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Guys this time having to thickness the back and sides, last time they were so close I sanded them, and I was wondering how to do this accurately as I don't have dial callipers and I've been told they have to be accurate to 0.1mm/0.004" otherwise they won't bent evenly. I have around 1mm to take off to I'll used a scraper plane and a scraper but wondered on the accuracy issue.

Thanks

John

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Formerly JJH

I learn more from my mistakes than my successes

Caliper and micrometers are not that expensive. invest in some . Proper tools are investments not costs. This is a case where you can't guess if you want good results.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

If I could afford things John I would I'm hoping the pound will rise so I can by heating blankets etc

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Formerly JJH

I learn more from my mistakes than my successes

Well, I have to say that you're sides will most likely bend just fine, even if they are more than .5mm thicker. Some people bend there sides at 0.065" right up to 0.100". That is a rather large range and I find it rather troublesome that someone told you they needed to be within 0.5mm (0.004") or else they wouldn't bend right. I think that's poor advice.

You could take a set of feeler gauges and stack up enough of them to get to your desired thickness. Then hold them against the edge of the plate and run your fingernail over the seem. You'll be able to tell if it's accurate enough. Do this on both edges at several spots and you should be fine.

If it were me and I didn't have calipers, I'd eye ball it with a 1/64" ruler and I'd call it good.

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the best advice I can give you then is to look at something you know is as thick as you are looking to get. clamp that between two business cards , that way at least will get you reasonably close.
john

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

dont know if its any good to you but theirs a homemade hacklinger guage in the the picture tutorial
guide section

How did the old guys do it? Did C. F. Martin have a drum sander?

Make yourself a feeler guage that you can lock into position at a thickness just a pinch bigger than where you want your final thickness. Use that to guage where you are in the thicknessing.

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Waddy

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I like Waddy's advice.

Also a small scale in mm should get you there. You should be able to interpolate to a 1/4 of a mm or so.

Sides needing to be with in .1 mm is a bunch of baloney. anywhere from .08 to .09 is pretty standard. Some will go even thinner.
They should be pretty even though.
Good luck, you can do this.

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Jim Watts
http://jameswattsguitars.com

I don't know if you are thinking you need one of those deep throut thickness calipers, 'cause you don't. I have a few sets of digital calipers and that is pretty much all I use. The always seem to be on sale some place in town (and I live right smack in the middle of nowhere, BUT WE ARE HOCKEYVILLE!) for about $15 CDN, that is just the cost of a few beer....They work great. I have a few sets just because it is easier to find them when there are more than one set buried in the pile of rubble.

Shane

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Canada

You could make a graduation punch, like violin makers use, for cheap.

http://www.darntonviolins.com/workshop/graduation.html

The picture hopefully is pretty self explanetory. You adjust the depth with the wing nut jobby on the bottom, then put your side wood in there and pull down with the lever, this leaves little poked holes in the wood, make a bajillion little holes all over the side and you then plane/scrape/sand untill the marks are gone.

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Jordan Aceto
Ithaca, NY

Hi,
I am building at this moment a dial thickness gauge.
Axminster sells one dial gauge for £12, the rest of the device I will make it myself with wood.
If you want I can send you the plans; there are 2 possibilities, it all depends on what system the dial gauge has to attach.
many models here:
viewtopic.php?f=10101&t=16333&hilit=thickness+gauge

2 cents from a currently 1st time builder....

Like others have said, calipers are cheap (unless shipping is an issue). I found a nice old pair of Brown and Sharpe on ebay for $26 USD, but i know you can buy new, cheaper versions of this.

When I thicknessed my top, back and sides, I had only a VERY crummy vernier calipers that did 1/32 inches. I was part way into the bending sides when I got my new calipers - found out that my thicknesses ranged from .080" up to .110" for the same side. THAT makes bending a little tough - I scrapped and sanded the already partially bent areas closer to .080". I don't recommend this. HOWEVER, looking at it now, you can see with the naked eye a .030" discrepancy in thicknesses, so I have no excuse for why I left them like that and then started bending.

I also saw an illustration in some guitar building book (not sure which one... Maybe "Guitar Maker's Workshop"???) that showed a thicknessing gauge made with a dowel/plunger that was marked to be read of of a simple wooden or metal ruler. It had a frame like the ones shown on that other thread, but was all wood with no dial caliper parts. Good luck

John, I have exactly $12 USD invested in this thickness caliper. A piece of 1" oak from the shop, a used metric dial indicator via Ebay and about 2 hrs. time.

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Peter

Nice,

You could also use a simple "C" setup with the plastic coated partical board out of the home depo scrap bin, got mine for 0.50

Im a bit pissed off here. I made a C style out of 1" x 1/4 aluminium, and it flexed too much when I pressed hard.

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Here is what a Parlor Guitar is for!
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Don't press hard. They'll all flex if you put any pressure on them. Mine will flex too, but is stable as long as I do not press on it. It holds "0", from one use to the next most days, and it is made of plywood.

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Waddy

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