[CAUT] install bridge pins?

[Alan McCoy]

Hi Folks,

Last job I coated the new bridges and caps with System 3 Clear Coat, a
penetrating epoxy. Letting it flow into the holes as it would. Rationale
being to seal the bridges as much as possible. This was done after drilling
and notching. I put the pins in dry. First one I've done with Clear Coat.
You can watch as the epoxy penetrates. It does not penetrate maple as it
does spruce, needless to say. But it does penetrate some. The hope is that
it reinforces the surface fibers for strength as well as form a humidity
barrier for the bridge as a whole. The jury is still out about longevity.
The only thing I don't like about it is the glossy finish as I'd prefer less
shine. (Holes were drilled deeper and pins were not seated or filed. No
lubricant used.)

Alan McCoy


> From: Mark Cramer <Cramer at brandonu.ca>
> Reply-To: "College and University Technicians <caut at ptg.org>" <caut at ptg.org>
> Date: Tue, 21 Apr 2009 14:03:52 -0500
> To: "College and University Technicians <caut at ptg.org>" <caut at ptg.org>
> Subject: Re: [CAUT] install bridge pins?
> 
> Yeah, that's what I'm chewing on at the moment Jim. I'm drilling a new cap,
> and have pretty much decided to drive the pins "dry" on this one, followed
> by a drop of CA at each pin.
> 
>  
> 
> A year or so ago I did a test to see whether CA, or epoxy (via a heated
> bridge-pin) penetrated the bridge cap better. After drying, I pulled the
> pins then sliced through the holes on a table saw. For the life of me, I
> can't remember the winner!?
> 
>  
> 
> I did this at the Banff shop, so maybe Bert can help out. I've really got to
> look into those memory enhancing drinks!
> 
>  
> 
> Any case, Ron Nossaman's suggestion was/is  that only the surface matters,
> so the depth (both went several mm) issue would be a moot point.
> 
>  
> 
> When a valid idea comes along, I think it's important to get some examples
> in place in a hurry, after all it takes a few years of seasonal cycling
> before any kind of responsible conclusions can be made.
> 
>  
> 
> Mark
> 
>    
> 
>  
> 
>   _____  
> 
> From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Jim
> Busby
> Sent: April 21, 2009 12:34 PM
> To: caut at ptg.org
> Subject: Re: [CAUT] install bridge pins?
> 
>  
> 
> I don't know if this has been said or not, but the Nossaman method of
> drilling the pin deeper than normal and using a laminated cap is extremely
> effective in keeping the top of the hole firm (laminated). Using CA glue and
> filling the hole may negate the advantage of the deeper hole by filling it,
> allowing the bottom of the pin to touch bottom, which has some negative
> effects.
> 
>  
> 
> Jim Busby
> 
>  
>