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Looking for a precision straight edge
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=14201
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Author:  James Orr [ Tue Oct 23, 2007 8:19 am ]
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Hi everyone

It's been a good couple of weeks for me in bringing my "If you had a
$1000" thread to life. So far I've ditched the $1000 mark and focused on
what I'd like to pick up. So far the Festool ETS 125, PC 310, two Lie-
Nielsen planes, and some King stones.

Next on the list is a precision straight edge. I'd like to find something
long enough to locate the saddle position, marked at least by tenths of an
inch. Do you have any that you've thought worked well for you?

Author:  letseatpaste [ Tue Oct 23, 2007 8:30 am ]
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I'm sure someone will come along and prove me wrong soon... But a ruler and straightedge are too different functions and usually two different tools from what I can gather.

My Woodcraft 24" straightedge has served me well. I also have their set of steel rules, but they go to 1/64", not decimal inches.

Author:  WaddyThomson [ Tue Oct 23, 2007 8:42 am ]
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James, I bought one of these on sale at Woodcraft, and like it very much.  It is light enough to handle easily, and the markings are precision engraved, and, it comes with a wall mountable storage board.  You might find it cheaper somewhere else, I just bought it locally when they were having their big sale.

Author:  Steve Walden [ Tue Oct 23, 2007 8:43 am ]
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James - Here is Starrett's ruler page on their website:


http://catalog.starrett.com/catalog/catalog/PLH2.asp?NodeNum =21812


Author:  JohnAbercrombie [ Tue Oct 23, 2007 9:14 am ]
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For locating the saddle, an alternative to a scale (aka ruler) is a scrap fingerboard, or a stick. Sorry to be so low-tech! Just scribe a mark at the 12th fret position + compensation amount.
If using a scrap fingerboard, it's best to rip it so that the sides are square to the fret slots. If you cut your own fret slots, you can make your own locating stick for each scale length you use. A scrap of flashing in the 12th fret slot can help to locate things.

Of course, if you are going to lay out fret positions (rather than buying a pre-slotted fingerboard (or template) to use as a pattern), then you will need an accurate scale.

Cheers
John

Author:  Glenn LaSalle [ Tue Oct 23, 2007 9:16 am ]
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I am in the market for a good straight edge as well - I was looking at these:


http://www.leevalley.com/wood/page.aspx?c=2&p=56676& cat=1,240,45313


Glenn


Author:  James Orr [ Tue Oct 23, 2007 9:33 am ]
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Thanks guys. It looks like I'll find a Starrett.

Author:  Michael Dale Payne [ Wed Oct 24, 2007 3:29 am ]
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Find a local machinest tool supply house or McMaster-Carr. you won't go wrong with Starrett.

Author:  Steve Saville [ Wed Oct 24, 2007 4:22 am ]
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Do you all think we need the precision of a straight edge for guitar making?
I've been using my 18" and 24" steel rulers. They seem straight enough for me.
I can't think of anything requiring that kind of precision, but I carve relief into my fretboard rather than making it straight.

Author:  Mattia Valente [ Wed Oct 24, 2007 4:45 am ]
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You can only tell what the relief is if you have a proper straight reference edge. The problem with rules is that they're a) not guaranteed to be straight (admittedly mine aren't fantastic, but few of them are actually perfectly straight, and none of the longer ones) and b) they flex, so bye-bye straightness, again.

I currently have a straightedge from Dick tools in Germany, heavy as hell, solid, massive, rubberized grip, knife edge, and it's a joy to use in all sorts of situations. I use machinist's squares for medium lenghts, and have two tiny straightedges (2" and 3") for fret rocking purposes that are like the big one, slightly comic rubber grips and all.

Still, I'm sometimes tempted to get some Incra rules, just because one cannot have too many rules.

Author:  James Orr [ Wed Oct 24, 2007 5:35 am ]
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Well, I'm planning on using it for things like setting neck angle and
marking the bridge location. Do you think I could do these two things
with something else?

Author:  Mattia Valente [ Wed Oct 24, 2007 5:48 am ]
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Setting neck angle and checking for fingerboard straightness are what a straightedge is for. You also need a rule.

Different tools, differen't purposes. You can sorta, kinda, maybe get by with a stiff enough rule (I freely admit I did for my first few guitars), but it's suboptimal.

Author:  JohnAbercrombie [ Wed Oct 24, 2007 7:00 am ]
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[QUOTE=James Orr] Well, I'm planning on using it for things like setting neck angle and
marking the bridge location. Do you think I could do these two things
with something else?[/QUOTE]

For setting/checking neck angle, I find it incredibly awkward to hold the neck up to the guitar ('offer it' in old-time lingo) and manipulate a straightedge and a ruler at the same time. It's just an invitation for putting a nick in the soundboard, in my hands.

It's a lot easier to make up a gauge using a strip of plywood and a small wood block- it's lighter and more convenient. Benedetto describes this in his book, and I'm sure he didn't originate the idea. Sergei deJonge uses similar sticks. Go/no go is always easier than measuring, and I don't set my necks to within a few thousandths of an inch.

As I mentioned earlier, you can use a fingerboard or a wood/plastic jig for setting saddle position as well- though that idea didn't get much 'traction', as the jargon would say.

For fingerboard relief measurements, you will need a good straightedge if you are measuring before you have strings on the guitar, and feeler gauges in either case.


Cheers
John

Author:  James Orr [ Wed Oct 24, 2007 8:37 am ]
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Thank you, both of you.

John, my necks bolt on, and I plan to bolt them on before checking the
angle. With the neck on, a straight edge resting on the frets, I'd like the
bottom of the straight edge to come right to the top of the bridge. I've
been using a yard stick, so this is an effort to upgrade.. This may change,
as I have a Mayes neck setting DVD coming from the swap meet. I check
relief after strings are on.

Author:  Michael Dale Payne [ Wed Oct 24, 2007 8:55 am ]
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Most quality stainless steel scales are relatively straight but the accuracy of the scribed scale has absolutely nothing to do with the flatness of the edge. truth is most are true enough for 90% of what we do but to check the FB/Bridge relationship and a few other things I like a precision ground edge. I have 2 pieces of 4140 HT alloy steel bars I machined here at my work place to flat with knife edge and gound them to within .002" over 4' on both edges. one knife edge on flat edge (.188" thick). To buy somthing like that you would pay about $400. It only cost me time as I got the bar from the scrap bend.

Author:  JohnAbercrombie [ Wed Oct 24, 2007 9:52 am ]
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[QUOTE=James Orr]
John, my necks bolt on, and I plan to bolt them on before checking the angle. With the neck on, a straight edge resting on the frets, I'd like the bottom of the straight edge to come right to the top of the bridge.   [/QUOTE]
James-
I guess this all depends on your construction sequence- your method sounds pretty well thought out. I assume you don't glue on the bridge until you have finished adjusting the neck angle, or that you cut the saddle later.

I like to check the neck angle as I go along; by the time the frets go in, things are pretty well lined up for me. I get pretty tired of bolting on the neck after every adjustment, and I get the neck angle set fairly closely before I cut the mortise and tenon- my tenon jig indexes off the end of the neck (the face that will go against the body).

Lotsa ways of getting to the same result, that's for sure.
Another method is to tape a wood block (dummy bridge) to the top and just use thread/string to check the alignment.

BTW, you have to really treat a straightedge with care to keep that 0.0005 inch accuracy/precision in your work- no nicks!

Cheers

John

Author:  Marc [ Thu Oct 25, 2007 3:34 am ]
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I have a central tools 24" steel and a Lee Valley 36" aluminum.   

The Central Tools is very precise but it's expensive and heavy, like the Starrett will be, also the edge must be kept oiled to make sure it isn't ruined by rust. It's easy to dent a top while trying to do bridge measurements because of the weight and if you forget to wipe it clean before use you can get oil on your fingerboard and top. I now only use the Central Tools edge for jointer and other power tool set-up.

For guitar building I prefer the aluminum Lee Valley, it's cheaper, lighter, cleaner, plenty accurate, broader edge, easier to handle.

Author:  WaddyThomson [ Thu Oct 25, 2007 3:49 am ]
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The weight and rust was the reason I liked the Pinnacle 24" from Woodcraft.  It is guaranteed to be dead flat, and sides are ground parallel, and the fraction of inch markings are machine engraved to within .0002".  It also, as I mentioned, comes with a protective MDF mounting board that keeps it locked in until you release it.  It doesn't sit around the shop getting beat up.

Author:  crazymanmichael [ Fri Oct 26, 2007 2:16 am ]
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i have a reange of rules as well as a range  of straight edges from <1' up to 36", as well as a range of rules from 6" up to 36". the straight edges are used for tool set up, guitar set up, neck work, etc. the rules are used for measuring. duh.

the two functions are separate and have differing requirements.

though starrett and others do make graduated straight edges i don't use one as the grads intervals are too large for my purposes.

and as far as the styles of straight edge, i feel the beveled edge to be more useful, particularly for fretwork.

ebay is a good source. there are a number of vendors offering new starrett tools. just be sure you know the retail price on the street before you get into a bidding war. i've seen to many items goe for above retail when egos and testosterone get out of control.


Author:  erikbojerik [ Fri Oct 26, 2007 3:23 am ]
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A straightedge is essential IMO if you are doing your own
fretwork.  Especially if you are working on electric guitars,
where the shredders are especially fussy about action, relief and
fallaway. 



Author:  James Orr [ Fri Oct 26, 2007 7:02 am ]
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Maybe I should just stick to my yard stick?

Just kidding. I'm rethinking some things now thanks to all this. Thanks
everyone.

Author:  JohnAbercrombie [ Fri Oct 26, 2007 7:41 am ]
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[QUOTE=James Orr] Maybe I should just stick to my yard stick?
[/QUOTE]

James:
WWTU?- What would Torres use??

John

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