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I spent some time yesterday getting ready to bend sides for the OLF SJ. I had made a template for the top and was going to the same for the sides when I ran across a bit of an issue.

I do not use a sanding dish but rather a jig and contour setup from KMG. See image below:



This setup requires that I have my rims properly sized prior to contouring. Unlike a big contour dish that will work all rim edges down at the same time, this jig puts a contour on opposing edges of the rim. It is a terrific tool and very easy use, but I must have the rims the correct height to start with or have a reference line that I can sand to. In reviewing Michael's plans for the OLF SJ this evening, I realized that the template for the sides has an even taper from the upper bout to the lower bout. The plans call for leaving the sides an 1/8" proud so the sanding dish can radius. As the back isn't flat, but has a 15' radius, the waist must be slightly higher relative to what is shown on the plans.

I wish the plans included drawings showing the actual finished height of the side, either with or without the top and back. Sort of like bending the sides, radiusing, then stretching them back out flat. This would be very helpful for guys like me that don't use a radius dish. As the plans do not have this drawing, I could estimate how much higher the waist needs to be and draw the taper in, or maybe someone out there wouldn't mind taking some measurements every couple of inches of a finished side. Any takers? The side drawings of the finished guitar on the plans show a flat slope from the upper bout to the lower bout, so I can't use that drawing for measurements either.

Thanks,

Ken

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http://www.casperguitar.com

Ken the first page of the Stewmac OLF plans has a side profile that the true side profile plus 1/8" for sanding IT IS NOT one continuous slope. it is a flat pattern. I gave seven different height dimensions at major side height elevation points and averaged the slope between them to avoid having 30 or 40 elevations dimensions. Once again the profile detail is not one continuous slope there several blended slope or you have a very old set. Sorry I did not draw to fit your buld method but You know it is the old Lincon thing you can never pelase all the people all the time

Michael,

Thanks for your reply. You do give several dimensions for the rims on Page 1, some are to the top of the rim including the 1/8" excess and some are to the top of the rim excluding the 1/8" excess. I was somewhat concerned though as I was expecting more of a rise at the waist, and the plans don't show that. So I was looking for some confirmation that if I ignore the 1/8" excess, the dimensions you give are the dimensions that my finished rims will be once radiused at 15'. For example, I don't want to precut my sides to within a 1/32" of the finished rim height your plans show or draw the finished height on my rims and plane down close to that after bending. Then glue on kerfing and find when I go to radius that the waist is too low and sits below my radius bar.

I don't want to be critical, I just want to make sure I understand what I am dealing with before diving in. My previous post was a little misleading. I actually do not have to have the rims the correct height to start with, but I have to have them close to avoid a ton of sanding, especially if I don't have a good reference line that I can work the rims down to with a plane. The KMG mold and radius setup I have will allow me to level and radius the rims in a very consistent, controllable fashion as long as I know the radius and have a good reference point for the neck and tail blocks, which your plans provide.

Can you quickly confirm if the finished height at the waist is as shown on the plans or if once radiused, most of that 1/8" excess at the waist is still there?

Many thanks!

Ken

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http://www.casperguitar.com

The dimensions given were taken first from a 3d model of this guitar fitted to a 15' back spherical dome and confirmed against the pattern I have used for the past five years!!!!!!!!! I am not going to confirm for you that you can cut your pattern with in 1/32" because to be that accurate I would have to give an elevation dimension every linear inch rather than averaging the slope at approx every 4". I can confirm that the dimensions give have worked for me for five years but they fut they have a tolerance of +/-1/16" I did not save the model file after confirming the dimensions and I cut my pattern as shown on the plans



Ken I am sorry that apparently you are the first to find my plans not accurate enough for your form of construction. That is a disappointment to me because when I have always strive for detailed accuracy on my plans long before I ever donated them to the OLF. That said they are accurate to within standard building tolerances as required in building guitars. Some dimension on the plans have +/- 1/16, tolerance some have +/- 1/32, tolerance some have +/- .001" tolerance and other have+/- .0001" tolerance appropreate to what is being dimensioned. Unfortunately what you are asking for ia tolerance to +/- 1/16" which is more than exceptable in most forms of rim profiling.

Ken,

I remodeled the SJ rim this morning. With a 15' dome back, true flat top rim profile with the dome's center axis at 9-31/32 (9.96875") from either edge and tited to achieve 4-9/32 (4.28125") at the butt and 3-11/16 (3.6875") at the neck, The waist elevation at the centerline of the waist is 3.8685". So if I was wanting to cut this 1/32 high I would cut it to 3-29/32" (3.90625") or 3-15/16" (3.9375"). Best I can do for you.

Just to be clear on how I dimension the rim profile. On the lower bout of the rim there are 3 major slope changes on an SJ, 6" from the waist center in the flat, 14" from the waist center in the flat and the center of the tail joint in the flat. So between the tail joint and the waist center I have plotted 3 slopes. While these slopes look close in angularity they are not the same slope angel. Now on the upper bout end there are also 3 major elevation changes one at 6" in the flat, 8" in the flat and then the neck joint. Here again I have plotted slopes between these elevations. So in total there are 6 different slopes that make up the back profile of my SJ Plan.

Theoretically I could have broken this down in smaller increments and had a more accurate image of the finish sanded profile. but to do so for the vast majority of builders was mostly pointless. as the accuracy of the elevations would quickly be in the .001" and realistically that kind of tolerance is not used in rim building so I used dimensions of no smaller than 1/32" which lead to six plotted slopes. If I had use 1/64" there would have been approx. 12 slopes and so on and so forth.

Because most builders sand the profile via sanding with a domed dish i added an 1/8" excess boundary (clearly labeled on the detail) to give a rough cut profile and assumed it was understood that if you sanded till you reached the tail and neck height dimensions that the rest would happen as long as the disk stayed in plane right to left.

If I had done this with 4" even increments each side of the waist center there would have been many more slopes plotted and many more dimensions required and I would have ended up with an over crowded detail view and many times more complicated pattern to cut and all that information was really wasted info if your are bowl sanding any way. S the intent of the profile details is to provide a rough in profile that on average you will have 1/8" of excess to sand away.

Thanks Michael for all the detailed measurements! You are too quick for me! I wanted to get back to you earlier, but didn't have time this morning.

Just in case you are wondering if I am the most anal guy on the planet. I'm not! Really! I'd like to end up 'close' to your plans, but I'll likely end up sanding the rims a touch more or less and the top or back thickness will vary from the plans, so I'll be close, but not spot on by any means. When I first started down this path I wanted to make a template so I could precut the sides and minimize as much sanding and sizing as possible after bending. As I am planning on building more than one of these guitars , I thought the template idea to be a good one, and I wanted my template to be as close as possible to the radiused rim height. I could then oversize as much as I felt necessary when I precut the rims.

This is my third guitar, so I am still working up the learning curve. When looking at the plans and imagining the finished guitar in my head, I thought a 15' radius would result in the finished waist being a little higher than what is shown on the plans, so before I cut my side template, I posted my initial message. In response you have provided a wealth of information, and I thank you very much. But the key piece is the you have confirmed the plans are good as drawn. I am still a little confused in my head and have some sort of disconnect there, but I'm moving forward on faith! I'll build my template per your plans and dive in!!

Thanks again for all the personal attention. I am pretty excited about this build and am very anxious to add a small jumbo to the guitar collection! Now if I could just carve out 30 or 40 hours this week to get on it!

Ken

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http://www.casperguitar.com