# Need advise for using Incra LS Positioner



## Ronnie1a (May 24, 2009)

I want to make blind dovetail joints; 1/2" stock to 3/4". The pattern book gives me one height for 1/2" wood with the bit and a different height for 3/4 wood. Which height would I use? I want 3/4" drawer front dovetailed to 1/2" sides.


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## Phaedrus (Jan 18, 2012)

Bit bit heights are approximate for the Incra templates. You have to fine tune the height with their bit height procedure as instructed in their manual. Which template letter are you using? 

I am assuming that you want the 3/4 front to be the half-blind pins, and the sides to be the 1/2 tails, correct? Will you also plan to be using 3/4 stock for the rear of the drawer?


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## Ronnie1a (May 24, 2009)

*Yes, 1/2 blind cuts on the 3/4 front piece*

Was planning on 1/2 wood for the back and probably will not use dovetail. The manual is clear on fine tuning but it lists two different heights or starting points, one for 1/2" and another for 3/4". Which height do I use for my starting point and then fine tune from there?

The 1/2 blind cuts need to be on the 3/4 front piece so they will not show when the drawer is closed.

The cut I am trying to use is DoveN in their pattern book. I have the right size bit.


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## Phaedrus (Jan 18, 2012)

Your drawer will only be as strong as your weakest joint, so you ought to DT all joints if possible. Looking at my guide for DOV N, the two depths of cut listed correspond to two different bit sizes. There is only one depth of cut appropriate for any given bit using the Incra templates. If you have a 1/2" 14° bit, 3/8" will be your approximate depth of cut. If you have a 1/2" 10° bit, 1/2" will be your approximate depth of cut. Through DT are quite picky about stock thickness, but half blind are less so. Either bit/depth combo should work for your stock; however, if you choose the 10° bit (1/2" depth), be careful when cutting the depth of the pins to not cut too deep.

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## Ronnie1a (May 24, 2009)

*Your info helped a lot*

I've got the depth, height, etc. down and have a nice fit. Now need to work on tearout on the 1/2" plywood. I will try backup boards on all the cuts.


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## Phaedrus (Jan 18, 2012)

Ronnie1a said:


> I've got the depth, height, etc. down and have a nice fit. Now need to work on tearout on the 1/2" plywood. I will try backup boards on all the cuts.


Great! Having a backer board is pretty important when routing beyond the surface of any wood, but especially plywood. Other factors are, of course, the grade of plywood, a good quality sharp bit, and your feed and rotational speeds. Having a backer board is an excellent start.

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