Tablesaw top not flat

[jim gossage]

I have a Dewalt hybrid table saw and the top is out of flat by about 0.10". It dips down near the throat plate. It was out of flat by 0.015" in the same place and Dewalt replaced it with the better but still imperfect version. 0.010" may seem trivial, but it significantly affects the edge when I am ripping narrow boards that are 2-4" wide because they "fall" into the dip and the edge ends up not square. It is enough of a problem that I had to build a false top from mdf that I had to double stick tape to the real top for a recent project - it worked perfect but its kind of a PITA to set up and I question its safety. It was a real hassel to get the original top replaced, so I'm not interested in going that way again. I was thinking of spreading a little epoxy in the dipped area, flattening it out, and then sanding the whole thing flat when it dries. Would that work? Any other ideas? Thanks

[Mike Cutler]

I have a Dewalt hybrid table saw and the top is out of flat by about 0.10". It dips down near the throat plate. It was out of flat by 0.015" in the same place and Dewalt replaced it with the better but still imperfect version. 0.010" may seem trivial, but it significantly affects the edge when I am ripping narrow boards that are 2-4" wide because they "fall" into the dip and the edge ends up not square. It is enough of a problem that I had to build a false top from mdf that I had to double stick tape to the real top for a recent project - it worked perfect but its kind of a PITA to set up and I question its safety. It was a real hassel to get the original top replaced, so I'm not interested in going that way again. I was thinking of spreading a little epoxy in the dipped area, flattening it out, and then sanding the whole thing flat when it dries. Would that work? Any other ideas? Thanks

Jim

If it's having that dramatic of an effect on your work. I'd get it replaced, but you've indicated that's a real PITA.
I'm not sure how well epoxy would float to level, or true in this application. But automotive bondo may be a solution. The Bondo could be worked to flat with high grit sandpaper, and the adhesion to the metal top would be better.

Just a few thoughts

Mike

[Myk Rian]

Is it .10" or .01"?
Either way, epoxy would be a waste of time. I can't see that thin a layer adhering to anything, and staying put.

.01" is one, one hundredth. Hardly enough to fuss over.
If you really don't like it, call Dewalt.

[Loren Hedahl]

If it has almost an 1/8" dip in the center, epoxy with a filler will adhere and fair out nicely to cast iron. Go to a marine supply such as West Marine and they'll have the stuff. Automotive filler, such as Bondo is polyesther based and is easier to work. However it has neither the adherence nor the wear properties that epoxy has.

Another route would be to take the top to a machine shop and have it ground flat. This might not cost as much as you'd think.

Perhaps what is happening is the tops aren't seasoned long or well enough by the manufacturer before final grinding. As time elapses, temperatures fluctuate and hard knocks happen that relieve the internal stresses of the cast iron.

If you are talkin' a hundredth of an inch, then you are in an area where woodworkers seldom travel. I wonder if any cast iron table saw top would be able to maintain such precision over a long time period. Maybe one of those granite top saws might fill the bill. I just don't know.

[Al Navas]

If it IS 0.010", it will likely be within manufacturing specs, as this is approximately what most aim for. Does the table top have wings on it, and are they aligned properly, such that no gaps show?

.

[John Downey]

Take a look at how the top and motor are mounted to the saw frame. Metals are not especially rigid in an absolute sense, so you may be able to correct the problem with shims near mounting bolts. Ever wonder why bandsaw tables have the pin that slides into the slot cut for blade replacement? Tables often warp over the years without it.

Personally I don't worry about figures like 0.01", its just too small to significantly influence what I make - but then I tend to rip a hair over size and joint after ripping.

[Chuck Wintle]

I have a Dewalt hybrid table saw and the top is out of flat by about 0.10". It dips down near the throat plate. It was out of flat by 0.015" in the same place and Dewalt replaced it with the better but still imperfect version. 0.010" may seem trivial, but it significantly affects the edge when I am ripping narrow boards that are 2-4" wide because they "fall" into the dip and the edge ends up not square. It is enough of a problem that I had to build a false top from mdf that I had to double stick tape to the real top for a recent project - it worked perfect but its kind of a PITA to set up and I question its safety. It was a real hassel to get the original top replaced, so I'm not interested in going that way again. I was thinking of spreading a little epoxy in the dipped area, flattening it out, and then sanding the whole thing flat when it dries. Would that work? Any other ideas? Thanks
I would say that .010 is not significant for woodworking.

[Ed Griner]

On this planet,nothing is perfect.(no matter what the sales people said)Everything is an acceptable compromise in life,(even at the NASA) and on machinery surfaces.Woodworking is fun! Enjoy woodworking.Be realistic have a good time. Relax!

Ed

[glenn bradley]

Some cabinet saw manufacturers have a tolerance of .08" and some go as flat as .04" and this is deviation across the table surface. You can check with DeWalt but .01" is probably well within their manufacturing tolerances for that type of a saw. As for a fix to your problem on a specific cut; adjustment of the blade bevel could be a solution if ugly in principle. Not faulting the saw but setting expectations for this type of machine; ripping a bit oversize and jointing the edge would be an expected series of steps IMHO.

If you want to pursue this, and I wouldn't fault you; is the top cast iron? If it is and the trunnions are cabinet mounted you can tweak cast iron quite a bit. If your trunnions and motor are hanging from the top, your challenge is stepped up quite a bit. I don't know how far I would be willing to go on that configuration before I chose an alternative method over trying to correct the top. It will be interesting to see how this plays out.

[Dan Forman]

I had a problem with the top on my Unisaw, a crown right near the blade opening that made it impossible to set the blade square to the table on both sides of the blade. I lived with it for almost five years until the warranty almost ran out. I finally sent it back, and got a new one form Delta, which is for all practical purposes dead flat, a big improvement over what I had. Yes, it was a big pain in the petute having to remove it, the fence, and the sliding table, then set it all back up again, but well worth it.

The issue is not so much whether the table is flat, but where is it not flat. A dip of that size in many areas would make no difference, but near the blade, it's a different story. Sounds like yours, like mine, is in an area that has a direct influence on the cut. If you can establish that with Dewalt (same parent company as Delta), they will probably send you a new top. Hopefully, third time will be a charm.

Be aware that if you have it reground, the miter gage may no longer fit flush to the top.

You might be interested in the thread I started about my top. Wish me luck with Delta customer service... (http://www.sawmillcreek.org/showthread.php?t=126606)

Good luck.

Dan

[Lewis Cobb]

Late to the party here but thought I'd toss in my .02 -

I have a PM2000 and posed the question of "what's the spec on flatness" once when I was talking to my friendly tech service guy. He said that .015 is the spec but they like to shoot for .010.

Cheers,
Lewis

[jim gossage]

The issue is not so much whether the table is flat, but where is it not flat. A dip of that size in many areas would make no difference, but near the blade, it's a different story. Sounds like yours, like mine, is in an area that has a direct influence on the cut. If you can establish that with Dewalt (same parent company as Delta), they will probably send you a new top. Hopefully, third time will be a charm.

The variance is in fact 0.010", not 0.100". I know that it seems trivial, but as Dan pointed out, it dips severely in the area right around the throat plate and can severely affect some cuts. If it was just a straight rip, I would re-joint as suggested. It specifically became a problem when ripping a 45 degree bevel. The pieces were short, so the bevel would be ripped at different angles depending on when the piece was dipping into the valley. I could not get my miters to close properly so I needed a fix. 0.01" is just within specs for the Dewalt, so I'm not confident I'll do any better with another replacement. I may just stick with my current fix for the occasional time that I need it. It does fine for most other cuts. On the positive side, I spent a lot of time perfectly aligning my miter slots and blade at 90 adn 45 degrees, and did learn alot about the different ways that a slightly off saw can screw up a cut!

[Phil Thien]

I'd try to pull it straight. Here's how:

I'd get a block of 2x4 as long as the main table is wide. I'd put some blocking on either side so the 2x4 is suspended an inch or two over the blade opening.

Now, find a strong block of white oak or something similar that you can slip down into the blade opening and then turn so that each end of the block are pulling up on either side of the opening.

Finally, use a clamp to clamp the white oak block to the 2x4 on top of the saw, and try applying a little pressure. Check w/ a straight edge and try to get the dip out.

Don't go ape you know what over it. A little at a time. And let it rest with the clamp on.

[Dan Forman]

The variance is in fact 0.010", not 0.100". I know that it seems trivial, but as Dan pointed out, it dips severely in the area right around the throat plate and can severely affect some cuts. If it was just a straight rip, I would re-joint as suggested. It specifically became a problem when ripping a 45 degree bevel. The pieces were short, so the bevel would be ripped at different angles depending on when the piece was dipping into the valley. I could not get my miters to close properly so I needed a fix. 0.01" is just within specs for the Dewalt, so I'm not confident I'll do any better with another replacement. I may just stick with my current fix for the occasional time that I need it. It does fine for most other cuts. On the positive side, I spent a lot of time perfectly aligning my miter slots and blade at 90 adn 45 degrees, and did learn alot about the different ways that a slightly off saw can screw up a cut!

Jim---When I first got my saw, I brought up the top issue with the store I bought the saw from. They told me that it was within specs, and if I sent it back, the next one could be worse. Same thing you are thinking. When I finally decided to do something about it again, I went right to the local Delta/Dewalt service center.

My initial contact with them didn't leave me feeling very confident that something could be done about it, but I disassembled the saw and brought the top in anyway. I think they were surprised that I didn't bring the whole saw, but it's in the basement and it's heavy! When they called back, they said a new top was on the way, and they had never seen one like mine before. Again, I think it's a matter of how you make your case. If you bring in the pieces that will show how far off the cuts are, that should help. I pointed out a number of times the fact that the location of the defect was critical. Have all of your documentation in order when you talk to them. I think it's worth another try. No guarantees of course, but maybe the variance will be in a friendlier place on the next one. Now that you have had so much practice, setting it up yet again will be a snap.:D

Dan

[keith ouellette]

I would rough up the area clean it over and over again with with Denatured alcohol and use some JB weld epoxy. the regular not the quick set. make sure its warm in the room and the ts table is close to room temp. use a metal straight edge to scrape off the excess and feather it flat. then sand till there is no hump.

I have gotten epoxy to boond to things that others told me would never work.

It has to be clean, clean clean.

[Terry Welty]

I think that if you use a filler, any kind of filler, you'll not be happy with the results... If you're convinced it is unexceptable, I'd insist the company stand behind it... but, to me, I wouldn't worry about it...

[keith micinski]

I don't know if any filler can be spread and sanded smooth to .001. I am positive that if you tried that you would be worse off. I think the only real way to get it fixed better then what it is would be to take it off and have it machined. Then have the bottom of your mitre gauge machined if you have to but you might not. It seems like this could be machined in an hour so I would think you get it done at a fairly reasonable price.

[jim gossage]

[QUOTE=Phil Thien;1307810]I'd try to pull it straight. Here's how:

I'd get a block of 2x4 as long as the main table is wide. I'd put some blocking on either side so the 2x4 is suspended an inch or two over the blade opening.QUOTE]

I might actually give Phil's idea a try and see if it will help. The cast iron is fairly thin in this area and the trunnions are mounted far away. Thanks for the suggestions.

[Chuck Wintle]

[QUOTE=Phil Thien;1307810]I'd try to pull it straight. Here's how:

I'd get a block of 2x4 as long as the main table is wide. I'd put some blocking on either side so the 2x4 is suspended an inch or two over the blade opening.QUOTE]

I might actually give Phil's idea a try and see if it will help. The cast iron is fairly thin in this area and the trunnions are mounted far away. Thanks for the suggestions.
is there a chance the cast iron top could be cracked with this method?

[John Downey]

f it was just a straight rip, I would re-joint as suggested. It specifically became a problem when ripping a 45 degree bevel. The pieces were short, so the bevel would be ripped at different angles depending on when the piece was dipping into the valley. I could not get my miters to close properly so I needed a fix.

You can joint a 45 degree rip just as easily as a 90, either with a good hand plane or with a power jointer. Easiest way if using the plane is to clamp it in a vise upside down and pass the wood over it as you would a machine jointer.

In all honesty, rip miters are notoriously hard to clamp and glue, I think that may be your problem less than the condition of your TS top. I think that's just a red herring that's distracting you from the real problem.

[jim gossage]

The pieces are clearly off after the rip miter. When the trailing edge of the piece falls into the dip, that edge drops down lower on the blade and was getting cut about 1/32" shorter. This was easily seen with a straight edge and square. So the pieces would not match up. Once I used a fake flat table top so there was no dip, all was good and the miters were perfect. Glue up was never really a problem because I used the tape on the outer corners method and folded the whole project up and taped the final corner.

[Carl Babel]

Iron is pretty malleable (ductile). I think you would have to bend it a lot more than that to get it to crack.

Jim, I really like Phil's suggestion. Even if you could get the manufacturer to swap yours for a "perfectly flat" top, it could end up "moving" over time. Makes you wonder if those Steel City folks with their granite tops might be right, after all...