How to set bit collar for 1.5"

[Shift]

The markings on the guide on the kreg jig show 1 1/4" and 1 1/2"  hovering around the same line.

 

Is the 1 1/2" collar setting made by extending the bit all the way to the end of the guide, or by using the the line between 1 1/4" and 1 1/2"?

 

[Shift]

Thanks James ... 

Where is the 1 1/2" line in that diagram though?

There seems to be a single guideline on the left for both  1 1/4" and 1 1 1/2" - the line that is sitting between the two labels.

 

 

 

 

[Shift]

thanks for clearing that up James.

[Dave]

If the  1 1/4 setting is the same as the 1 1/2 setting, why does the 1 3/8 setting on the other side go deeper than both of them?

[KregRep]

This compensates for the screw size difference.

If you reference your screw chart, you'll see that you're supposed to use 2" screw for both 1-1/4" adn 1-3/8" stock thickness. But the 1-1/2" stock needs a 2-1/2" screw. It's a combination of the screw length and stock thickness that determines the optimum depth collar setting, not the stock thickness alone. Since the screw is a bit shorter in the 1-38" setting, we can afford to drill a bit deeper than in the 1-1/2" stock...

Dave said:

If the  1 1/4 setting is the same as the 1 1/2 setting, why does the 1 3/8 setting on the other side go deeper than both of them?

[John Schaben]

I still like Jay's method. Set the jig, drop the bit in, put a nickel under the bit and tighten the collar.. done and done.

[Ken Kortch]

Being a new K4 jig owner ... I just realized that with the K4 guide at the 1-1/2" height and the drill depth collar at maximum length (so the hex screw can be tightened) the drill tip will end well above the jig base - much much more than a nickel height - maybe roughly 1/2" above the base.  The same is true for 1-3/8" and 1-1/4" material settings, though less so. The nickel height thing doesn't start until the jig is set for 1-1/8" material - or thinner.

I'm guessing that the screw shafts are designed with the smooth portions such that it doesn't really matter, and 1-1/2" to 1-1/4" thick material is pretty robust stuff (not prone to splitting and such). I'm wondering if the longer screws are such that use of the shorter collar depth (shorter than for 1-3/8") actually works better - or at least equivalently.