Let's start over, please

[elizabeth]

Hey, Tim!

Starting a new post because the other is too long already. I think I understand what you all meant by the diagonal distance and rise and run! It's like a 90 degree triangle, the rise is the measurement going up, the run is the leg that is horizontal, and the Pitch is the length of the slope that closes the triangle (I forget the name for that side), right? Couldn't sleep last night because of the studying I did yesterday on all your replies, and it came to me right after I woke up!!! I think I got it!!! I think I understand the concept! If I'm incorrect let me know. I'll work harder at it.

I made the sled and put the stop 1" away from and parallel to the fence, so I could prop the scrap wood up at a 45. (I'm following your instructions of May 5Th, on the sample box of 2"W X 3" L x 2" H. It looked the simplest to start with.

I ripped some scrap to get a piece 1" 13/32 wide X 14" long. I propped it against the stop of the sled and made sure it was angled at 45. It was.

Made my first cut on the end of the wood, with the miter at 45 going away from the blade. Moved the miter the other direction (going into the blade) and set it at 45. I was surprised at how far away the kerf of that cut was from the first cut. I thought, by the graphics, that it would enter the fence (not the sled base) at the same location. I moved the wood and aligned my measured mark (2") with that kerf line. Made that cut and got a wedge! My first!!!!

The problem: I didn't get a single piece the right size. Also had flying wood, so the tops kinda disappeared. (I wore my mask).

How do you measure the wood for this sort of thing and where do you align it on the fence? You see, I don't really know how to measure for miters, (or wedges! )

Also, I picked up 1/2 scrap and had difficulty propping it in the stop on the fence. I made the stop too tall, out of 3/4 plywood.

My continued questions:

• Did your measurements include a specific thickness of the wood?
  
• Do you bevel the edge that touches the stop so it stays propped at the right angle?
  
• Do you bevel both edges so all four pieces close at the top? Three of my pieces looked like they had been sawed off at the tip, the fourth wasn't.
  
• Do you flip the pieces, or move them?
  

In other words, how do you measure and cut the @#%$# wood? ;D ;D

As always, your Agee!

PS: I have to re-do the sled. When I made my first kerf cuts I accidentally carved out a triangle. For some reason I thought the blade was supposed to meet at the fence with the miter in either 45 position. Told you I can't do angles or math!

[TDHofstetter]

You've got it right exactly - the diagonal distance is the length of the hypotenuse of the right triangle. Ya see? I KNEW you'd grab up that epiphany!

Ok, lessee. The bottom edge needs to be beveled at 45 degrees, so the bevel lays on the table of the saw (or sled). In fact, both edges should probably be beveled on the same face, so one bevel lays on the table & the other lays on the fence.

As to catching the flying workpieces... this may be a job for... maybe a solid wedge of scrap against the miter saw's original fence, maybe just held in place by hand during the right-miter cut that cuts the piece off your stock. Or... lessee. A paper sack behind the saw? This one's a tough one, because of their very small scale. You got a table saw? You might be able to do this with a sled on the table saw, too. No matter what, the scale's gonna' be a bugaboo.

Measuring... you can sneak up on the left cut, the one that miters the end of the stock. The right cut, the one that removes the workpiece from the stock, is best measured by not measuring at all - just by carefully sighting along the sawblade and adjusting the workpiece until the top tip is barely visible past the blade.

The thickness of the wood is completely immaterial, if both edges are beveled. It can be anything from one solid hunk down to a thin veneer & still come out right.

Don't flip the pieces, just slide them in the saw for the second cut. If you get really lucky, or if you figure things just right, you'll end up with nearly 100% capture - the offcut that miters one piece will become yet another piece... that is to say when you make the left cut, the piece you cut off will be a complete working piece of roof if you sight the saw carefully - so that the "bottom point" is barely past the blade.

It's going to be very important for you to sight along the blade carefully, as if you were sighting a rifle for a long sniper shot. I usually hold the guard up so it doesn't interfere with my sighting, then drop it to power up the saw & make the cut.

I'll mull s'more & try to come up with a really k-schnazzy way of capturing the cut-off workpieces before they go Frisbee on you.

[elizabeth]

Thank you. I'm so proud of myself. I finally understood the concept! Thanks for your patience. I'm a slow learner and not accustomed of thinking this way.

I've given further thought on some measuring and hold-down jig I can make, and your idea of making a smaller wedge to put under the 1/8th thick roof pieces to support the wood is doable. I'd just cut it at a 45, but 1/8th smaller, no?

What I was thinking of doing to measure, is to cut up the board to the final length of each piece first. Then take two square block's of scrap and run then through the saw at the 45's. This will give me not only a pre-cut kerf on the sled that I can index on, but also the mating profile of the workpiece. I'd glue the blocks on the out-feed side of each kerf. Then I can just take one of the sides and slide it to the left or right until it touches the "stop" block. I know this may waste wood but it should give me the exact dimensions?

Then, to hold these tiny pieces down I'm thinking of making some blocks from 2 X 4. Cut the edge at a 45, and screw in some toggle clamps on the 45 angle face. This would give me the angle I need to hold the pieces in place. I'd position these clamps so they're not in line with the blade.

Any way. It's what I've been mulling today. I'm a little sick so can't get to the shop till tomorrow.

There was one other thing I wanted to ask you, though. I would like to position a backing board under the workpiece to prevent tear-out. If I do so, will this change the angle of cut? And if not, could I sandwich the workpieces over the backing board? I don't remember how angles behave.

Thanks again for all your help. Let me know what you think of these ideas.

[TDHofstetter]

Some really VERY GOOD jig-making ideas comin' out there!

Here's an idea... none of your actual workpieces need to actually touch the miter saw's fence. If you took, say, a 2x4 (or a 4x4, if your miter saw can handle one) and split it diagonally into two long wedges... you could make a pair of matching miter backers with complementary angles on their ends. To make one cut, you'd use them with one on the left & the other on the right. To make the other cut, you'd swap their positions. That'd provide you a zero-clearance backer for each cut, capturing your workpieces.

Toggle clamps would help keep your fingers out of the critical areas - good call.

None of the angles would change if you used a backer block, as shown here with the backing wedges.





If you stack workpieces, though... you have to stagger them or you'll end up as shown...

[elizabeth]

Gotcha! Will do one at a time. I don't have a miter saw, just a TBS. It won't cut a 4 X 4 unless I flip it. But that's not a problem because my pieces will be under an inch. Wanted you to see my first "roof" hot off the saw. It's rough, of course. I practiced on 1/4" ply. I'm ready to build the new sled with all we've discussed. Sorry the pics are blurry. I didn't use the tripod and my hands always shake.







Still working on the measuring thing. I didn't quite get it right, but it is roughly a 2" sq. roof with a 1" rise, as in our first example. I need to fine tune my measuring.

Also, I did bevel both edges first, like you suggested. Worked like a charm to position the wood on the sled. But, I don't know how to bevel. This was my first try. I don't know exactly where to position the edge of the wood with the blade at a 45. Every miter you've seen me do before I've used the router!

Told you I am a newbie! ;D

[TDHofstetter]

Oho, you're DEFINITELY in the groove, 'Lizabeth!

Quick way to bevel the edges on the table saw is to lay the blade down to 45 (verified), mark your wood at the appropriate spot, draw the bevel, use it to set the fence just a TITCH "long" (so the bevel's not quite perfect), make the cut, then nudge the fence nearer & nearer the blade by like hundredths of an inch until you hit the mark & split your pencil line. Once that bevel's cut, you reverse the workpiece end-for-end and the other edge's bevel will automagically come out right.

At this point... you're only a BREATH away from making octagon-shaped roofs, too - you've got all the concepts, the only thing different is changing the miter angle from 45 degrees to 22.5 degrees. Then the complex glue job...

[elizabeth]

Thanks, Tim. I'm very excited! I have two box bottoms ready for a little roof. I'm going to do those with four pieces first, until I can practice the more complex shapes. One box is for my Mom and the other for my Aunt. I'm very late in giving the box to my mother.

[fredbelknap]

Elizabeth you are doing great. Just be careful cutting those itty bitty pieces.

[elizabeth]

Thanks, Fred

I'm half done on my dedicated sled. Will definitely keep my fingers off the blade!