Likewise, there has always been significant discussion about how to get to a properly aligned machine. Most have found a way that suits themselves. Some have not.
As a starter in this effort, it is necessary that the carriage (which carries the table) and the headstock (which positions the blade) are in proper position too achieve that relationship. By design, the rubber bumper makes that relationship relatively easy to achieve. Simply push the carriage and the headstock together until both contact the rubber bumper. Of course, if you have no rubber bumper installed, this condition is difficult to achieve.
On my machines which are both 510s, my rubber bumpers measure 1 3/8" (1.375"). This is what that mating looks like.
- Headstock and Carriage Contact Rubber Bumper
- 20201031_091324 (1).jpg (319.65 KiB) Viewed 1440 times
Proper alignment being (in part) the saw blade parrallel to miter track and nearly centered in the table cutout.
The sketch presented earlier in this thread depicts what I believe the table, blade and insert should look like under these conditions.
A different look at this.
- 20201030_114543.jpg (195.27 KiB) Viewed 1317 times
I have bumpers both wider and narrower than the one referred to here. Not surprisingly, if I use them my blade will end up slightly to the left (for wider) or a good bit to the right (narrower) of center. Neither one prevents me from putting the blade in the center of the opening, if that's what I want to do. Or aligning the left side of the blade with the table legs. But neither really helps me to do either of those things either. The only thing mine do is provide some degree of certainty that with quill fully retracted while headstock and carriage are in contact with the bumper I ought to be able to lower the table over a saw blade without interference. Are these bumpers 'close enough?' To me the answer is yes, because their key parameter has nothing in common with any key parameter that I know about in alignment. I agree with the zip code analogy.