Comment Please

[cabinetman]

CMS's, SCMS's, and RAS's are designed to be accurate cutting machines. If yours isn't, it needs adjustment. I've never had a saw that couldn't be brought into tolerance. It may need some part replaced, or most likely to learn how to set up the tool properly.

Most all cuts and joinery can be done on a tablesaw, one way or another. If you feel it's easier to use a sled, you have the option to configure an accurate cutting jig.

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[woodturner]

I also struck out trying to use my Hitachi scms. No obvious wear or movements but there is no way to truely zero the saw.

That's really the issue with saws - with the possible exception of very high end saws, there is a limit to how accurately they can be adjusted. Chops saws, most radial arm saws, and miter saws are not intended to be high precision tools and are targeted more at the "rough" trades like cabinetmaking, finish carpentry, and construction, where the joints will be filled before finishing. However, even a tool like a good table saw that is intended to cut accurately has some tolerance and accuracy limitations. In addition, even when adjusted perfectly, there is enough flex in the saw blade to introduce small errors. Depending on your personal dimensional tolerance, they may or may not make a joint that is "tight enough" to satisfy you.

The guillotine type miter trimmers such as the Lion help solve this issue by using a rigid blade - but they also have to be adjusted to cut perfectly to give a perfect miter. Since they have fewer and simpler moving parts, however, they stay in adjustment better than a table saw or SCMS.

If you want "perfect" joints, the only way I have found to get miter joints accurate to a few thousands (so there is no visible joint line) is to use the Lion and then tweak it with a chisel.

However, if you want "pretty good" joints, there are a couple of "tricks" that can reduce time and effort and allow use of power tools:
1. For an application where the back is not visible (e.g. picture frames), angle and bevel the joint a degree or two, and cut the opposing joint faces on opposite sides of the blade. This results in a slight gap on the back of the joint, but makes a thinner "pointy" edge on the face. These edges can then be forced together with clamps to approach the appearance of a perfect joint.
2. Use a fine tooth handsaw to trim the joint. Cut the joint on the power saw, assemble the joint, then use a fine tooth hand saw to re-cut the joint. Since the saw kerf forms the new joint edges, the fit will be pretty good.

[cabinetman]

That's really the issue with saws - with the possible exception of very high end saws, there is a limit to how accurately they can be adjusted.

The only limit is how proficiently the adjustments can be made. There are plenty of videos and tutorials on the internet to help those that aren't familiar with the fine adjustments.

Chops saws, most radial arm saws, and miter saws are not intended to be high precision tools and are targeted more at the "rough" trades like cabinetmaking, finish carpentry, and construction, where the joints will be filled before finishing.

For the professional trades, and the hobbyists that require good joinery, miter saws and radial arms saws have been used for many years and maintained to produce predictable cuts. For those that receive questionable results, their technique and saw setup should be re-evaluated. The "rough" trades like framing construction, the saws' accuracy can be less than perfect due to lack of maintenance on the saw and how the tool is handled and utilized. I certainly wouldn't classify cabinetmaking and finished carpentry such as trim work as "rough" trades, as the joinery for finished woodwork isn't filled. Doing so reflects a lack of care and expertise in doing the work.

If you want "perfect" joints, the only way I have found to get miter joints accurate to a few thousands (so there is no visible joint line) is to use the Lion and then tweak it with a chisel.

For a finished wood joint, where there is grain in more than one direction, there will be a visible differentiating "line". With good joinery there just won't be any gaps.

However, if you want "pretty good" joints, there are a couple of "tricks" that can reduce time and effort and allow use of power tools:
1. For an application where the back is not visible (e.g. picture frames), angle and bevel the joint a degree or two, and cut the opposing joint faces on opposite sides of the blade. This results in a slight gap on the back of the joint, but makes a thinner "pointy" edge on the face. These edges can then be forced together with clamps to approach the appearance of a perfect joint.

With this method there will be a gap on the vertical planes, as that was created by a degree or two of an angle to get just the top edge to mate. Mating edges of a joint should dry fit perfectly so they don't have to be clamped under excess pressure to make them fit.

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[chopnhack]

I never thought of cabinetry and trim as "rough" trades... I always thought and classified them as finishing tradework and accordingly they have their own tools. Will a miter saw appear in a framing crews arsenal - maybe. Most framing and "rough" construction crews can do all of their work using a circ. saw. Gang cutting studs, notching birds mouths, these are the things done in the framing trade and done quickly with circ. saws. Nobody is going to sit there with a miter saw setup and batch out studs....

As for moldings etc, much caulk is used in paint grade, but the joinery should look good before application of such. I maybe a glutton, but in my own house, I coped all the crown that had inside corners. When done right, the tight line digs into the adjoining piece and keeps stable as things acclimate.

As for adjustments on a sliding compound miter saw... well I admit I never had the best of luck with them. I have one and cherish it, but also am aware of its or my limitations. Just my opinion, there is too much play in general in the mechanisms of my saw to do very accurate framework. I even notice how I lower the blade and how I apply pressure can deflect the line of cut.

Those shears are in practically every frame shop I have ever visited and I am sure there is a reason for it

[capncarl]

I do not believe that the accuracy of this Hitachi is engineered into it to obtain the degree of accuracy needed to fabricate picture frames. If you set it up to get a perfect 45 that you are happy with and swing it over to cut the other side it will be off. For set ups I used the angle plates off my Jet JMD vertical round column mill to obtain a perfect 90 between the blade and the fence on the Hitachi using a toothless blade. Then set 45 degrees either side using the 45 degree angle plate from the mill and they degree scale says 46 something, the other side will say something else. Unless you have a machine with positive stops that you can set up and left you are stuck with what the manufacturer puts out. On a side note, the 12" Dewalt csms seems to have infinately better accuracy than this Hitachi, I can't speak for the others but would imagine that their accuracy could be gauged with their retail price.
capncarl

[woodturner]

I never thought of cabinetry and trim as "rough" trades... I always thought and classified them as finishing tradework and accordingly they have their own tools.

I didn't mean "rough" in a perjorative sense, just that the expectations for an acceptable joint are different than for "higher end" work like fine furniture. People tend not to look at a door frame as closely as a high quality chest of drawers, for example, and will tolerate a larger joint gap, especially if the gap will be filled anyway.

As for moldings etc, much caulk is used in paint grade, but the joinery should look good before application of such. I maybe a glutton, but in my own house, I coped all the crown that had inside corners. When done right, the tight line digs into the adjoining piece and keeps stable as things acclimate.

Coping is definitely a better way to go, but most crews and finish carpenters don't seem to want to spend the time to do it.

Just my opinion, there is too much play in general in the mechanisms of my saw to do very accurate framework.

Yes, it is an inherent limitation in the mechanism, and it's impractical to design a better mechanism that can be produced at a salable price. It's a physical limitation of that type of saw essentially.

Those shears are in practically every frame shop I have ever visited and I am sure there is a reason for it

Yes. They are easy to use with minimal training, do a good job, and are relatively safe (though you could certainly chop off a digit with one ).

[chopnhack]

No, we are using "rough" in the same sense, however, kitchen cabs, especially high end are intolerant of gaps.