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 Post subject: Bridge height
PostPosted: Fri Oct 21, 2016 7:43 am 
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First name: Ed
Last Name: Minch
City: Chestertown
State: MD
Zip/Postal Code: 21620
Country: United States
Focus: Build
Status: Amateur
I am building my first resonator - a biscuit bridge instrument. I have a Beard cone and biscuit, and the only plans I could find are Resophonic Outfitter's of a metal bodied guitar even though I am building out of wood.

The plan shows that the bridge is 5/16" taller than the biscuit itself. The bridge and biscuit that I have leave 5/8" above the biscuit. I know that there will be a of of fiddling, but I have to plan for some dimension.

So - when I calculate the location of the cone shelf, how much bridge above the biscuit should I allow?

Also - the bridge is maple with an ebony addition, so should I remove material on the maple side or the ebony side to get to the final height - or both?

Also - how much should I allow for compression of the cone with string tension on it? I have read several things most saying that the compression is negligible.

Thanks much - Ed


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 Post subject: Re: Bridge height
PostPosted: Fri Oct 21, 2016 3:17 pm 
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Cocobolo
Cocobolo

Joined: Thu Feb 09, 2012 4:10 pm
Posts: 114
First name: Chris
Last Name: Reed
City: Stowmarket
State: Suffolk
Zip/Postal Code: IP14 2EX
Country: UK
Focus: Build
Status: Amateur
I recently built a resonator ukulele. I found that the defining factor was the cover plate. You need the biscuit to sit just, but only just, below the hole in the cover plate, and the saddle (the maple/ebony slice) to be as high as you can under the guard piece to give you a decent break angle over the saddle.

I'd take your dimensions as a starting point, but refine them once you can put the cover plate on the top. In hindsight my sound well should have been 2mm deeper, and I could have planned to make it so and shim up the cone with glued on veneers if too deep.

My cone sank less than 1mm, I believe 2mm is likely with steel strings.

Reduce the saddle from the maple edge, leave the ebony intact.


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 Post subject: Re: Bridge height
PostPosted: Fri Oct 21, 2016 7:15 pm 
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First name: Ed
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Thanks prof

you said: "I found that the defining factor was the cover plate. You need the biscuit to sit just, but only just, below the hole in the cover plate, and the saddle (the maple/ebony slice) to be as high as you can under the guard piece to give you a decent break angle over the saddle."

If the cover plate HAS to sit on the top of the guitar top, isn't the defining factor the depth of the soundwell - how low the cone is mounted? You noted this in your next paragraph. So understanding that the saddle has to be a scoch below the cover plate/bridge cover thingy, starting with a "desired" saddle height above the biscuit lets me determine the depth of the soundwell. So if I plan on paper for the 5/16" above the biscuit that is on my plans, and the cone compresses 1-2 mm, then the saddle height will end up about 3/8".

So build for the 5/16" saddle height, leave the saddle full height, and adjust once the whole thing is together

Sounds like a plan

Ed


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 Post subject: Re: Bridge height
PostPosted: Fri Oct 21, 2016 9:13 pm 
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Koa
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Joined: Thu Nov 04, 2010 1:46 pm
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First name: Freeman
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Ruby, let me make a couple of assumptions. Most reso's have flat tops. The most common cone well depth for a biscuit guitar is one inch, that will put the top of the biscuit itself about 5/16 above the plane of the top. Radius your biscuit to match your fretboard and cut string grooves like you would an nut - maybe slightly deeper. Now adjust your neck angle by shimming the stick until you have approximately the action you want (will vary depending on your ratio of slide to fretted). You can make minor tweaks to the action by filing the slots a little deeper but most of it comes from the stick.

That should clear most commercial cover plates but I always advise getting cover plate, cone and biscuit before your start and doing a mock up of neck angle to make sure.

You can remove material from either side. The biscuits that I have purchased have the saddle glued in so its a moot point. Cone compression has been negligible in my case.

Image

Image

Thats actually a carbon fiber biscuit - pretty expensive and I couldn't tell any advantage. The NRP Hot Rod cone was a definite improvement over the stock one - if you haven't bought your cone I recommend that one. The tailpiece should have a piece of leather or foam glued to the bottom so it won't rattle on the cover plate - that pretty much sets your break angle.

When I built my tricone I set the neck angle so the fret plane just hits the bridge without the insert in it - that gave me a reasonable amount of saddle to make the final action adjustment and it cleared the cover plate fine

Image

Image

Image

With all of your thinking about geometry add one more confusion factor. Most resonators have no bridge compensation - the saddle is exactly at the scale length. If you play a lot of fretted stuff it will be sharp, particularly if you have the action a tad high for slide. Consider adding a little compensation when you lay out the cone well - your slide will still play in tune (you have the ultimate compensator on your pinkie) and your fretted notes will be much better. I think I put about 1/16 on the treble side and 2 or 3/16 on the bass side of the tricone - I play about 50/50 fretted and slide.


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 Post subject: Re: Bridge height
PostPosted: Tue Oct 25, 2016 7:49 pm 
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First name: Ed
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City: Chestertown
State: MD
Zip/Postal Code: 21620
Country: United States
Focus: Build
Status: Amateur
Freeman

Thanks for all that. I don't plan on much slide, just plain old fretting, so I have moved the soundwell about 3/16" away from the 12th fret thinking that if I need about 1/8" of extra string length, then 1/8' angle to the saddle, then if I spin the cone a touch with the center at 3/16", things will play like a normal acoustic. I am making the shelf 1/16" bigger in radius (1/8" in diameter) then the cone so I can move it a bit. Just today I thickness sanded my Ash top back and sides after installing my "rosette".

Thanks again

Ed


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