[Slolearner]

So when i use a 45 lock miter, how do i cut for length? If iam making a 48" by 24" box how long do I cut my material? Do i add a inch and a half to the total length of both the long board and the short side?

 

[Stick486]

take a piece of scrap and measure it..
cut the lock miters..
remeasure...
the difference is how much you allow for...

 

[Cherryville Chuck]

Because the corners are mitered the end result is the exact dimensions of your box, i.e. 24 times 2 and 48 times 2. You are supposed to set up the cut so that the bit cuts only to the corner of your board and not past it. There are some tricks that can help with that. For example, on the piece that lays flat on the table you can stick another board on top of it with double sided tape and have the ends flush and the top board will help prevent digging in at the end of the cut on your bottom board. On the vertical cut clamp a board to it that will ride the top of your fence. That will keep it from dipping down at th end of the cut.

 

[Slolearner]

So as it turns out you need to add a 1.5 inches to each board for the proper length, provided your using 3/4 board..

 

[woodknots]

So when i use a 45 lock miter, how do i cut for length? If iam making a 48" by 24" box how long do I cut my material? Do i add a inch and a half to the total length of both the long board and the short side?

So as it turns out you need to add a 1.5 inches to each board for the proper length, provided your using 3/4 board..

Mark - are your dimensions inside or outside - you didn't specify. As Charles said above, if they are the outside dimensions, then the boards are cut to exact length because the corner is mitered - see this illustration
.... but if you think you need to add 1 1/2", then I'm going to assume your dimensions are inside.

 

[DesertRatTom]

I agree that it would be best to use the outside dimension and cut to exact length. If the miter is accurate, that would make the final outside dimension work just right. If you use the inside dimension, the you'd have to add the exact width of wood, which means accurate planing of slightly over sized stock. In the photo, very careful measurment shows the lighter piece appears to be slightly thinner than the dark piece. You can see the effect of that on the inside of the miter joint. The outer points of the miter align, but the inside joint has a slight misalignment.

 

[jj777746]

Hi Mark,think you'll find most plans/drawings are outside measurements.If otherwise, then you have to add the extra length to the boards. Follow Sticks advice & cut & measure on scrap.When you find the width/length of the cut your bit makes then double & add this measurement to all your boards.Jamesjj