like a charm! I had some red chalk for a snap line and am just brushing a bit on the lever and it's holding that last little bit.

Thanks!!!!
PMoMC
User avatar
Andy Birko
 
Posts: 125
Joined: Fri Jan 06, 2012 5:02 pm
Location: Rochester Hills, MI


Return to String Instrument Repair: Practical and Political Issues

Who is online

Users browsing this forum: No registered users and 1 guest

Your purchase from these sites helps support the MIMForum, but only if you start at the links below!!!
Amazon music     Amazon books     Amazon tools     Rockler tools     Office Depot    

The MIMF is a member-supported forum, please consider supporting us with a donation, thanks!
 • Book store • Tool store • Links •