Perfect angles on the CMS

[Chester]

This weekend, I had to make a small frame for a project. Normally I do a lot of lap joints at corners because I hate 45-degree miters. They never seem to come together like they should. My chopsaw normally gives me pretty good 90-degree cuts and I check it for squareness with my carpenter's square.

But a 45-degree miter, if not perfect, will show poorly immediately. My carpenter's square shows the saw to be good at 45-degrees but I still get a poor fitting at that "last corner."

I have a digital gage that I use to setup my table saw and it reads to 2-decimal places. But it reads only off of a vertical axis. I got the idea to cut a test piece on the chopsaw at 45-degrees and then lay it flat on the bench with the angled cut in the vertical position. With the test piece in a vertical position, I was able to determine that the "set angle" on the CMS was cutting at about 45.75-degrees. Using the test piece and performing additional cuts (after manual nudging of the CMS), I was able to get my digital gage to as close as 45.05-degree. I figured at that point, I was close enough.

When recutting my frame pieces and assembling them, I was close enough ... but still not perfect. The real problem with this method is that "nudging" and cutting samples is a very poor way to do a regular setup.

What method do you use for good, repeatable 45's???

Chester

[PaulMarcel]

I have a hand miter box I use for molding and frames. It seems to have a pretty perfect ("close enough") 45 miter although my recent frames were pretty large so the error can be easily hidden.

As for those digital angle gauges, I've seen many with two digits after the decimal but if you read the description, they are "accurate to 0.2º" so to me that second decimal digit is all marketing. I'm thinking that the next Woodpecker's sale to come 'round, I'll get a 45º setup block as it seems I could calibrate against it better than my speed squares.

Eager to read other responses... this is a calibration problem every time...

[DeanJackson]

What method do you use for good, repeatable 45's???

/quote]

To check if the blade is a perfect 45, cut a piece of scrap wood with it, pushing with a miter gauge that's perpendicular to the blade. Then put the pieces together backwards, and see if the internal and external corners are a perfect 90/square.

After I had the blade to where I could repeatedly move it to 45 degrees (really 45, I checked, rechecked, readjusted, rechecked, readjusted, and so on!)... I built a table saw sled (blogged here), and use stop blocks to make sure everything is the same length.

It really, really, really makes it a lot easier, although building the sled is a pain in the butt.

[Gregory Paolini]

I generally don't use a CMS for anything other than rough cutting materials... Even the real nice ($600+) saws have a little too much slop in their pivoting mechanisms for accuracy...

When I need precision, I either turn to the table saw with miter gage, or a shooting board.

-gp

[Rapid Roger]

For picture frame type miters, I use my table saw.

I made a sled for my table saw Just like my crosscut sled but, the fences are at a 45 degree angle to the blade. I made a fence for the right side and one for the left on the sled. Try to get it as close to 45 as you can but, more importantly is to get the two fences at 90 degrees to each other and meeting at the center right in line with the blade. If you cut one end on the left fence and the other on the right fence on each piece, they must fit perfectly as a 90 degree corner! Even if the 45 is not PERFECT, the recip. angle will match it up so that it looks right.

Using stop blocks help to keep the lengths the same helps alot. The only problem then is making sure the lengths are equal to the sides or top and bottom. If on dry fit, you find that they do not square up with nice, tight miters, one of the sides is too long. Then, you put the long side back on the sled and shave off just a touch or use a hand plane to get every thing exact.

If this doesn't explain well enough, say something and I will try to post a picture but, I really don't want to because, my sled is UGLY!!! But, it sure works good.

Rog

[Bobby Slack]

I don't make mitred doors but I did a lot of casing for which I use an attachment made by Collins Tool. My method uses the Kapex + Collins tool (not cutting the mitres at 45 degrees) + 2 dominos per joint + pocket screw and a plug. In doing a Casing I cheat with the angles, it would be interesting to find out what to do in the case of a door ...

I am thinking of buiding some mitred doors to check it out.

According to an article on Fine Woodworking, I think was a joint competition, the strongest one was the lap joint, so you are using a very solid way to put your stiles and rails together.

[Bobby Slack]

Here it is ... the mitre tite!

http://www.collinstool.com/base.php?page=home.htm

[Vic]

I have a hand miter box I use for molding and frames. It seems to have a pretty perfect ("close enough") 45 miter although my recent frames were pretty large so the error can be easily hidden.

As for those digital angle gauges, I've seen many with two digits after the decimal but if you read the description, they are "accurate to 0.2º" so to me that second decimal digit is all marketing. I'm thinking that the next Woodpecker's sale to come 'round, I'll get a 45º setup block as it seems I could calibrate against it better than my speed squares.

Eager to read other responses... this is a calibration problem every time...

Save you money on an expensive 45 square for that and just go to a drafting/office supply store and pick up a set of the drafting triangles. They are VERY accurate and somewhat "disposable".

[Rick LoDico]

I cut aas near to 45º as I can get on the miter saw. I fine tune the angle with a miter trimmer for a perfect fit.