bengreen

Bow - Cracks in Head

Recommended Posts

This is my stand partner's German (as in German grip) bass bow. I'm not in the shop right now but if I remember right it's a Schuster.

I took it on to replace the tip and rehair, but found cracks in the head.

59ea8c1400879_KeithBowFront.thumb.jpg.f4d9bbe2b1f5bbc2ee2049bb87ce8040.jpg59ea8c2f950ec_KeithBowBack.thumb.jpg.ce1fa736ab27aa6ef2e3df1ef8e71fc8.jpg

 

I've never seen cracks like these in an old bow. They look like checks in drying lumber. My eyes are not what they used to be but when I squeeze the front I think I'm seeing some very slight movement. There don't appear to be any cracks looking inside the mortise.

I'm at a loss what to do about this. The owner asks if can't just wick some CA glue into the cracks and continue on with the original work. I'm having trouble convincing myself that's a permanent solution. Especially since he's a pretty powerful player.

Any ideas?

Thanks.

Share this post


Link to post
Share on other sites

It appears to be the typical damage which can happen if the head plate is damaged as we see it here. Once it's stabilizing function is lost, the pressure of the wedge causes the wood to crack along the grain lines (that's what makes it look like an assembly). IMO the first thing to do is remove the plate, then clean and reglue the cracks as suggested, at least fit a new headplate.

Share this post


Link to post
Share on other sites

H Bengreen - just to make the suggestions unanimous - acetone or MEK wash and instant glue.

In 1964 my cello bow developed a crack that started high up on the left hand side of the tip and ran at an angle towards the centreline. Being a freshly graduated engineer I carefully watched this slow motion development of a stress failure - thinking that within a short time I would be faced with buying a new bow. 

The crack slowly grew longer - my daily inspections covered weeks, months, years and eventually decades.

Finally the crack could be seen to move when squeezed and an almost retired engineer yielded to an urge of "Fix-It".

A couple of drops of MEK to flush the surfaces of the crack, a blast from a hair dryer to remove all traces of the MEK and a drop of super glue massaged into the crack and  then held tight for a count of 60. The following day I carefully removed the surface excess and buffed up the tip.

The repair has been holding for the last 17 or so years - so this now-ancient engineer can report that it is also a well tested repair routine.

Go for it.

cheers edi

Share this post


Link to post
Share on other sites

They are checks in the wood following the grain, possibly always been there . They generally dont cause much of a problem due to the direction of the checks.

There are high end Tourtes ,Peccattes etc... that have had these for 150- 200 years .  Bow wood blanks  often show cracks of this type which show up when the wood is heated and all but disappear when the wood cools. If the cracks are going from left to right or skewed through a critical part of the stick then that is when to worry.

These cracks often go right through the wood and are maybe only held together  by small areas inside the wood.

If you can get hold of Hxtal nyl-1 optical epoxy ,which is quite expensive it might wick in and settle the owners nerves a bit. It is as thin as water but takes around a week to dry.

http://www.hxtal.com/

The bow head also looks to have been knocked quite a few times on the top of the head ,which may have made the cracks more visible.

Share this post


Link to post
Share on other sites

Yeah, it's been through the wars.

Thanks for the comments. I'm not feeling so pessimistic now. A new tip is definitely on the agenda. Plenty of CA and Acetone on hand but I'm intrigued now about the Hxtal. I had read Jerry P's articles on using Optical Epoxy and been curious but didn't realize it was so thin. I'll order some and experiment, then decide which to use.

Next up will be the frog. Even worse shape.

Share this post


Link to post
Share on other sites
3 minutes ago, bengreen said:

Yeah, it's been through the wars.

Thanks for the comments. I'm not feeling so pessimistic now. A new tip is definitely on the agenda. Plenty of CA and Acetone on hand but I'm intrigued now about the Hxtal. I had read Jerry P's articles on using Optical Epoxy and been curious but didn't realize it was so thin. I'll order some and experiment, then decide which to use.

Next up will be the frog. Even worse shape.

My use of it has it not as thin as water, but still yet VERY thin compared to regular epoxy for sure. It is expensive, but it's opical properties (or lack there of) are incredible.  For bow fills, it's truly amazing.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.