Mitered joints

[tdukes]

Hello,

I cut out and routed three pet urns this past weekend, in three different wood species, white oak, cherry and walnut. All boards were planed down to the same thickness last weekend. I have made two previously in red oak and cherry. The mitered joints are like tight and flush. When glued together, you can barely see the joint.

The three I did this past weekend, I used a miter sled, rather than a miter gauge that I used on the first two. I use the kerf to line up the cut with just a little over to make sure there's not a blunt edge on the miter.

The cherry urn has a tight, flush joint, the white oak and walnut have about a visible gap, I'm estimating 1/16". All were made in one run with no change in blade alignment and all in probably less than 10 minutes.

I don't get it. Blade getting dull, difference in wood species? Brand new Freud thin kerf 50 tooth combination blade used on all five.

The white oak and walnut urns going to the scrap bin.

TIA

 

[Jeff]

I use this type of miter sled so that the angles are complementary, 44.X + 45.Y = 90 degrees. A few pics of your miter sled and the not so perfect miter joints may help to understand why you're getting the 1/16" variance vs the perfect 90 with your miter gauge.

http://www.finewoodworking.com/2005/10/25/picture-frame-jig-that-masters-the-miter

If the pieces slip just a hair in the miter sled or the miter gauge then they won't be the same length and the miters won't close flush. Slipping is pretty common with angles cuts so it's helpful to have stop blocks to prevent that.

 

[tdukes]

I use this type of miter sled so that the angles are complementary, 44.X + 45.Y = 90 degrees. A few pics of your miter sled and the not so perfect miter joints may help to understand why you're getting the 1/16" variance vs the perfect 90 with your miter gauge.

http://www.finewoodworking.com/2005/10/25/picture-frame-jig-that-masters-the-miter

If the pieces slip just a hair in the miter sled or the miter gauge then they won't be the same length and the miters won't close flush. Slipping is pretty common with angles cuts so it's helpful to have stop blocks to prevent that.

Thanks, Jeff!

I use the miter jig in this article. Someone posted the link to it in one of my previous posts. I'll have get back on the pics of the joints.

http://www.startwoodworking.com/plans/build-jig-hidden-spline-joinery

 

[tdukes]

Here's A pic of the joint

 

[Wyatt Co.]

I had the same problem with my miter sled. I have much better and more consistent results with the miter gauge.

http://www.ncwoodworker.net/pp/showphoto.php?photo=84538​

http://www.ncwoodworker.net/pp/showphoto.php?photo=84539​

 

[Jeff]

Here's A pic of the joint

? no pic.

 

[tdukes]

? no pic.

Ooops!!

 

[tdukes]

Here's the one in cherry using a miter gauge

 

[tdukes]

I had the same problem with my miter sled. I have much better and more consistent results with the miter gauge.

​

​

That is one tight joint!!

 

[nn4jw]

Looking at the pictures of the bad miters it looks to me like the cuts are rough. I'm thinking the thin kerf table saw blade was flexing or vibrating while cutting the harder woods. I'd make a few test cuts with a good cross cut (not combination) regular kerf blade and see if that takes care of the problem.

 

[Wyatt Co.]

Like I said, I had the exact problem with the sled. I took the first apart and built another one. Different materials, slightly different design. Same problem. Just real inconsistent. I went back to the miter gauge. Problem solved. I too use a Freud thin kerf 50t blade.

 

[tdukes]

Looking at the pictures of the bad miters it looks to me like the cuts are rough. I'm thinking the thin kerf table saw blade was flexing or vibrating while cutting the harder woods. I'd make a few test cuts with a good cross cut (not combination) regular kerf blade and see if that takes care of the problem.

That maybe the case. It feels like its grinding when I push it through. There are also burn marks that aren't there on a 90* crosscut.

Here are some hard maple strips from where I had to trim the sides for a serving tray I did with the same blade after the urns. They are 0.044 in thickness.

 

[McRabbet]

I'd suspect that your sled runners have some wobble that creates an inconsistent cut. It doesn't take much to create the gaps you are seeing. If you get a good cut using the miter gauge, then the blade is less likely to be the cause.

 

[nn4jw]

It does look like that blade is better at ripping than crosscutting. FWIW I have the same blade and mainly use it on plywood or ripping. Mostly I don't use combination blades much any more. I just get better results in general with rip or crosscut blades. That said, your problem could well be a combination (no pun) of the blade and the jig. Hope you get it worked out.

 

[tdukes]

It does look like that blade is better at ripping than crosscutting. FWIW I have the same blade and mainly use it on plywood or ripping. Mostly I don't use combination blades much any more. I just get better results in general with rip or crosscut blades. That said, your problem could well be a combination (no pun) of the blade and the jig. Hope you get it worked out.

I have a 80T crosscut blade that usually use for plywood. Will give that a try with the miter gauge and sled and see what happens.

 

[Jeff]

The three I did this past weekend, I used a miter sled, rather than a miter gauge that I used on the first two. I use the kerf to line up the cut with just a little over to make sure there's not a blunt edge on the miter.

Is this your miter sled by Doug Stowe? Leave a few inches towards the waste side of the cut like Mr. Stowe so that you're not inadvertently deflecting the saw blade by trying to "shave off" <1/16" and not waste a bit of good wood. Also, cutting slower can reduce blade deflection.

http://www.finewoodworking.com/2012/07/11/how-to-cut-mitered-sides

All were made in one run with no change in blade alignment and all in probably less than 10 minutes.

8 miter cuts/box x 3 boxes = 24 cuts. Slow down!

The cherry urn has a tight, flush joint, the white oak and walnut have about a visible gap,

Pics of the almost perfect cherry box using the sled for comparison with the walnut box?

 

[tdukes]

Is this your miter sled by Doug Stowe? Leave a few inches towards the waste side of the cut like Mr. Stowe so that you're not inadvertently deflecting the saw blade by trying to "shave off" <1/16" and not waste a bit of good wood. Also, cutting slower can reduce blade deflection.

http://www.finewoodworking.com/2012/07/11/how-to-cut-mitered-sides



8 miter cuts/box x 3 boxes = 24 cuts. Slow down!



Pics of the almost perfect cherry box using the sled for comparison with the walnut box?

It won't let me watch the video unless I subscribe.

All the parts were cut about an 1/8 over of final length. Had them stacked up ready to miter. I left about a 1/16 over the kerf so as to not have a blunt end. I used a visable line in the plywood plys to line up over the kerf.

 

[Jeff]

Had them stacked up ready to miter. I left about a 1/16 over the kerf so as to not have a blunt end. I used a visable line in the plywood plys to line up over the kerf.

So you cut a stack in one go, rather than 1 at a time? Did you do the same thing using the miter gauge too?

 

[tdukes]

So you cut a stack in one go, rather than 1 at a time? Did you do the same thing using the miter gauge too?

No, I made two weeks a part from each other when I was using the miter gauge. The last three were all at the same time with the sled.

Going back to the blade deflection that you mentioned. Think I should add a little more to the length of the piece?

 

[Jeff]

Leave a few inches towards the waste side of the cut like Mr. Stowe

I said this earlier. It's worth a try to see if the cut improves. Also, a cross cut blade instead of a combo may work better too but I wouldn't rush out and buy one 'till you try the new cuts. You got nice cuts using the same blade and the miter gauge.

I meant did you stack the pieces up on top of one another (2-4 pieces like a sandwich) and cut instead of just laying one piece on the sled and cutting it, flip and cut the other end using a stop block on the sled fence for the 1st cut end so that all pieces are the same length?