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Thread: Table Saw Not cutting 90* (HELP!)

  1. #16
    Join Date
    Apr 2013
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    Stone Mountain, GA
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    594
    Looks like you've checked everything pretty thoroughly. 0.001 is very good for miter-slot to blade alignment and I doubt you'll hear anyone telling you to dial it in further. Also the runout of 0.0015 on the blade is quite good, translating to an arbor runout of much less than 0.001.

    To be honest I am not sure what is causing this, in particular the curve to the cut. The only thing that still stands out is the fence...if it's wonky then it can be putting side forces on the blade as you feed the piece through which might contribute to the weirdness you are seeing. However you say it does the same thing if you use the miter gauge, so the fence can't be the main problem.

    The only thing I can think of is that the piece is somehow rocking as you feed it through. It starts out angled a bit away from the blade, so you get a deeper cut on the bottom, then it angles in towards the blade (or vice versa). This could be due to the table not being flat or the workpiece not being flat. It could be quite subtle and cause the issue you are seeing. Maybe focus on flatness just in the area between the miter slots, checking for twist as well. See if a flat piece rocks even slightly as you press down in different areas.

  2. #17
    Robert, the piece rocking somehow did occur to me last night. It would explain the curved edge as well as the burn mark that seems to be happening at about the same point from the end of the cut almost every time. I'll get some time later today to check the table for flat. All I have done is checked across the table with a straight edge. I should probably due front to back and diagonal as well. Is there any other method you suggest I use to check for flatness?

  3. #18
    Check table flatness, especially around the insert in all directions. Could be that the insert has a dip at the blade. As the wood contacts the blade, the blade pulls the wood down into the dip. Depending on your workpiece flatness, the cut will vary. Also, make sure there is no blade wobble. Forces on the blade are extremely strong and could tweak the blade out of square at any opportunity. If you can push the blade out of square, the same may be occurring during the cut.
    By the way...is your plywood test piece completely flat? It looked like there was daylight under the straight edge in one of your pics.

  4. #19
    Join Date
    Apr 2013
    Location
    Stone Mountain, GA
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    594
    Maybe the best thing to do is take a very flat workpiece, mdf works well if you have some on hand, about the size of the pieces you've been having problems with. Retract the blade, clean all dust off the table, and set the piece down on the table where it would be as you'd make a cut. Check where the edges of the piece meet the table, look for any gaps. Press firmly on each side, at each end, and each corner, look for any movement. Repeat the check on the infeed side, the outfeed side, and right over the blade.

    Try this as well with the workpiece situated like you were going to make a crosscut with the miter gauge.

    I think you'll probably find a little movement, but the question will be if that's whats causing your problem, especially if its just a small amount. And what would you do about it if it is? One thing to try is cutting on a sled, which should minimize the effect of table flatness. If your sled cuts come out straight, without the swoosh, then that starts to confirm the table being the problem.

  5. #20
    Join Date
    Mar 2006
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    SoCal
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    20,282
    Quote Originally Posted by Kenny Southerland View Post
    I also remember someone asked if i took the cut off and laid it next to the piece if they look joined, like they match. The answer is "kinda-ish", until I flipped one of the pieces upside down and then it was really off.
    What a battle. I'm sorry this thing is fighting you so much. When 2+2 doesn't make 4 as when your measurements of the saw (which are good) do not jive with the results (which are bad) I'm afraid we have to dig deeper. Thanks for doing all the leg work and checking alignment, flatness and all that. It's good that you are using ply because that removes the poorly milled stock problems that many experience.

    At this point I am starting to suspect that something is loose or cracked / broken. That is, when the saw is put under load during an operation, something with a loose screw or bolt position is shifting or a cracked casting is allowing movement. If your picture 2.jpg is showing the wood with your thumb on the surface that rides the table the top of the blade is tilting to the left during the cut. You have already confirmed that the top of the blade is at 90 degrees when you are not performing a cut so the problem seems to be during operation.

    A loose or broken portion of the trunnion at the front of the saw could allow this. For example, a front left trunnion attachment point, if cracked, would allow that corner to be forced away from the underside of the table resulting in the plane of the blade leaning to the left. A parts diagram could help us identify other likely points of issue. Wait . . . here it is:

    C-man 315.228390 trunnion.JPG

    So we want to check for damage to the "ears" on part(s) labeled "7". Your model does use the center trunnion locking handle, part "9" in the diagram. This is for locking the bevel position but, could help with stability when at 90 degrees as well. Is it tight when you are making your cut? I see that part(s) "7" have three bolts each. The extreme front and rear hold the bracket snug while the four 'corners' are loosened for blade alignment. Your alignment is good so I would not loosen these but, I would make sure that they are tight and that those castings are not cracked. It would be great to just find something that had worked loose instead of something that has broken as many parts for these saws are no longer available.
    Last edited by glenn bradley; 05-20-2020 at 9:28 AM.
    "The Danish government believes that if we train 5,000 designers, and produce
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  6. #21
    Come to think of it, one of my first table saws was a Craftsman similar to yours. Because of cut frustrations like yours, I ended up returning the saw and moving up to a 3hp, Jet cabinet saw. As I recall, there was movement in the lightweight trunion construction, causing the poor cuts. The more stress there was on the blade, the poorer the cut. Does taking a shallower cut make any difference?

  7. #22
    I own a Rigid saw that looks similar to yours. Although I've never had as severe a problem, if I don't engage the bevel lock the arbor assy tends to rock a bit when cutting with the blade at 90 degrees.
    The problem doesn't really show up just making static measurements.
    Does your saw have bevel lock?

  8. #23
    Kenny, your pictures make me less sure we even know what the symptom is. The way you are assessing square has too many different issues that can affect square -- too hard to narrow in on the problem.

    In the two pictures you sent of the cut, the first looks like a flat face that might be at an angle (camera perspective can fool you). In the second, the cut face doesn't look flat. Those are two very different problems. The first smells like blade angle relative to the workpiece (I say to the workpiece, not the table bed as it's possible the workpiece is not sitting flat to the table where it passes the bed). The second is a product of blade movement, either from vibration or deflection, or from the workpiece moving as it exits the cut (e.g., if the workpiece is not flat, if the fence isn't straight/parallel, or the saw bed isn't flat front to back).

    You need to prepare a workpiece to test performance, a piece of plywood probably at least 20 inches long, 30 is better. Do you have a jointer? This workpiece needs to have a true edge, straight and square. It's really important that this piece start with a dead straight edge. If you don't have a jointer, then a factory edge of the plywood will have to do. Make sure there are no goobers protruding from that edge, knock them off with a sanding block (not loose paper).

    Take that piece of ply and put the true edge against the fence and see if the fence and the piece mate tightly along their length (you're looking for a bent fence).

    I would take a piece of plywood maybe 20-ish inches long and rip it (trued edge on the fence, obviously). Then lay the cut pieces next to each other, not on edge, but the way they were in the piece before the cut, and push them together. See if they mate tightly both across the thickness front and back and along the seam between the two. Flip them over and check the joint along the length on the bottom side.

    Next, return the pieces to their original orientation and slide them so that the leading edge of one is in the middle of the other, and vice versa. Check fit. Then check when they are aligned leading edge to trailing edge and vice versa.

    Next, take the piece that was between fence and the blade (that has the true edge on the right) and spin it around so the true edge is against your offcut. Assess how they mate in all the ways I just described.

    Next, take the piece you ripped, put the straight edge against the fence, put the leading edge right at the front teeth of the saw (power off, obviously), and bring the fence over until the teeth are just rubbing the workpiece. Then push the workpiece through along the fence just like you were ripping it, but without the saw on. Do the leading edge teeth rub the workpiece the same way for it's full length? Do the back teeth rub to the same degree? Does the workpiece bind at any point along the path, or does it become loose in the gap (no longer rubbing the saw teeth)?

    Your comments about the sound changing as you rip and getting burning on the face of your workpiece smells of fence issues (I know you have similar problems with the miter gauge, but still). The burning means the piece between the fence and the blade is getting pushed into the blade significantly; the kerf clearance isn't enough to keep the workpiece from rubbing the sawblade. This can happen if, among other things, your fence is further from the leading edge of the blade than the back edge. That noise you get as the piece exits is the teeth cutting back into the work pieces as the pressure is relieved and the workpiece moves back into the blade, the blade bends back to vertical, or both. A twisted or bowed fence can do the same. I can't see what fence you have, but many contractor's saws have fences that lock down on both front and back rails, and they often don't lock down the same way each time.

    The problem with how you are testing for a square cut is that it reflects the aggregate effect of irregularities all along the cut, not just in one place. You need a square that will allow you to assess square at any point along the length of the workpiece. You want to be able to hold the cut edge up to the light, put the square across the cut edge, and look for light. It's the same idea as what you are doing, but you can check at a single point along the edge.

    In addition to not allowing you to directly assess squareness of your cut edge, your speed square is not generally considered a precision square. I'd recommend you get an engineer's square for machinery setup, probably 6". Until you do, make sure you assess square with your speed square from both sides of the workpiece, and that the complementary irregularity is observed when you measure from the other side of the workpiece.

    I also noticed a little fuzz on your workpieces from veneer tearout. To be expected, but make sure you don't have some of that fuzz affecting how the workpiece sits on the reference surface.

    Let us know what you learn.

    Dave

  9. #24
    Join Date
    Apr 2017
    Location
    Tucson, Arizona
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    Kenny,
    Are you sure that your insert is completely flat with no dips, and also that the top surface of the insert is indeed at the same height as the table surface? In the case of my older Craftsman table saw, I don't believe that there is a factory provision for leveling/adjusting the insert.
    David

  10. #25
    Join Date
    Feb 2010
    Location
    Collegeville PA (30 min west of Philly)
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    695
    I didn’t read all posts but wonder if testing with a sled would be worthwhile.... would eliminate fence and table from equation
    - Bob R.
    Collegeville PA (30 minutes west of Philly)

  11. #26
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    Apr 2017
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    778
    Good Idea Bob!
    David

  12. #27
    Quote Originally Posted by Bob Riefer View Post
    I didn’t read all posts but wonder if testing with a sled would be worthwhile.... would eliminate fence and table from equation
    Might work...might not. If the blade and/or trunion is the problem, then not.

  13. #28
    Join Date
    Jan 2020
    Location
    Hoschton, Georgia
    Posts
    55
    It sounds like the saw is adjusted well enough to cut a straight line. The problem seems to show up when under load. I'm thinking like Glenn, it sounds like you have a bad arbor bearing or a broken casting that is allowing the blade to flex when under load. It wouldn't take much flex of the arbor, translated out to the end of a 10" blade to make a big difference. I think checking for arbor movement would be the next step. How you accurately do that is going to be a challenge. Crawling under the saw with a flashlight and wiggling the arbor might show something loose/broken.

  14. #29
    Quote Originally Posted by glenn bradley View Post
    C-man 315.228390 trunnion.JPG

    Your model does use the center trunnion locking handle, part "9" in the diagram. This is for locking the bevel position but, could help with stability when at 90 degrees as well. Is it tight when you are making your cut? I see that part(s) "7" have three bolts each. The extreme front and rear hold the bracket snug while the four 'corners' are loosened for blade alignment. Your alignment is good so I would not loosen these but, I would make sure that they are tight and that those castings are not cracked. It would be great to just find something that had worked loose instead of something that has broken as many parts for these saws are no longer available.
    My Craftsman saw has the same tilt lock that is present on the OP's saw. The blade tilt mechanics of this saw have enough play (gear and linkage backlash) for the blade to want to tilt one way or the other unless you use this locking device. I can tell you from experience with my saw that leaving the locking handle loose can cause problems with your cuts whether ripping or cross cutting. I always use my tilt lock.
    Last edited by Lee Schierer; 05-20-2020 at 7:56 PM.
    Lee Schierer
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  15. #30
    Got a chance last night to look at the top of the saw. I was definately not doing it right before. I was using a quality straight edge, but it extended all the way to the wings. I started with a small piece of flat plywood and went and moved it over the table, then moved to using the straight edge of my combination square. Part of the problem was my insert. I had been checking the insert at the front and back because I had read that's where the problems occur. My insert is bowed upward in the middle. Its made of really solid steel. I managed to take some of the bow out by pushing it against the edge of a 2x6. Another part of the problem is that the table is dished on the right side of the insert.

    So it cutting better now, but still not what I want.

    My wife mentioned upgrading when I told her about it last night. I just about told her that I didn't want to spend the money to upgrade, that I wanted my saw to work, but fortunately I was smart enough to keep my dumb mouth shut.

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