Official Luthiers Forum!

I noticed a curious thing today. I began work on my first OLF SJ the way I do any new guitar--tracing the plan with tracing paper so I can transfer it to a sheet of stainless steel for the template. I traced the top, including all braces, from the main top (underside)drawing. Later I noticed I didn't draw a centerline in, so I went back to the plans, but there was no centerline on that drawing. I did notice there was a centerline on the drawing of the top pattern, so, I tried to align my drawing to that pattern to draw the centerline. After 15 minutes of trying to get everything just right, I couldn't get the pattern lined up properly without being a couple mm's off somewhere. Finally I turned my tracing paper over, and it fit perfect the first time. Is the OLF SJ pattern a little asymmetric, or are the patterns only supposed to be used as a rough guide? Does 1-2 mm not make much difference in the grand scheme of things? I'm thinking the outside pattern isn't that critical as long as my mold is accurate, and my bracing is accurate. Do you guys agree?

John

I too, just recieved the OSJ plan and made my templates, molds, and forms. I made a few very minor changes along the way so mine is not quite per the plan. I simply used it as a starting point. My thinking is as long as it looks like a SJ and it will fit in a "SJ" case. it's all good.

Good luck

Interesting!

How does this impact those of us who bought the OLF SJ plan, mold, and bending form?

CrowDuck

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Chris Nielsen
Soquel, CA.

The couple of mms off might also be from the printing, even Stew Mac warns customers of this on their plans, it's no big deal IMHO.

Serge

You could always trace the bending mold twice if you have Johns mold or if you don't, maybe someone could make a tracing for you

If they are asymmetrical, it is the copier not the drawing. The drawing is perfectly symmetric. That said when a copy company runs prints, if using laser printer if they do not keep the "X" feed rate adjustment tuned just right they can get out of scale. Also the paper they are printed on is heated at the time of image transferred. Some paper will sirinkg back more some less and so may not shrink the same all over.

I assure you the plans are symmetrical. this does not help I know since you are working with a printed copy. There is a centerline on the main view
MichaelP38845.4181828704

[QUOTE=RCoates] I too, just recieved the OSJ plan and made my templates, molds, and forms. I made a few very minor changes along the way so mine is not quite per the plan. I simply used it as a starting point. My thinking is as long as it looks like a SJ and it will fit in a "SJ" case. it's all good.

Good luck[/QUOTE]

OLF SJ will not fit most SJ cases. It ias a bit shorter than an Olson SJ which seems to be the standard that most case are fitted to

Lance has the drawings printed from DWF files created by me in AutoCAD. The only place they can get off symmetry is during the copy printing. If you check the asymmetric copies at the wides point of the lower bout the the dimension will be something other than 15.50"MichaelP38845.3812037037

I figured it was probably something with the printing but wasn't sure since I never built a SS before. I thought their might be a chance it was shaped a little different to voice bass/treble response. I'm thinking the 1-2mm difference could also be attributable to the folds in the paper and trying to get them to lay perfectly flat while tracing. I should have said in my original post that I'm not concerned about the plans or the way the guitar will come out, I just wasn't sure if it was deliberate or not. I do have John H's mold and bending form for this so it should come out fine.

John

They will be fine I use them

The plan that came with my LMI kit included a note warning that it might not be exactly "life-size" because of errors in the copying process. It appears that this is a common problem.

So, what do you do if you get a plan that's a little off? How do you trace from the plan to a template and adjust the size in the process?

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John Cavanaugh
Saint Paul, MN
"What could possibly go wrong?"

John for bending forms and assembly mold .03 or 1 mm is so minacule it is not a biggie. . If one side of the body is accurate per the dimensions then use that one side twice. Now if you like and are willing to pay postage I will run you a Mylar plot of the body shape complete with centerline that will be 100% dead accurate and trasparent to bootMichaelP38845.5893402778

So Michael, what is the part of the OSJ that falls outside the line of the "standard" SJ? IN other words what causes it not to fit the standard SJ case?

Michael, as I understand from a previous post the OSJ plans are sold out at this time. I would like a set and will pay the OLF but would like a Mylar plot you are describing. What will it cost, I am in Texas and willing to pay postage. Give me some direction.

Thanks

Mike
White Oak, Texas

Body length is shorter, the distance from the butt to the waist is therefore different. These are the two main things, but my waist is different radius by just a little and other small things. To be clear OSJ is commonly used as an abbreviation fro an Olson Small Jumbo OLF SJ is my guitar “Official luthier’s Forum Small Jumbo” in actuality the SJ is a stepchild of Lances E2 series guitars. I took one of his early bending forms and adapted it to my design. Dimensionally there are just very minor differences between my SJ and Lances E2

Olson SJ is approx 21" long
OLF SJ is 19 15/16" longMichaelP38846.4046527778

I can not supply a plan sets as I donated the rights to the plans to the forum to provide monatary support forthe forum. The forum is the only place they are available. I will for postage send you a Mylar body shape plot with centerline but nothing else

I guess I should also say that I will not be able to provide mylar full sets even if you pay the forum as that would lead to shipping cost for me, and you would have to pay for my shipping plus the plans cost to the forum. just a bigger pain than it is worth. If I do it for one I would have to offer to all. The cost of 4mil double mat mylar I have available is about $.80 per sq foot. There are 3-36"x48" sheets to a set. That would be $28.80 per set just to cover my cost of mylar. So you can see how this just does not work well.

    Most people make this assumption that blueprints are accurate and to scale NOT!!!!. seldom will you find a plan or blueprint that is perfect. This is because the blueprint is a REPRENSTATIONAL DRAWING . Unless it is marked SCALE don't expect it to be such.
    I am a machinist and work with this stuff everyday. Drawings can be close but they are not scaled as a rule. Trust your ruler and the measurement of the print never the actual drawing.
   I use some CNC and with the sanding and finishing molds will be a bit off one from another by .050 or so. To try and keep higher tolerances will add undue costs.
   If I am makeing molds and patterns and I don't know if the source is accurate or untried I will use the 2 sides of the drawing and split the differences. This will get you as close as you can expect.
    For a guitar I think this is plenty. Having worked on old martins and gibsons I have seen as much as 1/4 inch differences . rememebr the old guitars were made off patterns and alot hand work so there is alot of descrepancy.
    Good luck
John Hall