Help with Miters

[Craig Walls]

Hello all,

It's been several months since I've visited. I'm happy to say that I've been busy building things.
Here's my challenge de jour: miters seem to kick my butt more often than not. The ones that do work, do so because I trimmed or sanded, etc to make them fit. Another aspect of miters I have trouble with is length. It's tough to get identical pieces once one end has that dang point on it! I have a regular old delta c-pound miter that seems to be accurate when I check for angle, square, etc. I've tried them with my miter gauge on the table saw... :(

Who has some advice for their best miter cutting jig, technique, etc.
Thanks in advance. Craig

[J.R. Rutter]

Miters are definitely hard to get perfect. I make cabinet doors for a living, and have a mitered style that I do regularly. Although I now use a CTD double miter saw with fixed heads and pneumatic clamps, I started with 2 DeWalt CMS. Here are a couple of tips to getting good fitting joints:

1. Measuring fence - it helps tremendously to either set up a stop for each identical length or have an indexing fence system. The fence needs to be 90 deg to the blade for straight crosscuts.

2. Hold the piece securely - a toggle clamp and/or some sandpaper on the saw table will help hold the part still while cutting. Hand pressure on a bare table isn't enough.

3. Blade - I evaluated many blades when I was starting and found the Forrest Chopmaster to be the best combination of price and quality. Believe it or not, they are about in the upper-middle of the range for price.

4. Saw angle - after getting the above figured out, double check the angle detants on your saw by cutting 4 identical mitered pieces and assembling them into a square. The wider the and longer the better to see discrepancies. Keep making them shorter and recutting as you fine tune.

[Brian Ross]

2. Hold the piece securely - a toggle clamp and/or some sandpaper on the saw table will help hold the part still while cutting. Hand pressure on a bare table isn't enough.



I like the sandpaper idea. I have thought of this many times but have never got around to doing it. I have strong hands but when cutting 45 's I have seen the saw pull the piece. Great idea and you are the first one I have seen post it. When making mitered doors what method do you use to hold the miter? TIA

Brian

[Fred Voorhees]

I would start with a good aftermarket miter gauge. That is the biggest thing right there. As for repeating identical lengths, I have made up jigs incorporating the 45 degree angle and attached that to the gauge and this would allow the previously cut 45 degree miter to nest into it and allow repetitive cuts.

[Bryan Berguson]

Craig,

Let me first explain that I make all cuts from the same side of the saw and do not change the angle of the saw. Half the cuts will be with the good side down and the opposite cut will be up. This way, corners will always be 90 degrees, guaranteed. With a good blade and slow cuts, you shouldn't have any tearout.

If I'm making squares or rectangles with mitered corners I do the following:

1. Layout your pieces the way they will be put together.
2. I mark each cut with a line to show the direction.
3. I then mark each cut by writing "up" or "down" on it. Each corner will have an "up" and the other will be "down".
4. I also number or letter the boards so I can put them back together in the same order.
5. I do all the "down" cuts first.
6. I measure and cut one of the "up" cuts.
7. With the blade down and 1st board "up" cut tight against the blade, I set a board stop.
8. I cut the 2nd board.
9. If this is a square, I cut the 3rd and 4th boards.
10. If rectangle, do 6 thru 8 for the other 2 boards.
11. Perfect 90 degree miters.

For door trim, I basically do the same thing. I cut all the miters first and then cut the verticals to length just before I install. I've done all my house trim with hickory and there is zero room for error with wood that hard. All natural finish and no filler any place.

Hope this helps.

Bryan

[J.R. Rutter]

I like the sandpaper idea. I have thought of this many times but have never got around to doing it. I have strong hands but when cutting 45 's I have seen the saw pull the piece. Great idea and you are the first one I have seen post it. When making mitered doors what method do you use to hold the miter? TIA

Brian

I use a Hoffman dovetail machine for mitered doors. It is a fancy router that precisely positions, clamps, and routes a dovetail along the mitered edge, on the back of the part. Then when you put the two parts together, there is a bowtie shaped key that you tap into place. This pulls the joint tight and aligns everything while the glue dries (no clamps!). It also provides some long-term mechanical strength.
http://www.hoffmann-usa.com/htm/machines/mu2p.htm
Between the CTD saw and Hoffman machine, it was a signifigant investment. But compared to a MMT (miter/mortise/tenon) machine, it was about 1/4 the cost.

I'm just about to make up a sample for a local shop of a maple shaker door using black bowtie keys on the front of the frame. They originally asked about square "peg" inlay, but the dovetail looks cool and is faster to build.