Adjusting Blade/Miter Groove Alignment on 1950's Craftsman Table

The most important thing is that the blade and riving knife are centered with each other. If not, you may have to shim the riving knife.

The bolts that hold the carriage under the table are intentionally sloppy so that you can loosen them and align the blade/knife with the miter gauge slots.
Lay a long metal straight edge against the side of a carbide blade teeth with the blade all the way up, and make sure the straight edge is parallel with the miter gauge slots in the table. Then tighten the bolts on the underside.

Do an online search for "table saw tune up" and sort through the articles to find one that gives detailed instructions on how to check for blade runout and how to test blade alignment with the table top. Here's one that covers the basics quickly and concisely, but there are many to choose from. Compare them with information from your powermtic user's guide.
It's a laborious process that will take a day or two and you need to loosen the bolts that fasten the saw trunnions/ mechanism to the cast top, and physically shift the alignment of the saw arbor relative to the mitre slots, then recheck it for alignment, etc. until you get it right. Sometimes you can loosen several corners and leave one kind of tight to shift the saw in the direction you want to move. Download the online manual from powermatic here by choosing your model and you'll have onhand a detailed parts diagram to guide you. If you're not up to a gruelling process, and don't have the appropriate tools, I recommend you re-check your blade to ensure it's not at fault and see if you can't live with it as is.
Otherwise, good luck and be patient. It's worth it to have it right, but wood is only wood, and at some point you have to just do the woodworking.

I hope this information allows you to resolve this issue. If you need further assistance, please post back with a comment to this thread.
If I've managed to answer your question or solve a problem, please take just a moment to rate this post....thanks!

I'm betting that the table isn't square to the blade. My Cabinet Makers Table Saw does the same thing - the top plate (the big heavy cast iron plate that weighs about 50 pounds) sits on top of the sheet metal box that houses the motor and motor lift. This cast iron plate is held onto the sheet metal box by 3 screws (usually).

Loosen the 3 screws and the cast iron plate can move around on top of the sheet metal box (the holes for the screws are large enough to allow 1/8 inch movement). Looking down from the top, you can rotate the cast iron plate clockwise and it will move the front of the blade closer to the fence and the back of the blade away from the fence. Counter-clockwise does the opposite.

For the best adjustment, use a dial indicator mounted to something that slides in the track of the table top. Position the dial indicator agains the blade and slide it back and forth in the track of the table top. This will accurately set the table top to the blad (so they are parallel within 0.0005 inches).

Then check the accuracy of your fence (sounds like this is good). Don't forget to check the alignment of your riving knife/guard & splitter to the blade (if it's off you can't feed wood because it will hit the splitter).

Instruction manual for your saw is here. See Page 21. You need to adjust your blade alignment to the miter slots. As mentioned in the manual, there are a couple bolts that hold the rear trunnion in place. Loosen them up, shift the motor a bit (not an easy task). Keep checking blade alignment until you've got it down.

There are after market trunnion alignment kits for table saws that make this a bit easier. Check out PALS (Precision Alignment & Locking System). For $20 or so, it makes the process MUCH MUCH easier.

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I assume that your alignment procedure is about adjusting your miter gage. But you should first verify if the blade is parallel to the miter slot (the slot the miter gage slides in). This is adjustable underneath the saw, and sometimes comes crooked from the factory or comes loose later on. To check if the blade is parallel to the miter slot you can do this.....1. unplug the saw. 2. Raise the blade as far as it will go. 3. Clamp a piece of wood to your miter gage so that it just touches the blade as close to the front of the saw as possible. 4. Use a marker and mark that spot on the blade. 5. Now slide the miter toward the back of the saw, and rotate the blade by hand so that your piece of wood hits the same spot as where you checked in the front. You can see a large misalignment by eye. But you can get a little precise by using a piece of paper between the wood and the blade as a feeler gage. Or better yet, use a drop indicator instead of the piece of wood and you can measure the difference. If this isn't as close to parallel as you are able to measure it, you need to turn the saw over and find the bolts that attach the whole assembly under there to the table top. Once you have this in alignment, you should be able to set your miter to be square against any good square. If you don't have a high quality square, you can go to a tool store (Sears or whoever) with your miter gage in hand, and set it to be square against their most expensive square. If the square is square, and the blade is parallel to the slot and it still won't cut square you either have a bad blade or there is too much play in the saw's arbor. Try to wiggle the blade side-to-side - any wiggle at all is too much.

To be that far out of alignment, there must be something loose. Unplug it, turn it over and look for what it is. If you have a drop-indicator gage, and you can clamp it to your sliding miter gage, it will help you get the alignment dead-on. Slide the miter gage toward the front and back in the slot with the tip of the indicator in contact with the blade. Have the the blade at fully elevated postion. If you don't have such a gage, you can clamp a piece of wood to the miter gage to get pretty close. You will probably have to do this with the saw laying on it's backside so that the top and the bottom are accessible at the same time.

Here's the owner's manual
http://www.hitachipowertools.com/product/files/saws/table_saws/C10RA3_OM.pdf

Here's the parts list with an exploded view
http://www.hitachipowertools.com/product/files/saws/table_saws/C10RA3_Breakdown.pdf

Either take it back, or take it apart and make the holes bigger. For that kind of money, you should be able to adjust it dead-on. I thought I had the same problem on an old Craftsman, but I found that I just hadn't loosened things up enough. It's hard to see how much wiggle room you really have under the washers. And if there are aluminum castings involved, there can be a burr raised by the initial setting that it gets stuck on.

The Blade Arbor is held to the bottom of the table with mounting screws and stop/adjusting screws. Loosen the mounting screw and adjust the stop screws to make Blade true with miter slot.

ok yep your blade is out of alignment with the fence. It is closer to the fence at the rear than the front. You need to make the modification or adjustment to your fence, if it allows that, and then worry about the miter slots later (which should be adjusted miter slot to blade, not miter slot to fence). You might be able to adjust the miter slot to blade by moving the actual table and then securing witht he table mount bolts. Check your manual for how to align the fence.

You do want to fix that though as it can be potentially dangerous and result in kickback of the workpiece which is a rather SCARY thing, and very dangerous.