Lynn's box joint jig issues

[Tony Caro]

It has been suggested that I start a new thread on this topic so here goes.
I have built this jig and am getting less than accurate results. It would be a lot easier if my saw could take dado blades but alas it can't (I have a Triton Workcentre set-up which does not allow installation of dado blade) so I have a blade which has a reputed 2.8 mm kerf but I believe it to be a bit more (approx 3 mm due to run-out I believe). The jig I built is very sturdy (using 3/4 inch plywood mainly) and I used regular nuts sunk into the timber rather than t-nuts but am yet to get any consistent results. There is no slop in the jig that I can discern, I can only think that the inconsistent saw blade (which I thought would cancel itself out) or my counting (I am mixing metric with imperial measurements) is throwing me out.
Has anyone come across a way to easily record fractional turns on this sort of jig?

[Stytooner]

I posted this on the other thread as well.

"I just found this link today and put it on my LJ page as well.
Pretty detailed info. Should really help to clear up a lot of jig issues.
I admit I didn't do as good a job preserving and presenting the plans as I would like to have done. I didn't know how to use Cad back then. Do now and maybe one day I will get to it. May not need to though if this other gentleman comes through first."

http://worldofwood.proboards.com/ind...nt&thread=1509


I know one might have some trouble with a thin kerf blade. I had the best results using an outer blade from my dado set. I think it was 1/8" kerf or very close and had a good grind for making smooth cuts. No need to use a stack, though it might save some time.

As long as the blade isn't wobbling during the cut, it should cut consistently. You might have to measure how many metric cuts equal and inch fraction that you are looking for, but once found, it should stay the same throughout the process. One could also use a metric rod.
That might really simplify things. Just a little practice though is all it took to get perfect results for me.

[Tony Caro]

Thanks, Lee for your reply. I had thought about using a metric rod but went for the popular 3/8th version as I had some lying around. Also, the joints I was going to cut were 1/4, 3/8 and 1/2 inch sizes. I don't know why the jig would be any less effective with a thin kerf blade unless it flexes more but I'll keep trying until I get this sorted out.
By the way the link that you mentioned appears to be dead.

[Tony Caro]

Lee, actually tried the link from the other thread that I posted and it worked. Go figure. I did use most of that information when constructing the jig, it is well set out and I'm happy with the construction of the jig. It's the accuracy that I'm not achieving.

[leehljp]

Here is the correct link for use within this thread:
http://worldofwood.proboards.com/ind...nt&thread=1509

[Stytooner]

Here are some printable scales that can be attached to the back of the jig. I couldn't locate the ones originally designed for this, so I drew these up.

http://leestyron.com/pdf/Box%20joint%20scales.pdf