How to tell if a square is square - Woodworking Talk - Woodworkers Forum
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post #1 of 22 Old 08-07-2009, 12:50 PM Thread Starter
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How to tell if a square is square

I am having trouble setting up my compound miter. I am going to get into picture frames and needs to be on. +-= 0
I have 8 squares that don't agree with each other. I have adjusted the miter with each square to find if it would be on with one of the squares. So far I have enough fire wood for next winter.
Other than a machinists square is there some way you can check your squares to see how they are. I am thinking mathamatical,numbers on the square or graph's. I am sure a machanical engineer could make a square.
any idea's Thanks Waldo
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post #2 of 22 Old 08-07-2009, 12:57 PM
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Waldo: take each square and do the following:
a nice clean sheet of paper, use a table or something with a straight edge like a table etc, then with the square using that edge draw a line, then flip the square right to left or visa versa, draw second line starting from the EXACT same point, if both lines cover each other than square is square, if the lines diverge then half the amount of space between the lines is your error.
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post #3 of 22 Old 08-07-2009, 12:59 PM
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You could just take your framing square and make a mark on the edge of a section of any sheet goods. Hook the short leg to the left of the mark and draw a fine line down the long leg. Then flip the square over on the same mark and draw a line down the long edge. It should be exactly on the same line as the first line.




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post #4 of 22 Old 08-07-2009, 01:05 PM
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But!...if a framing square is out...you can adjust it with a shallow pointed punch...provided you know what you`re doing. Rick

Never... I mean always... never mind Rick
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post #5 of 22 Old 08-07-2009, 01:07 PM
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If you're setting up the saw, do this: Take a piece of flat plywood about 8" wide. Set it against the fence and make a cut. Rotate it CCW and make another thin cut, rotate again and repeat until all 4 edges have been cut. Put a square against the first cut and the last cut. The amount that it is out is 4 times more than your saw is out of whack. This takes a little time but when you're done, the saw will be perfect.

Bud

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post #6 of 22 Old 08-07-2009, 01:09 PM
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If you are going to be making picture frames using your sliding miter saw(SMS) is it not the 45 degree angle that should be correct? You are not going to butt join the frames are you?

George
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post #7 of 22 Old 08-07-2009, 01:41 PM
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Quote:
Originally Posted by TS3660 View Post
If you're setting up the saw, do this: Take a piece of flat plywood about 8" wide. Set it against the fence and make a cut. Rotate it CCW and make another thin cut, rotate again and repeat until all 4 edges have been cut. Put a square against the first cut and the last cut. The amount that it is out is 4 times more than your saw is out of whack. This takes a little time but when you're done, the saw will be perfect.

If I'm understanding correctly, the problem with that method is if the second edge isn't 90 degrees to the first, then the first cut and the last cut will remain in the same configuration.






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post #8 of 22 Old 08-07-2009, 02:16 PM
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Maybe I didn't explain it right. But if the saw is off just a tad, this tad is multiplied by 4 by the time you make the last cut. Sometimes if you just make a 90 deg cut and check it with a square, it looks good. But it may be off slightly and you won't be able to notice. This method multiplies it by 4 so if it's good at that point, it HAS to be good everywhere.

Bud

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post #9 of 22 Old 08-07-2009, 04:02 PM
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I guess what I did on my radial arm saw is use this method. But then after the 4th cut, I flipped the piece over and put the 4th cut against the fence and the 1st cut parallel to the blade. Then I pulled the carriage forward and noted how far the blade was away from the cut (1st cut). It was about 1/8" away near the end. So, then I loostened the arm up and moved the arm to bring the blade 1/4 of that distance (1/32") closer to the board. Then I did the test again. It worked very well. So, I guess I didn't even use a square.

Bud

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post #10 of 22 Old 08-07-2009, 04:06 PM
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Use a Incra miter gauge and table saw for frame precision. I used to try my miter saw for this and could get it close, my Incra is perfect. I promise a good table saw and miter gauge will make you look at your miter saw in a different light.
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post #11 of 22 Old 08-07-2009, 04:18 PM
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Quote:
Originally Posted by Nate1778 View Post
Use a Incra miter gauge and table saw for frame precision. I used to try my miter saw for this and could get it close, my Incra is perfect. I promise a good table saw and miter gauge will make you look at your miter saw in a different light.
My Rockler sled on the table saw also has very good accuracy. The scale in degrees is very large (read accurate) for miter cuts.

However, I am still very comfortable with my miter saw.

George
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post #12 of 22 Old 08-07-2009, 06:05 PM Thread Starter
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What is a Incra miter

Last edited by Waldo; 08-07-2009 at 06:06 PM. Reason: spel
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post #13 of 22 Old 08-07-2009, 06:50 PM
where's my table saw?
 
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You have been given advice on squares

Quote:
Originally Posted by Waldo View Post
I am having trouble setting up my compound miter. I am going to get into picture frames and needs to be on. +-= 0 I have 8 squares that don't agree with each other. I have adjusted the miter with each square to find if it would be on with one of the squares. So far I have enough fire wood for next winter.
Other than a machinists square is there some way you can check your squares to see how they are. I am thinking mathamatical,numbers on the square or graph's. I am sure a machanical engineer could make a square.
any idea's Thanks Waldo
So, after you checked all your 8 squares (it's hard to believe that they are all "off" !) I think there is a problem with the saw that won't give repeat accuracy. If you make a 90 degree cut on a 6" board, then just turn the board over and make another cut to see if you take off a parallel amount, that's one check. You didn't say what brand of saw, what blade, what fence, all these could enter into this issue.
The Incra Miter gage is an indexing miter with stops at 5 degree intervals, very precise and repeatable. The suggestion was to use a table saw and this miter gage to cut your frames, rather than the miter saw. bill

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 #14 of 22 Old 08-07-2009, 10:14 PM Thread Starter
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Quote:
Originally Posted by woodnthings View Post
So, after you checked all your 8 squares (it's hard to believe that they are all "off" !) I think there is a problem with the saw that won't give repeat accuracy. If you make a 90 degree cut on a 6" board, then just turn the board over and make another cut to see if you take off a parallel amount, that's one check. You didn't say what brand of saw, what blade, what fence, all these could enter into this issue.
The Incra Miter gage is an indexing miter with stops at 5 degree intervals, very precise and repeatable. The suggestion was to use a table saw and this miter gage to cut your frames, rather than the miter saw. bill
Yes I am talking about making 45 deg. angles. I looked up the Incra guage and it looks like it would work,altho a little pricey. But now days what isn't. I guess I better save my sheckles and get one. If I just order it,my Wife will be all over me. She is 5' tall and 94 pounds wet and I am scared to dead of Her.
Cowerdly Waldo
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post #15 of 22 Old 08-07-2009, 10:15 PM
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Quote:
Originally Posted by Waldo View Post
I am going to get into picture frames and needs to be on. +-= 0.....
With the above statement can I assume you are 'getting into' picture frames as somewhat a part-time business? Well, other than rustic frames, most common even the fairly high dollar chop saws are not smooth enough nor accurate enough (repeatability) for a framing business. Check local picture frame shops and 90% of their usage is on a large knife type cutting set-up. The other 10% is with very high dollar chop saws made specifically for the picture frame industry. Good frames and matting are very expensive but the customers expect perfection.
I have made frames on occasion and without the proper set-up, you can get into trouble. If on the other hand, they are for yourself and family, I have wasted a lot of space on here. In either case I wish you the best.


Tony B

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Retired woodworker, amongst other things, Sold full time cruising boat and now full time cruising in RV. Currently in Somerville, Tx
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post #16 of 22 Old 08-08-2009, 05:46 AM
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Waldo, How about cutting the miters on a table saw with a sled, it will give you much more accuracy by compensating for any small deviation from 45 or 90 (of the blade to the table).

If you decide on "yes", I can direct you to a few posts on how to build the sled (if you don't have one already) and using it...

I made many frames with this methods and it's "From the table saw to the gluing table" no adjustment needed...

niki
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post #17 of 22 Old 08-08-2009, 06:40 AM
where's my table saw?
 
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Amazon has the Incras from $50 up

http://www.amazon.com/Incra-MITER1000SE-Miter-Special-Telescoping/dp/B0007UQ2EQ bill

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; 08-08-2009 at 06:48 AM.
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post #18 of 22 Old 08-08-2009, 07:35 AM
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Wow, that's a good deal on that Incra. Wish I had 100.00 laying around. Waldo, I have a friend in the frame business and he uses a fixed, dual-head chop saw with the heads at opposing 45's. And even with that he still sometimes gets losers, but that's occasional operator error. I suggest you look into something other than just a basic miter saw. With the degree of accuracy you are wanting you are gonna have to figure on spending some money to buy either a quality square or a quality tool/fixture/whatever. Better to buy accuracy up front then chew through your quality frame stock.
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post #19 of 22 Old 08-08-2009, 09:33 AM Thread Starter
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miter help

Quote:
Originally Posted by niki View Post
Waldo, How about cutting the miters on a table saw with a sled, it will give you much more accuracy by compensating for any small deviation from 45 or 90 (of the blade to the table).

If you decide on "yes", I can direct you to a few posts on how to build the sled (if you don't have one already) and using it...

I made many frames with this methods and it's "From the table saw to the gluing table" no adjustment needed...

niki
Niki Yes I am interested in building a sled and I would love to see some ideas on it. Thanks Waldo
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post #20 of 22 Old 08-08-2009, 09:42 AM
where's my table saw?
 
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I just took my own advice

`And bought one. And 2-24" extensions. bill


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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