Hardening Bridge Caps

[Euphonious Thumpe]

David,
     

You may want to use super-thin CA  for just these
reasons, but still put a  drop of epoxy on each pin
before inserting. ( CA dries too hard and isn't sticky
enough when cured--fractures. )
Thumpe

P.S. Epotek 301 is a  UV resistant, low viscosity
epoxy I've  used for bridge tops with small
fractures,and mixed with West's high density filler
for gaps.


--- Ron Overs <sec at overspianos.com.au> wrote:

> David, Dale, Dell and all,
> 
> I also agree with the practice of coating the top of
> the bridge. One 
> of the reasons why multi-laminated bridge caps are
> so effective is 
> that the laminates are permeated with glue during
> the gluing process. 
> Any minor checks in the laminates, which can occur
> if they are dried 
> too fast at any time from tree to product, are
> simply glued up to 
> eliminate the risk of splitting. But the top surface
> of the top 
> laminate will not be permeated fully with glue
> unless it is also 
> deliberately coated on the top surface.
> 
> After finding that the top laminate can occasionally
> develop small 
> checks after the bridge is pinned unless the top
> layer of the top 
> laminated is also coated with glue, we have been
> manufacturing our 
> laminated bridge caps by applying a layer of glue
> over the top 
> laminate also. The plastic sheet which is placed
> underneath and over 
> the top of the entire cap before the vacuum press
> diaphragm is placed 
> in position prevents glue from getting all over the
> diaphragm. When 
> the cap comes off the press both the top and bottom
> surfaces are 
> sanded prior to fitting to a bridge. Caps laminated
> in this fashion 
> are essentially a matrix of West system and maple.
> 
> In your case David, it might be worth considering
> making your own 
> multi-laminated caps. It would save you the detailed
> clean up of the 
> pin holes before pinning. We don't make our own
> laminates these days, 
> since quarter cut 0.5 mm thick Rock Maple veneer can
> be purchased 
> locally. We use seven layers for each cap to make up
> 3.5 mm, just 
> enough thickness to accommodate the notching depth.
> The thinner 
> veneer layers also allow for a more complete
> permeation of glue, 
> which I prefer.
> 
> Below is an image-link showing the treble end of the
> bridge from our 
> most recent piano, no. 7. The notching extends down
> into the seventh 
> laminate.
>
http://members.optuszoo.com.au/ronovers/oversno7.2.jpg
> 
> Ron O.
> 
> >When cutting a new bridge cap I typically paint on
> a low viscosity epoxy to
> >both harden and seal the cap.  I do this after
> drilling and notching but
> >before pinning, sanding back the bridge top flat
> again before inserting the
> >bridge pins. 
> >
> >I'm considering doing this same process with a thin
> CA glue which seems like
> >it will offer some advantages: cures faster, wicks
> into the wood better,
> >requires less sanding afterward. 
> >
> >Any thoughts on the differences in terms of
> providing a seal and adding
> >density to the wood between the two substances?
> >
> >David Love
> >davidlovepianos at comcast.net
> >www.davidlovepianos.com
> 
> 
> -- 
> OVERS PIANOS - SYDNEY
>     Grand Piano Manufacturers
> _______________________
> 
> Web http://overspianos.com.au
> mailto:ron at overspianos.com.au
> _______________________


Euphonious Thumpe


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