Violin Forum/Message Board Forum Index Violin Forum/Message Board
Provided by Violin Vision
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

split bow head

 
Post new topic   Reply to topic    Violin Forum/Message Board Forum Index -> Bow Making Forum
View previous topic :: View next topic  
Author Message
Mat Roop
Senior Member


Joined: 24 Mar 2007
Posts: 911
Location: Wyoming Ontario

PostPosted: Mon May 18, 2009 9:49 pm    Post subject: split bow head Reply with quote

Some time ago there was a discussion on how to repair a split bow head. I had done a couple of such repairs using the method of glue the split and install a hidden pin from under the tip. Michael D had advised that will not work because of the different expansion rates for the pin and head. I soon (after 1 year) found out that the two I had done had failed. So the next avenue was the Harry Wake method of a spline for which I used .8 mm pernambucco ... so far it has not failed... but it does leave the edge of the spline insert visible.
But I got to thinking... (and that is dangerous!) would the pin method work if a small carbon fiber rod were used as the pin with the G2 epoxy?? I am assuming there is little expansion or contraction with the carbon... and the carbon rod is apparently used successfully for pinning broken shafts.
I am curious because I do like the fact that the pin method is virtually invisible.
Thoughts?? ... and Cheers!! Mat
Back to top
View user's profile Send private message Send e-mail Visit poster's website
FiddleDoug
Member


Joined: 08 Sep 2007
Posts: 227
Location: Hilton, NY

PostPosted: Wed May 20, 2009 5:13 pm    Post subject: Bow spline/pin Reply with quote

Matt,
I'm not an expert, but I'm of the opinion that the location of the break might make a difference on which method to use. If the break is right up even with the lower edge of the stick, the pins don't have much to stick into on the top end (and I would go for a spline). If the break were a little lower, I would go for carbon pins. (I need to order some to have on hand in case this comes up.). I'm using a thin Micarta material for splines (experimental- see my website for details).
_________________
Doug Wall

www.wallindependent.com
Back to top
View user's profile Send private message Visit poster's website
Jack H.
Super Member


Joined: 24 Mar 2007
Posts: 346
Location: Israel

PostPosted: Wed May 20, 2009 5:38 pm    Post subject: Reply with quote

in my experience pins just do not work.
A screw would be much more effective. It would actually hold the pieces together even if the glue joint fails. It would also be less likely that the glue joint fails when the screw is taking the stress with the joint.
The issue of the screw is this; is there enough wood for the screw to get a good bite and hold...
The spline is a proven method when done properly ( good fit, no glue lines, no damage to the head while trimming the spline... ), and while it is visible, representing a broken bow as anything but is not very ethical... so the visibility of the repair is not an issue.
Back to top
View user's profile Send private message Send e-mail
Mat Roop
Senior Member


Joined: 24 Mar 2007
Posts: 911
Location: Wyoming Ontario

PostPosted: Thu May 21, 2009 9:19 pm    Post subject: Reply with quote

Doug... I have just ordered on line some carbon pins from Dragon Plate and also a carbon fiber sheet 1/16" for splines.... do you think carbon sheet would work as well as the Micarta? I am thinking more of using the pins experimentally for shaft breaks... but I have also had good luck with pernambucco splines for breaks.
Jack... I tend to agree with the concept of making a repair visible.

Do you folks think that the talk of carbon pins and splines is overkill... after all, a healthy thickness of pernabucco or ebony is pretty tough to break... the key being the glue and my confidence is building for the G2 epoxy.
Thanks for your thoughts...I should send a penny!Smile
Mat
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Jack H.
Super Member


Joined: 24 Mar 2007
Posts: 346
Location: Israel

PostPosted: Fri May 22, 2009 5:22 am    Post subject: Reply with quote

The two pins that failed after a year... were they done with the G2 epoxy???
What kind of wood was the pin???
Back to top
View user's profile Send private message Send e-mail
FiddleDoug
Member


Joined: 08 Sep 2007
Posts: 227
Location: Hilton, NY

PostPosted: Fri May 22, 2009 9:40 pm    Post subject: Carbon splines Reply with quote

Seems to me that I saw some info from some other shops about using carbon splines. Should work just fine, but 1/16 may be too thick. 1/16 is 0.0625" the Micarta that I'm using is about 0.028". The Micarta finishes to a very close color to the pernambuco, but is not invisible.
_________________
Doug Wall

www.wallindependent.com
Back to top
View user's profile Send private message Visit poster's website
Mat Roop
Senior Member


Joined: 24 Mar 2007
Posts: 911
Location: Wyoming Ontario

PostPosted: Sun May 24, 2009 10:18 pm    Post subject: Reply with quote

Jack H. wrote:
The two pins that failed after a year... were they done with the G2 epoxy???
What kind of wood was the pin???

These were done with maple pins and 5 minute epoxy... before I knew about G2..
Cheers, Mat
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    Violin Forum/Message Board Forum Index -> Bow Making Forum All times are GMT - 4 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group