Need some help with Leigh Super12 Dovetail Jig...

[Clark Harbaugh]

I've used this many time for through dovetails and single pass half dovetails with no issue. But, I have a large drawer for a desk that requires half dovetails that are spaced out a bit. The spacing is dictated by the fact that the Super12 doesn't come with enough finger guides for me to have done a single pass half dovetail. At any rate, the problem I'm having is that no matter what I do, I can't get the pins to tighten up. Not sure if the pics will show good enough, but I've adjusted the cut depth until I have about 3/16" left under the cut (should be around 1/8). The gap on the one I'm holding is right at 1/16"; the other is about 1/32". Any suggestions on this??

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[Tom M King]

Are the boards nice and flat, and clamped together tightly? Lowering the bit tightens everything up. For half-blinds on most any kind of jig, it takes a bunch of test cuts in scrap before you get it dead on. I keep dedicated routers set up for different jigs that are set for one purpose-including half-blinds, except for the Leigh jig I use for regular dovetails, but even for that one I keep two dedicated routers with the bits in them set to work in 3/4" material.

[Clark Harbaugh]

Yep. Flat, square, and tightly clamped. The 2 pics are after about a dozen or so test cuts. I normally can dial in within 3 or 4 cuts, but this one is kicking my button for some reason.

[Tom M King]

Yeah, sometimes it gets aggravating. I think I've been using my half-blind jig for kitchen drawers for over 30 years, and I haven't touched it for decades once I got it like I wanted it. I don't build kitchen cabinets every year though. The digital gauges for setting router bit depth are handy to have to if you have one you use for different things.

I always try to hold the router in the same orientation to the jig all the way down. If something is not set up perfect with the template guide, it can cause issues otherwise.

[Ken Krawford]

On the second image it appears that the gap is on the left side of some joints and on the right side of others. This could indicate that you are turning your router when making cuts. If the guide bushing isn't exactly centered in the router base, this will happen. Also check the manual and be sure you're using the correct bit required for the thickness of stock you're using. I almost always use 1/2" stock for drawers but recently made some big drawers out of 3/4" stock. No matter what I did, I was unable to tighten the joint. I emailed Leigh a picture and they quickly diagnosed the problem as using the wrong bit for 3/4" stock. Problem solved.
I'm sure you're anxious to move on with this project but if none of these suggestions work out, give Leigh a call on Monday. I've had great help from them both over the phone and via email.
Good luck.

[Clark Harbaugh]

OMG! The bit. 1/2 single pass uses a different bit than variable spaced on 1/2. I've been backward and forward and guess I just kept overlooking that difference. Looks like a trip to Woodcraft to get the different bit.

Thanks for the suggestion.

[Clark Harbaugh]

Confirmed - the bit was the problem. For the life of me, I can't figure out how the 4 degree difference between the two bits was causing the problem, but it was.