Bridge caps

[Ron Overs]

Greg,

You wrote;

>. . . . .
>A few months later I was looking at Ron Overs web page where he was
>recapping a bridge by routing quite a good ways down. . .  Now I
>think I saw 2 rails on either side of the bridge for the router to ride
>on. Is that right?

Yes you did.

>If that is the case, would you not experience the
>same difficulty following an unpredictable crown in the board? I was
>thinking, (dangerous ... especially for me), why not attach the rails
>directly onto the underside of the router plate and let it ride on that.

Firstly, the rails are attached to the board via masking tape which 
first covers the sound board panel, and then body filler repair putty 
(for car body repair) which attaches the rails to the masking tape 
(which has been de-waxed with thinner prior to its application.

>More like a sort of free hand approach. Would this be unstable? Would it
>possibly eliminate a straight rail not mating quite so perfectly to a
>crowned board?

The procedure is very easy. The lower edge of the rails are roughly 
planed to the curvature of the board prior to installation. The 
height of the rails are set slightly higher than the required 
finished height also prior to installation. After installation, the 
rail height is scraped and finished to that height required for 
removal of a predetermined height of the original bridge.

>In your drying process are you left with a completely
>flat board and therefore this is not an issue? If this is the case how
>do you maintain the moisture content of the board while you are
>performing the various procedures on the bridge? If you followed a
>crowned board then would you have difficulty attaching a replacement cap
>to what would then be a crowned bridge base? Does any of this make any
>sense or am I just spitting into the wind again? Thanks!

Even if you end up with a slight convex curve in the machined surface 
of the bridge, as is often the case, the new bridge cap will flex 
easily to fit. The curve will always be very slight and uniform. Ron 
N raised this issue a few months ago when referring to the fit of 
flat-planed bridge bases, when fitting them to the curved sound board 
panel. Again, no problem, the bridge cap will pretty much follow the 
profile of the board with a slight backward tilt.

Hope this answers your question.

We're doing some other new stuff with bridge caps recently. Still 
checking reliability of the new stuff as yet, so far it's looking 
good.

Ron O
-- 
Overs Pianos
Sydney Australia
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Web site: http://www.overspianos.com.au
Email:     mailto:ron@overspianos.com.au
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