dusty wrote:Ed in Tampa,
Is this the Magna-Set that you have? If it is, when you have used it successfully would you please post details of your efforts. I have recently discovered that I have one. I found it amongst my horde of things I couldn't do without, still wrapped in its original cellophane wrapper. So far, it hasn't helped improve alignment. Documentation that came with it promises successful adjustment in just minutes.
http://www.woodcraft.com/family.aspx?FamilyID=908
Earlier in this thread, there was some discussion about height of the outfeed table with respect to cutter blade. Use of the Magna-Set would imply that the blades should be the same height as the outfeed table (+/- .002"). This seems consistent with what others have reported.
Dusty
That link is it. I used something identical to this when I was shown how to sharpen and adjust jointer and planner knives. I thought the instructor had built his jig but years later I saw the one Shopsmith offered it and I bought one.
As I previously reported I was instructed to adjust the blades perfectly even with the out feed table (although the outfeed table was adjustable and we did sometimes tweak it after the initial adjustment).
I can understand setting them slightly proud of the table surface as Nick explained to compensate for spring back.
As the wood is being cut there would be a certain amount of compression of the wood at the cut line at the instant the blade is at it's highest and making the cut. The wood would then immdiately spring back and end up slighly lower than the blade. If the blade was exactly even with the table this spring back could cause the wood which is lower than the blade at this point to snag on the table.
However I think the problem is declaring that spring back to be "X" thickness. I would suspect that each wood would react differently and the only way to compensate for this would be to set the blade slightly proud of the table. Then the question becomes how much is slightly proud, I would think it would be somewhere between 0 and 0+.
My way of thinking about things is to toss the dial indicator. From watching old tool makers use dial indicators I learned they often spent more time insuring the measuring point never changed than they did actually measuring.
Everytime I pick up the dial indicator to measure something on my SS I find that hand pressure, a slight location change, and my poor rigging of the dial indicator introduced more error than I want to figure out how to remove.
Think about it, the wood fiber fuzz on the bottom of the jig could introduce as much as .001 error depending on which way you moved the jig last. Then consider the effects of varying hand pressure holding the jig, dust, location of the jig on the bed, and etc. When your measuring in .001 you must have a reference point (standard) that is uneffected by any changes at all.
I think the Power Tool Wood Working for Everyone book probably comes the closest to the correct slightly proud measurement by insuring the blades rub a test piece of wood.
While I haven't used "my" Magna Set guage, I have no doubt it will work as well as the one I used before. And yes it sets the blades height to be even with the outfeed table as best I can determine.
Frankly I would think a better way to adjust the table should you really want an .002 difference would be to use the magna set (or something similar) set up on the infeed table that is adjusted EXACTLY .002 above the outfeed and the adjustment is left there until the measurement is finished. That way the infeed table reference would never change, it would be polished metal to polished metal and little or no chance of introducing an variation in the reference point (standard).
Ed