Carbon Fibre Thickness for Bridge

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Mitch Lees
Gidgee
Posts: 9
Joined: Mon Jan 08, 2018 3:54 am
Location: Findhorn, Scotland

Carbon Fibre Thickness for Bridge

Post by Mitch Lees » Thu Aug 16, 2018 2:10 am

I am making a contemporary classical walnut bridge. I intend to use 2 layers of carbon fibre cloth which is .5mm thick - is this OK or does the cloth need to be thicker to give the correct amount of stiffness?

Assuming .5mm is OK - and the walnut slices are 2,3, and 4mm then the bridge blank will be 10mm - this is already one mm thicker than the blanks I normally use (9mm then reduced about a further 1mm when fitting to the dome of the top). If the blank were any thicker than 10mm it may result in the saddle not protruding enough.

Interestingly when studying the photo in Vol 2 (20-8) on page 20-5 it looks like the middle walnut slice is the thickest - not he bottom one. Is this just an illusion?

Grateful for advice please.

Mitch

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Trevor Gore
Blackwood
Posts: 1381
Joined: Mon Jun 20, 2011 8:11 pm

Re: Carbon Fibre Thickness for Bridge

Post by Trevor Gore » Thu Aug 16, 2018 11:36 am

Mitch Lees wrote:
Thu Aug 16, 2018 2:10 am
I am making a contemporary classical walnut bridge. I intend to use 2 layers of carbon fibre cloth which is .5mm thick - is this OK or does the cloth need to be thicker to give the correct amount of stiffness?
The CF cloth as spec'd in the book (198gm/m2) measures up at ~0.27mm thick. Works fine.
Mitch Lees wrote:
Thu Aug 16, 2018 2:10 am
Assuming .5mm is OK - and the walnut slices are 2,3, and 4mm then the bridge blank will be 10mm - this is already one mm thicker than the blanks I normally use (9mm then reduced about a further 1mm when fitting to the dome of the top). If the blank were any thicker than 10mm it may result in the saddle not protruding enough.
Check out the drawing on p 20-4, which gives finished dimensions. The CF thins out even further under clamping pressure.
Mitch Lees wrote:
Thu Aug 16, 2018 2:10 am
Interestingly when studying the photo in Vol 2 (20-8) on page 20-5 it looks like the middle walnut slice is the thickest - not he bottom one. Is this just an illusion?
Yes, but I see what you mean! Go with 4mm on the bottom so that you can sand the top curvature into it without getting the string holes too low.

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