Official Luthiers Forum!

The resonator forum seems very quiet so I thought I would ask a few questions here.
One of my next projects is a single cone biscuit bridge wood body resonator guitar. I have order the Beard plans.
I have never built a resonator, but have the itch.

Why do resonators have a large wooden block/beam that extends from under the fretboard all the way to the tail block? Is it necessary. Can I build one with my standard double mortice and tenon joint and skip this long bar/block?

Also does anyone angle slightly the biscuit so that it can be compensated a bit?

Thanks

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Andy Z.
http://www.lazydogguitars.com

On a lot of reso's, that beam is an extension of the neck and the connection at the tail block is the neck mounting method, but if you mount your neck with other hardware or a dovetail, you can bypass that. I've built both ways and I like the bolt on method. I did have to drill a small hole in the sound well side so I could get a long allen wrench through there to tighten the neck hadware, but that did not weaken the well and worked fine.
The cone is held in place by string tension so it can be rotated to get some compensation every time you change the strings. I did make my own biscuit once with a wider bridge piece made of ebony so I could compensate it with mixed results. I seem to recall reading that one of Al Curruth's students determined that buscuit needs to be light so maybe that was the problem with mine.
Kent
PS. A lot of us watch the Resonator forum for new posts so if you do post there you will probably get a quick response.

That's called the neck stick. A short history:
Reso's were arguably invented by the Dopyera brothers, who were banjo builders before hand. The neck stick is typical MO for a banjo. On a metal bodied reso the neck stick runs clear through to the heel (where the heel block would be) and is held in place by the strap jack screw. Since the neck isn't glued to the body you can set the neck relief by adjusting the stick and putting in the screw.
Not all wood bodies have the stick. My 30's Dobro (with a spider bridge the cone hangs down into the body so a stick would get in the way), and my 30"s era National Trojan do not have them. Structurally it's not a bad idea, since the "top" has a big hole cut in it the stick will help to transfer/support the spring tension. My Dobo's cone hole needed to be made round again after 70+ years it had gone "oval" on me. Some reso's have a "sound well" in them too. Again neither of mine do. I'll also say that my two are the best sounding of their types I've ever played.
Do not tilt the saddle. You'll tip the biscuit and bend the cone.
If you mean rotate the biscuit, that's fine.
I'll try to get a pic posted of how to compensate (the B string) by using a trick my friend Mike Dowling ( http://www.mikedowling.com/ ) showed me. Mike is a tremendous player and a very skilled tech.
-C
PS Reso's rule!

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Freeborn Guitars
and home of BeauGuard©

Thanks

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Andy Z.
http://www.lazydogguitars.com

First off John Dopyera designed and built the first reso which was a Tricone . The neck stick also serves to support the sound well. I would put one in and not take a chance of the top moving with time. It doesn't have to be a through stick if you use a different neck joint. My wood reso has a dovetail neck joint and the stick is doweled into the neck and tail block. There is plenty of and if not the most info on reso's over at MIMF's library. Check it out is a must if you want to build a reso. There is even a picture tutorial of 100+ pictures on how to build a metal body reso by some goofy guy there. Goofy as he is I gotta say he builds a real sweet german silver Tricone.

Thanks Chris
I always find it very difficult to find stuff on the MIMF
The searching never gets me what I want.
Any tricks???

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Andy Z.
http://www.lazydogguitars.com

Just go to the Resonator Guitars and Other Resonator Instruments
section in the library and open it and start reading any discussion that you think will be of help. It will keep you busy for awhile.

Hey Andy,
I actually built a roundneck Beard kit last year with a spider bridge and was surprised how good it sounded. It was all 1/4" baltic birch plywood. A real tank. It had a flush fitting bolt-on neck and a soundwell. As mentioned you have to line up one of the holes in the soundwell to allow access with a long socket wrench to the neck bolts. One thing to watch out for is that the upper bout of the body has no angle on the plans and the neck set shown really does not give you enough saddle height for a roundneck. I wound up with almost a 4 degree neck set with a shim under the fretboard and that worked fine. If you are building a square neck I wouldn't think that would be as big an issue. I tracked down the Stew Mac instructions for their discontinued kit and they were a big help as were the resonator setup instructions on their website. ( www.stewmac.com/freeinfo/i-5290/i-5290.pdf) The Beard instructions rivaled the old Martin kit instructions for brevity. Good luck.
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

The spider cone is different from the biscuit cone that he is building. The National style has a tapered back and you can also let the fret board extension lay on the body as fall away instead of the wedge if you want. You're really not going to be fretting up there playing slide.
Andy did you get the National plan ? That's the plan I based my Tricone construction off of and a template of a Tricone at MIMF also. There's a good book called "National Resonator Instruments" by Bob Brozman also.
Nice job T.K., how long did it take to grow and what fertilizer did you use?

Chris
I feel like a dork. I cannot find a resonator section on the MIMF.
Could you send me the link


Never mind. I wasn't logged in so the library wasn't visible

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Andy Z.
http://www.lazydogguitars.com

I would but it's in the library and if you aren't registered and signed in then you can't access the library. Go to the library and scroll down, it's under guitars.

Well we had a rainy spring last year Chris. One day I saw part of a peghead sticking out of the ground and really didn't have to do much more except put a stand against it as it grew so the neck wouldn't warp.
TJK

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Another question...sorry

For most wooden roundnecks, it seems that the top is very flat. (No radius like a standard acoustic)
Does this mean the neck angle is 90 degrees.
If it has to be something other than 90, it will have a 12th fret dip or hump.

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Andy Z.
http://www.lazydogguitars.com

Tell me if I am thinking backwards. In steel strings I build so the neck angle matches the body angle so there is no change at the 14th fret.....no hump, no dip. I build my bodies with the appropriate angle so the fretboard on top of the bodies give me the perfect bridge and saddle height.
For my acoustics with 25 radius and 24.9 scale length and a 91.5 angle at the head block I get it. I just match the neck to the body.

For the resonator with a biscuit bridge, here is my thought process. Tell me if it is flawed.

If the body angle is 90 degrees and I know my fretboard thickness, crown height and preferred action. You can calculate how high above the top plate (Flat) the top of the saddle needs to be. If you have a typical biscuit saddle around 0.25 to 0.375 when finished. The remaining variable is how low to set the cone. Create a sound well that allows the cone to sit in it with the biscuit bridge and saddle to give me the calculated height.

Then the neck angle is set to match the body with no change at the neck body junction.

Does this make sense to think of it this way. Build the depth of the sound well to create the best height for the action you want. Make that a bit of a variable. I am sure it will end up around 1 inch deep. With most biscuits you have a lot of play. I would like a 0.25 to 0.375 saddle height to be in the middle of my desired action setting so I have some play to leave it a bit higher or lower if necessary

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Andy Z.
http://www.lazydogguitars.com

The sound well is 1" deep. and you build it just like an acoustic flat top with a radius fret board of your choice. My box in my wood reso in the avatar is from a Martin OOO kit. If i recall there is a 3 degree neck back set. The neck back set is important because if you don't have enough then you won't have enough saddle back angle. If you don't have enough saddle string back angle then you won't have enough pressure on the cone and it will rattle. It should be on the plans and read that material at MIMF, it's all there. That's where I learned to build resos with the help of Mike Dotson. The tongue of fret board will have fall away or you will have to put a wedge shim under it like T.K. did. That's your call Dave.

The tops aren't totally flat on a round neck, at least on a National. The lower bout needs to be flat so the coverplate mounting surface is flat, but the upper bout drops off quit a bit. On my El Trovador, if I lay a straight edge on the top on the upper bout, I end up with a gap of about 3/16" between the edge the guitar top at the bridge. That's a estimate, as I can't get a straight edge on the centerline with all that hardware there and I'm in the middle of a move and can't find my protractor so I can't give you a neck angle, but it's a lot. There is no radius to the top, so National is just putting an angle on the upper bout, much like Charles Hoffman discusses on his website.

The coverplate is a constant that limits what your saddle height can be. I think if you create a soundwell that gives you a .25 saddle height and some clearance under the coverplate(which is about what the El Trovador has), you can create the neck angle you need to get the action you want by the angle of the upper bout and the resulting neck angle.
Does that make sense?
Kent

Or you could build one of these !!!!

I converted a 6 string to an 8 string multiscale monster .. the guy busks in the the Toronto subways and this thing howls down there inthe caverns ....

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

When you set the neck it's like an acoustic and you use the top of the biscuit like the top of a bridge. Put a straight edge on top of the fret board and it should rest on the top of the biscuit. If your well to deep you will loose the saddle string back angle. When you get to the MIMF library you will read several times to have all the parts on your bench before starting to build. You will need to check the measurements of the parts to make sure you get no surprises. The cone, biscuit, cover plate and tail piece. I hope this is of help to you. The saddle string back angle is something that you probably wouldn't have been aware off. In fact, you can shim the tail piece up and achieve more of a sustain to the strings. It's like thinning the top braces to voice it for fingerstyle. The more pressure on the cone the faster it dampers the string or cone from vibrating. But going to high and there's no pressure on the cone to drive it. There's no rule saying you can't dome the top at a 25' radius like an acoustic either to get rid of the tongue wedge.
The wood body Nationals I think were may by Harmony and I think they were sort of like a pressed plywood archtop.

I my vast experience of one Beard kit I had to do a rough guess of the neck angle needed to get an adequate saddle height and get enough down pressure on the cone, then string it up and see how much the string pressure depressed the cone and fine tune. I wound up increasing the neck angle a little more. Somewhere's around 4 degrees. The Beard roundneck plans were a little misleading to my eye showing a considerably flatter neck angle than I wound up with.
BTW, very cool machine you made there Tony!
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

That's amazing Tony! Particularly that oversized angled saddle on that biscuit! And I believe they were worried about intonating a standard biscuit saddle?

Incredible,
Joe

Here's the trick I mentioned before about intonation.
When I restored this guitar I changed the scale to 25.4", which exacerbated the intonation issues.


Basically you grind away the saddle where the string passes and add a little piece behind for the new string notch.
Pretty simple.
-C

_________________
Freeborn Guitars
and home of BeauGuard©

You should intonate the saddle on a reso pretty much the same as you would on an Archtop. Except the base strings slot might be a little bit deeper and have a V cut to it so that when doing string snaps if it rises up off the saddle then it will fall back in place. Yeah, you simply rotate the biscuit at the same angle as any other guitar for intonation purposes. It's the same as an archtop except you are driving a cone or cones instead of the top. Don't make it more difficult then it needs to be guys and take the same care in shaping the saddle. The saddle slot can be off set back or forward by a 1/4" if need be without it effecting the cone if needed but better to get it right the first time.
I don't know about that Chas? It works but I just don't care for the looks of it. You can do better then that.

Perhaps you need to see more of the guitar:


This was a $500.00 eBay basket case. It is now an everyday working guitar that lives and travels in a gig bag.
Making it all purty under the coverplate is akin to lipstick on a pig. The saddle mod took 10 minutes and now it plays in tune. Works for me.
-C

_________________
Freeborn Guitars
and home of BeauGuard©

I hope you didn't take that as offensive. Wasn't ment to be. It's like the Cobbler's kids run bare footed.
I can't see the picture for some reason.

Another try at the image.

-C

_________________
Freeborn Guitars
and home of BeauGuard©