Replies

1. 
   john_c2 | Jun 17, 2021 03:21pm | #1

   I have a Lee Valley 24 inch aluminum straight edge. I use a piece of 48 inch aluminum angle iron from the home center for longer things. I have two, and can use them as winding sticks too. I use the sharp edge of the angle for both tasks, not the legs.

   It's dead straight and dirt cheap.

1. 
   AndrewSmithCanada | Jun 17, 2021 05:46pm | #3

   Thanks John. Did you ever find the fact that it's aluminum a problem? I'm trying to understand why people pay more for steel.

1. 
   john_c2 | Jun 18, 2021 11:04am | #15

   Aluminum hasn't been an issue for me.

   To test a straightedge you need 3 of them, not two. Look up the Whitworth method.

   If 1 is convex and 2 is concave, they will mate, edge to edge. If 3 is concave, it will mate with 1, but not 2. If 3 mates with 1 and with 2, all three are straight.

2. 
   Mike_H3 | Jun 17, 2021 05:23pm | #2

   I use a 12" Veritas steel straight edge along with a poor man's straight edge or what John White calls a Master Bar in his book Care and Repair of Shop Machines, (John White is a woodworker and machinist who maintained the Fine Woodworking workshop). The bars are accurate to within thousandths of an inch. He also discusses these bars in a Fine Woodworking article on tuning a jointer here https://www.finewoodworking.com/membership/pdf/22944/011142038.pdf

3. 
   user-1118538293 | Jun 17, 2021 06:20pm | #4

   I have never owned a steel straightedge, but I do have the Veritas 36”. One thing that’s nice is it is extruded, so it has a profile—wide at the bottom for stability, narrow waist to save weight, and medium-wide at the top, perhaps for rigidity. Also nice in the hand. They take the extrusion and grind the edge straight. A comparably stable steel tool would be absurdly heavy, I think.

4. 
   489tad | Jun 17, 2021 06:22pm | #5

   I have LV 36” and it’s fine.

5. 
   user-1118538293 | Jun 17, 2021 06:27pm | #6

   Forgot something: note that a Starrett combo square is good to .002 in 12”. That’s worse than the .003 in 36” promised by the aluminum straightedge. They’re not measuring exactly the same thing, but in terms of tolerance they are both solid. In my shop the 12” Starrett has the last word in any dispute about accuracy.

6. 
   mikaol | Jun 17, 2021 06:35pm | #7

   Me, I found square aluminum tubing at Ace. Longer than 5' it tends to flex. but up to that point its straight as the proverbial arrow. And on one edge I drilled pencil-width holes for laying out circles. The holes don't affect the straightness and don't get in the way. And for what it's worth, I use an aluminum yardstick when I need a flat straight edge.
   Actually, the only steel straight edge I own is a framing square. I imagine there are those yawning & grimacing over my choice, but c'est la guerre, I'm too old to care.
   Mikaol

7. 
   esch5995 | Jun 17, 2021 06:54pm | #8

   I for one don't have confidence in Home center angle irons and tubings being dead on accurate, probably something similar to your old straight edge which you aren't satisfied with, but we each of our own standards. Most of the time we don't have to be as precise as a machinist but when I'm dialing in a machine like a jointer is one time I try to be. That said, as you know the longer the better but there are other priorities such as price. A 36" straightedge should be good enough to do the job. Now for the debate between steel and aluminum; there are two characteristics to aluminum that could become a factor the most likely is that aluminum being softer will be more easily dinged and kicked on the edges which would likely affect its accuracy, the second characteristic of aluminum that could be detrimental is that it expands and contracts with temperature changes and over time could become distorted enough to throw off its accuracy, but that's probably the least likely to happen. Anodized aluminum does offer some protection from both these issues have you checked out Woodpeckers offerings?

8. 
   beasleysevin | Jun 17, 2021 08:11pm | #9

   Here's my 2 cents. Aluminum is better than steel. Get the longest edge you can afford. Three thousandths is close enough for woodworking.

   Here is why I think the above. I had a steel straight edge. I live in a very humid climate. It rusted - then it was no longer a straight edge. Longer is usually better for setting coplanar on jointers. It lets you check the exes. Wood is constantly expanding and contracting. Even multiple passes of compounding .003 errors, four passes is still less than a hundredth of an inch. Breathe on the wood and it will swell that much.

   There you have it. That's all I got.

1. 
   EdWeber | Jun 18, 2021 11:21am | #16

   Well said,
   I get the beds aligned with an inexpensive aluminum straight edge, more importantly, I check the cut afterwards.
   Having reference edges that are precise to the thousandth is nice to have but as stated, not really necessary when working with wood, IMO
   Hope it works out for you

9. 
   Rob_Sp | Jun 17, 2021 08:35pm | #10

   I think 36" would be penny wise and pound foolish, you will find it too short. For an 8" jointer 48" would be a fair minimum. 60" would be better yet.
   The cross section of the LV Aluminum looks to be sound and it is available at 50".
   The square edge versions are a plus for jointer tables as they will stand on edge without assistance.
   Here is another source, the alternatives don't need to be Starret which are admittedly too pricey.
   https://www.mcmaster.com/precision-straightedges/edge-shape~square/

10. 
    elmaduro | Jun 17, 2021 09:13pm | #11

    I’d search the past. All current accurately straight products have been cancelled ..

11. 
    AndrewSmithCanada | Jun 17, 2021 09:58pm | #12

    Thanks for the advice everyone. I ordered the 50" aluminum Veritas.

12. 
    rob_ss | Jun 17, 2021 11:05pm | #13

    No opinion on the specific item but I do keep a 'reference' straight edge in my shop - was a home centre one.

    I went through the box of them and compared one against another until I found two that could be perfectly opposed. It took a while and the staff thought I was mad but the bows in some good-looking ones were 2.5mm or more over a 1.8 m length. I got an ugly-but-perfect one for much less.

    If your straight edge will not stand up on it's own, it will flex and reduce accuracy so make sure you get a nice rigid one with a decent cross-section.

    I also keep a boxed set of reference squares which are only used for final setup checks. Not too expensive from chipsfly.com.

    If you have a table saw, the table will usually be flat enough for comparison work.

13. 
    copperminevt | Jun 18, 2021 09:24am | #14

    I bought a 48" steel straightedge from McMaster-Carr. It has been great for accuracy in my shop.

14. 
    [email protected] | Jun 19, 2021 05:15pm | #17

    One issue that cant be ignored is the flatness of both tables.I was having trouble at a friends shop ,went and got my straight edge ,and found that the infeed vtable was warped.Only a long straightedge yld have detected that warp.He had the table re ground

15. 
    hoovermd | Jun 19, 2021 11:05pm | #18

    So, as a former moldmaker I have to ask... how straight does a straightedge need to be? How flat is flat?
    Do you need a Grade AA, A or B plate?
    A Starret 12" x 12" x 4" Crystal Pink Granite Surface Plate - Grade AA is about $300 whereas a grade B is half that....

    We used to say that a reference tool be it a 123 block or a set of JoBlocks needed to be 10% more accurate that the thingy it was used on...

    So, if your target was .001 then your reference needed to be accurate to .0001.

    I've not found woodworking need to be better than a thickness of a piece of paper (.003 or .001 if you are using zig-zags) and personally I would find even those tolerances to be unobtainable in wood.

    I used to grind angular surfaces to within a tolerance of .0001 over 6 inches or so and am still learning to live with less today.

1. 
   flyfisher111 | Jun 20, 2021 10:00am | #19

   I have to agree. Arguing between 0.0015" and 0.0006" is beyond my ability to set up (and see) more likely, less than the flatness of the beds.

16. 
    ysu65 | Jun 20, 2021 12:11pm | #20

    I agree with hoover and fly regarding tool tolerance. When you run something over a truly flat jointer, will there any residual stress that will cause the board to move another 0.002" above square. And what happens when temperature or humidity change? Use clamps to join stuff together. Woodworking is not in CNC jig borer territory.

1. 
   hoovermd | Jun 20, 2021 11:01pm | #22

   I pre-date the CNC version ;)
   https://www.practicalmachinist.com/vb/greatest-hits-and-links/what-jig-borer-used-110652/
   Cant believe for $300 you can get this: https://www.ebay.com/itm/Lufkin-Inside-Micrometer-Measuring-Rods-w-Wood-Box-72-of-Standards-Jig-Machine-/293548043215

17. 
    kbull | Jun 20, 2021 10:11pm | #21

    I purchased a 36" LV steel straight edge a number of years ago to tune-up my 8" parallelogram jointer.
    After a day of less than fantastic results, I went out and purchased a 48" LV aluminum straight edge - much better for that task.
    While rust hasn't been a problem, I seldom use the 36". The 48" unit is my go-to straight edge. Excellent value.

18. 
    ct_engineer | Jun 21, 2021 12:38pm | #23

    Shop metrics

    Straight edges for woodworking should not need to be as accurate as for metal working or (heavens) optical benches. Wood is a material where you might aim for straightness and flatness, but once achieved this ideal deteriorates pretty quickly due to interactions with the environment. To the craftsmen of 100 years ago, a jointer plane and a winding stick was all they needed to achieve straight and flat. I doubt if anyone is building furniture or cabinetry to a higher standard today than the antiques of 100 years ago.

    I have a 1/8' x 3" x 10' piece of aluminum that was cut on a large shear. I check it periodically by tapping two brads in a 10-ft board and laying the edge against them then drawing a fine pencil line. Then I switch the edge to the other side of the brads and draw a second line. I can easily see if anything is not straight this way. I store this piece supported evenly across its length on inserts I screwed to the main joist in my basement. I have a similar piece that is 5' long that I check the same way. I also have a couple cheap aluminum straight edges that I can use to set the table delta on my jointer. All my straight edges can be verified as above, and I think fine pencil lines are good enough for woodworking.

    I check all my squares regularly by drawing parallel lines from either side. I have carefully sanded one of my try squares true in this fashion.

    I have the "A-line It" dial indicator kit to set square and true on my table saw and it is useful for my drill press table too.

    I check my levels periodically by putting them on a flat surface then switching them end for end.

    It is important to check, verify and correct any of the tools you rely on in your work. But more errors and misfits are caused by failure to use those tools properly than by having your saw fence or jointer table .002" out of true. I feel I benefit from spending more time thinking about how to do the job right and safely than striving to get that final .001" accuracy on my tools.