When testing the operation of my Craftsman 4-1/8" jointer/planer (model #21789), I noticed immediately that the cut along the length of a board resulted in a curved edge rather than a perfectly straight edge. I had already verified that the in-feed and out-feed table surfaces were parallel by laying a steel straight edge along them, and I knew I was feeding the wood properly. The only way to get a straight, even cut was to press down really hard on the wood as it passed over the cutter head - a really dangerous practice since a slip could cause my hand to fall into the cutters. What was happening didn't make sense because theoretically the cutter head removes material at a thickness equal to the difference between the in-feed and out-feed table heights (see drawing below).
Laying a straight edge on the out-feed table and rotating the cutter head to position one of the blades at its highest point showed that my Craftsman jointer/planer came from the factory with the cutter head a little below the out-feed table height. That fully explained the behavior. Since the blade was not removing enough material, the output and input sides of the wood were not riding parallel to the tables. The solution was to adjust the out-feed table height to be slightly below the height of the cutter head blades, as shown in the photo below.
The cutter head is fixed in height relative to the out-feed table, so it was necessary to remove the out-feed table to lower it; the height of the in-feed table has no effect on this phenomenon. I removed the three hold-down bolts from the in-feed table, removed it, and discovered a metal shim under each of the three support points. Hoping they were the cause, I removed them and reinstalled the out-feed table (see photo below). Amazingly, it was still slightly too high. It was clearly necessary to remove material from the support points. Fortunately, the metal chassis casting is made of a fairly soft alloy so a metal file easily removed enough material to move the out-feed table down to the point where the cutter head blades were about a paper thickness higher than the table (see photo above). If too much material is removed, you can easily add some shim thickness back.
In fact, after the first attempt at setting the out-feed table height, I discovered that the wood was getting a 'sniped' area at the very end. The cause was that now the cutter head was a little too much higher than the out-feed table because I removed too much metal from the supports (see drawing below). The factory shims were too thick, so I ended up using three layers of metal foil duct tape under the table support closest to the cutter head to get it right. Now I am getting absolutely perfect planing action. The entire process took about half an hour - time well spent!
I have to admit that as much as I like Craftsman tools, there have been an increasing number of issues with them as received from the factory. Internet forums are full of examples if you do a search. Yes, all brands have problems, but over four decades of woodworking and metal working I have owned many, many Craftsman hand tools (powered and unpowered) and shop tools (radial arm saw, table saw, lathe, band saw, drill press, belt/disc sander, jointer/planer, jig saw, grinder, etc.) and it seems to me the quality is ebbing. Maybe it is due to everything being built by Chinese slave labor where the concept of quality is not a cultural thing. Most workers there cannot afford to own and use the tools they build, so there is no accumulated experience of what does and does not make for a quality, dependable tool.
March 5, 2016 Update:
Upon further use of the jointer, I noticed that the input and output feed table surfaces were not in exactly in the same plane, causing the work piece to not be square even when the vertical fence was squared with the output feed table surface. A visual check showed that the output feed table was parallel to the cutter blades, so the input feed table needed adjustment. Fortunately, Craftsman provides a means to make it.
When you remove the input feed table, you will see that two of the three table support points are are threaded and adjustable. Set screws lock them in place. All that was needed was to turn them until the input table surface was parallel to the output table surface and then tighten the lock screws. Make sure while doing this that the correct input/output feed table alignment per the above original information is retained.
Posted January 3, 2016