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Resurfacing Table Saw Top

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  • #16
    My contractors saw from the 70's has never been flat. Both sides tilt towards the blade. I just use a sliding plywood jig.

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    • #17
      Can't help you with the current accuracy problems.
      However if you desire a stable surface over time I suggest a new table be made from a material that is less likely to dash your hopes and dreams in the future.
      The Iron/Nickle alloy called Invar would be an excellent choice, granite would be another material of interest.

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      • #18
        Originally posted by Bented View Post
        Can't help you with the current accuracy problems.
        However if you desire a stable surface over time I suggest a new table be made from a material that is less likely to dash your hopes and dreams in the future.
        The Iron/Nickle alloy called Invar would be an excellent choice, granite would be another material of interest.
        There was a company, was it Powermatic, making Granite top Artisan table saws.
        Might be easier to find a "servicable" granite rock to blue the table against before scraping. But the saw top would probable have to be blued in a pre-stressed state.

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        • #19
          Originally posted by reggie_obe View Post

          There was a company, was it Powermatic, making Granite top Artisan table saws.
          Might be easier to find a "servicable" granite rock to blue the table against before scraping. But the saw top would probable have to be blued in a pre-stressed state.
          That was a joke.
          I can see a future where the advertisement reads like so.
          Artisanal Picture Frames Made by Hand Using Granite Topped Saws.

          A thing of beauty. The only thing better would be Made With 18 Carat Gold Plated Tools, consumers equate gold with value.

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          • #20
            Maybe you can add some steel structure underneath. Shim or jack your table so it's straight (er)

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            • #21
              I have some experience with a Craftsman radial arm saw. When I tried to do the adjustments as per the manual, I could never get it to come out right. Turned out that it was warping every-which-way when I moved it on the concrete floor. Even a move of a fraction of an inch resulted in all my previous adjustments being completely lost.

              I finally had to bolt it down in one and only one position on that floor. Then I was able to do the adjustments in the manual with only one run through the procedure. And it cut with as much accuracy as one could measure with wood and wood tools until management decided to move it. I never got a chance to go through the procedure again.

              My point is, if you are going to try to get this kind of accuracy in a wood tool, you need to bolt it down to a solid floor (concrete) and never move it, not even for a small fraction of an inch.

              As for scraping it, 0.010" is an awful lot for that. I would start with sandpaper, probably with a power sander. A Mouse style sander may be a good choice. Then, once it is down to 0.001" or so, decide if it is worth going further with scraping.
              Paul A.
              SE Texas

              Make it fit.
              You can't win and there IS a penalty for trying!

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              • #22
                I think a table saw marketed by Steel City did have a granite table.
                Larry on Lake Superior

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                • #23
                  As a woodworker who repairs machinery for fun and profit, I would never have that top ground. The miter gauge bar won't be right, nor will any off the shelf jigs or accessories. In addition. if the arbor is attached to the top, the added weight will change the shape (flatness). Just mounting that on a magnetic chuck, will change the shape and when they grind it, they may release tensions in the top and again it may change shape when you put it back on the saw.

                  I am known for "supertuning" my machines and this is not where I would go. I have medium sizes tools. 12" table saw, 8" jointer, 25" drum sander, etc.

                  Wood is not stable like steel. Make a cut, go to lunch and when you come back, measure it with a micrometer and it will have changed. Tensions released, moisture content changed! I have friends that make furniture that sells for 6 figures and I do work on their machines and they are not dealing with dimensions much under 1/32" or occasionally 1/64". The wood moves more than this.
                  Peter
                  Grantham, New Hampshire

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                  • #24
                    Originally posted by SVS View Post
                    Should be low in center if wear is the issue.

                    Looks like a nightmare to set up on grinder to me. I bet the quote is toe curling.
                    Well yes and no. If your running planks to the right or left of the blade then most of your wear is going to be right where the low spot is either side of center. Keep in mind my stupid uncle ran a lot of cement scale / dust demolition through that saw when I was too young to sneak it out of his garage and hide it in mine. In fact...I can remember him running 10" wide planks that were a full 2" in thickness trimming an inch or so off the edge. That puts the whole board on the right side of the blade. Right in the area of wear. I'm sure he did it on both sides.

                    JL.....................

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                    • #25
                      Originally posted by J Tiers View Post
                      The issue I see is that when the table is flat by itself, with no external forces, that's great, but then you bolt it down to the frame of the saw. That bolting is going to cause warpage unless the frame is flat and the bolting points are all flat.

                      The top is not nearly as rigid as a lathe bed, so it will not stay flat even if you make it flat by grinding, any issues with bolting will pull it "out"..

                      If you really want it flat, you might have to skim the mounting bosses as well, and then possibly SHIM the mounting points to maintain flatness, and probably adjust the feet of the frame as well. I am not sure that "the game is worth the candle", it's a lot of work for something that likely makes little difference, for most saws with pressed metal frames.
                      I have no idea what might happen. That top set on the corners of the cabinet and everything else hangs off of it.
                      There is a U channel bolted across the bottom of the table on the infeed side. I'm guessing that was there for support. I don't think shimming the corners is going to do anything for the warpage.

                      It's a real PIA to take all this apart. Then there is the issue of aligning the trunnions so the blade is in parallel with the miter slots. I've had this apart a couple times. Last year to replace the arbor bearings. Go to pull the screws and their mounts etc. and all of that has to be done working inside the cabinet. I had a stiff neck and back ache for three days after I finished.

                      JL.................

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                      • #26
                        I like the idea of scraping it yourself. It's already built, whatever stresses are manipulating the table from the trunnions bolted on, to the weight they are carrying, to the mounting of the table to the stand- all of that is stable now. You could send it out and pay big bucks to have it 'flattened', only to find that it's worse once you have it all back together. I think that's likely, in fact.

                        I've gone through this more than once, with my own saw at home and with three others at work. I scraped high spots until they were mesas instead of mountains, and left it at that. As far as 10 thou of error- I would not like that, but it's probably less than 20% of the error that wood materials would exhibit.

                        The worst thing that I find is when a high spot on the table causes a burnished track down the piece of material you're working with. If you don't see this, you have nothing to worry about.

                        I've found that high spots are often centered around the insert, the table surfaces adjacent to the slots, and the left and right edges of the table. You're not going to be removing enough material anywhere to interfere with the depth of the slots.

                        When it comes to getting a nice cut, you will find that aligning the axis of the arbor to be perpendicular to the slots is most important- after that comes aligning the fence. High spots on the table will have virtually zero effect in this regard- including as far as maintaining a completely square cut. A much bigger problem is getting and maintaining a flat and level surface across the insert.

                        I've never yet seen an insert which is perfectly flat, or will stay that way. You can scrape that too. You would want to play with the adjustment screws so the insert does not rock at all, and at the same time get the height just right. When you scrape the table you should see some action on the insert too. This can get tricky since the insert will want to rock when you're scraping the front and back extremes- you would probably play with shims to prevent this while you get the scraping done.

                        When all is said and done, don't be shy about treating the table top with a surface coating. I've got a couple cans of Glide-Coat sitting near me- that stuff works well. Do the slots as well, and the side of the fence, and any in and outfeed tables.
                        I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                        • #27
                          Originally posted by BCRider View Post
                          I agree, the risk here is that the top isn't naturally out like this. It may be but it's also equally possible that it is being pushed to crown like this by the trunnion assembly bolted from below. You may go to a lot of trouble and expense only to find that when you re-assemble it the same high spot is back again.

                          If you're keen enough to do this in the first place I'd say start by removing the wings, front and rear bars. Then double check the table with that one source of stress removed. If it's still got the high spot then remove the top and trunnion group from the box and double check in case it's the box. If the hump is still stable then loosen the trunnion assembly and check again. if things suddenly change then you might want to check on how the trunnion assemble fits to the mounting pads. There may be a nasty wracking in the assembly that is stressing the table.

                          If there is still a hump in the place and the trunnion assembly fits evenly and stress free into place then at least you have the saw broken down and ready to ship off to the guys that can do the job.
                          I pretty much have done what your describing here. I've had both the trunnions out. They have three bolts. The trunnions are pretty heavy and solid. I did check the mounting surfaces or faces and they were al even.
                          I find it hard to believe that the top is being bent by the weight of the wings and if I remove them it will spring back to flat.

                          JL.................

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                          • #28
                            Originally posted by Tim Clarke View Post

                            I have a saw that's similar in looks, and age. Mine is a contractor's model, several pay grades below this one. Similar design and trim make me think they're from the same factory. The table is also warped, bit it's low where Joe's is high. On rip cuts, it's not very critical, but when making miter cuts, like for a picture frame, it gets tough to make a nice job. In my case, I was getting a dish effect. Once I figured out what was happening, I was able to work around it to some effect. I'm pretty sure Dad never had any problems with this while he used it on construction job sites. He did high quality finish work, but used a high end miter box for trim work.
                            Sounds like you know exactly how a slightly warped top can cause imperfect joints.

                            JL...............

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                            • #29
                              Originally posted by reggie_obe View Post

                              There was a company, was it Powermatic, making Granite top Artisan table saws.
                              Might be easier to find a "servicable" granite rock to blue the table against before scraping. But the saw top would probable have to be blued in a pre-stressed state.
                              I'm sure that a saw with a granite top would have all the inner workings mounted to the cabinet and the top just sits on the cabinet and is easily shimmed to align to the blade.

                              JL.............

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                              • #30
                                Originally posted by BCRider View Post
                                As for you guys saying that there's no need to work to .010". Well, that's right but it's also not right.

                                There may not be the need to work to some very specific value. But when you start playing with some wood working joints there very much is the need for very precise cuts to achieve the sort of fit that is needed and for the results to look good. And at those times the need to accurately split a fine pencil line or even a knife scribed line is needed.
                                You are 100% correct.
                                When I run a perfectly flat board through the saw it dips on the right side of the blade because there is a low spot there. then I look at the edge and I can see where the blade wandered a bit.
                                try to make clean glue joints with a cut like that. Smaller piece will follow the uneven contour of the table and that shows in the cut.

                                JL............

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