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sorry if this sounds elementary guys but here is the problem. i am dry fitting my soundboard and back to the sides. how close of a fit should i strive for in the dry fit before i glue down the soundboard and back. for example, the back sits flush with about 80% of the sides but at the top section there is about a 2mm gap where the neckblock and adjacent sides are.

also, what is a good way to glue the soundboard and back to the sides. i dont have a go bar deck that fits my guitar when it is in the mold. i am thinking about following the Cumpiano and Natelson book which uses those wooden clamps, but ill have to go and buy them.

i have been using this forum for only a week now and i can see what a great site this is. here in hawaii a rule that we learn early on is that we dont take without giving. is there a donation section for this site?

This is NOT elementary. The guy who should do a photo essay on this is Lance. He has the cleanest back and top fit of anyone I have ever seen. It is a freak of nature.

However, in the ASIA journal (Guitarmaker) #51 there is an article on this that has a pretty detailed approach. I have used it and it works well.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

I'm using go-bars as we speak to glue a box together...glue the back on first with the sides in the mold and the assembly resting in the top radius dish...use enough go-bars and cauls to distribute pressure all around (evidenced by glue squeeze-out)...when it's all dry, trim the overhang and glue on the top the same way, with the assembly sitting in the back radius dish...

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http://www.presnallguitars.com

Humm not sure I know what is causing your top gaps. If you made your bracing to the proper radii, gluded them up in a radius bowl and sanded your sides and linings with a sanding bowl then they should fit near or perfect. If you use the method described in StewMac's kit instructions then it should still be very close. But 2mm is just .0787" so that is not a lot but I would try to find out what is causing the miss fit and correct it.

As for attaching, the cheapest method would probably spool clamps. You can make them for about $1.50us. They consist of 2 pieces of hardwood round plugs 1 1/2" or 2" dia x 1" or 2" long, cork pading, 1/4" all thread and wing nuts Or StewMac and LMI sells them for about $2.50 each it will take about 14 per side depending on the size of guitar. If you use these dry practice a lot first because ther are a lot of clamps and little working time depending on glue used.

i to use the go-bar system now but I started with Spool clamps.MichaelP38743.5900347222

maybe i misunderstood the question. I thought you were asking about notching the linings.   

I clamp mine up with a zillion cam clamps.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

Kama, first off, welcome!
I'm with Michael, I'd try to find what's causing the misfit.
As for an even cheaper way to attach the plates, you could try this: get yourself a pound of Plymouth #107 rubber bands. They're inexpensive. Drill some small holes all around the outside of your mold. Insert short dowels in the holes so that a couple of inches protrude. Clamp the sides into the mold with enough clamps to hold the rim assembly firmly. Lay on the plate (top or back), then lace the rubber bands back and forth over the plate, while looping the rubber bands over the dowels. Distribute them evenly over the length and width of the plate. Go diagonally too. This really does exert quite a lot of pressure!
Going end-to-end, you'll want to tie a few bands together to get a strip long enough.

It's the opposite plate that causes trouble in this scenario. You'll have to devise a way to keep the bands from pushing the assembly right out of the mold. (Clamps will have to be removed for this step.) The opposite plate could be glued with cam clamps here quite well. Or, clamp the mold itself to a dished board to stop the sides from moving, then clamp on the other plate with the bands.

This is to be sure a minimalist approach. Don't take too many pictures of this to put on your website, as it is decidedly low tech. But it works.

Just another approach....

Steve

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From Nacogdoches...the oldest town in Texas.

http://www.stephenkinnaird.com

one more note, i dont have a radiused dish or sanding dish. i used the workboard described in the Cumpiano and Natelson book. maybe that is why i dont have an acurate fit. do you folks think it would be better to build another gobar deck that fits my mold or to use those cam clamps across the soundboard and back. should i keep the sides in the mold when gluing up?

I think I understand what Kama is asking about. My first guitar was built using the Cumpiano book for instructions. There are two problems that I ran into. The first has to do with the ladder style bracing on the back. The best you can do by radiusing the braces is cause a cylindrical shape in the back. When you place the back on the sides, you have to apply some pressure to the areas that meet up with the neck block and tail block to get everything closed up.

The second problem comes from building things kind of 'free hand'. There is no mention of a radiused sanding dish, and the instructions for sanding a radius into the back are difficult to master. Sanding a radius into the sides so it matches the back was very time-consuming, and almost impossible for a first time builder to get right. And since Cumpiano doesn't advocate using a mold, it makes sanding the sides even harder than it needs to be.

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53% of all statistics are made up on the spot
http://driftwoodguitars.blogspot.com/

Go-bar deck is quicker clamp time. Are you saying that you mold won't fit inside your gobar deck peremeter? or are you speaking of the height issue with the bars. I have one set of full length bars and a specificly cut to length set of bars for attaching tops and backs. (one set for D's and SJs and one set for OMs.

You can use
Stewmac's brown masking tape. It's got a bit of stretch to it, so it makes a good clamp. Just trim the back/top fairly close so there's not a ton of overhang, and break the sharp edge with some sandpaper so the tape's not as likely to rip. Easy and cheap. You may want to add a clamp and caul of some sort at the neck block so you get good contact over that whole surface.


That tape is useful for all sorts of stuff. I ordered a whole bunch after we used it a lot in Harry Fleishman's class.

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Jonathan Kendall, Siloam Springs AR

steve, i like that approach. cheap and easy. some questions for you. using this method should i do the soundboard or back on first? size dowels and approx. amount around mold? also the size rubber bands you use because i called around and found that no one carries plymouth brand rubber bands around here (must be too far) so i will have to find a comparable size. thanks

I used a sanding board with 2 deg bevel for the tops and 5deg for the backs for the first couple years but I did use assemby mold from the get go. I guess I have been lucky and had no real fit issues with tops and backs other than brace notch fit-up but once properly fitted tops and backs fell right into place. I would suspect that free form build could make this harder. Compaino resitances to molds has to do with forced stress being built into the box. But if you build properly, use good completed bends, aviod forced fitups and use the mold as a form square and not of a forced confiment system I don't think you impart any more forced stress than free form.MichaelP38743.6538078704

michealp, the perimeter limitations will not allow my mold to fit in the go bar deck.

waynec, i think you have an idea of what is happening. i am having the most trouble fitting at the neckblock and heelblock. how is the guitar you finished using the Cumpiano book? is the body still sound with the small space in those areas. i assume the glue is strong enough to hold the back and soundboard on but i wonder about the stress that it is putting on the wood.

Kama,

I did have a gap at the neck block and tail block before glue-up because the back is forced into a cylindrical shape by the ladder bracing, but the sides are sanded to accept a dome shape. So far everything seems sound. My second guitar is being built with an X-brace on the back to pull it into a dome. I suspect this will help with the fit before gluing.

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53% of all statistics are made up on the spot
http://driftwoodguitars.blogspot.com/

John,

I used that very same rubberband approach for my first two guitars & it really worked great. Instead of dowels I used 3/4" #6 woodscrews but that's a small detail.

If anyone wants to use this approach just be sure to not have too much overhang of your plate while gluing onto the ribs as you can easily split off a bit of the top near the edge. Luckily for me, the purfling & binding covered the little edge of missing spruce. You know, spruce really likes to split with the grain - amazing

Skip

Is this gap on the outside edge of the block or at the interior end of the block? If it is on the interior end of the block and you sanded using a sanding board and sanded perpendicular to the sides near the block, you sanded off too much of the interior end of the block.

If you put the pivot end (non sanding end) of the tapered sanding board on the opposite block and sand the block rotating the board at a point on the apposing block, the sanding board will impart a taper to the block that closely matches the taper formed by the spherical shape of the back or top. If you sanded flat across the block perpendicular to the corresponding bout then the interior end of the block will match the height of the nearest perpendicular side, there by becoming too short to meet the dome.

The underside of a good sturdy heavyweight desk makes a great go bar deck. The place where your legs normally go. Just make a platform to support the pieces to be glued, and cut the fiber rods to an appropriate length. If planned properly one can make several platforms of varying heights for different glue ups, and use the same length rods. This is cheap if you already have a suitable desk, rods are cheap, and platforms can be scrap plywood & 2X4's.

CrowDuck

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Chris Nielsen
Soquel, CA.

[QUOTE=WayneC]The best you can do by radiusing the braces is cause a cylindrical shape in the back. When you place the back on the sides, you have to apply some pressure to the areas that meet up with the neck block and tail block to get everything closed up.[/QUOTE]

As a rank beginner I have glued up my second kit top and back and don't own a radiused dish. After reviewing StewMacs pdf instructions they make no mention of a radius dish and as stated above the best one can hope for with properly radiused ladder bracing is a cylinder that will need clamping pressure at the heel and tail block to get anything remotely resembling a raduised arch when contacting the rim.

For a chuckle, I am JUST NOW understanding that one can create a back that actually fits the sides WITHOUT clamping and forcing the heel and tail sections to fit. Doesn't even seem possible, but it appears there is a lot to learn.

Thanks
Larry

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Thank You and Best To All

Kama, you could look up Plymouth brand on the internet. Perhaps an office supply store. But whatever, these bands I mentioned are 7"x1/16"x5/8". Of course that's not critical. But you will need something big.
As for dowels, I dunno, 1/2" should be enough. Actually, more like Skip, I have used 16 penny nails! 20 or so per side--this isn't rocket science. The spruce splitting is a good caution. When I have done this, with a 2" mold all around the sides, the bands weren't pulling down in a straight shear force. (More of an angle....)

Steve

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From Nacogdoches...the oldest town in Texas.

http://www.stephenkinnaird.com

Kama, you could use Skips suggestion of the screws into the mould and than just rope the back down. Use some rope with a little bit of stretch to it and it should be fine.

Or Jon Kendall's tape method, that's very easy also and should work just as well.

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