More on blade squaring
Original Question :
THE ONE PROBLEM I HAVE WITH MY DEWALT AND IT IS NOT A PROBLEM MENTIONED IN ANY ALIGNMENT PROCEDURES, IS THE FRONT TO BACK BLADE ALIGNMENT. MY DEWALT DOES NOT HAVE AN ADJUSTMENTS FOR SQUARING THE BLADE TO THE TABLE FRONT TO BACK. MY SAW WAS ABOUT 3/8" OUT(REAR OF TABLE LOW). TO SQUARE THE BLADE, I REMOVED THE REAR TABLE SUPPORT, SHIMED UP THE REAR OF THE TABLE, AND CLAMPED THE REAR OF THE TABLE TO THE MAIN FRAME. THIS HAS HELD FOR SEVERAL YEARS. I CANNOT TILT THE TABLE BY I DO NOT HAVE A NEED TO DO SO. HAVE YOU HEARD OF ANY REPAIR OR FIX FOR THIS PROBLEM? I HAVE TALKED TO SOME DEWALT SERVICE REPS AND THEY ALL TELL ME TO TAKE IT INTO A SERVICE CENTER. AS OF NOW, THIS IS NOT AN OPTION.
Very very few people I have ever heard of try to align the front to back. That is just the way the saw is designed and seems to not make a lot of difference in the cut. If you feel good about doing it then I guess it must be good for you.
I MUST BE MISSING SOMETHING. IF IT IS IMPORTANT TO SQUARE THE BLADE LEFT AND RIGHT WITH THE TABLE, WHY IS IT NOT JUST IMPORTANT TO SQUARE THE BLADE FORE AND AFT? IF THE BLADE IS NOT SQUARE FORE AND AFT, THEN THE BLADE WILL CUT DEEPER ON TOP THAN ON THE BOTTOM OR VISA VERSA AS YOU ARE FEEDING THE WOOD INTO THE BLADE. IF CUTTING THICK WOOD OR STACK CUTTING, THE RESULTS WILL BE THE SAME AS IF THE BLADE WAS NOT SQUARE LEFT/RIGHT. CAN YOU SHED SOME LIGHT ON THIS?
If you cut into a piece of wood and look at the cut that is made after you come to a stop. The final cut will be almost perfect square front to back.
The blade does not travel a perfect square to the table movement, it oscillates. So at one point in the stroke it is top too far forward, yet in another part of the stroke it is too far back. Averaging the two out it leaves a cut that is close to square.
Look at the blade from the side and turn the motor over very slowly and watch the blade movement, it does not travel straight up and down. Set up you dial caliper on the blade if you want to check the real accuracy of front to back movement if you want. Trying to get the accuracy you want be sure to check it at the table height, and then again at the height off the table equal to the thickness of the wood you are going to cut. It will make a difference in the measurements. The only saw on the market that does run square through the whole stroke is the Eclipse.
If you want to get to measuring thousandths of an inch difference you can, but most scrollers are not that accurate when they cut, normally a 1/64/ to 1/32 inch is close enough.
Another thought on the rest of you question. You cut with the blade cuts from the front, so the left right affects the cut. Like setting a table saw at 10 degrees and trying to get it to cut square by cranking the height up and down throughout your cut. The far left side of the blade is going to cut the left side of your kerf, If your blade is at a angle, left to right, still the fartherest left part that comes into contact with the wood is what is going to cut.
The forward and aft is just blade movement, you have to look at the arc of the swing of the blade in it complete stroke of the blade. When the arc changes throughout the stroke you cannot define where the measurement needs to be taken from.