Accuracy of Fret Leveling Beam

I posted the question on TGP but didn't get much info, so I thought I would ask here. I'm about to try doing my own fretwork again. My previous attempt at a refret was passable and playable but not professional. I want to try again and this time I'm wanting to do top quality work. The right tools for the job weren't available to me last time, and that's why my results suffered. This time I want to do it right. Money is still tight though, and I don't want to needlessly spend money on luxury tools. So on to my question...

How flat does a leveling beam for guitar fretwork need to be? Stewmac doesn't post specs on their leveling beams, so I have no idea how true theirs are. I have found a Bostitch 16" precision beam level at Lowes for $25. It is accurate to .0005" over 1". In the worst case scenario, it could be out as much as .008" over it's length. Is that acceptable, or should I keep looking/saving for something else?

Thanks,
D

I have been using an 18" aluminum carpenters level for 30 years to level frets. Works great. I would imagine that the Bostitch is plenty flat enough. Hold an accurate straight edge up to it and see if its flat. You can easily see a gap of 3 or 4 thousandths so as long as you have no gaps, you are good to go.

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Originally Posted by Barry Daniels

I have been using an 18" aluminum carpenters level for 30 years to level frets. Works great. I would imagine that the Bostitch is plenty flat enough. Hold an accurate straight edge up to it and see if its flat. You can easily see a gap of 3 or 4 thousandths so as long as you have no gaps, you are good to go.

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I bought it earlier today (can always take it back). Unfortunately, I don't have anything that I know to be true to test it against. This is one of the problems I'm always bumping up against (not having a precise way to check surfaces or tools). As expensive as they are, one day I'm going to have to break down and buy a precision straight edge I guess.

D

Standard reference for a straight line is a tensioned wire. Some thin steel wire, like maybe a guitar string, attached to a piece of wood with some way to tension it ... like maybe on a guitar ;-)

Or maybe lay it on something flat and smooth and run a Sharpie down the edge. The flip it over and eyeball it to the line and see if there are any noticeable gaps.

I know people that use a piece of mahogany passed over the jointer. I don't think it's all that critical because you'll be averaging out any small imperfections over the length of the stroke. So how straight? I don't know....straight enough. I've never had a fret job fail because my leveler wasn't straight enough. In the good 'ole days, we simply used a file. They were never dead straight, and they weren't even all that long, yet we managed to flatten frets.

You know, I should mention that Dan Erlewine used an aluminum level for years. Seems to be a popular choice.

Thanks guys! I'm going to move forward with the level. I checked it against some straightedges last night and it looks good to me. It appears to be true as best I can tell. At the least, there is nothing about it that seems obviously untrue when compared to various straigtedges I have around the shop (none of which have been verified by any known reference surface, but comparing to three straightedges I should have seen a problem if something was grossly out).

I'm not trying to obsess over this, but if I'm going to spend money on a tool to do a job I want to make sure I buy the right thing this time. Last time, I was starting with tools I knew left a lot to be desired. My results weren't all that great, go figure... I'm older and hopefully wiser now and am tired of buying the wrong tools in an effort to save money that rarely pays off.

D

I also have a level for fret levelling. It is every bit as flat as my StewMac bar. Even the relatively inexpensive levels are machined pretty flat these days, as long as you don't bang it around too much. I think you will do just fine with that, and it is a good place to save some money. Getting a good straightedge is much more important. Another tip from Dan Erlewine: If you are really short of cash for a straightedge, find an old-school draftsman's T-square. They can be had quite cheaply, and the edges on those are remarkably straight too. It's far from perfect, but it will get the job done.

When I started building and repairing guitars back in the mid 70's the very first tool I bought was a quality machinest's 18" rule. I still use it as my main reference. The 18" length is perfect for working on fretboards. Also, it is thick enough to stand up on edge which is helpful when checking relief.

However, since you have two or more straight edges around your shop you can check the straightness by checking them against each other. Hold two of them edge to edge. Hopefully, they fit tight. Now flip one of the rulers over and hold it against the other ruler. If the fit is tight then they are both straight. If there is a gap, then at least one of the rulers is warped and the extent of the warp is half the distance of the observed gap. If you have three rulers, then you should be able to determine exactly which one is the warped one by checking all possible combinations.