Replies

1. 
   gordsco | Nov 29, 2009 04:20pm | #1

   You can do it mathematically but you will need to measure precise angles and then calculate how these acute or obtuse angles relate to a miter saw which does not cut 0 deg but rather 90 deg.

   Or you can miter some pieces of scrap, set them in place and cut the angle on both pieces a little more or less untill you have a perfect fit.

    

2. 
   Novy | Nov 29, 2009 04:43pm | #2

    Gord pretty much answered your question but just to clarify a bit. Use a protractor and a t bevel to get the angle and bisect the angle .

    Then set your miter saw and cut a couple of bits of scrap. Test fit. Repeat as neccassary.

    Make sure your test pieces are long enough to get you clear of the dw mud corners if it is crown, base or wall trim far enough to give you a sensible reading.

    

   On a hill by the harbour

3. 
   danno7x | Nov 29, 2009 04:43pm | #3

   Trial and error with scraps will give you  the most accurate results. That trouble your having is why inside corners get coped when doing mouldings that have a profile, no walls are made just right and cutting the miters can be tough.

4. 
   DonCanDo | Nov 29, 2009 04:45pm | #4

   First of all, be aware that what a miter saw calls a 0° cut is actually a 90° cut.  So if your math tells you that you need a 44° angle, you need to set the miter saw to 46° (90 - 44 = 46).

   Also, be aware that it's a rare corner that maintains the same angle all the way into the corner.  Usually, there's a little compound or plaster build-up in the corner that prevents the molding from running all the way into the corner.  Coping resolves this issue, but if you're mitering, you may need to crop the long point of the miter just a bit.

1. 
   Novy | Nov 29, 2009 05:01pm | #5

   Morning Don,

    Sounds like you were phsychicaly hearing me type my post. 

   On a hill by the harbour

2. 
   DanH | Nov 30, 2009 01:58am | #9

   Yeah, the way I figure it is how far the joint is from 90 degrees. If it's wider than 90 then I know I need to make the miter cut blunter; if it's narrower than 90 degrees the miter cut needs to be sharper. So 96 (= 90 + 6) degrees would mean that the two cuts need to be 45 + (6/2) = 48 degrees. But then you still have to make a trial cut or three and fine tune it.
   This country will not be a permanently good place for any of us to live in unless we make it a reasonably good place for all of us to live in.  --Theodore Roosevelt

1. 
   pete123 | Nov 30, 2009 05:17am | #10

   Wow...thanks for all the help. The realization that the saw cuts 90 not 0 degrees (of course) is revelatory. One cut I measured the wall angle at 50 but the saw set at 20 made the joint fit. The walls are certainly not flat and it's probably time to true up the saw as suggested.

1. 
   Novy | Nov 30, 2009 06:30am | #11

    Funny little thing that was taught to me years ago....

    Always keep the miter tight on the outside. 

   On a hill by the harbour

5. 
   florida | Nov 29, 2009 05:05pm | #6

   With flat stock like 1 X 4 it's easy. Run one piece past the corner about an inch. Now take the other piece, put it on the other wall and run it over the top of the first piece. Draw a line on each side where the top piece crosses the bottom piece. Connect the 2 opposite corners of the line which will give you an angle to saw. Set your saw up, cut that angle and then cut the other piece to the same angle. Should be bang on.

6. 
   YesMaam27577 | Nov 29, 2009 07:11pm | #7

   The others have given great advice.

   I'll add one other element.

   Measure the angle between the wall and the countertop too. If it's not a perfect 90, then you have a compound angle to cut. (If either the wall or the counter are not plumb/level...)

   Which is a completely different kettle of fish.

   I won't be laughing at the lies when I'm gone,
   And I can't question how or when or why when I'm gone;
   I can't live proud enough to die when I'm gone,
   So I guess I'll have to do it while I'm here. (Phil Ochs)

1. 
   alias | Nov 30, 2009 01:39am | #8

   http://www.mathopenref.com/constbisectangle.html Thats a jumping off point , then you have to probably tweak it .When it's either open in the front or the back. Take the full visual ,just for random number an 1/8" take a sixteenth of each one.
   also true your saw go to art store get a architect triangle and use it to get a good 90 degree than try a 45 degree and check it a couple more times .Then adjust the indicator arrow.Edited 11/29/2009 5:47 pm ET by alias <!-- KIPCARP -->

   Edited 11/29/2009 5:48 pm ET by alias

7. 
   silver77 | Nov 30, 2009 09:06am | #12

   I skimmed this thread and lots of good advice...and I've used all methods...

   but since I bought a starret miter tool...recommended by BT... I put the 2 blades on the angle to cut-like a protractor

   but-it gives me the chop saw setting for a single cut

   or the setting for a miter cut

   put the saw on the number-within 1/2 degree the first cut

   tweak-and move on to the next angle

   great for the top and bottom of stairs or quickly bisecting any angle and cutting it on the saw

   cheers,

   silver

8. 
   Mytrkut | Dec 01, 2009 01:32am | #13

   I have been using a Craftsman Angle Bisector for the last 30 years or so...Basically just two wings about 6" long on a straight edge that work on inside or outside corners....Even works where trim is cut at the top of a skirt board and landing skirt board...I call that an off the saw cut that a jig is made to cut the trim....I also now use a Bosch digital angle finder that is wonderful....

9. 
   Jercarp | Dec 01, 2009 02:05am | #14

   For many years I did the compass-bevel square bisect thing on scraps of wood.
   Then I got the Starrett angle divider which is not bad.

   But last month I got taken in by the sight of a digital angle finder & took the bait. Used it on a stair job, and so far so good. It gives the angle and the miter and the one side is a level. It's about 16" and cost about $60.

1. 
   brownbagg | Dec 01, 2009 04:51am | #15

   I just use the protractor I bought that you measure the angle and it tell you what to set your saw at,

1. 
   Jercarp | Dec 02, 2009 03:42pm | #23

   digital or the Starret?

1. 
   brownbagg | Dec 02, 2009 04:08pm | #26

   Starret

10. 
    AitchKay | Dec 01, 2009 07:19am | #16

    If you're cutting around a chase, say, that protrudes from the main wall about 3" (a pretty common occurrence), that chase is theoretically supposed to come out at 90º, and go back on the other side at 90º.

    Very few carpenters will anticipate the build-up at the corner bead and shim the inside corner to compensate. As a result, most of these angles exceed 90º when the drywall mudding is finished.

    But trim should look as crisp and correct as possible. Wall surfaces, and their caulked intersections with trim, can be MUCH more forgiving. Proceed accordingly:

    Don't go overboard by slavishly following angles that are a little bit off. Cut the runs on the back wall a hair short, so that there will be a bit to caulk behind the short chase legs at the inside corner, and shave a hair off of the back of those same side legs at the outside corner so that they measure maybe as little as 11/16” thick at the drywall bead.

    Your goal is to achieve 90º out from the wall, 90º across the face of the chase, 90º back to the wall, and 90º to turn and continue along the wall. Or at least the visual equivalent of that -- you’re the only person who will ever check those angles with a protractor.

    AitchKay

1. 
   Henley | Dec 01, 2009 03:46pm | #17

   Just thought I'd mention block planing the back of the trim. Not the day in day out solution, but another tool in the box.

1. 
   AitchKay | Dec 01, 2009 05:06pm | #18

   Yeah, block planes can do wonders. That's what I was envisioning using when I said, "shave a hair off of the back of those same side legs at the outside corner."My old #60 1/2 from the early 70s is one of my favorite tools. And one day, back in about '83, two #65s showed up on the shelf at the local lumber yard. They were brand new, but I could tell from the old-style blue paint, and the fact that #65 was engraved on the side, that these two planes had been made in the 60s.I didn't ask any questions, just snatched 'em up!AitchKay

1. 
   Henley | Dec 01, 2009 05:15pm | #19

   It's funny how in this day of lasers and compound miters saws
   a block plane,a pull saw, a couple of chisels, and a piece of 120
   Can makes the job go from ordinary to art.

1. 
   pete123 | Dec 02, 2009 07:26am | #20

   This has been a very informative string...much to be learned. I intend to incorporate a block plane as well as investigate some of the suggested tools. Like the Starrett and the Bosch Angle Finder. More tools is always better right? The below string I also found very intersting exploring the various merits of block plane use in trim work. I am curious if the block plane can be used on end grain to fine tune a miter?

    

   http://forums.taunton.com/n/find/findRedir.asp?webtag=tp-breaktime&mg=B0CB5E26-0771-4590-8211-828DF1B8EEF3

2. 
   silver77 | Dec 02, 2009 07:43am | #21

   This has been a very informative string..Pete-I'm pretty sure it's called...a thread...otherwise-I concursilver

3. 
   pete123 | Dec 05, 2009 10:10am | #34

   of course...while seemingly synonymous in this context thread is of course correct...apologies. I am looking forward to adding a plane or two to the tool box...it seems to be a much beloved tool among the artisans who frequent this forum.

4. 
   silver77 | Dec 06, 2009 07:22pm | #35

   pete,lee valley has a good selectionthe low angle stanley is a good start inho...if you can find someone to show how to plane a 45 miter casing to fit...you will have added a very handy trick to your bag..."miter me this" I got to a kitchen job late on friday-6:30 pm after installing the storm door from helllong way to go-short time to get there had to put the oak trim on the front of all the counters for the tile guyI looks around-oy lots of angles get out my starrett magic miter findermark all the angles first-gives me the miter angle then start cutting...after a while my mojo kicks in-I'm hot-everythings fittingkitchen done by midnight collect cheque life is wonderfulcheers,sil;ver

5. 
   Henley | Dec 02, 2009 03:17pm | #22

   <<I am curious if the block plane can be used on end grain to fine tune a miter?>> Yeah, it's done all the time. Not the best tool for that operation but it works, just watch for tear out.

6. 
   Jercarp | Dec 02, 2009 03:57pm | #25

   "exploring the various merits of block plane use in trim work."I do mostly trim and restoration. No way could I do my work without a block plane. If you get one, get one of the higher end ones like a Lie Nielsen, Lee Valley, or one of the new Stanley lines. I have 6 or 7.
   It takes a while to learn about all the uses and how to keep a plane tuned, but once you do, you will see a real improvement in the work. The two that I carry in my tool bag are the LN apron plane and the Lee Valley low angle block. Half the battle of a plane (or any hand-cutting tool), is learning how to sharpen and keep them razor sharp.

7. 
   Novy | Dec 02, 2009 05:10pm | #27

    Second that on the block plane quality.

    I bought a Lie Nielsen 60 1/2 R last year because I thought my lee Valley low angle had gone missing. I have since found the Lee Valley one which is a very nice plane but I love the Lie Nielsen.

     

   On a hill by the harbour

8. 
   AitchKay | Dec 02, 2009 05:42pm | #28

   "...Lie Nielsen, Lee Valley, or one of the new Stanley lines."Or one of the OLD Stanley lines. They're not as easy to find as they used to be, but they're not rare -- I just picked up a #7 jointer for $10 at a garage sale, no rust.Block and smooth planes are the most commonly found models, along with the occasional jack.I've not used a Lie-Nielson, and, although I'm sure I'd love it, I don't think I'd want to spend $150 or so when I've already got a half-dozen or so, three of them nicely tuned.Hock blades make for a relatively painless upgrade of any plane, so that's the route I've gone.I have a feeling that a tighter screw feed is the feature I'd appreciate most -- even the good old ones have a quarter turn or so before they reverse properly.As I said,I haven't used one, but the screw does look very finely machined.AitchKay

9. 
   Jercarp | Dec 03, 2009 03:43am | #29

   The old Stanleys made before the 1960's are fantastic planes. I have the full set except for the #1 (which I have just found a lead on!).
   If you can get hold of the old Stanley Bedrocks, those are even better. I have 4 of those. Substitute a new A2 blade on one, tune it up, and you're pretty close to a Lie Nielson.The #7 was my first real plane. It's a pre-war corrugated bottom and remains one of my favorite tools to use.

10. 
    Novy | Dec 03, 2009 04:04am | #30

    Nice 

    On a hill by the harbour

11. 
    silver77 | Dec 03, 2009 08:06am | #32

    Substitute a new A2 blade on one-hock blade??

12. 
    Jercarp | Dec 03, 2009 03:49pm | #33

    No, on the old one. I like Clifton's blades, they fit the old Stanleys.

13. 
    silver77 | Dec 03, 2009 08:04am | #31

    Hock blades make for a relatively painless upgrade of any plane, so that's the route I've gone.what's a hock blade?otherwise I totally concur-I use a low angle stanley block...love it but the dang backlashsilver

2. 
   Jercarp | Dec 02, 2009 03:47pm | #24

   Being handy with the plaster & mud, I like to float the wall to a perfect 90. I feather it down a few feet and no one can tell the difference. The eye is drawn to nothing but consistency then. Sometimes I get the block plane & rasps out though.
   It's a great tip you give.
   Bottom line is to check all corners inside & out and plan accordingly.

11. 
    Olivermaxwell | Jul 17, 2020 05:17pm | #36

    miter angle are one of the necessary part for a perfect Miter joint or corner. So start by measuring the complete angle change and divide it by the number of pieces you need to make the turns. The number that you get as a result is the angle to which the miter must be set. 45 degrees is the most commonly set miter angle on the saw.

    and remember "Verify the miter angle by making two cuts as a test and check the resulting corner using a square." That will help you to make a perfect miter joint

    After the cuts have been angled, one side of the wood would look longer compared to the other. For instance, the inside will be equal to your wall but shorter if it is an outer corner piece. It will be the opposite in case of an inner corner piece.
    Ho[e that might help you