# Joining Two 45 Degree Miter Cuts to Make 90 Degree



## thecrus8r

Greetings,

I am having an issue joining 45 degree miter cuts to make a "waterfall" edge entryway table. I made the cuts, verified they are 45 degrees, but they will not join properly. What am I doing wrong? Is there something I can do to make this entryway table sit flush? The pictures provided are 90 degrees on the outside and inside of the table. I have access to a full shop, so maybe using the miter saw wasn't the best option. Table saw? Besides the standard table saw miter gauge it comes with, I don't have a crosscut sled or anything.

Please see the images for reference.

Thank you!


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## bndawgs

How did you verify that they were 45?


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## thecrus8r

I used the miter gauge from my table saw and set it on the cut, it read 45 degrees.


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## HokieKen

Yeah, that ^ Either your angles aren't 45s or it isn't sitting at 90s now. Unless geometry has changed a lot since I graduated ;-)

But, here's my advice… don't worry about whether they are actually 45 or not. Pick either the legs or the top and start trimming up the miter to fit the other one and form a right angle. Doesn't really matter if the angles are 45/45 or if they're 46/44, it'll look fine. If it were me, I'd fine tune the fit with a block plane.


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## thecrus8r

Thanks, Kenny. I will look into your idea regarding the block plane. I used the miter saw, instead of the table saw, because the top piece is 6 feet and would have been really difficult to maintain an accurate cut without a crosscut sled.


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## Rick Dennington

You need to make a miter sled for your projects that require cutting 45's…..Maybe a small one for small projects, and a larger one for….well…you get the picture……!! A miter sled makes all the difference with using the table saw……. Here's a small one I made for my saw……!! I have a bigger one for larger stock….!!


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## thecrus8r

That type of sled would definitely be beneficial in the future, but the type of stock that I am working with, I don't think that'll work too well.


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## Bonka

The boards also have to be the exact same length, e,g, the two longer one the same and the two shorter. I use shooting boards to square and get exact 45's. Look up mule's ear. The would plane to 45d on flat ends. They were worth the one time effort to make for me.


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## John Smith_inFL

one of the best investments you can make for your table saw
would be a Digital Angle Gauge with a magnetic base.
it will stick to the saw blade to give you the correct angle you need.
BUT - the saw's table must be perfectly level for it to work properly.
(I would not have used the miter saw).










.


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## 000

> BUT - the saw s table must be a perfectly level for it to work properly.
> 
> - John Smith


That's what the zero button is for.


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## therealSteveN

"I have access to a full shop, so maybe using the miter saw wasn't the best option"

Most of your answers have been TS oriented, so maybe they agree. I find it really hard to get really sweet cuts on a chop saw, so I do use the TS for miters that count, you get a lot more control. Your cuts here once you figured how you were going to figure for length of your pieces, a stop on the miter guage fence is what I would do, unless they are longer than 3'

Using a cube, like the Wixey Zero it out on your saw table, hang it on the blade, and crank it around to 45* Make the cuts smoothly, but don't dally around, a nice slow stroke while holding the work, or better yet clamping it to your fence on the miter gauge, or you will meet Mr Creep.

Do that and see if they aren't tighter.


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## thecrus8r

> "I have access to a full shop, so maybe using the miter saw wasn't the best option"
> 
> Most of your answers have been TS oriented, so maybe they agree. I find it really hard to get really sweet cuts on a chop saw, so I do use the TS for miters that count, you get a lot more control. Your cuts here once you figured how you were going to figure for length of your pieces, a stop on the miter guage fence is what I would do, unless they are longer than 3
> 
> Using a cube, like the Wixey Zero it out on your saw table, hang it on the blade, and crank it around to 45* Make the cuts smoothly, but don t dally around, a nice slow stroke while holding the work, or better yet clamping it to your fence on the miter gauge, or you will meet Mr Creep.
> 
> Do that and see if they aren t tighter.
> 
> - therealSteveN


The entire project is based on 3in x 12in lumber, the legs are 3ft and the top is 6ft. I am sure I would be able to use the 3ft legs on the table saw, but I really don't know how to go about the 6ft top with the table saw.

Thoughts?


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## clin

When you say "lumber" are you referring to construction lumber (which it sort of looks to be)? That is it's own problem. If it is construction lumber, it may have more internal stresses than a good quality of properly dried furniture grade lumber. So even if you make a perfect cut, the wood will move and won't even maintain the same angle across the cut. Making an initial rough cut, then just trimming the last bit will help.

But in any case, if the wood is not flat to start (construction lumber won't be). Then it is never likely to work well short of hand fitting the piece. Even then, if the wood is not dried, then a perfect fit today won't be perfect tomorrow. It can change overnight. So, once the pieces fit well, I'd join them immediately. But again, if the wood is not dried completely, none of this will matter. The joint will likely pull apart as the wood dries.

If the wood is good quality and properly dried, then I'd do test cuts on scraps until the angle is just what you need. Then make the final cuts on the finished pieces.


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## therealSteveN

6 foot stuff, and larger is jumping from bring the work to the tool, and going into bring the tool to the work territory. You mentioned waterfall table earlier so I'm thinking Track saw. Not sure about them all, but the big 3 all will tilt 45* and they reference off the tilt, crisp clean cuts rip or crosscut. Easy peasy. Huge cash outlay if you don't have one though.


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## bandit571

Maybe just a circular saw…tilted to 45 degrees….guided across the grain with a speed square-like guide clamped to the boards….









Something like this? 









Trimmed the bottom edges of two panels, so they would match each other, and be square. In your case, set the guide to the motor side of the saw, after you tilt the saw to 45 degrees. Mark your cut line…measure from to "outside" of the blade towards the fence location…square a line across to set the guide to. Run the saw through the cut, keeping pressure on the saw to ride against the guide.


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## jutsFL

> The boards also have to be the exact same length, e,g, the two longer one the same and the two shorter. I use shooting boards to square and get exact 45 s. Look up mule s ear. The would plane to 45d on flat ends. They were worth the one time effort to make for me.
> 
> - Gerald Thompson


Thats what ive found for my picture frame frustrations. The miters can all be 45s, but if the opposing sides are not EXACTLY the same length - it will be off.

My guess is that if you are 100% sure all miters are at 45deg, then your 2 opposing legs are indeed not the same length. Worth taking a quick peek at.


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## therealSteveN

Bandit, not so many years ago that was a track saw. You just needed more measuring, and clamping, so yes. Now that I do have a track saw I tend to forget what I used to do.

My circular saw, which I hardly ever use anymore has a big 5 1/4 magic marked on the top of the plate, so I don't need to measure the distance between blade, and the edge of the saw plate.


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## Lazyman

Another factor in getting perfect 45° cuts is that your stock has to be perfectly flat and the faces parrallel to each other (consistent thickness). Likewise on such long boards, you have to make sure the support keeps the board perfectly level and flat on the surface of the miter saw. Any bowing or tendency for the board to pivot during the cut will guarantee it won't be 45°. Test making the cut with short pieces. If you cannot make it work with short pieces, it is most likely the saw setup or adjustments that are out of whack. If it works with shorts, then it is bowing or pivoting board on the longer pieces that are likely the culprit.


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## CaptainKlutz

One method to making 45 degree from vertical cut on miter saw is make sure you use proper cutting side to ensure your angle cuts are mirror of each other, I.E. the two sides of joint are cut on opposite sides of blade (without changing the angle). Hard to explain, wish I had picture handy, but here goes.

Assume you set the blade tilted to towards right (top of blade on left and bottom on right); When you cut top board ends, you want the top board on the right and cut off on left side (best surface up). Then when you cut the legs, you want the leg board on left side (best side down) and cut off on right side. If you cut the ends this way, even if you have blade set at 44 degrees, then second cut will be 46 degrees and they will form a 90 corner. (Switch sides listed if you tilt opposite direction)

As others mentioned, the hardest part of any 45 miter cutting process with wide stock is to ensure use the same blade setting, same reference side for each cut, and that surfaces are flat/square to your fence. If there is any error due twist, warp, or even dust on table; then the angle will be just a little off. The biggest issue with this 'do not move the miter blade' method, is that leg cuts are referenced to opposite edge compared the top board. The requires that you have straight/parallel edges, or the joint can be perfect on one end and slightly open on other. 

Another miter process that doesn't require a table saw, is to use a router. Whiteside sells a 45 degree edge bit with 1-1/2" cut height. Using it, you can miter standard construction lumber or panels too large for table saw.
With any miter cut, especially the router type: getting the board length exactly same across the cut is important. So you must use a solid fence clamped square to board, and measure 3-5 times before miter cut the edge.

+1 use hand plane to adjust.
When best settings and jigs fail to create perfect 90 corners, use a plane - preferably with a miter shooting board/box as described here.

Best Luck.


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