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Mat Roop Senior Member
Joined: 24 Mar 2007 Posts: 911 Location: Wyoming Ontario
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Posted: Mon May 18, 2009 9:49 pm Post subject: split bow head |
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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 |
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FiddleDoug Member
Joined: 08 Sep 2007 Posts: 227 Location: Hilton, NY
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Posted: Wed May 20, 2009 5:13 pm Post subject: Bow spline/pin |
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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 |
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Jack H. Super Member
Joined: 24 Mar 2007 Posts: 346 Location: Israel
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Posted: Wed May 20, 2009 5:38 pm Post subject: |
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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. |
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Mat Roop Senior Member
Joined: 24 Mar 2007 Posts: 911 Location: Wyoming Ontario
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Posted: Thu May 21, 2009 9:19 pm Post subject: |
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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!
Mat |
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Jack H. Super Member
Joined: 24 Mar 2007 Posts: 346 Location: Israel
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Posted: Fri May 22, 2009 5:22 am Post subject: |
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The two pins that failed after a year... were they done with the G2 epoxy???
What kind of wood was the pin??? |
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FiddleDoug Member
Joined: 08 Sep 2007 Posts: 227 Location: Hilton, NY
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Posted: Fri May 22, 2009 9:40 pm Post subject: Carbon splines |
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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 |
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Mat Roop Senior Member
Joined: 24 Mar 2007 Posts: 911 Location: Wyoming Ontario
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Posted: Sun May 24, 2009 10:18 pm Post subject: |
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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 |
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