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Leigh TD330 Dovetail Jig

3K views 13 replies 4 participants last post by  jdonhowe 
#1 ·
I have purchased a Leigh TD330 dovetail jig and have just cut my first test piece. The first project has 2-3/4” wide pieces. The jig gave me this:
Wood Wooden block Rectangle Wood stain Flooring

I want equal sized pins and tails. I have watched the videos and read and read the instructions and cannot figure out what I did wrong. Any help would be greatly appreciated.

thank you, Stan Messick
 
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#4 ·
Can you please explain how I miscalculated? As it stands right now I have paid around $110 for a jig that I can’t use. So far Leigh hasn’t been able to help because they can’t see what I mean because the photos come up too small.

thank you, Stan Messick
 
#5 ·
It's not clear what you mean when you say "equal sized pins and tails". In your photo, the top pin looks smaller than the bottom pin. As already mentioned, this is likely due to misalignment of the side stop.

If, however, you want the relative widths of the pins vis-a-vis the tails to be similar, i.e., "fatter" pins, and "skinnier" tails than in your picture, you're asking a lot from this jig. If that's what you want, the only way I can see you doing that is to use thicker boards. They will give you narrower tails and wider pins. The router bits and combs are fixed, so there's not a lot of flexibility in varying dovetail sizes. If you want to adjust pin/tail dimensions to your liking, regardless of the board thickness, you need to step up to the D4R, or try hand cutting.
 
#12 ·
My bad! First, a confession: I don't own this jig, so take this for what it's worth (absolutely nothing!). I scanned through the DT330 manual online, and from what I glean the spacing between each finger is set at 1-1/4" (I conclude that based on the table on page 45 (section 7-16) of the manual, which says that even joints are multiples of 1-1/4"). Based on that, I drew a crude diagram of the joints.
Handwriting Rectangle Font Slope Parallel

Trying to wrap my head around the geometry, with the bits included with the jig, the size of the pin "base" (widest part) is determined by the dovetail bit, so is fixed at 1/2". With that, if my math is correct (and certainly open to criticism), theoretically the narrowest the tail would be is ~3/4" (1-1/4" minus 1/2"). I said in an earlier post that pins and tails would become more equal using thicker boards. I'm pretty sure, looking at the drawing, that I was wrong with that suggestion. To the contrary, the thinner the boards, the narrower the dovetail. My apologies!

That said, the only way I can see of making tails and pins about equal (bottom width) with this jig is to use a larger dovetail bit, and perhaps a commensurately smaller straight bit. For the D4R jig, Leigh makes 11/16" and 13/16" dovetail bits. Either of these would make larger pin openings. A smaller straight bit (7/16" or 3/8"?) should then result in larger pins. One way of fine tuning the pin size would be to place shims between the support board and your pin board, which will make the pins slightly narrower. Perhaps the people at Leigh can give you guidance before chasing down various bits. Due to the template side used for cutting tails, you are obviously limited to 8 degree dovetail bits.

Trying to visualize the geometry gives me a headache. FWIW, I feel your pain in having a tool/jig not meeting expectations. I was fortunate to find an older used version of the Leigh D4R, and while it does not allow table mounted routing, is really a nice jig to work with, once dialed in.
 
#13 ·
Thank you, you have gone to a lot of trouble sorting this out and I appreciate it. I have had an ongoing email discussion including photos with Leigh customer service and was unable to make the CSR understand what I am talking about. I think it’s pretty simple and straightforward: the manual shows pins and tails the same width at the tops and bottoms. What I got was double wide tails and single wide pins. I can’t understand why he couldn’t see this.

Bottom line is I’ll have to go back to the Incra jig I have been using and live with it’s drawbacks.

Thank you for pursuing this.

Stan Messick
 
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