Leveling Table Saw: Where to Find Good Local Straightedge 24, 30, or 36 inch? - Woodworking Talk - Woodworkers Forum
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post #1 of 26 Old 06-05-2019, 11:43 AM Thread Starter
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Leveling Table Saw: Where to Find Good Local Straightedge 24, 30, or 36 inch?

I want to "level" the cast iron wings with the central table on a table saw to align them all in the same flat plane. It is part of the assembly process. I have several good quality metal rulers up to 18 inches, two inexpensive metal meter sticks, and two Starrett 12 inch combination square blades. The problem is that the combination square blades and rulers are too short, and I am not convinced that the longer meter sticks are straight enough for this job.

I would like recommendations for inexpensive local sources to find a "perfect" straightedge. Ideally, it would also serve as a imperial and metric ruler, but the straightness is critical with an error of a few thousandths at most. I need something that is reliably straight.

The table saw flatness is rated at 10/1000 inch across its surface. The wings are rated at 20/1000s across their surfaces. According to the manufacturer, you can use clamps or body weight to align (tweak) the somewhat malleable cast iron wings as you tighten the screws that attach the wings to the table and fence rail.

I thought about buying a 24 inch Starrett combination square blade. It is short compared with the ideal 30 inches, but might have many other uses over the my lifetime. Unfortunately, they are expensive.

I hope that someone here can suggest a quick, easy, inexpensive, and reliable alternative.

P.S. I should have made the subject "Flattening Table Saw: ..." instead of "Leveling Table Saw: ..." I hope everyone understands that I want to make the table saw table and wings flat relative to each other, not really "level to the ground."

Last edited by Tool Agnostic; 06-05-2019 at 12:02 PM.
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post #2 of 26 Old 06-05-2019, 12:06 PM
where's my table saw?
 
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Use an aluminum spirit/bubble level

Go to the local hardware, Home Depot or Lowes and look at the levels. There will be some up to 72" long, but I would start with a 48" and maybe a 24". Compare them by placing them side to side and looking for a "light" gap in between them. After you find a "zero light gap", flip it end for end and test it again. Just pick out the straightest one. You will NOT use it as a level, it's original intended purpose!

https://www.amazon.com/Goldblatt-48i...gateway&sr=8-3

The advantage to using a level is the width of the face it rests on. It won't tip over like a single steel straight edge when you let go of it to do other checking. If you determine that the wing is not level with the table, you can use thin shims to tip it up or down as needed. It can be flush at the joint, but still not be level.

There are steel scales for measuring, like these:
https://www.amazon.com/Swordfish-800...gateway&sr=8-3

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 06-05-2019 at 12:52 PM.
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post #3 of 26 Old 06-05-2019, 12:22 PM
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Your fingers can detect differences as small as 13 nanometers, that’s really small. Running your fingers over the seam will get you real close.

Check the levelness of the wings to the top by running anything with a sharp corner back and forth and it will get caught on the seam if it’s not aligned. That is as close as you need to get with the wings.

Trying to put a straight edge across the entire top and checking with feeler gauges is just going to frustrate the piss out of you when you discover dips in the work surface that you can’t do anything about, and probably won’t make any difference anyway.


In woodworking there is always more then one way to accomplish something.
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post #4 of 26 Old 06-05-2019, 02:21 PM
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I use my 48" level....
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post #5 of 26 Old 06-05-2019, 04:59 PM
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I also used a 48" level.

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post #6 of 26 Old 06-06-2019, 10:02 PM
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48" level would be the first choice, not having that I would look around for something else before putting out big money to buy something, straight is straight whether it is a length of wood, tubing, shafting, angle iron for whatever. For that matter the factory edge of a sheet of plywood or MDF would do the trick.
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post #7 of 26 Old 06-07-2019, 10:11 AM Thread Starter
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Yesterday I went to Home Depot and a local hardware supplier that caters to professionals: McFadden/Dale Hardware, which is probably similar to Grainger (?).

The straightedge rulers were wrapped in hard shrink-wrap plastic, and the levels were all in packaging sleeves that prevented me from holding them side by side. There was no way to test them at the store. I tried, but the packaging interfered with testing.

I bought a wide Empire 48 inch ruler which was also labeled "Straight Edge" on the label with the barcode. Frankly, I bought it because it had imperial and metric scales and I have been looking for one like it for a long time. Even if it does not have a perfect straight edge, I wanted it for basic measuring and marking anyway. I have not had a chance to examine it carefully, but a quick test says that it is straight.

There was a bewildering array of choices of 48 inch levels at both hardware stores. They ranged in price from $10 to over $80. They were nearly all Empire brand. Only the most expensive ones had flatness specs printed on the labels. The young (inexperienced?) store clerk could not vouch for the flatness of the less expensive ones. The packaging prevented testing.

I have a couple of levels at home. One is 24 inch and I just discovered that it has a slight rocking motion from corner to corner. The other is a badly pitted 48 inch level that was abandoned by construction workers. It would require cleanup just to test it.

I do not expect perfection and won't drive myself crazy trying to achieve it. My goal is to set up the saw so that it can cut to its best potential. I want the seams to be as close to invisible as possible. At the same time, the table and wings should be as coplanar as possible. I expect small dips and rises in the table and wings, which won't affect wood cutting. Even an overall dip or rise in the wings would not be too bad if it is very small; my goal is to minimize THAT by making the full table as coplanar as I can. After all, the wood will move a tiny bit just from the heat of the cutting blade, the coolness of the table, etc.
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post #8 of 26 Old 06-07-2019, 12:31 PM
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Every time I read these posts about precision machine adjustments I am so glad I was working for profit before the internet age when I brought new tools to the shop, cleaned off the grease and put them to work.
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post #9 of 26 Old 06-07-2019, 01:16 PM Thread Starter
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Quote:
Originally Posted by FrankC View Post
Every time I read these posts about precision machine adjustments I am so glad I was working for profit before the internet age when I brought new tools to the shop, cleaned off the grease and put them to work.
Understood. Your message is "Don't let trying-for-perfect get in the way of good enough."

Hopefully this is a one time exercise. I want to optimize the table as best I can, and then use the saw for a long time. (It is kinda' like restoring hand planes - a lot of work up front, but needed only once.)

The few extra hours may be wasted time, but it is my time. In return I earn the satisfaction of knowing that I gave it my best effort. If it saves me from messing up just one project, then the time and effort may be worth it. Those few hours will not be noticed when amortized over the (hopefully) many years of table sawing to come.
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post #10 of 26 Old 06-07-2019, 03:12 PM
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I am in the camp of "If it works don't fix it", if something is out of kilter of course it has to be taken care of, I can tell you that in my experience more machinery is misaligned or damaged by someone fiddling with it to make it perfect than it arriving from the factory out of adjustment.

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post #11 of 26 Old 06-07-2019, 03:25 PM Thread Starter
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Quote:
Originally Posted by FrankC View Post
I am in the camp of "If it works don't fix it", if something is out of kilter of course it has to be taken care of, I can tell you that in my experience more machinery is misaligned or damaged by someone fiddling with it to make it perfect than it arriving from the factory out of adjustment.
Good point, but it doesn't apply here. In this case, the table saw wings arrived detached. I want to attach and align them correctly the first (and hopefully ONLY) time.

Frank, you made your point. You were very clear and thoughtful and I appreciate your message, even though I want to do a little more than you would do. You may be right and it may not matter, but I want to give it a try.

Obviously, what is mildly important to me doesn't matter to you. There are probably unrelated things that are important to you that don't matter to me, too. That's okay, and I got your message.

Thank you once again.
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post #12 of 26 Old 06-07-2019, 04:39 PM
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You are over thinking this! 20 thou is a pretty sloppy tolerance even for a table saw. But think of it this way, at 18" from the blade if you have a .020" difference (that's the thickness of 5 Coke can sides) that will represent an angle at the perfectly square blade of .06359832 degrees. I'm willing to bet that you can't adjust your blade to that level of tolerance!
Unless you have a very high end professional level saw the arbor and flange will have more runout than what you are worried about. Same applies to your saw blades and for that matter your hands feeding the saw.
Make stuff. It is far more rewarding than fighting a loosing cause.
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post #13 of 26 Old 06-10-2019, 06:11 PM Thread Starter
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The Empire 48 inch straight edge / ruler (model 4004 M) gave me just what I needed to measure and flatten the top. I checked the straightedge on a "reference" table saw, and it is perfectly straight.

I used the new straightedge to measure my saw table excluding the wings. It was flat in every direction except diagonally across the opening, where the straightedge rocked back and forth. At first, it seemed very large, out of spec for sure. I borrowed Spouse's feeler gauges, and learned that the rise is tiny, well within spec. The high part was near the front of the opening, and it made the fulcrum for a "large" gap at the back of the saw, where you could easily see it raise and lower as you rock the straightedge back and forth. When I actually measured the gap at the back, I was surprised to learn that it was only ~0.012 inches, meaning that the rise at the front of the opening (the fulcrum) had to be tiny, but was magnified in the back of the table. As soon as I understood that, I moved on.

I loosened the bolts attaching the two wings. I reworked the seams, and they are much better now, close to perfect. Once I had the seams optimized and the bolts fully tightened, I reattached the front and back fence rails to the main table only, and aligned them with a depth gauge.

I used the new 48 inch straightedge to align the top. Thanks to my previous measurements across the blade opening, I knew that the smallest gaps were far smaller than the 10/1000 inch spec for the table and 20/1000 inch spec for the wings. I used the straightedge as a guide. I used 10 inch handscrew clamps and my own muscles (both lifting and pressing) to "tweak" the outside ends of the cast iron wings as I tightened the wings to the rails. When all was done, I put the straightedge across the full width of the table and wings on the front and again on the back to check my work. I saw tiny ripples in the cast iron with tiny light gaps in a few places under the straightedge, but it was as flat as I could get it, which is all I wanted. It took between two and three hours to redo the work to my satisfaction.

The cast iron table and its wings are as seamless and level as I can make them. They are not perfect, but I never expected perfect. I know I did my best, and that's what counts. I spent way more time than @FrankC would have considered reasonable, but as I said before, it was my time to spend. I do not expect to touch any of those bolts again in my lifetime, except to brush off the sawdust from time to time. :-)

I ran out of time yesterday to complete the saw assembly and alignment, but will finish it soon.

Thank you once more for everyone's advice and suggestions.
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post #14 of 26 Old 06-10-2019, 10:41 PM
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If you have it all set up just perfectly can't knock that, how about some photos of the completed project.

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post #15 of 26 Old 06-11-2019, 11:34 AM
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Idea, good or bad I don't know but

How about getting the main table and wings as flush as possible and then using a digital angle gauge to measure the "levelness" of the two parts?
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post #16 of 26 Old 06-11-2019, 01:12 PM
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Not necessary .....

Quote:
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Idea, good or bad I don't know but

How about getting the main table and wings as flush as possible and then using a digital angle gauge to measure the "levelness" of the two parts?

What would you learn and then what would you do if they weren't?


Flush across all surfaces is all that's needed. Level with the world really doesn't matter, in my opinion. If the floor isn't level and you haven't leveled out the table, then yes, out feeding onto another support may matter.



In my case, I have 3 saws, 2 tables and one router extension ... all one surface.... in theory. Table flatness I can't fix.

Leveling, I can and have done by shimming the legs and the outfeed table on the top of the file cabinets. Most important to me, is being able to feed straight through onto the outfeed table with no interaction or interruption...... smooooth!



The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #17 of 26 Old 06-11-2019, 02:38 PM
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I am a believer that machines, benches, shelves and everything else need to be level with the world, it just makes it easier to line things up and removes the doubt you may have when a squared upright does not line up with another object such as the side of a cabinet behind it.

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post #18 of 26 Old 06-12-2019, 10:26 AM
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Quote:
Originally Posted by woodnthings View Post
What would you learn and then what would you do if they weren't?


Flush across all surfaces is all that's needed. Level with the world really doesn't matter, in my opinion. If the floor isn't level and you haven't leveled out the table, then yes, out feeding onto another support may matter.



I wasn't suggesting level with the world, set the digital angle gauge on the main table and zero it, move the gauge to a wing and see if it is still zero. If the edges are flush and table and wing are both zero then the two parts should be aligned as you would like them to be.

Like I said though, I don't know if this would work well or not .
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post #19 of 26 Old 06-12-2019, 02:56 PM
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How flat things are by measurement are not important as the actual cut piece.
If you ran a bunch a boards through the table saw and then edge glued them up to make a table top and the top comes out flat, would the measurements you are worried about even matter?

Check your cuts and see if it really matters. If it does, check you saw blade for 90* to table top. That would be more important than extension wings

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post #20 of 26 Old 06-13-2019, 01:11 AM
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