I currently own a Delta 36-655. Since new April 2004, it has had a little bit of blade wobble that I can clearly see when the blade starts up and shuts down. I'm sure it is there all the time when the blade is running, I just can't see it. Needless to say, I finally have gotten into my first substantial project, a blanket chest/deacon's bench, and am now having trouble making cross cuts with my mitre gage. The saw seems to rip fine. I have squared the mitre gage to the blade numerous times, checked the blade squareness to the table numerous times, and can't seem to get it to cut perfectly true and square when crosscutting. Last night I got fed up with it. I finally removed the belt from the arbor assembly and removed the blade and with my naked eye, I can clearly see that the flange attached to the arbor shaft is not perfectly round and has a bit of an egg shape to it. When I attach the blade as normal and spin it freely without the belt attached, like I said before, I can see a constant warp in the way the blade spins. Would this be enough to cause cross cuts to not cut properly, but not have any trouble with ripping (although I do get very slight saw marks with a Freud glueline rip blade). I've been through two table saw books about squaring your saw, and I've also spoken to Dave Wooland (the table saw wizard who does table saw seminars at wood shows}, and he also told me that I have to get the arbor replaced. I also spoke to a warranty service guy who is coming out to my house on Thursday to look at my saw and I'm sure that my arbor will be replaced through warranty (it had better be!).
The only way a wobbly arbour will affect the accuracy of your cross cuts is if you used a portion of your blade for reference that represented the wobble portion of the blades path and didn't use a portion that represented a "straight" path. By this I mean that even if the blade wobbles, as it rotates there is going to be a location on the blade that is in line with the "true" or desired (flat) path of the blade. This is that path that would be followed if the arbour was flat. If you then use this point as a reference point from which to set up your saw, your miter slot should be square to the "net" plane of the blade which should result in a square cut.
If this is done, the drawback to a wobbly blade will be a wider kerf and you'll have to know where the blade cuts relative to the centerline in order to do fine work.
I'm guessing you're not lined up to this point but are lined up to a point that represents a plane (or blade path) that's off center (is part of the wobble). The reason you can get accurate rips is because your rip fence is aligned with the plane of the blade (either by design or by fluke). Further, if your rip fence is set up properly, the workpiece will only contact the blade and fence simultaniously at the begining of the cut, regardless of the wobble.
The fact that you say you get "the odd" blade mark from the Freud rip line leads me to believe your fence is set up extremely close to "0" meaning the odd tooth contatcs the wood when it's coming up out of the saw.
So yeah, your observations make some sense if the saw is accurately set up as you indicate. Hopefully you'll get a new arbour and can be done with it. If not, take the arbour you have to a machine shop and they can re-face the flange to assure minimal run-out.
Thanks for the response Rob. You make alot of sense in what you are explaining. I am wondering though, how you know where the true plane of the blade and arbor is? How can I find it? I mean, if you square your miter gauge to the blade and the blade is not sitting in the right position you would never get a nice clean square edge. If that makes any sense. Thanks for helping guys.
Are you absolutely sure it is the arbor? I had a King cabinet saw and had the same problem. It ended up being the washer that goes against the blade wasn't flat and was causing all the grief. I tried the one from my General cabinet saw and the wobble went away.
I can't say that I am absolutely positive about the wobble being caused from the arbor but I can say that I have tried just about all other tips and tricks that I have ever heard of including things like trying to true the blade washers by rubbing them around on some coarse emery cloth. I also use blade stiffeners and the same woble happens but I can only use one as the inside blade washer is a solid one piece joined with the arbor shaft.
Messing with a washer or blade stiffener on the outside of the blade if the inside washer is fixed to the arbor and is bad won't help.
Whether it's the arbor or the inner washer is academic at this point. Get it replaced, especially if the saw is still under warranty. Any other solution just causes you to drive yourself nuts and saves the saw manufacturer money.
First off, I agree with Ken. the arbour needs to be replaced or fixed to run true. There's no other "permanent" solution. Anything less will drive you batty.
But to answer your question, in order to find the true plane of the blade you'll need a dial guage set up to contact the side of the blade when the blade is raised to it's highest point. In order to gain more accuracy, have the indicator contact the blade at it's largest diameter.
And PLEASE unplug the saw first!
Set the dial indicator so that it will measure both +ve and -ve discplacement and as you rotate the blade by hand, you need to rotate the face of the dial guage so that you get a max +ve reading equal to the max -ve reading. Continue to rotate the blade until your gauge shows zero and you've found the mid point of the runout (with that blade on that saw at that location at that time). Mark it with a sharpie.
Set your dial gauge on your miter gauge (make sure your miter gauge is tight in the slot...really tight!) so that the dial gauge will contact the blade at it's largest diameter at the front of the saw down low near the table. Rotate the blade so the point you marked with the sharpy is against the dial indicator. Zero the dial. Slide the miter gauge/dial gauge assembly to the back of the blade and rotate the blade so that the dial gauage can contact the blade on the point again, at the point you marked with the sharpy. The dial gauge should read zero (atill). If it doesn't, it will read a value equal to how far out of alignment your miter gauge is to the blade. If this amount is unacceptable (Mine's to within 0.001 on a contractors saw...or at least it WAS until I forgot ther dust shield on the back of the saw and tried to tilt the %&#* blade to 45° and wondered why it was being difficult so I tried harder!!), loosen three of the four trunion bolts one at a time and re-tighten them until the barely seat. Then using a rubber mallet, and while watching the dial indicator, move the trunion 1/2 the amount of the value you were out of alignment. Snug up the trunion bolts again, but do it in sequence and watch the dial indicator for movement. You do;t want movement, but you'll get some. Learn how the trunnion moves and compensate accordingly when you bump it around.
Now repeat the measuring process and if required, repeat the alignment process until you're happy.
Yeah, I know what I've done, and how to fix it. I still can't believe I did it!
BTW. For aligning my TS (and other things) I bought a TS Aligner Jr. from Ed Bennett a few years back and thank him every time I pull it out of the case. It's a simple set of tools that can be shop-built if you're industrious, but he packaged them, wrote a manual and charged a fair price. I'm always glad I bought it.