Main Table Alignment

[dusty]

The image used in this thread depicts the main table that I use but the proposed jig could be adapted to any Shopsmith table.

There has been a lot of discussion lately about aligning the Shopsmith table and rip fence. There have been several different methods for doing this mentioned. All of the methods, if employed properly, give good results. I myself have successfully used a few different methods but in so doing I have developed what I believe is a totally acceptable alternative.

I use the proposed jig on a very regular basis to "verify" table alignment before I begin a project.

To make the work, it simply needs to be cut to the dimensions that are appropriate for your table configuration.

Alignment Gauge for 520 Table and Maybe Fence.png (271.87 KiB) Viewed 2053 times

[dusty]

The same jig can be used to align the fence.

[reible]

This would give you a close alignment based on your last alignment. I'm not sure that all the givens don't add up to being more then .005" off. It would have to be a blade that is flat, current alignment you use the same tooth to check on each in the in feed and the out feed, in your case you are depending on a cut which involves all the teeth so if one tooth is out farther then all the rest then it is providing the outside edge of the cut...... that tooth can be any where on the next alignment.... below the table, at the in feed or out feed location, an unknown.

You would need to select a stable material for the jig, movement is not uniform in wood so it would need to be plywood or mdf or some stable plastic, so this it do-able.

The next issue is how are you going to make sure it is just "kissing" the blade and not exerting force on it, any force is likely to cause some flex in the tooth on the blade and again it is not going to be uniform.

You would pretty much need to dedicate a blade to just this function, use of the blade can or at least could cause it to be different then it was when you first started. When we cut things to a duplicated size a small error of a few thousands is not a concern because wood is/was a live element but for doing alignment those numbers count.

I'll have to think on this some more, it has liabilities and advantages but who wins I'm not sure.

Ed

[dusty]

Please do give it some thought. Your opinions are important.

It might be of interest to know that I have been using this type jig for about a year (prior to my medical leave).

I did cut the jig, as you suggest, immediately after performing an alignment the "normal way". I use it with any blade that happens to be mounterd and yes, you must just kiss the blade with the jig so as to not impart error. My jig is made with a good grade of plywood (not baltic birch as it probably should be).

When I first did this, I likened it to using the miter gauge and stop rod to perform the table alignment. I just replaced those with a piece of wood. Back in those days I did not even own a dial indicator so I don't know how many thousandths I was off.

How close to perfect do we really need to get. I suppose that sounds strange, coming from me but that is now how I am seeing this precision alignment thing.

[reubenjames]

One thing I'll note, which Ed alluded to, when I was doing my alignment last night from the miter tracks to the saw blade, though I was .003" off from same spot rotated infeed to outfeed, I did also use the dial indicator to check the blade itself for flatness: it was not flat. The particular blade I was using was convex in the center, probably only .008" or so, not enough to concern me, but depending on the flatness of your blade (or lack thereof), you could get a false negative on that jig, where it looks like it's not touching the infeed or outfeed side due to alignment, when it could be due to blade inconsistencies.

When I saw that, I immediately thought back to some of the users who mentioned, in my high speed steel blade dilemma thread, that some of the sharpening shops will check for and correct discrepancies in the blade bodies like that (or at least that's what I think they meant by flatness of the blade).

[reubenjames]

As you stated that this was for verification, I think I like this jig for a quick-and-dirty verification. I don't think I'd align to it, though, but you didn't make it seem like you were doing that, either.

[Gene Howe]

When aligning the fence, if the flat steel sanding disk is used, teeth don't matter.
Works for me.

[reubenjames]

Per my manual, even the sanding discs can have a high spot--the alignment instructions, by the book, have you find and mark the high spot (and have you use or navigate around it during alignment). The disc *might* be "flat" but that doesn't mean the disc is perfectly perpendicular to its own spindle.

Also, I don't think they typically are perfectly flat, since a sanding operation is moving at high enough speed that the sander can still sand flat, even without the disc itself being perfectly flat. You'll get slightly more wear on the high spot, though maybe not noticeable. The high spot is noticeable during alignment, however.

[JPG]

Per my manual, even the sanding discs can have a high spot--the alignment instructions, by the book, have you find and mark the high spot (and have you use or navigate around it during alignment). The disc *might* be "flat" but that doesn't mean the disc is perfectly perpendicular to its own spindle.

Also, I don't think they typically are perfectly flat, since a sanding operation is moving at high enough speed that the sander can still sand flat, even without the disc itself being perfectly flat. You'll get slightly more wear on the high spot, though maybe not noticeable. The high spot is noticeable during alignment, however.

If you are 'using' a 'high' spot, the disk need not be perpendicular. Indeed the existence of a 'high' spot implies it is not nor is it flat.

[dusty]

As you stated that this was for verification, I think I like this jig for a quick-and-dirty verification. I don't think I'd align to it, though, but you didn't make it seem like you were doing that, either.

Aaah but I do align to it. I did so for almost a year. During that time I would periodically verify alignment by using the dial indicator. This jig has worked well for me and I will continue to use it.

I have come to believe that we make far too much of precision when doing alignments in the wood shop.

I was told that by several, here on the forum, over the past few years. I have come to believe that they were right. Dial gauges and Starrett Rulers and straight edges are not really needed in a typical home work shop. They are nice to have but are not really needed.

If you disagree, so be it but please tell me how a .005" (or even .015") misalignment of the main table miter slots to blade or fence to blade will adversely effect performance in the shop.