# Getting perfect miter joints



## lateralus819 (Jul 22, 2012)

So i've attempted to make a small box roughly 10x7 for my mom 3 times over now and every time i mess it up. Are there any tips to get a seamless edge when glueing? I just watched a video on using tape which seems like a great idea. Are there any tips as for as what to do with the table saw or chop saw to make sure i get a good seam?


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## woodnthings (Jan 24, 2009)

*your miters need to be perfect*

Here's an example where if you line them up edge to edge the line formed should be straight. If not the bevels are off a smidge. Check them with a square.


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## jschaben (Apr 1, 2010)

lateralus819 said:


> So i've attempted to make a small box roughly 10x7 for my mom 3 times over now and every time i mess it up. Are there any tips to get a seamless edge when glueing? I just watched a video on using tape which seems like a great idea. Are there any tips as for as what to do with the table saw or chop saw to make sure i get a good seam?


Two things are needed to get a good miter. The opposite sides MUST BE EXACTLY equal. The miter cuts must be EXACTLY 45°. Other than that, piece of cake:smile:


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## lateralus819 (Jul 22, 2012)

jschaben said:


> Two things are needed to get a good miter. The opposite sides MUST BE EXACTLY equal. The miter cuts must be EXACTLY 45°. Other than that, piece of cake:smile:


is there a trick to get them exactly equal


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## GeorgeC (Jul 30, 2008)

First thing for you to do is check the saw that you are using to make sure that the 45deg point is exactly 45 degrees. Also make sure that there is no tilt toward either wide.

George


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## lateralus819 (Jul 22, 2012)

GeorgeC said:


> First thing for you to do is check the saw that you are using to make sure that the 45deg point is exactly 45 degrees. Also make sure that there is no tilt toward either wide.
> 
> George


Any way to do that without fancy tools?


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## jschaben (Apr 1, 2010)

lateralus819 said:


> is there a trick to get them exactly equal


Usually get it by using a stop block, some will cut both boards at once to make sure they are equal.
These things are surprisingly accurate for no more than they cost.
http://www.homedepot.com/Tools-Hard...=10053&langId=-1&keyword=square&storeId=10051

May want to sort through several at the store though just to make sure. :smile:


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## FrankC (Aug 24, 2012)

One of the handiest things for matching up opposite sides is a good disk sander which will let you tweak the dry fit.
http://benchnotes.com/DISK SANDER /Disk_Sander.html


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## BZawat (Sep 21, 2012)

Dude just get a small machinist's square. Lay it down flat on the table of your miter saw with one leg against the fence. With the saw head down, check to be sure that when set at 0 the blade is square to the fence. If not, make it square and adjust the miter gauge to 0. 
Next check that the blade is square to the table when the bevel setting is at 0. This one is usually the culprit in an out of square miter. If you're beveling the saw to 45 degrees, be sure to check it again for square (to the fence) before you cut. They're not always reliable. 
I always make sure to get the surface of the square up against the side of the blade and not on the teeth, it's easier to square up that way. 
If your saw's dialed in properly it makes cutting perfect miters WAY simpler. 
By the way Lateralus is hands down my favorite TooL album
Good luck!


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## lateralus819 (Jul 22, 2012)

Well i tried again and its %100 square. Problem is there are still gaps on the seams which I'm not sure how thats possible, but it could be because the oak seems as though its hard to get a nice crisp cut. I did the cuts on a table saw and then ran them on a belt sander with a miter gauge. Who knew woodworking could be so hard. 

One of my co-workers thinks im nuts, but I've always been a perfectionist. I really like woodworking, it sucks im so new to it, but i want to become as good as i can. I hope to be able to pick up a nice table saw and miter saw in the near future.


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## Keith Mathewson (Sep 23, 2010)

The words beltsander and perfection don't belong in the same post. If you want to become proficient at woodworking get rid of the beltsander.


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## Calzone (May 15, 2012)

My experience with a miter joint:



> preparing the joint for glue
> Oh! well, this looks good so far! Miters are crisp! Little overhang though, but it will work out fine after I sand
> glue is applied
> Still good! gaps are a little big, and everything's sliding around, but I think I can hold it in place
> ...


I just ditched miters in general. It's a poor joint for gluing purposes anyways. Always put a spline in, maybe a biscuit, or do a Lock miter bit if you can swing it. Those things are nice!


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## lateralus819 (Jul 22, 2012)

Calzone said:


> My experience with a miter joint:
> 
> 
> 
> I just ditched miters in general. It's a poor joint for gluing purposes anyways. Always put a spline in, maybe a biscuit, or do a Lock miter bit if you can swing it. Those things are nice!


well, what would you suggest instead of a miter joint for a box? I was thinking of doing a rabbit type joint. Far easier to get nice for me.


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## Calzone (May 15, 2012)

Put splines in the box to sturdy the miter. A rabbet will work, but a miter is good for matching two corners so the grain is consistent, and almost nothing else.


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## del schisler (Nov 5, 2009)

lateralus819 said:


> So i've attempted to make a small box roughly 10x7 for my mom 3 times over now and every time i mess it up. Are there any tips to get a seamless edge when glueing? I just watched a video on using tape which seems like a great idea. Are there any tips as for as what to do with the table saw or chop saw to make sure i get a good seam?


first you need a good blade. I belive mine is a 82 tooth . Cuts slick as glass, Is the space in the back of the glue up or the frount. That will tell you which is off. What you can do is glue up only 2 pieces at a time or 1/2 of the square than when you put it togother you can sand the frount of back of the 2 pieces to make them fit . one way to do it. That is what segmented bowl makers do. But you should get good 45's any way. see if any movement in the blade at all side ways and back and forth. Is is a thin blade ? 10" blade, rip or cross cut how many teeth. I have a maketa and the arbor beiring had a little wooble in it sometime's it would make good 45's and than not. so i replaced the beiring now all perfet 45's good and smooth. good luck


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## GeorgeC (Jul 30, 2008)

Keith Mathewson said:


> The words beltsander and perfection don't belong in the same post. If you want to become proficient at woodworking get rid of the beltsander.


A very nice sounding statement that does not hold up in practice. Most people that have been woodworking for long find that there is a place for the belt sander. They just do not use it as a tool that "solves all."

George


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## cabinetman (Jul 5, 2007)

GeorgeC said:


> A very nice sounding statement that does not hold up in practice. Most people that have been woodworking for long find that there is a place for the belt sander. They just do not use it as a tool that "solves all."
> 
> George


Hey...I'm one of those guys. Some things need belt sanding, and others don't. You can set up a table saw, radial arm saw, or a miter saw (CMS/SCMS) with a plastic drafting template. You can get a right triangle (45/45/90) in many sizes, and they will be accurate.










 







.


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## Keith Mathewson (Sep 23, 2010)

GeorgeC said:


> A very nice sounding statement that does not hold up in practice. Most people that have been woodworking for long find that there is a place for the belt sander. They just do not use it as a tool that "solves all."
> 
> George


George,

While people do things in different ways I haven't used a belt sander in years and never for joinery.


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## Flatlander (Oct 14, 2012)

I had the same trouble making miter joints for moulding. What I ended up doing was making a shooting board and finishing the miter edges with a hand plane.
It can be very difficult to get a perfect miter even if you have the best machinery, it does not take much to get a slight error in the angle of the joint, a slight movement on your part, a slightly misaligned blade, it does not take much!


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## Rashed (Oct 15, 2012)

After all the replays and trouble shooting, i recommend to check if your boards are straight and square. It could happen some times. 😬


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## Rashed (Oct 15, 2012)

( 😬) is an emoticon oops!


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## jharris2 (Jul 9, 2012)

Rashed said:


> After all the replays and trouble shooting, i recommend to check if your boards are straight and square. It could happen some times. ?de2c


Agreed. If your boards are cupped or warped even slightly it will effect the joint. Also if the wood is not held or clamped firmly in position during the cut it can wander causing the cut to be off.

Jeff

"I have never let my schooling interfere with my education"

Mark Twain


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## DaveTTC (May 25, 2012)

An old tradie I knew when I was an apprentice had a little trick on the job. He would tack or clamp his pieces in place and then re-cut the joint with a handsaw. The joint would come up a treat. 

As for cutting on a table saw, that would be my last choice unless you have a good quality saw with a sliding table. I just use a 12 inch drop saw. Good sharp blade is a must.

Dave The Turning Cowboy


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## Phaedrus (Jan 18, 2012)

I can attest to TS being a poor choice. I'm making a small frame for the wife right now and the angles that I am getting from my TS seem like 45, but just aren't. I am thinking that a miter box might even be a good solution. I should mention that I am using a miter gauge for the 45 instead of tilting my blade. I feel like this is a better choice since I don't have any kind of digital protractor or tilt box.

I fiddle with it,  curse, leave it for a day, repeat.


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## woodnthings (Jan 24, 2009)

Phaedrus said:


> I can attest to TS being a poor choice. I'm making a small frame for the wife right now and the angles that I am getting from my TS seem like 45, but just aren't. I am thinking that a miter box might even be a good solution. I should mention that I am using a miter gauge for the 45 instead of tilting my blade. I feel like this is a better choice since I don't have any kind of digital protractor or tilt box.
> 
> I fiddle with it,  curse, leave it for a day, repeat.



Having issues is not the TS's fault. There are things you can do to make good miters using the miter gauge.
You should install an extended fence on the miter gauge, run a strip of sandpaper on the contact side to prevent the work from shifting AND use a draftsman's triangle to set your 45 degree angle.

A clean, sharp blade will make a huge difference also.

Anything less than that and you are asking for inaccurate miters. 

You can make a 45 degree "frame" sled, but that will only be as accurate as you make it and you need an accurate triangle to do that. The degree stops on stock miter gauges are not accurate. Some have adjustable stops that you can lock once you get it set up, others have 5 degree stops like the Incras and are much better. :yes:


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## Phaedrus (Jan 18, 2012)

woodnthings said:


> Having issues is not the TS's fault. There are things you can do to make good miters using the miter gauge.
> You should install an extended fence on the miter gauge, run a strip of sandpaper on the contact side to prevent the work from shifting AND use a draftsman's triangle to set your 45 degree angle.
> 
> A clean, sharp blade will make a huge difference also.
> ...


That looks like some helpful advice. I have been using an acrylic drafting 45 to set my angle. It is a stock 80's craftsman miter gauge, so certainly not a device of serious accuracy. I will have to try the extension on the gauge. I think I have one that I already made out of 3/4 MDF that mounts w/ machine screws and t-nuts. The blade is fairly new and sharp. I need to do some measuring I think. I have this crazy theory that perhaps my miter slots are not parallel. I'll have to try attaching some sand paper as well. 

It really should not be as difficult as it is some days.:blink:


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## FrankC (Aug 24, 2012)

Cutting mitres on a table saw with a miter gauge is tricky business, only thing I can add is to clamp the material to the extension, holding it by hand even with sandpaper attached will not always be enough as just too much is is going on all at once.

I clamp the material with my miter saw as well.


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## lateralus819 (Jul 22, 2012)

So i did another attempt went and bought more lumber.....sigh..

Ya know side rant here. A $40 box has turned into a $100 box heh. Learning curve i guess. Seems like everything i've built for myself came out great but this box for my mom is a pain in the ass..anyways.

I have it glued and i rounded the corners and theres a 1/32nd line at the joint. How tight should the joints get? I dry fit them first to check for tightness and it looked great, I'm happy with it, was just curious. Also, any way to get rid of it or is it just gotta be what it is? 

Also, i did the tape method on all the joints then folded it together and some ended up a smidge taller then the others whats the best way to get a flat bottom/top. Surely a planer would tear this thing apart?


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## Flatlander (Oct 14, 2012)

You can set up a TS to make perfect miters but you need to make a jig for best results.
I have a beautiful Delta Unisaw that I have had for 25 years or so. The miter that came with it wiggles in the slot from side to side.
So no matter how much I fiddle with the fine tuning adjustments it's almost impossible to make a perfect miter.

So I made a sled, I made the runners out of plastic from an old cutting board my wife was throwing out.
You know the white plastic stuff. I cut a bunch of strips at one time so they were a slip fit with some resistance. 
I screw them to the bottom of my sled which is just a flat piece of plywood, I like Baltic Birch to make this type of jig.
Then I take a block or two of squared up wood to make a fence depending on the type of fence i need. 
Using a known accurate tri square or protractor I lay out a line at whatever angle I am looking for on my sled measuring off the tablesaw blade.
Then I screw one end down with a drywall screw short enough not to mess up the table. Keeping to the line I put a nail in to tack the other end and make a couple of 
test cuts. I put the two pieces together to make sure I have a 90 degree angle, once I am sure it's exactly correct I screw the other end down, if I need to adjust I pull the 
nail out a bit and swing the fence to adjust it. Now you have a dedicated jig for whatever angle you need. 

Here is a trick to glue your miters together without clamps.
Get yourself some brown craft paper, you know, the stuff paper bags are made of.
Slather your glue on one pair of the miter cuts, press them together on top of a piece of the craft paper on a flat surface and press together for a few seconds.
Get yourself a wet rag and wipe all the excess glue off right away, don't be shy about getting the wood wet.
Repeat for the other joints and go play golf or something while your waiting for the unit to dry.

What happens is the brown paper acts as a clamp as the cellulose absorbs the glue and holds your pieces together. After its dry just sand off the brown paper.
If you wiped off all the glue thoroughly you will not have anything to clean up or mess up your finish later.


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## lateralus819 (Jul 22, 2012)

Flatlander said:


> You can set up a TS to make perfect miters but you need to make a jig for best results.
> I have a beautiful Delta Unisaw that I have had for 25 years or so. The miter that came with it wiggles in the slot from side to side.
> So no matter how much I fiddle with the fine tuning adjustments it's almost impossible to make a perfect miter.
> 
> ...


Thanks for the help bud! I use the tape method, works great it uses the tape as a clamp on 3 of 4 corners so for the last i wrap a ratchet strap around it and clamp er down and check for square and it works great. 

I just wasnt sure how tight a mitered joint should be, as i have a teency line at the joints.


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## jharris2 (Jul 9, 2012)

jschaben said:


> Two things are needed to get a good miter. The opposite sides MUST BE EXACTLY equal. The miter cuts must be EXACTLY 45°. Other than that, piece of cake:smile:


Sure. Easy for you to say! 

"I have never let my schooling interfere with my education"

Mark Twain


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## jharris2 (Jul 9, 2012)

I'm not sure whether I heard this on TV or read it somewhere.

A salt shaker was found in a very old woodworkers chest along with several vintage tools.

The person who had acquired the chest looked into it and found that adding a touch of salt to the joint after glue application prevented the joint from slipping. The joint strength was not negatively effected by the salt as it was dissolved by the glue.

No mention was made of the type of glue used in this method so I'm not sure how well it would work with different glues.

Have anyone of you ever heard of this?

Jeff

"I have never let my schooling interfere with my education"

Mark Twain


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## Keith Mathewson (Sep 23, 2010)

Salt is used to extend the open time of hot hide glue which would have been the glue used at the time.


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## jharris2 (Jul 9, 2012)

Thanks Keith,

So the application of salt really had nothing to do with reducing workpiece slippage during assembly?

Jeff

"I have never let my schooling interfere with my education"

Mark Twain


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## FrankC (Aug 24, 2012)

Salt also acted as a preservative for the hide glue as it was an animal based substance.


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## lateralus819 (Jul 22, 2012)

Anyone care to elaborate on my topic? is a glue line like that normal?


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## woodnthings (Jan 24, 2009)

*yeah, probably acceptable*

Perfect miter/bevels are harder to get than a miter like on a frame because the bevel has to be exact AND over the entire length.
On a flat frame miter you can immediately see any gaps and make a correction. With the blade angled over at 45 degrees and just the width of the material like 1/2" or so, any deviation will show as a gap either inside or on the edge and you won't be able to tell unless you assemble it. On a flat frame you can lay the pieces down inside a framing square and see how they line up and any gaps will be apparent. On a bevel you have to have some of the parts assembled or have a transparent square box to see the gaps. You can dry fit the pieces overt a known square box with an edge guide on one side as a checking fixture.

I hope I'm making my point clearly ..... I donno? :blink:


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## jharris2 (Jul 9, 2012)

lateralus819 said:


> Anyone care to elaborate on my topic? is a glue line like that normal?


Sorry bud,

We got into joint slippage and I thought my post might be helpful to someone.

No highjack intended. This happens sometimes in this forum.

We take it with a grain of salt. 

Jeff

"I have never let my schooling interfere with my education"

Mark Twain


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## TimPa (Jan 27, 2010)

1. the miters do not need to be a perfect 45 degrees, they just need to add up to 90 degrees. often a miter gauge is off the same amount on both directions, so if you cut one angled piece on one direction of the miter, cut the other angle mating piece on the other side. this holds true on miter saws also. cut mating pieces on opposite sides of the blade.

2. my trick to close up a glued joint with a gap - sand the joint (med grit) after gluing and clamping. the sawdust fills the gap in the joint and the glue holds it in there, and it will look tight. stains and varnishes fine also.


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## Phaedrus (Jan 18, 2012)

Alright, round two. I've built sacrificial extensions for my miter gauge for left and right side usage. I then aligned my miter gauge with my blade (from max height position) using a C-line acrylic drafting 45.



My results weren't perfect, but it is much better. I then glued the miters and secured the frame together with a small amount of tape around the corners and then a ratcheting strap. With the strap tight, I then clamped the frame flat between two scraps of MDF.



The bad news, though, is that my frame is now too small b/c I removed too much material re-cutting the miters over and over.:laughing::thumbdown:


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## GeorgeC (Jul 30, 2008)

PLEASE, PLEASE go back and reduce the size of your photographs.

George


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## Phaedrus (Jan 18, 2012)

GeorgeC said:


> PLEASE, PLEASE go back and reduce the size of your photographs.
> 
> George


I'm working on it right now, sorry about that. My forum app constantly crashes when I try to upload photos in the app. I was trying another solution, but it isn't working out so well. :thumbdown:


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## HandToolGuy (Dec 10, 2011)

There a couple of options to the power tool techniques that have been discussed so far. I mention them because the power tool techniques are finicky and often do not yield the desired results. But, if you develop hand tool skills and learn to use them properly, them you will come to understand better how things go together plus you will have another arrow in your quiver that you can use when you need it. 

The first picture shows a bookcase that I am building. The corner is a mitre joint, right? Look at picture 2. The corner was dovetailed with a mitre at the front end. An advantage to this corner is that it goes together at 90 degrees every time!

The third picture shows a mitre joint that was laid out and cut with a backsaw. No mitre box, no jigs. I know that this is not the joint you are trying to do, but it demonstrates that you do not need power tools, jigs, etc to do mitre joints. BTW, you are looking at the plinth for the book case.


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## HandToolGuy (Dec 10, 2011)

If there is any interest, I will be happy to show how these joints were done.


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## Phaedrus (Jan 18, 2012)

I'm game. I love a good demo!


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## HandToolGuy (Dec 10, 2011)

Phaedrus said:


> I'm game. I love a good demo!


Ok, here we go. I will post this in stages.

I am building a "Jefferson Bookcase" for my granddaughter. According to legend, Thomas Jefferson had his library in boxes of different sizes stacked five or six high. When the government bought Jefferson's library, they just laid the boxes on their backs and nailed on covers for shipping.

I have already built the bottom two boxes and the "plinth": the piece that the bookcase sits on. Look at the picture. The boxes appear to be joined with some sort of mitre joint.

In fact, the boxes are dovetailed.

We start with a stack of lumber marked so I will know how deep to cut the dovetails.


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## Glassnwood (Jan 29, 2012)

*That my friend*



Flatlander said:


> I had the same trouble making miter joints for moulding. What I ended up doing was making a shooting board and finishing the miter edges with a hand plane.
> It can be very difficult to get a perfect miter even if you have the best machinery, it does not take much to get a slight error in the angle of the joint, a slight movement on your part, a slightly misaligned blade, it does not take much!


Is why Man made caulk & Paint :laughing: (_sarcasm)_


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## HandToolGuy (Dec 10, 2011)

The pictures below show cutting the pin board first. Right now, it looks like a normal pin board with two full sized pins plus two half pins. I cut down to the line with a dovetail saw. Then I mark the waste with X's. I chop the waste out with two chisel strokes: the first one ahead of the line, the second one on the line. After some cleaning up, I am ready to lay out the tailboard.


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## HandToolGuy (Dec 10, 2011)

Now, it's time to mark out the tails, saw to the line and start chopping out the waste from the interior tails. BUT, the 1/2 tail on the leading edge of the board is NOT through cut. Instead, we make a sloping saw cut on the inside of the case only! Instead of sawing that half tail, we cut it at a 45 degree angle. We also cut the 1/2 pin on the front edge of the pin board on a 45 degree angle to match the mitre on the tailboard. Then we begin to bang the two pieces together.


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## Phaedrus (Jan 18, 2012)

Thanks for taking the time to document this. You're making it look easy, even with some rough looking boards. Are you using a template to mark your joints? Also, what kind of saw are you using?


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## GeorgeC (Jul 30, 2008)

Thanks for a very nice tutorial.

I am curious. Why do you want it to look from the front like it is a plain miter joint, when in reality it is dovetail?

George


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## HandToolGuy (Dec 10, 2011)

Phaedrus said:


> Thanks for taking the time to document this. You're making it look easy, even with some rough looking boards. Are you using a template to mark your joints? Also, what kind of saw are you using?


You're right, the lumber is just big box store construction lumber. The original boxes were also made of pine, so why not?

I do not use a template to mark the joints. The pin board is cut freehand. The completed pins are used as a template to lay out the tails.

My go to saw of the moment is a Veritas Dovetail saw filed rip. I also have a traditional Disston dovetail saw.

And thank you for your kind words. It may look easy, but don't be fooled; I have done nothing but dovetails for the past year and I am still far short of where I want to be. For the record, I screwed up two pin boards doing this little demo.


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## HandToolGuy (Dec 10, 2011)

GeorgeC said:


> Thanks for a very nice tutorial.
> 
> I am curious. Why do you want it to look from the front like it is a plain miter joint, when in reality it is dovetail?
> 
> George


Thank you for the compliment.

I am using the dovetail that looks like a mitre joint in the bookcase because that is thought to be the way that Thomas Jefferson had them done. It originally came up here because of a comment earlier in the thread that it is difficult to make a box with mitre joints glue up square. This joint looks like a mitre, goes together square and, if the dovetails are tight, glue is optional.


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