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I just can't get my 45 degree mitered edges to line up. I've tried and tried. I spent today trying to make a small jewelry box for my wife out of some 5" decorative moulding. Square box, with 45's at each corner. I made the cuts with my compound miter saw, set on 45 degrees. Made the cuts, put two pieces together, and they are not square. Made 2 more cuts, this time at 46 degrees...still not square. Went up to 47 degrees, same results. By not square I mean under 90 degrees. I've heard to cut miters a little over 45, but I figured 47 was plenty over. I've tried both putting the saw head itself at 45 and cutting with trim flat on table, and putting the saw table at 45, and cutting trim on edge but get the same results both ways.

Am I doing something wrong, or skipping a step? This is getting frustrating! I just want clean mitered edges without having to use wood filler!!!
 

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Old Methane Gas Cloud
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Try gluing (3M 77) some sandpaper (400 grit) to the table of the CMS. It may be that the molding is moving during the cut. (A common problem)

Also make sure that the saw is cuting 90° vertical.

And, if you are doing crown molding in a house, maybe cutting at 46 or 47 would be a good idea so that you can ram the two pieces to gether in an inside corner but not for fine woodworking.

One other tip. Create a small table for the saw to allow the molding to lay in a position as it will be in the final installed position.
 

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John
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I just can't get my 45 degree mitered edges to line up. I've tried and tried. I spent today trying to make a small jewelry box for my wife out of some 5" decorative moulding. Square box, with 45's at each corner. I made the cuts with my compound miter saw, set on 45 degrees. Made the cuts, put two pieces together, and they are not square. Made 2 more cuts, this time at 46 degrees...still not square. Went up to 47 degrees, same results. By not square I mean under 90 degrees. I've heard to cut miters a little over 45, but I figured 47 was plenty over. I've tried both putting the saw head itself at 45 and cutting with trim flat on table, and putting the saw table at 45, and cutting trim on edge but get the same results both ways.

Am I doing something wrong, or skipping a step? This is getting frustrating! I just want clean mitered edges without having to use wood filler!!!
Usually, the second biggest problem is having the opposite sides of unequal length. The way I am reading this, you are putting two pieces together and checking them with a square, yes? If this is the case I suggest you recheck the saw for square with the table and with the fence. If you are putting all 4 pieces together and having problems, check and make sure the opposite sides are dead bang equal. I usually use a stop block for cutting those.
Good Luck.:smile:
 

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Both good answers and i only have one thing to add. Is the square square. If not everything will be out. I've seen squares and levels both out of whack it might not happen often but it can happen.
 

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Really underground garage
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Yes,I read that its a compound mitre.......but theres still two ways to orient the part in saw.Are you standing the part on the "vert" or are you layin it flat on table?

The cutting forces are markedly different in those two examp. above.You'll get slightly more blade flexure when layin part on table.Not sayin thats what happen'd.....just pointing out the difference in force vectors.

Blade flex also occurs when you try to "sneak up on it",irrespective of part orrientation....thin kerf blades suffer from this.Again,dosen't happen in every examp,but it can crop up.

One thing to try is cuttin the 45*'s on a cpl longer pcs.The notion being,the longer the "legs" the easier to accurately determine their respective angles....IOWs if you're trying to check a cpl 6" long pcs compared to 2' long pcs,the latter will be easier to check.BW
 

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where's my table saw?
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A few questions...

I just can't get my 45 degree mitered edges to line up. I've tried and tried. I spent today trying to make a small jewelry box for my wife out of some 5" decorative moulding. Square box, with 45's at each corner. I made the cuts with my compound miter saw, set on 45 degrees. Made the cuts, put two pieces together, and they are not square. Made 2 more cuts, this time at 46 degrees...still not square. Went up to 47 degrees, same results. By not square I mean under 90 degrees. I've heard to cut miters a little over 45, but I figured 47 was plenty over. I've tried both putting the saw head itself at 45 and cutting with trim flat on table, and putting the saw table at 45, and cutting trim on edge but get the same results both ways. ........
You describe 2 ways:
Trim or molding flat on the table, saw head itself at 45 degrees, miter gauge set to 0 degrees ....That would be a bevel. The only thing important here is that the saw blade at precisely 45 degrees when checked with a mag angle block or draftsman triangle. Avoid taking minimum cuts off an end which tends to distort a thin blade. Make a full kerf cut so the same amount of material is removed from each side of the blade.

The other way you describe, trim vertical against the fence 5" tall, saw head at precisely 90 degrees vertical, and miter gauge set to 45 degrees. That would usually be a miter if the material were flat on the table. If the saw has a 5" vertical capacity then it's probably a 12" chop or sliding miter saw.
AS was suggested verify your setup with 24" or longer pieces by checking after cutting with an accurate square.
They must also be held precisely vertical with blocks known to be 90 degrees, to test the joint.

Short answer: "It's the set up" Your miter gauge is not 45 degrees as indicated or the saw head angle is not 45 degrees as indicated, use a measuring device, not the indicator marks on the tool. :thumbsup: bill
 

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Make sure you're not "white knuckling" the saw handle as you pull it down. Sometimes if I'm holding the handle too tight, I also don't realize that I'm actually applying unwanted lateral push or pull to the blade and actually flex the arm on the miter saw a degree or two off. This is more common with my 12" saw as the arm is more flexible than with my 10". Sounds a little too simple I know, but I've fought quite a few unsquare corners. Also make sure there is no cup to your stock.
 

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Saw blade?

How sharp is the blade? If you are using an alternating top bevel cross cut blade, they sometimes pull themselves askew during a miter cut even when sharp especially in harder woods. Try cutting your piece just a tad long (1/16"or so) then make the final cut. That way the blade isn't put under as much stress and may not wander as much. Or try a different blade.

Bret
 

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Since everyone else is jumping in on this (with good ideas, BTW) I thought I'd throw a tip in, too. After you make your cut, release the switch on the saw and let it come to a complete stop in the down position before returning it to the top.

Bill
 

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Discussion Starter #12
All great answers, and I appreciate each and every one!

A couple of answers... It is indeed a 12" saw, and I just put a new 80T blade on it yesterday morning. They were really short pieces (two at 6" and two at 10"), so that could be part of the problem. The other part could be me just holding them during the cut. Makes sense that the piece could slide or move before the cut is finished. I've been meaning to build a miter sled for my TS with some hold downs and stop blocks. Sounds like this could be the perfect time to do that. That should eliminate a variance in length or any movement during the cut.

I'll give all these ideas a try and see how it turns out! Again, much thanks for the ideas! It's amazing what can be learned here.
 

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I'll chime in with a related question, not an answer.

I've read that one way to improve 90 degree joints without worrying about getting the 100% exacto perfect 45 degree bevel was to cut the pieces by turning one over, or on the other side of the saw, or..... (something). The idea was that if one piece ends up cut at 44, then by cutting the other piece "on the other side", the other piece would end up being 46, and all the operator need think about was doing the right sort of flip-flopping. Please pardon my lack of words to describe this. The trick was in a table saw book. Would this approach help at the miter saw if all these other great suggestions have not solved the problem?

(Also, I wonder how many here rely on shooting boards to dial in perfection?)

Steve El
 

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SteveEl: In a word; yep.

I'm not sure it's a fine furniture maker's approved technique, but the process of moving the work piece rather than the saw head is completely valid as the angles will always add up to 90 degrees. I do it all the time, but then again I'm a hack so take from that what you will.

Basically it works like this: Let's say you were setting up a 90 degree joint and wanted to use this technique. You would set the saw head at 45 degrees (even if your miter gauge isn't perfectly accurate it will work with this technique). You would make the first cut with the work piece to the left of the saw head. Then, to make the second, joining cut, rather than adjusting the saw head to the other 45, you would just cut with the work piece off to the right of the saw head. Even if the blade is slightly off 45 degrees the two sides will aways add up to a 90 degree corner as they're two sides of the same angle.

I'd love to hear the pros chime in on this as I'm betting they have a better method (other than get a better cms).
 

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I just can't get my 45 degree mitered edges to line up. I've tried and tried. I spent today trying to make a small jewelry box for my wife out of some 5" decorative moulding. Square box, with 45's at each corner. I made the cuts with my compound miter saw, set on 45 degrees. Made the cuts, put two pieces together, and they are not square. Made 2 more cuts, this time at 46 degrees...still not square. Went up to 47 degrees, same results. By not square I mean under 90 degrees. I've heard to cut miters a little over 45, but I figured 47 was plenty over. I've tried both putting the saw head itself at 45 and cutting with trim flat on table, and putting the saw table at 45, and cutting trim on edge but get the same results both ways.

Am I doing something wrong, or skipping a step? This is getting frustrating! I just want clean mitered edges without having to use wood filler!!!
I've always struggled with the same issues from my compound mitre saw, the truth is no matter what the saw gauge says the angle is at, the angles are either always off by a few too many or less.
one of the best purchases I have ever made was this


it's called the Wixey digital angle gauge, it's magnetic so it should stick to basically all blades.
you might be better off using your table saw mitre than using your compound mitre saw. I don't care how expensive and nice of a compound mitre saw you have, those things never cut accurate unless they are set to 0*
 
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I usually cut just a hair long and then put my angle in a jig I have made up and block sand a little. perfect every time
 

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I have the same trouble with my 12' CMS whenever I try to make a single cut on a vertical piece. Luckily mine is also a slider, so I have found that if I pull the saw all the way out so it misses the board completely on the down stroke and then make the cut while sliding the saw in it works perfectly. It also works fine if I tilt the head and cut down on an angle into a horizontal board.

My 10 inch CMS doesn't seem to have the same problem. It cuts perfect 45's all day long in either the horizontal or vertical position.

Of course the 12" in my preferred machine as its mounted to a work station in my "shop" while the 10" is my back up and/or the one I toss into the back of the truck to take to a job site.
 
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