Miter saw fence problem: solved! (in theory at least)

[Stwood_]

But, I was glad to see the thread going on because this is what the forum is all about: people making noises and not going silent. Among the several woodworking forums where I troll, oops, visit, this is the second quietest one; the quietest one is almost dead! It is more like a private club with just a few old men (& women?) playing bridge...with dead silence in the background. The busiest one, which I am sure some of you visit, has new topics generated everyday, and some topics have over 100 replies each before they "end" or get locked or deleted!


Simon

Too many basement dwellers and mods that do not have an active interest in woodworking.
Basement is always in shambles, while the other forums just kind of put-put down the street.

[Tapper]

 

If no one else replied to threads, you would be awful lonely in here.

Hardly the point, but you knew that didn't you?

DT

[camp10]

It's not that manufacturers are completely out of touch with their customers, it's more about who the target customer is and inevitable competitive pressures.  Miter saws aren't targeted at fine furniture makers, they are made for contractors, trim installers, and mostly for DIY'ers.  If you want high precision you use a table saw sled or well tuned RAS.  I'm not saying a miter saw can't be adjusted for high precision, only that that was not the primary objective of most manufacturers.  When someone like the OP tries to dial one in so it will cut precisely they uncover the short cuts the manufacturers took so they could meet a certain price point.  Sometimes, it just requires some extra time to adjust the saw; other times, you end up having to re-engineer something, and sometimes no amount of rework will ever make it right.  
If you want really high precision you have to start with the right machine, or use a shooting board.  
John

This ^^^^^

I have the DWS779 and wouldn't think of using it to get precision anywhere near what I could get with my table saw & sled.  Sure, maybe the fence could be reengineered to allow for some tuning, but what about the twin aluminum tubes that the thing slides on?  There's a little play there.  And the miter lock down doesn't feel like it's repeatable to anything better than a half degree.   Same with the bevel.

I think it's a great saw at it's price point.

[KingwoodFan1989]

Welp, after a couple days of tinkering, I got both sides of the fence to within .005" of perfectly in plane with each other as well as the right side of the saw to cut to within the same amount. The left side still cuts perfectly, and I tested it over a board that just so happened to be around the saw's maximum cutting capacity. I discovered one key error that I actually knew was there but overlooked the severity of (more on that below), so that probably made this process quite a bit longer than it could have been otherwise.

What was weird yesterday is that I found myself having to make the fence be bowed TOWARDS me in order to get a square cut on both sides. Something there certainly did not add up, so I had to resort to desperate measures today...

Since DeWalt sent me another fence, I took the one that came with the saw (which was a tiny bit more bowed than the one they sent me), and I took the plunge and cut it in half. I got the fences to be pretty much where they are now in terms of being in plane of each other (basically perfect), and I STILL found that I was not only getting an out of square cut with the right side of the fence, but when I took the right half of the fence off the saw completely and firmly held the board against the left fence (which was square, or so I thought) alone, the side of the board that sat on the right side of the blade was even out of square then. I thought...this doesn't make ANY sense. I tried changing the blade out, and that didn't make a difference either. There was something I was overlooking, though, and some people touched on it in the previous thread...

My try square was actually out by probably .010" or so...my plastic one is pretty much perfectly square, and in past times I had put my try square up against the plastic one, only to see that the try square was out at the far end by a noticeable amount. Still, I foolishly kept it around to check my work with, since I'm usually MUCH more lenient on my work when it's a tad out of square than I am on my tools. BIG MISTAKE...this whole time I was checking my boards for square using that one out of habit rather than the brand new square I got at Home Depot (which is pretty much right on). When I tried checking again with that square, I found the left side of the saw I thought was perfect was actually out by a hair. I adjusted it, tried cutting from both sides, and I'm more than happy with the results.

Needless to say, that old try square is going in the recycling bin. 


The only issue left, really, is having to potentially re-machine the fence extensions to fit with the aftermarket screws I put in...now that I know I can easily get it dialed in to within my specs, at some point I might try putting the original screws back in on the left side or even trying the new fence I got again (since I got that one almost perfectly in line without any mods). For now, though, this whole thing is resolved.

That's the last time I use a less than perfect square to check the accuracy of a machine's cut...
 (<<<What I feel like doing to myself right about now)

[Phil Thien]

For a guy that demands perfection, what are you doing with a square that isn't?

[jteneyck]

Glad you got it sorted out.  

You should use a tri-square to check for square only as a rough check.  You'll get a much better look at square, or not, by cutting two pieces of wood on one side of the blade, then flipping one piece over so the top is on the bottom, butting the edge of both pieces you had against the saw fence against a straight edge, and bringing the two cut faces together.  This doubles any deviation from 90° and it's much easier to see.  Or use the five cut method on a single piece of plywood and you'll see 4 times the error. 


John

[KingwoodFan1989]

For a guy that demands perfection, what are you doing with a square that isn't?

I demand perfection from my machines....if I do the same with my projects, I don't know when to stop and I sometimes end up messing stuff up worse than I would have if I would have just left it at "close enough". I guess it was the habit of checking for square on boards with that try square that took me down the wrong path here. It wasn't until I decided to check the full capacity of the saw with a wider board that I was forced to use my bigger framing square that I bought in the last couple weeks. That was when the proverbial lightbulb turned on in my head.

Like I said, I might try putting on the new fence they sent me without any mods just to see what the best results I can get out of it are. I used the worse of the two fences for my sawing experiment (the one that came with the saw in the box), so I still have a stock fence. Now that I know my try square was a lot of the issue, I think it's only fair that I try out the stock equipment to see how close to perfect it is before writing an honest review of the saw. Granted, I'll probably continue to use it for several months or a year before I write a review (as how well it holds up over time is part of the quality test). If the results aren't quite as good as I'd like, it'll be easy to re-calibrate the modded fence (technically now it's two fences) now that I'm actually using a proper square. 

[Stwood_]

Hardly the point, but you knew that didn't you?

DT

Yes, and I'm not in here trying to mess a thread up.

[KingwoodFan1989]

I tried to use the fence they sent me, and while I was able to get pretty much the same results leaving that fence whole as I did by sawing the other fence into two halves, I still had to use my own screws and washers either way. Thus, it would seem the lack of adjustability of the fence is the design flaw here. I think I'll have to machine a little bit off the bottom of the wings whenever I need to use those (unless DeWalt comes up with a better fence design before then).

Still, after my stupid mistake with using a bad square all this time, I feel like I'm gonna be a little less tough on these companies when I talk about their obvious blunders of not making their fences more adjustable (or at least making an optional replacement fence model that is). Just a LITTLE less tough. 


For all intents and purposes, I declare this problem...SOLVED! (*pounds gavel*)

[KyleD]

I tried to use the fence they sent me, and while I was able to get pretty much the same results leaving that fence whole as I did by sawing the other fence into two halves, I still had to use my own screws and washers either way. Thus, it would seem the lack of adjustability of the fence is the design flaw here. I think I'll have to machine a little bit off the bottom of the wings whenever I need to use those (unless DeWalt comes up with a better fence design before then).

Still, after my stupid mistake with using a bad square all this time, I feel like I'm gonna be a little less tough on these companies when I talk about their obvious blunders of not making their fences more adjustable (or at least making an optional replacement fence model that is). Just a LITTLE less tough. 


For all intents and purposes, I declare this problem...SOLVED! (*pounds gavel*)

Great, now that you have your miter saw figured out move your fine cuts to a sled on the table saw as mentioned by several people on this forum- zero clearance on the two important sides, better supported blade (smoother cut), wider capacity, almost no chance of going out of square, and ability to safely cut much smaller pieces.  Your miter saw will become a rough cut tool as it should be.