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Avoiding lumps


Splintazert

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I'm building a few bodies from my own designs without templates. I have cut the outer profile with a bandsaw and then moved onto spindle sander, rasps and sandpaper for finishing. I wondered how you guys get the 'lumps' out from the edges, that is, those inevitable peaks and valleys that you can't see but can feel? Any tips and tricks will be much appreciated.

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One of the advantages of using a template is that it's easier to refine the shape on thinner material - involving less elbow grease to get it to the correct shape. The router then transfers that shape accurately to the wood.

You have really answered your own question. Touch is about the most important sense in guitar building imho. Persevere with refining your shape by feeling the bumps and troughs, and looking at it from a distance, close up, in different lighting conditions. Something like a shinto rasp or dragon file can help to remove material quite quickly, followed by coarse sanding using a range of suitable blocks, and then maybe finer grits or cabinet scrapers. Try to keep the sides perpendicular to the top too (another advantage of templates + router) - it's very easy to drift away into an undercut or overcut.

I've used various things hanging around the garage for sanding blocks - from chunks of mdf to short lengths of copper pipe to drill bits to offcuts of beading. The way I do it is to sit down, grip the body between my knees and use both hands to guide the sanding block. Focus sanding on the bump initially, then blend it into the surrounding wood with progressively longer strokes (and repeat a lot), stopping every now again to feel it, usually with my eyes closed. Given enough patience and perseverance I'm sure you'll get it "right" :)

I think I have a photo of my favourite sanding "block" (a length of "D" shaped beading) on my phone - I'll edit this post and add it if I can find it

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As you run your sanding block over the hump you can feel it drag a bit more. Keep making your strokes longer as @Norris says and when you feel the drag even out the hump will be gone, the curve will flow smoothly and you'll no longer be able to find it with your fingers.

SR

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Thanks for those replies chaps, all makes perfect sense. It's more or less what I'm doing at the moment, but it's still good to see that there isn't an easier or better way that I'm missing.

I guess I was really hoping that someone would say "Here's a simple jig I made for that...". 😄

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Block sanding. It knocks off the high spots sooner than the lower ones. Pencil in where you feel a low spot and then concentrate on knocking back the areas you didn't mark. I also run my sanding blocks around in longer strokes rather than scrubbing one area.

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