problems with miter cuts....my cp box is all screwed now(pic)

[hulkster]

check out this pic.  i was using a miter saw to make the box sides fit together nicely.  but whats the deal with the boards being off?  did i forget to do something?oh and by the way, that miter cut is just a practice board, but regardless when i do make the actual cuts on the side panels, the angled cut will be like 1" and the side of the mdf is obviously 3/4"!!  ah, what should i do!?!?

[Pyro]

The edge of a miter will always be longer than the edge of a square cut. You can solve this by doing one of two things:

1. Keep the cuts as they are and when you glue them together, keep the exposed edges even. This will leave an uneven surface on the unseen/inside edges.

2. Measure the angle of the two boards that need to be fastened together. Divide that angle by two, then cut miters using that figure on both boards that need to be joined. By having an even miter cut on both boards, you end up with a joint that is even on both sides.

I hope this helps,

Pyro

[hulkster]

okay, if i have some gaps in the boards, will wood putty fill in the gaps?  i mean, how much can the wood putty fill?

[Rawker]

you shouldn't have gaps, if the gaps are because the angle is too big then just change the angle. just a FYI, always cut your angle side first, then mark the other side for length and cut, that way if you ever have a problem with the angle you have enough wood to fix it.

[madk]

a²+b²=c²

 

[hulkster]

aw damn dude, too much math.  i just used a protractor, and then cut with the miter saw after making the angle on the saw.  however, some the angles were off, and i think its cuz i didnt clamp the saw down or something cuz it keeps moving.  so ill just have to make some more sides.  any tips on miter cuts?

[krick]

Pyro is right about splitting the angle and mitering BOTH boards.

That's the correct way to do it.


You could also just assemble it as it currently is and then sand off the "point" that sticks out past the unmitered board.  however, that will give you exposed end grain.  This may or may not be an issue depending on the finish you intend to use.

[DrewKaree]

He won't have "end grain" cuz it's MDF.  Splitting the angle in half is the only way to get it correct, especially since your CP only has the two back corners @ 90 degrees.  If my guess is correct, those two pieces are for either the side-to-front angle, or the front angle-to-front angle along the front face....there's absolutely no way to get those to match up without the math...do it, you'll thank yourself later.

As an aside, whenever you are using a tool that has "preset" detents, don't trust them....they're oftentimes notoriously sloppy, i.e. the detent @ 45 degrees could actually be off by a degree (44, 46) OR MORE!  

Sanding can probably solve THAT edge...hope you didn't do all the cuts at once!  

[Wade]

If he sands the tip off, he won't have "end grain", but the sanded part will always be rough.  MDF does kindof have a grain, the layers run along the long flat.  If you have any sides exposed that aren't the smooth, flat, original sides, it won't look very smooth.  Also, trying to put screws into the edge of MDF will usually split the MDF along the "grain".  Or at a minimum, the screws won't hold well.

Wade