Shopnotes Vol. 20 Issue 115 Expanding Table

[pugetsoundwa]

So glad you posted this. I have yet to buy a ShopSmith as tax refund isn't back but I do like the idea of a expanding work table. Glad I saw this thread before I went out and bough a work table. Please keep us informed and post a photo or two.

[greitz]

Michael- from the Jointers section of the online PTWFE:

At the end of the cut, the hands are still in about the same position on the stock. Avoid heavy downward pressure at the end of the cut, since this might tilt the stock into the cutter, resulting in a gouged end.

The link is

http://www.shopsmith.com/academy/jointers/index.htm


Gary

[charlese]

Also check the alignment of the infeed and outfeed tables. They should be level. I believe you can only adjust the infeed table to align with the outfeed table.

[wannabewoodworker]

If I remember last year when I redid my jointer with everything else I did go through the alignments on it but I will definitely recheck all of those again before trying to joint another piece. The comment about downward pressure is something I noticed on my first few attempts on scrap pieces. So I intentionally put extra pressure on the outfeed table side of the piece but still got gouging. So again I think I will revisit this as soon as I get a day when it isn't freezing outside as I have no heat in my garage. I am also going to go back and read the jointers manual again. Thanks for all the advice and feedback.

[JPG]

Trailing end snipe! An indication of lack of alignment of the tables and the blades. Caused by the workpiece reaching the end of the infeed table and dropping down into the blade slightly further.

Check that the infeed and outfeed tables are coplaner when feed depth is 0. A straight edge should maintain contact with both tables regardless of where the straight edge is positioned. This contact is constant all along he straight edge. I will assume at this point that the 'check' was successful.

Once the table alignment is confirmed, blade alignment is next. With a straight edge hanging over the blades from the outfeed table, determine that the blades at their highest point just contact the straight edge. It is best to use a known straight piece of wood so as to not dull the blade. The height must be checked at both ends of all three blades.

Once the blades are aligned to the outfeed table, all that remains is operator technique.

The difficult thing about feeding a workpiece through a jointer pass is maintaining proper amount and direction of force applied to the workpiece. Consider what must take place. The workpiece must maintain flat contact with 1) the infeed table 2) the fence 3)the outfeed table 4) All the while the workpiece must be moved past the blades. Not a simple task at all! Attention must be held to ALL those 'details' ALL the time.

If the blades are 'low' the workpiece will snag as it contacts the outfeed table. This results in a possibility of leading end snipe.

If the blades are 'high' the workpiece will drop as it leaves the infeed table. This results in a possibility of trailing end snipe. This also results in the possibility of the workpiece not setting flat on the outfeed table and at some point 'teeter tottering' resulting in two non coincident surfaces 'jointed'. Teeter tottering is to be avoided at the end of the pass as has already been mentioned.

So as you approach the blades with the workpiece, contact with the infeed table(downward pressure) AND simultaneous side pressure against the fence(side pressure to maintain contact at both the top and bottom of the vertical face of the workpiece) must be maintained as the workpiece is also pushed towards the blades.

That contact must be maintained as the workpiece passes over the blades.

Once the workpiece reaches the outfeed table, the downward pressure is gradually shifted from the part of the workpiece over the infeed table to the part of the workpiece over the outfeed table. At the end of the pass, all the downward pressure should be applied to the outfeed end.

It looks so simple when you watch it being done. Actually there is a lot going on to make it successful.

Key point: At the start, the workpiece must be held down against the infeed table. This pressure must not cause the workpiece to rock on any high area.
-------------At the end, the workpiece must be held down against the outfeed table. There should not be any 'high' spots at this point.
-------------At the middle of the pass, the workpiece must be held down against both tables.