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View Full Version : Dovetails on Incra Jig Process Imporovement



tprofera
11th July 2009, 04:06 AM
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Had trouble with getting the Incra Ultra to cut joints the way I wanted consistantly. Loose joints drive me crazy! Anyway I set to tighten things up with a process approach towards improvement.

My system now cuts flawless 1/2 blind and full dovetails about every time now. I'm now looking forward to progressing some of the more advanced joinery thats possible with the Incra system.

Of particular note: replaced the slightly chewed up runners on the base of the Horizontal fixture with custom made plywood/polyethylene runners. Extended them another 2" out the back from the originals for added support. The polyetylene was cut from a large cutting board purchased from sams club. That stuff even joints nice! The fixture slides much better now.

Hope this is helpful to somebody out there. Let me know if you have any questions.

I very much appreciate all that I've learned from you good folks here.
TJ
Charlotte NC USA

Life is too short...this is not a rehearsal.

tprofera
15th July 2009, 01:51 AM
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I added a handle and a cross plate for the extended base runners. It feels like it adds control to the cuts by permitting more downward and right pressure to keep base of fixture on the fence.

It also adds degree of safety as I use one hand to hold the stock to the top of the fixture to minimize any vibration, and the other hand to push the stock through the bit with the handle. This ensures both hands are out of the path of the bit as it moves through the work.

Waldo
15th July 2009, 11:09 AM
G'day tprofera,

Sounds like you've sorted out the problem that I'm trying to work my head around to get tighter d/tails. What in the scheme of things did you do/mean by tightening up the process and was it more than just put extended polyethylene runners on the jig?

tprofera
15th July 2009, 10:44 PM
Waldo;
Thanks for the reply. I now realize that cutting quality dovetails of any sort (in a box for example) requires a level of precision that may not be necessary in other WW enbdeavors. As such I set about to make precise the many factors that might have an influence on the result. During some down time at work I made a listing of these items and although I'm not completely finished working on them I now have the confidence to make near perfect (or at least from what my eyes see) dovetails with the Incra jig on the router table.

Here is my list. Please bear in mind there are still items to be attended to:

DONE – Tighten all Screws on Fence and jig
DONE – Verify Incra Jig Fence is 90 to router table top (or leaning away from the bit at the top) – shim if needed
DONE – Remove jig from table and blow out dust – blow out and brush black incra jig teeth
DONE – Adjust Router Table plate to be level with table top height
DONE – Verify Router Plate is tightly secured to router table plate
DONE – Measure dovetail router bits with calipers to ensure correct sizing to +/- .001
DONE oMark all bits with indelible marker on bit shaft size and angle.
DONE – Clean dovetails bits of pitch and touch up with diamond stone.
Make dovetail rabbeting standup push jig.
DONE – Make new Horizontal jig jig runners from UHMW or Polyethylene Cutting Board.
DONE – Make spares runner part for future use (both 5” and 7”)
Add Aluminum or Wood Cross Member to runner extensions.
Add Lead Weight to top of base of Horizontal Fixture.
Add a handle to Horizontal fixture to push with.
Install UHMW on inside of horizontal fixture Al slide.
Test cuts with an MDF backer board on Horiz. fixture?
DONE – Test locking the router height. Note: not needed
FUTURE – Install in the table dust collection?
FUTURE – Install a tabletop dust collection catch.

Waldo
15th July 2009, 11:16 PM
Thanks for the reply. :2tsup:

Squirrel
16th July 2009, 11:05 AM
tprofera,
Your timing for this thread is excellent and just what I have been looking for. Just last week I purchased a "Incra Jig Ultra" (from what I can tell a very cheap price). I am in the process of making a new router table, being a copy of Norm Abram, Deluxe Router Station and trying to make sure the setup is right and make any necessary modifications.

Squirrel

Mike Wingate
17th July 2009, 04:00 AM
Snap! Here is my version of a handle on my Incra RAJ, which also has the slippy plastic runners, all plastic, no ply and a throw-away sacrificial support at the bottom (MDF), stuck to the plastic with doublesided tape.

Barrie Restall
19th July 2009, 08:33 PM
There's some good ideas there for improving the right angle fence. I found that what really matters in making tight dovetails is preparing the timber, setting the bit height and centering the timber, especially for through dovetails. Follow the instructions carefully and remember that for through dovetails you cannot adjust the bit height to your timber thickness; you have to make test cuts to get the height precise for the fit you want. I thickness the timber to just below that recommended for the particular bit, then do test cuts. Centering has to be exact, and any thing that puts it off will affect the dovetail eg bits of dust, chips between fence and timber. Keep it clean between fence adjustments. Check timber pieces are square after you clamp them to the fence, sometimes the clamp pressure will move them slightly. Hand screw clamps seem to work best for me.

Good luck with them.

Regards

Barrie

Squirrel
19th July 2009, 09:12 PM
Very nice and neat looking dovetails. For those who have purchased the Incra book, is it worth while.

I haven't used my jig as yet, got other projects that I have to finish before I build my new router table.

Tempted to buy the book but it is a bit exy.

Squirrel

Barrie Restall
19th July 2009, 09:51 PM
Hi Squirrel

Not sure what book you refer to. The Master Reference Guide is a must as it contains 59 or so templates for every type of dovetail that you can think of, as well as all the instructions you will ever need. The Project Book is useful but not essential. It has a lot of good tips and some nice designs. The author has a few handy tables eg templates organised in groups according to the router bit to be used with them, and the stock thickness for blind or through dovetails. You can work this out for yourself from the Master Reference Guide.

If you havent already got it, get the Master Reference Guide. Then get someone to give you the Project book as a birthday/Xmas present (or borrow one!).

Regards

Barrie

Squirrel
19th July 2009, 10:42 PM
This is the book, I think once I get my Incra Jig Ultra set up it will be a must have.

Squirrel...

tprofera
5th August 2009, 07:26 AM
Another tip is to clean out all the chips with fine sandpaper from the insides of pins and tails before assembly. Makes for a cleaner fit without pounding with a mallet.

John Schroeder
23rd September 2009, 12:12 PM
Thanks for the great ideas on improving the incra right angle! I put on the UHMW runners and a jig handle and it slides perfectly. I am making a bookcase that will require dovetailing a 48" piece upright, so I also added a larger phenolic face plate to provide a bigger area to clamp to. Given the weight in the front, I also used a leftover piece of UHMW to provide a top slide that attaches to the fence above the runner that sticks out in the back. It prevents it from tipping forward at all, and it can only move forward and backward. Hope this helps.

Pics attached...

Mike Wingate
23rd September 2009, 06:08 PM
I like the addition of the slide limiter on the fence to stop the RAJ tilting.

tprofera
23rd September 2009, 10:00 PM
John, That top guide you added is a really nice upgrade

Barrie Restall
24th September 2009, 07:09 PM
Hi John,

Just when I was trying to work out how to control tilt on large boards, you've come up with a great solution. Well done, saved me a lot of time! Any more tricks in your bag? How did you get on with the 48 in dovetail piece?

By the way, where did you get the phenolic plate for the upright?

Regards,

Barrie

John Schroeder
2nd December 2009, 05:25 AM
So, after a bit of a delay getting all the stock ready to go, I finally put my new and improved right angle jig to use. I must admit I was quite nervous as the two side panels were 48" long, and the 36" top is a beautiful piece of birds eye maple. Funny enough, it worked! And it worked surprisingly well at that. The sliding action was smooth and precise, and the pieces were quite stable and machined quite easily. The two end pieces were done together, and when clamped upright with a backing board produced a wide enough surface that was very stable.

The thing to watch is the fence itself will flex if you aren't careful. It's aluminum and lacks the rigidity and precision I'd like to have. That said, if everything is set up properly I can attest to the fact that you can dovetail a 48" high board.

One thing I didn't take into account was the height of the backing board. As you can see from the pictures, unless you use a 12" high backing board, the height of the phenolic plate is largely wasted. I think I may buy some cheap flat pine and make a couple of 24" high by 12" wide boards specifically for backing large case work. I'll just cross cut the dovetailed end off after each use, so that should give me 12 to 15 or so cuts. I do think the plate provided more stability and a more rigid clamping surface even with the smaller backing board.

I also needed to make a sliding dovetail for the bottom shelf, and tried a couple of different approaches to make the male ends. I ended up using two rockler right angle plastic clamp guides to stabilize a 36" shelf that I dovetailed the ends on. After extensive testing on scraps, I got it to the precise width and a tight but smooth fit. Boy did that work well, and I'll be using that joint more in the future. Being able to tune the fence .001" at a time really made the fit precise, and no issues with the glue altering the fit. I'd read a few real horror stories, including one by David Charlesworth, so I was prepared for the worst. A couple of taps with a deadblow hammer at the end was all it took.

Pics attached!

John Schroeder
2nd December 2009, 06:10 AM
Hi John,

Just when I was trying to work out how to control tilt on large boards, you've come up with a great solution. Well done, saved me a lot of time! Any more tricks in your bag? How did you get on with the 48 in dovetail piece?

By the way, where did you get the phenolic plate for the upright?

Regards,

Barrie

Barrie, FYI I ordered the phenolic plate online here in the states from McMaster Carr at McMaster-Carr (http://www.mcmaster.com).

Barrie Restall
2nd December 2009, 12:57 PM
Hi John,

Thanks for the info; I didnt realise you were in the USA. I'll get off my butt and source the stuff locally.

The stabiliser for the RAF works really well and I reckon INCRA should pay you some money and include it in their design. I guess every one makes a blanket box sometime! Nice photos too and another good trick with the clamps for the sliding dovetail.

Keep up the good work.

Thanks again for sharing your ingenuity.

Regards,

Barrie

John Schroeder
2nd December 2009, 01:12 PM
No worries Barrie, happy to share. I've gotten so much help from WWF II feel obligated to post anything I come up with that might help someone else out. BTW, those right angle stabilizers clamped to the upright are really the bomb. They not only hold the board vertically, they provide two nice safe hand holds to keep the piece tight against the fence and slide it along. I'll be using those again. All in all, I'm very pleased with how the Incra performed, especially given how dicey I thought it was going to be in the beginning. I'm very glad to have run across all the good ideas here that others were kind enough to post.

damian
2nd December 2009, 03:43 PM
FWIW I've found this interesting reading. Thank you, and may I encourage anyone else with similar ideas to post them also.

(Just in case you thought no one else was interested).