JPG wrote:Nay Chuck!charlese wrote:It is not too often we get a chance to correct this guy!JPG wrote:With 'slot mortising' the concept of climb cutting is unavoidable. As Buckeye stated the resultant force when feeding needs to be towards the rigid fence.
In the example, the edge between the fence and the bit is plow cutting, and the edge outside the bit is climb cutting. More important with slot cutting, is the area ahead of the cutter (end of slot). There the bit forces the workpiece towards the fence.
Actually the edge between the fence and the bit is climb cutting, and the edge outside the bit is plow cutting. No big deal but we want to get this straight.
More important is the area ahead of the cutter, as said in the quote.
Also the edge away from the fence is being pulled slightly toward the fence when the workpiece is moved from left to right as is the example. This force actually helps to keep the workpiece next to the fence, while the climb edge is having less force.
It is a good practice to use a small diameter bit for a shallow first pass. A shallow groove is followed by more passes to get to the desired depth. After the desired depth is reached, move the table backward a little, insert the bit into the slot (on the right side) and cut again. Repeat this until the correct width is reached.
Draw it out.
The bit is rotating counter clockwise as viewed from the 'top'.
The workpiece is fed from left to right again as viewed from the top.
As far as climb/plow, the fence is irrelevant. The relative motion of the bit and workpiece determines which is occurring.
However one wants to use the fence so the forces are under better control.
When the workpiece is moved left to right, the rotation of the bit against the 'inside' work surface will resist the workpiece in the feed direction. That be plowing.
The rotation of the bit against the 'outer' work surface will pull the workpiece in the feed direction. That be climbing.
I did however have the cutting action wrong. The bit will be cutting the 'trailing' end of the cut and thus will be pulling the workpiece AWAY from the fence.
Thus the fence provides a stop for the pressure required to keep the workpiece tight to the fence.
Unless you have a reversing switch on the motor the bit is turning clockwise when viewed from above.
Anyhow, this is much ado about nothing. If you use a standard router table you always feed right to left. Most of the time you are only cutting on one side of the bit which is trying to push the stock away from the fence. We do this all the time with no problem so I don't see how this can be a problem with slot mortising.