Dovetail Jig: design feedback sought - Page 3 - Router Forums
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post #21 of 35 (permalink) Old 01-25-2020, 12:20 PM Thread Starter
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Nice design on the graphic...I would think you could make the fingers for box joints one piece. For variable, just pick the finger section that suits your spacing. Don't think you need to make individual fingers due to the nature of the box joint. Since you can't cut both boards at the same time, you could save on alignment and manufacturing issues by using one side for both boards. Just offset the second board by the width of the pin against your alignment pin...just a thought on saving some time making your fingers...
Yeah, that's true (easy to make all one piece). Variable spacing would need spacers to direct where the cuts should be. (thinking that spacers are needed to avoid mistakes when doing DTs, also)

I probably won't make the box joint fingers because there are lots of ways to make box joints. I use an Incra LS which is fast and easy (and cuts 2 boards at once). Though, anyone could make them if they wanted. I consider this an "open" design.
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Last edited by PhilBa; 01-25-2020 at 12:25 PM.
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post #22 of 35 (permalink) Old 01-25-2020, 12:24 PM Thread Starter
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This is all looking great Phil, looking forward to the finished and working design!
I'm hoping it will be easy enough for someone less experienced like me to build.
Thanks for the feedback. It is absolutely a goal that high skill is not needed to build it. Only the fingers need precision and I'm playing with ideas to simplify the number of cuts and a jig to make them. Sort of a metaJig!

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post #23 of 35 (permalink) Old 01-25-2020, 01:09 PM
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Yeah, that's true (easy to make all one piece). Variable spacing would need spacers to direct where the cuts should be. (thinking that spacers are needed to avoid mistakes when doing DTs, also)

I probably won't make the box joint fingers because there are lots of ways to make box joints. I use an Incra LS which is fast and easy (and cuts 2 boards at once). Though, anyone could make them if they wanted. I consider this an "open" design.

Other equipment for box joints is a good idea...

Nick

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post #24 of 35 (permalink) Old 01-25-2020, 01:12 PM
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Looking at the finger joint jig makes me wonder if using 1/2" key way stock for both fingers and spacers would work? Key way stock is very accurately sized. 1/2" is the smallest size pattern bit I'm aware of so I think that would be the minimum size.
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post #25 of 35 (permalink) Old 01-25-2020, 01:41 PM Thread Starter
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Looking at the finger joint jig makes me wonder if using 1/2" key way stock for both fingers and spacers would work? Key way stock is very accurately sized. 1/2" is the smallest size pattern bit I'm aware of so I think that would be the minimum size.
That's a great idea. All that would be needed is to cut the two shallow(1/16") dados to lock onto the T-Track and a 1/4" hole with a counter bore (though counter sink is OK, too). None of those require much precision other than the dados being at 90 degrees. I'm also looking at how one would use a bolt smaller than 1/4" - I think #10, M4 or M5 would work fine.
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post #26 of 35 (permalink) Old 01-25-2020, 02:03 PM Thread Starter
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Here how it would look using simple square stock (like for keyways). Note this is with a new version of the base. It includes holes in the sides for clamps (for shorter workpieces) and generally reworked positions of the alignment holes and T-Track. This requires using a pattern bit.

I think it would be fairly easy to cut accurate finger stock on a table saw. But note that as long as the pattern bit is smaller than the width of the finger stock, the actual width doesn't matter. Consistency does, though. All in all, fairly low precision is required.

Note also, I've drawn the workpieces with a sacrificial backer board to prevent blowout. This also works for DTs.
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post #27 of 35 (permalink) Old 01-25-2020, 03:51 PM Thread Starter
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I spent some time thinking through how to make a jig to cut the dovetail fingers. The only precision operation is to get the 7 degree angle correct. To that end, I set up the dimensions so they are fairly coarse standard Imperial values. There is one slight imprecision of 2.1 mils (21/10000") which can be ignored. I believe this angle can be cut fairly accurately on a standard taper jig by carefully marking the lines on the blank and aligning them on the taper jig. The rest of the cuts can be made on a router table. Once the jig is done, the finger blank is rough cut to shape and the bolt hole is drilled. The hole/bolt serves to ensure that the blank is correctly positioned. Then the blank is mounted on the jig, one side of the finger trimmed with a straight bit, flipped over and trimmed on the other side of the finger.

Of course, this has to be tested but I'm pretty confident it can be made to work.
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post #28 of 35 (permalink) Old 01-25-2020, 04:43 PM
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I spent some time thinking through how to make a jig to cut the dovetail fingers. The only precision operation is to get the 7 degree angle correct. To that end, I set up the dimensions so they are fairly coarse standard Imperial values. There is one slight imprecision of 2.1 mils (21/10000") which can be ignored. I believe this angle can be cut fairly accurately on a standard taper jig by carefully marking the lines on the blank and aligning them on the taper jig. The rest of the cuts can be made on a router table. Once the jig is done, the finger blank is rough cut to shape and the bolt hole is drilled. The hole/bolt serves to ensure that the blank is correctly positioned. Then the blank is mounted on the jig, one side of the finger trimmed with a straight bit, flipped over and trimmed on the other side of the finger.

Of course, this has to be tested but I'm pretty confident it can be made to work.

Phil...I think you lost me on the need for the angled finger...are you trying to cut the dovetails with a straight bit rather than using a dovetail bit...?

The shape of the finger and the dovetail bit going all the way through the work piece is what would make the angles on the work piece...

see this jig as an example... https://www.woodcraft.com/products/f...-jig-woodriver (this one happens to be 8 deg, but you get the idea)

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post #29 of 35 (permalink) Old 01-25-2020, 05:22 PM Thread Starter
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Yes, for through DTs you need to cut on an angle with a straight bit. All the jigs that do through DTs use both a DT bit and a straight bit. That's how both sides can have flat bottom cuts and a perfect fit. That template you pointed to uses both straight and DT bits.

Blind DTs can be cut with just a dovetail bit and have gaps (though they are hidden if done right).
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post #30 of 35 (permalink) Old 01-25-2020, 06:41 PM
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Yes, for through DTs you need to cut on an angle with a straight bit. All the jigs that do through DTs use both a DT bit and a straight bit. That's how both sides can have flat bottom cuts and a perfect fit. That template you pointed to uses both straight and DT bits.

Blind DTs can be cut with just a dovetail bit and have gaps (though they are hidden if done right).

Okie, doke then...anxious to see what you end up with...good luck

Nick

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