With respect to shimstock, as mentioned in the earlier thread many hobby shops and Ace stores sell brass shim stock in a small set that typically includes 0.001", 0.002" 0.003", 0.004" and 0.005" sheets. Lee Valley also sells an assorted kit if you wish to go mail-order.
First thing that you should verify, since all measurements are relative to this: Have you verified that your new 48" straight-edge is, in fact, straight. I know we expect new things to be perfect, but precision straightedges can become distorted from improper packaging and rough handling in shipping. It pays to verify that it is in fact perfectly straight -- you paid good money for it -- or you will really wind up pulling your hair out trying to make sense of paradoxical measurements, so go ahead and take a moment to double-check before proceeding.
I am assuming that all your positive values are really negatives (i.e. low spots) rather than positives (high spots) since your other values make no sense the other way around.
Error of nearly 0.01" (or 10 mils) is more than enough to cause aggravation at the jointer. What troubles me is the fact that your measurements with respect to the left-hand side of the infeed table are paradoxical (I'm not terribly concerned with the minor depressions mid-table). If the measurements are correct (and the straigtedge is indeed straight) then I need you to use a small (but accurate) straightedge to measure the table front-to-back at the left, middle, and right ends to search for severe localized depressions that might explain your readings.
The pardox is that you show measurements for the infeed table that show 0.000" at each end with a modest depression mid-table for both the front and back sides of the infeed table. However, when you repeat this same measurement spanning both infeed and outfeed tables you are showing a 0.006" low spot to the rear of the infeed (left side) but a 0.010" low spot to the front of the infeed table (again, left side). If your earlier measurements are correct then these two values should essentially be identical to within +/- 0.001" . Before we start shimming we need to account for the 0.004" discrepency
Please investigate the source of the 0.004" discrepency (are you measuring a localized depression, is the table twisted, etc.) before we proceed with shimming. Please chart this out and I will try to provide you with more specific instructions on where and how much to shim by -- or go ahead and give it a try yourself and let us know how it goes. I really wish you lived nearby (I'm in Anderson, SC) or I'd offer to help you get your jointer properly setup -- the process is much smoother once you've been through the process several times. Also try to chart the offset to each end of the cutterhead at top-dead-center.
Your measurements do not include such, but in addition to shimming the tables to bring them coplanar with one another we must also ensure that the front and back sides of the cutterhead (or its knives, depending on how you setup your knives) are also even with the infeed and outfeed tables when all is complete. We want to aim for no more than 0.001" error over the length of the knives/cutterhead. Depending upon the results of your shimming the table(s) it is not uncommon to also need to shim the cutterhead itself to bring the knives/cutterhead perfectly even with the freshly adjusted tables.
Although this is generally a one-time operation (or at least once in a very long time) you will need to double-check coplanarity whenever you move the jointer or whenever you encounter issues that suggest coplanarity issues. Once everything is setup, make it a point never to 'lift' the jointer by its infeed and/or outfeed table and avoid placing heavy weight towards the outer ends of either table as these actions can alter the way the tables and their dovetailed ways mesh. If you ever do encounter errors after such an action, first try raising and lowering the tables to see if this reseats them (and spares you re-shimming them). If that fails, try loosening the affected table(s) gib screws, then retighten them and check again. With luck this will reseat things back to the way they were and spare you having to reshim the jointer.
TIP: When installing shims, bend about 1/4" of the shim's length at a right angle to serve as an insertion and removal tab. Once a shim is placed in the gap between the table and the main body (the dovetailed ways) it is very difficult to remove them without this tab. The tab ensures that the shim does not get drawn fully into the gap and also makes it easy to locate the shims and readily identify which corner(s) you have shimmed.
Also, given the choice it is generally better to focus on shimming the outfeed table such that it is coplanar with the infeed table. Because the outfeed table is seldom adjusted for height (typically only very minor height adjustments after knife changes), shims installed in the outfeed table will be subjected to considerably less wear and tear and are also less prone to falling out (from height adjustments). In most instances it is possible to install most, if not all, your shims on the outfeed table -- just put yourself in the mindset that the infeed table is "flat" and think what adjustments (shimming) you would need to do to bring the outfeed table into that same plane -- keeping in mind that you can easily raise and lower the outfeed table with the height adjuster. Install the shims on whatever side or end requires raising (i.e. the low side/end) to bring it coplanar ... if the high end is too high, use the table height adjuster to bring the high-side even with the infeed table.
HTH
