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the hardest part
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Author:  jonhfry [ Sun Oct 21, 2007 4:10 pm ]
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Just for background of where I am:
I have been buildiing about 7 or 8 months, going slowly and building each part repeatedly as I obtain tools. I am 80% tooled up (bandsaw, drill press, planes, chisels, router, blankets, thickness sander, dust collection, and many other hand and hand power tools.) I am currently holding off further purchases of the final tools til christmas. So I have been joining and bracing plates, bending sides, rouging out necks slotting fret boards etc. The most important of the last tools I have not obtained are fretting tools.


So over the last month I have had the time to go over the plates and ribs very closely, and join, brace, and bend another set. I am feeling pretty confident with these steps. I have enough stuff for 3 boxes ready to be glued now. But still no fret boards for the necks til christmas.


Tonight I am going over everything very closely. I can just not get the profiling of the darn sides down.


What is the trick. I am using dishes that I made that are of average or above average quality. The back is steep probably about 18 ft radius, and the the top dish is about 22-25 ft radius or so just (guestimates).


Do you guys profile the sides with the bandsaw before you even bend them?


Maybe the sand paper i have just sucks. I have put 80 grit on the dishes but it is awkward and extremely time consuming to use the dish as a sander. But, it is just that when I go to lay the plate on the ribs, it just always seems to have some hopeless gaps.
Author:  Steve Saville [ Sun Oct 21, 2007 4:17 pm ]
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[QUOTE=jonhfry]

Do you guys profile the sides with the bandsaw before you even bend them?

[/QUOTE]
Yes.

You need to stop your dishes from moving or you'll be at that step forever. If you are sanding the sides first without the linings, you do not have to be perfect on the sides. If there are some gaps, the kerfed linings can fill in. Remember that you are going to rout away and add bindings. Your linings need to be right, but don't worry too much about the sides. When you add the linings, leave them a little proud. If you profile the sides first, it is much easier.
Author:  jonhfry [ Sun Oct 21, 2007 4:25 pm ]
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thanks,


I already have linings in one decent EIR that has a screwey neck block and might not be the perfect numero uno. I am kinda just practicing with it. But I have another set bent without linings yet, and too nicer sets waiting on the benders. I will band saw them again with a template of the radius before bending, and do the linings as you suggest.
Author:  Steve Saville [ Sun Oct 21, 2007 4:26 pm ]
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Look here for a method of making your side template. Then let Colin know that how much you liked it!
Author:  Mattia Valente [ Sun Oct 21, 2007 4:32 pm ]
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I trim in the rim. Block the dish (I use a bolt in a scrap of wood clamped in the workmate, dish goes on and can thus spin freely if need be, but only requires one clamp to 'fix' in place, then suspend the guitar body over the dish, mark the final taper (with some sort of following device keeping the pencil equidistant from the plate surface. Scrap of wood with hole in it works well), trim the taper by hand using saws (I like a small japanese handsaw) and then a plane, and THEN sand. Whole process takes maybe 15 minutes. Then linings, proud, and sand until it conforms all the way around.
Author:  jonhfry [ Sun Oct 21, 2007 4:56 pm ]
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thanks


 
Author:  DP LaPlante [ Mon Oct 22, 2007 12:36 am ]
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It is much easier to profile your sides before bending, make sure to mark the waist and bend accurately (front to back) to get an even profile. I usually clamp the sides together to profile them on my belt sander so that they are identical.


Who the heck ever said that a guitar's back curvature had to be spherical???!


Guitars such as Martin had backs with multiple radii, i.e. the radius of each back brace was different from the arc of the back in general. Radius dishes were introduced by manufacturers to eliminate the difficult hand fitting of these plates with a huge mechanized rotating sanding disk. Good for them but extremely awkward for an individual maker especially if they are not experienced as you can't see what you are doing with one of these things.


 Ditch the disk and fit the back (now that you have pre-profiled your sides) using a rasp file and small plane. If you must sand, prepare a curved sanding stick by glueing multiple layers of thin scrap wood into your dish..........much easier to control and see what you are doing.


And remember, it just has to be a fair curve through the "doming" not spherical. 
Author:  letseatpaste [ Mon Oct 22, 2007 2:26 am ]
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Just to add another option to the mix... Here's how I profile sides. My neck and tail blocks are cut to the right height before I glue them in. The boxes I've built so far are either cylindrical or true flat top so I don't need to shim like Hesh shows, but that looks like a good idea.



So I prop up my dish with the same size block on each end, and then my precision marking tool is set so the pencil point is the same distance as the heights of the blocks. A little tape to stabilize the dish from rocking and then you just trace around to transfer the spherical profile. Then it's quick work with a block plane to cut to the line, then glue in linings, then just a bit of sanding.
Author:  Sam Price [ Mon Oct 22, 2007 2:30 am ]
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[QUOTE=ToddStock]

I actually find that Cumpiano's method works fine and has the advantage of providing some flexibility (e.g., lower bout radiused/upper flat)QUOTE]

Amen to that. With practice it's a technique that can be mastered, and best of all, it works for me.

I JUST can't fit any more jigs into my tiny shop!!!!

Author:  KenH [ Mon Oct 22, 2007 2:46 am ]
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I actually have a template that I use to draw out the profile of the sides prior to bending. I cut out the sides to the drawingsusing the band saw and then bend and glue everything up. I have very little sanding to do when it comes time to radius the top or backs.


One fellow came to my shop last week to have a look at whaqt it takes to build guitars. I made sure to show him all of the templates and jigs I have laying around. You can build guitars without them, but it sure makes life easier.
Author:  burbank [ Mon Oct 22, 2007 3:22 am ]
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I'd say go with a method with the fewest interdependencies (project management buzzword from days past).

Success in profiling before bending works well as long as there's good control of positioning the sides in the bender. So, one could have success in cutting a profile on the sides, but that outcome could become compromised by poor location of the waist in the bender, a problem I once had. Profiling after bending, by marking like Jon showed in his post, would pose fewer risks in profiling. After a few more builds, with a more predictable outcome for positioning the sides, profiling before bending has a better chance of success.

I've used a method similar to Jon's, only with the rim right side up, marking the inside of the sides.



Plane or spokeshave to the line, sand lightly in dish, glue linings a bit proud. Chalk on the edge of the sides, then sand in the dish again until the chalk is gone.

JAWTSAC (just another way to skin a cat).
Author:  burbank [ Mon Oct 22, 2007 3:36 am ]
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Also, bear in mind that the plates are being forced into their quasi-spherical shapes by the radiused braces. I wouldn't expect to have a gap-free fit unless the plates are held down on the rim with clamps or go-bars.
Author:  Mattia Valente [ Mon Oct 22, 2007 5:30 am ]
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I find dishes are what made making the boxes on my first couple so simple. Almost no thinking required, no super-duper intricate measurements needed to get a predictable, even, accurately shaped top edge and back edge, and the dishes themselves don't take up that much space. Seriously. If I could store them in my previous digs, they can be stored anywhere. For me, it's about making the process controllable and accurate, ergo I use dishes. I found that the weight of the rim set in the mold was plenty to have top and back conform easily to the rimset, zero light gaps.

Dishes also double as a clamping caul (glued plate down in the dish, rims on top, apply go-bars, done).
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