I'm gluing up some door casings prior to installation and while some miters are perfect, some show small gaps on the visible side of the thicker portion of the profile. I'm curious as to the cause; seems like my miter saw should be cutting them perfectly. It's almost as if the ends being joined have edges slightly rounded over. Any thoughts?
I'm not sure that I can picture exactly what you are describing. But, I still might be able to help.
Why do you think that your miter saw should be cutting miters perfectly? Have you gone through some extensive alignment and precision adjustment procedure or are you just trusting the scales on the machine?
Here's an article that you may find helpful. It talks about the accuracy needed to produce tight miter joints. It also talks about different methods for achieving that accuracy.
Thanks, Ed Bennett snipped-for-privacy@ts-aligner.com
Assuming that the saw is adjusted properly it could be that the wood is slipping slightly as you cut... some sandpaper glued to the fence and/or using the clamp that goes with the saw may solve the problem.
John
Thanks Ed.
Well, I guess "consistently" is a better word. Some of them are perfect; why aren't they all?
I have measured the angles and they seem dead on; however, I'm not concerned about that. My doors jambs probably aren't perfectly square, so the miter angles will take some adjusting anyway.
It just seems to me that if you slice two pieces of wood with the same blade, the cuts ought to join with no gap. Why not?
Ed, I think your website gave me the clue I needed. It mentioned possible blade warping on thin cuts. I noticed the edge of my cut that was rounded was where the blade withdrew *last* from the wood, where the damping of the blade would have been least with the thin cut.
When I stopped the blade after the plunge and withdrew it while stopped, my cuts were clean again.
Thanks!
I've had a hard time figuring out how to clamp stuff with this saw (DeWalt). It didn't come with a clamp and the fence isn't the ideal clamping surface. And these flat pieces of trim don't offer much to grip either. Still, I don't think it's moving. Looks like I had poor technique.
Thank you
Lee wrote:
RE: Subject
The easiiest way to get perfect 45 miters is to build a sled using a factory corner from a sheet of 3/4 ply.
See Fred Bingham's book, "Boat Joinery & Cabinet making", for details.
Lew
Gotcha. Not an issue yet. I can only do one miter at a time, so there's just a leg and header.
Miters can lose their tight fit if you wait around to glue them.
Most chop saws that I have looked at don't hold "picture frame" miter accuracy when the table is clamped. The near side of the table climbs (squirms up) when the clamp is tightened taking the table surface out of square with the fence. That takes the cut out of glue-up precision. You can still frame a garage with it but . . . My old Porter-Cable stays pretty true and likewise the Delta version. I've seen some awful examples of this, though, with Bosch and DeWalt.
The sliding miter saws son't necessarily cut so true, either. Ther're good for joist cutting, though.
Tim
Maybe I'm not understanding. Is the 45° accurate and it is just not meeting on the finish surface? Most carpenters set a pencil or nail under the trim so that there is a slight back cut on the miter to allow the front face to meet.
If the 45 is not making, you might glue a strip of sand paper to the back splash and/or table of your miter saw to prevent creep.
On numerous occasions I've noticed that my DeWalt 708 (slider) tends to pull the stock ever so slightly as the blade makes it way through the cut. Or, maybe it's due to the Jessada blade tooth configuration (30 deg ATB). It could also be the casings themselves. If they are off-the-rack, store-bought millwork then you can NEVER count on one piece being exactly the same dimension (on any plane) as the next.
I'd gage the corner angle before I'd trust the plywood.
DanG wrote:
I bought them at a millwork shop, but yes, I've noticed that different batches seemed slightly "off" from the pieces I had.
Ellestad wrote:
Yes, I myself exhibit this kind of sloth quite often. :-)
People put way too much stock in books and magazine articles. Just because it's in print doesn't mean it's right.
You really shouldn't trust that the unskilled minimum wage sawdust jocky at the plywood factory managed to put an accurate corner on one of the 10,000 pieces of plywood he cut that day. If the corners of plywood have any spec at all, it's probably on the order of +/- 1/8".
I'll have to add this one to the "Myths and Ledgends" section of the web site.
Ed Bennett snipped-for-privacy@ts-aligner.com
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