Replies

1. 
   JLMCDANIEL | Jun 08, 2008 05:18am | #1

   I suppose and obvious question would be , did you check your square?

   Jack

2. 
   gregjones | Jun 08, 2008 01:17pm | #2

   In addition to checking what Jack recommended, I'd also suggest squaring your miter gauge to the miter slot, not to the blade. It's important to have the blade parallel to the miter slot for safety reasons and to reduce burning, but miter cuts will only be square if the miter gauge is square to the miter slot. If you square the miter gauge using the blade as a reference, then you add any error of the blade-to-miter slot setting with the miter gauge-to-blade setting, which increases the error of mitered cuts.

3. 
   HowardAcheson | Jun 08, 2008 05:13pm | #3

   Cross cuts that are not at 90 degrees are always the fault of the miter gauge. There is no other reason.

   Here's the process many professional have used. Rip a 1x4 of lumber about 12-24 inches long. Be sure the 1" sides are truly parallel. Now make a pencil "X" near (about 2") one end and cross cut the board through the "X". Take set the board on the tabletop on its 1" surface. Take the cutoff and turn it so it's part of the "X" is away from you (opposite the long board) and butt them together. If your miter gauge is truly at 90 degrees you will see no space between the blocks along the cut edge. If you see a space, adjust your miter gauge and run through the process again until you have no space. I run this test every time I need to be absolutely sure I have a 90 degree cut. You can use the same process to be sure your sawblade is exactly perpendicular to the table top.

   Don't rely on a "square". Just make cuts and adjust the miter gauge until it produces a 90 degree cut.

   Of course, you must be sure that your "square" is square.

   Howie.........
1. 
   dustup | Jun 09, 2008 01:37am | #4

   Thanks Howard for the suggestion. As soon as my garage(shop) cools down this evening I'll give it a try. I live in Fort Worth so the average daily temp at this time of year is about 95, and my shop is shop gets up to 120 or so.

1. 
   forestgirl | Jun 10, 2008 06:04pm | #10

   Dustup, the test that Howard mentioned is invaluable, as squares often aren't or they go out of square or the human eye fails.  I use that test and a couple other whenever tuning my miter or table saw, and took some pictures for a how-to a couple years ago.  Look here if you're interested (post is about miter saw, but can be used on both).forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

1. 
   dustup | Jun 10, 2008 09:50pm | #11

   Thanks,
   as always, the pictures are worth a thousand words.

1. 
   forestgirl | Jun 11, 2008 05:20am | #12

   You're welcome.  I think the "thousand words" thing applies in spades in this particular instance, and that's why I put the time into taking those pictures and making that post.  The process is so much harder to explain than it is to simply show to someone.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

2. 
   HowardAcheson | Jun 13, 2008 12:39am | #15

   FG, I didn't realize you had those pictures. Great. It's a process that can get convoluted when you try to describe it but is fairly simple with illustrations.In the shop I was involved with, none of the guys ever used fancy squares to check the tablesaws. Nor did we even own a dial indicator.Howie.........

1. 
   forestgirl | Jun 13, 2008 12:48am | #16

   "It's a process that can get convoluted when you try to describe it ..."  Well put!  After trying a couple times, off to get the camera, LOL.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

2. 
   JohnWW | Jun 09, 2008 05:03pm | #6

   An out of square miter gauge is not the only reason that you can't get a square cut. If the blade is out of parallel to the miter gauge slot no amount of adjusting the 90 degree setting on the miter gauge will correct the problem. I've serviced many saws that "wouldn't cut square" and always solved the problem by getting the miter slot parallel to the blade first before adjusting the miter gauge. John White

1. 
   gregjones | Jun 10, 2008 03:58pm | #7

   John, let me first say that I have the greatest respect for your experiences (which are far more comprehensive than my own) and opinions, but the dynamics of the relationship between the blade and the miter slot (with one notable exception) does not support the idea that errors in blade/slot alignment can cause inaccurate miter cuts. Ignoring issues of safety and stock burning for the moment, the only problem that a slight deviation in blade/miter slot alignment will cause will be a wider kerf. This can be most easily explained using a router table as the example. How do you align a router bit parallel with the miter slot? You can’t, yet it is possible to make miter cuts on a router table (not the recommended tool for the job, but still possible). If the miter gauge is square to the router table’s miter slot, the mitered cuts will be accurate-same for the table saw.

   <!----><!----> <!---->

   I have proven the dynamics of the blade/miter slot interaction to my satisfaction by first aligning the blade to within .002 to the slot, aligning the miter gauge to the slot, and then checking the alignment with the 5-cut method. I then changed the blade’s alignment to the miter slot to an error of .010, left the miter gauge settings untouched, and repeated the 5-cut method. The results in the accuracy of the cuts were identical. There is one notable exception that I alluded to earlier. If the saw blade is way out of alignment to the miter slot, then the blade could cause some deflection in the stock that would have an impact on the accuracy of the mitered cut.

1. 
   JohnWW | Jun 10, 2008 05:39pm | #8

   "If the saw blade is way out of alignment to the miter slot, then the blade could cause some deflection in the stock that would have an impact on the accuracy of the mitered cut."Exactly my point.John W.

1. 
   zolton | Jun 10, 2008 05:54pm | #9

   "If the saw blade is way out of alignment to the miter slot, then the blade could cause some deflection in the stock that would have an impact on the accuracy of the mitered cut."

   Exactly my point.

   John W."

   And exactly my experience. Not to mention burning..

   ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

2. 
   GW52 | Jun 13, 2008 10:26pm | #18

   John,

   Maybe I am not seeing something. If you take a drawing square, set it against the blade and then have the 90 degree leg on the miter guage, would this not produce a square cut?

   Greg

2. 
   HowardAcheson | Jun 13, 2008 12:34am | #14

   John, I have to differ with you. If a blade is out of parallel with the miter slot, all that will happen is that the kerf will be wider and the cut may not be as clean. If the miter gauge is perfectly perpendicular to the miter slot, the cut will still be square. Of course, this assumes that the board is not creeping along the miter gauge face.Howie.........

3. 
   PlaneAround | Jun 15, 2008 02:19am | #21

   Howard, I would suggest that if the blade isn't running parallel to the mitre gauge slot, and most particularly if its "toe" (outfeed end) is closer to the side the mitre gauge is sliding along, there will be a tendency for the wood being crosscut to be pushed away ever so slightly away from the blade as the cut proceedes. This will result in an incorrect crosscut, even with a mitre gauge set to precisely 90 degrees. It will also result in burnishing or burning, because the side of the teeth are thus being relied upon to do some of the cutting. On the other hand, if the blade has its "heel" (infeed end) closer to the mitre gauge side, the cut will be 90 degrees, however under close examination there will be a concavity to the cut face. The smaller the blade, the more pronounced this effect will be. The above assumes one is using a mitre gauge that runs in the mitre gauge slots of the saw. With the ever increasing popularity of slider tables and systems such as Jessum's Mast-R-Slide that don't slide in the mitre gauge slots, their set-up is greatly simplified if one trues up the table's left-side face with the blade. The reason for this is that these devices affix to the machine along that side of the tabletop. Getting back to your comment, for precision work, most especially in very hard woods, there's nothing like having ones table saw truly tuned correctly. And that includes ensuring the mitre gauge slots are in line with the blades. Please excuse my excessive fanatacism for precision in setting up tools, however I've found that such investments in time reap considerable dividends in the long run.Marty Schlosser
   martyswoodworking.ca

4. 
   BrianDerr | Jun 09, 2008 08:30am | #5

   Sounds like a problem I had recently. I was triming the ends of face frame members or something on my crosscut sled which had been very, very accurate up to this point. All of a sudden I couldn't get a square cut. I started to second guess the sled and readjusted the fence back and forth for what seemed like half and hour. I'm not sure how I realized this but the problem turned out to be a dull blade. When taking less than a full kerf off the end of a board, the dull blade had a strong tendency to deflect and avoid the hard wood. It would start out trying to cut for the first inch and then not be able to hang for the rest of the crosscut. Not a particularly thin blade, either, but the thickest I want to run on my 120V saw.

   Brian

1. 
   dustup | Jun 14, 2008 06:14am | #19

   Brian,Just thought I would let you know, A new blade did the trick. Thanks, I would never have thought of that. Actually the meter gauge itself was off a bit. But even after correcting that, the cuts were still less than perfect. When I changed out the blade, I was suddenly on the money every cut!

1. 
   BrianDerr | Jun 14, 2008 09:34am | #20

   Whew! thought you would never say so! It just sounded too much like my own experience not to post. Thanks for letting me know. You've definately sparked some discussion with this thread, though. John's point about the blade not parallel to miter slot NOT affecting squareness of cuts was a good reminder for me. That's kinda my theory about bandsaw 'drift'.Brian

5. 
   WillGeorge | Jun 12, 2008 03:06pm | #13

   What to try next .. I would just ask if you changed to  a thin cerf blade?

6. 
   mike4244 | Jun 13, 2008 08:36pm | #17

   Try this to square your miter gauge if it is the problem.

   Loosen the lock knob a bit, turn miter gauge upside down, push into the slot. Push the head up to the table and then lock the knob. The front or the back of the table and the miter slots are square to each other ,even in the cheap benchtops I have found.If the gauge is square to the slots you should get square cuts,even if the blade is out of square to the miter slots. If this is the case correct it, otherwise the least of your problems would be burning of the stock.The worst would be a kickback.

   My own saw cannot be accessed to the slot the way I described. In the front the rail is in the way, the back the outfeed table is in the way. I solved this routing accurate slots in mdf for a squaring template. One slot is for 90° another for a true 45°.

   mike