Main Table Alignment

[dusty]

When doing a Main Table Alignment, the primary objective is to set the miter tracks parallel to the saw blade.

As a secondary objective:

Does anyone endeavor to also set the table so that the blade is in the center of the table cutout (table insert)?

[reubenjames]

X axis or Z axis?

[dusty]

X axis or Z axis?

The answer to your question is the X axis.

The table does not facilitate alignment to center on the z axis. However, I do take note of table position in that axis. It is not important for saw operations. That axis does come into play when you go to the drill press mode.

On my table when aligned the way I want it, the drill meets the table 9" from the rear of the table. Table movement during alignment does not allow much deviation and what it does allow is of no consequence.

I have a separate table insert for use in drill press mode. It is 3/4" thick and has the center point marked because I have drilled into it.

[reubenjames]

I usually center it manually when I am just dropping the table down. Some of my third party arbors are slightly different lengths, so it would only be centered for whichever ones matched the one I based it off of. Ultimately, though, while it would be nice to slide it right up against the bumper and have it be centered without thinking about it, I don't find eyeballing it to center to be overly cumbersome. Plus, I'm often aligning it slightly left or right (or extending the quill) to deal with thin cuts on the waste side that I don't want to drop through. I don't have zero clearance inserts for all my blades, and I don't have one installed all the time. That is my fault, and something I could rectify, but the ability to easily adjust the position is easy enough for me.

[charlese]

Why would a person be concerned about exact centering? Did anyone actually do such measuring? What measure would one use? Thousandths inches?

I worked for a year or two without a rubber bumper.

[dusty]

Why would a person be concerned about exact centering? Did anyone actually do such measuring? What measure would one use? Thousandths inches?

I worked for a year or two without a rubber bumper.

You ask me such question, Charlese???

I center it because I think it should be that way. Yes, I actually measure it to make certain that it is centered. The table cutout is 3 1/64" wide. I center it to 3" as measured from both sides and if it is not 1 1/2" (and it won't be because of the blade) from each side I do what I can to make it that way.

And now I have to ask...Why did you bother to purchase the rubber bumper after working successfully without it for so long? Don't answer that. It is, after all, a rhetorical question.

[JPG]

I presume +x is straight out from the quill towards the tailstock.

I presume +y is towards the rear(away from the 'operator' position.

z is irrelevant.

Answer to the question - never in over 50 years. Plastic bumper is 'close enough'. Manual quill adjustments when required.

ZCI? Rarely.

[reubenjames]

In my mind X is quill to tail stock, Y is floor to ceiling, z is front to rear. Z axis is usually toward/away from POV. Anyway that is how I was intending in my question.

[reible]

I see a few issues here. First and foremost is we do not have access to design data from shopsmith. So what is right or wrong or centered or not we don't know.

Seeing as how we don't know and they don't give us a hint as to needing to center the blade in the slot I'd say it doesn't matter. The holes on the table used to move it for adjustment will give it some range, my guess is that range is small and thus the possible locations of the blade are with in some small range. So long as all the parts meet specification the design is robust enough to work.

Now if we were to really want to center the blade we would have to ask what blade? There are thin kerf and then are standard kerf so if you want both of these to be centered then you will have to adjust for each one. Why? Well the normal set up is with the quill not extended and against the rubber bumper. A saw arbor mounts to that and the headstock side of that is a control surface or if you will datum. The width of the blade then extends from there. A wider kerf blade extends farther then a thin kerf and the centers will move depending on which blade is used.

If you happen to a zci user and I am, if you happen to use a regular width blade in a thin kerf zci it always trims to the out side, away from the head stock.

Given one could attempt to find the center of a blade and align to it but only if the prime directive is taken care of first. That being the table aligned to the blade. Then if there is some wiggle room to move the table in that axes it could be done. My guess is that it a very small window and with manufacturing tolerances it may not some thing that every set of hardware is able to to do. The are "conditions" called MMC's maximum/minimum material conditions and if you end up on one end or the other with the parts it might meet all other requirements but unless the centering of the blade is a requirement it might not meet that.

At this point other then as a point of discussion I don't see any need to make this a requirement for my alignments.

Ed

[dusty]

Ed, even if we had access to design data we would not necessarily know "right" or "wrong". We might know, at best, what some engineer along the way thought was right.

You are correct, however, in every thing you said in your response.

In that regard, I do not center the blade. I use the left hand face of the blade for the datum. The left hand side of the blade is located by the arbor and how the arbor is attached to the headstock. It is more or less in a fixed position. A major assumption being that the quill is fully retracted for ALL alignment procedures.