12-29-2009 06:40 PM
I have the Makita 10" CSMS and I don't have any problems at all with any "slop" in the entry....I have cut a bunch of pretty darned nice angled and compound angle cuts that were dead on accurate. Operator skill goes a long way in making a tool work correctly.
12-30-2009 02:32 PM
Since I do most of my work in the shop, I turn to my Griz 10 inch tablesaw for most miter cuts...however, when I
work on quick-builds with a large crew, I wind up using a 10 inch DeWalt slider, which is plenty accurate for regular interior trim. It al depends on your situation.
12-30-2009 07:48 PM
In the case of making picture frames, a sled can really help your accuracy. For each 90 deg corner, if you leave each piece a little long after the first cut. Then, put both pieces back in the sled and do a final cut on each piece at the same time, they have to fit together really nice. If any error is introduced in one piece, equal and opposite error will be introduced in the other piece, resulting in a very good fit.
12-30-2009 09:32 PM
The real answer (IMHO) is because when you build a sled and use a 90 degree guide, no matter if the guide is off by a degree ( say 44 on one side and 46 on the other), you will always get a 90 degree corner (44+46=90).
When cutting framing (or trim for that matter) 45 degrees and it's opposite is CRUCIAL to a square frame.
A SCMS is just as crucial but with use have more of an error margin (spelled SLOP) and while it CAN be used with accuracy, is harder to get repeatable settings.
Iif you really want to check your SMCS accuracy, take a 1x4 and cut 2 opposite 45 degree cuts in the middle of the board. Then flip one side on to the back side, but them together and see if and see if you get a straight line with the joint tight ( a 6 ft stabila level works good as a straight edge).
12-31-2009 06:43 AM - edited 12-31-2009 06:45 AM
I'm pretty much in Dragon Mike's camp on this. I have a sled for 90 degree cuts and another for 45's, AND I have a Delta 12" miter saw (great saw - not slider). I use both but I won't use the miter for FINE cuts like FLAG BOXES or picture frames.
The sled fences are set AFTER the saw kerf is made with an accurate (like Starrett) angled square measured against the saw kerf NOT the front of the sled. You build in the accuracy "up front" (no pun intended) and because many sleds are "fixed" you get spot-on accuracy. A "finish" carpenter doesn't need that kind of accuracy on most jobs and neither does a rough carpenter but talk to a "picture framer" and you'll discover a whole different world of fit&finish.
Now if you're asking about the "store bought" adjustable sleds I'll only add they are MECHANICAL and MOVEABLE meaning over time their accuracy lessens too.