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Learning the Incra Jig Round 2

Project by SPHinTampa posted 583 days ago 1960 views 2 times favorited 22 comments Add to Favorites Watch

This design comes from the Incra project book (kind of). It was a joint effort with my wife because she wanted to learn how the boxes were made. I would post her picture but then you would never look at the box.

The box is made of Padauk and curly maple and finished using real tung oil, followed by a tung oil/vanish combo (4 coats). I love how the curly maple “shimmers”. God knew what he was doing when he made trees.

Even though the Incra jig is kind of “paint by the numbers” for joints, my observation is that it demands very close attention to stock preparation and ensuring that that the jig is very well set up to begin with. It is easy to get average results with the jig but not so easy to get really fine work. I would rate the system a 9 out of 10 based on great design and solid construction. I still use my homemade fence (it is bigger) for basic routing tasks. (See shop for pictures)

I do encounter problems cutting dovetails with the incra jig and I am wondering if others do as well. I find the cut is very heavy in many case and no matter how I vary the feedrate, about 1 in 5 times, the dovetail bit shatters the wood rather than cutting it.

I am guessing that there are a few possible reasons:
- too high of a feed rate (I get better results slowing down but not perfect)
- insufficient backing (I use a backer board and ensured it is tightly clamped to push block) and zero clearance insert in the table opening
- too much power behind router bit (I am using a 3HP router running at full speed (22000 rpm))

I have not tried to dial back the speed, but that is my next trial. Nor have I tried a zero clearance insert in the fence (which would not work well with the incra system as it interferes with the push block)

-- Shawn, I ask in order to learn


22 comments so far

View odie's profile

odie

1602 posts in 737 days


posted 583 days ago

If what cut is very heavy? Do you mean the end cuts? 1/32” at a time will work. I have a little experience.

-- Odie, Confucius say, "He who laughs at one's self is BUTT of joke". http://woodstermangotwood.blogspot.com/ (my funny blog)

View Grant Davis's profile

Grant Davis

481 posts in 806 days


posted 583 days ago

A fine looking piece Shawn.

-- Grant...."GO BUCKEYES"

View RonE's profile

RonE

5 posts in 603 days


posted 583 days ago

Definitly slow the router down. Hardwoods need to run slower. I, too, had the same problem. Solved it by slowing the router to 16K, and slower feed rate for creating the double/double dovetails. The project looks very good, but regulate the router speed to the wood used. Take your time with feed rate.

View SPHinTampa's profile

SPHinTampa

155 posts in 583 days


posted 583 days ago

Odie,

I sneak up on the end cuts in 1/32” increments but I am usually shattering the wood on the 3 or 4th cut towards the center.

My use of the term heavy for the center cuts is the due to the fact that you are forcing a fairly large profile though the middle cuts in a single pass. I was thinking of trying to make one pass with a straight bit to remove most of the wood and then trying second pass with dovetail bit for shatter prone woods like paduak, wenge and jatoba. I am guessing there is probably a better way though.

Thank you for responding to my question.

-- Shawn, I ask in order to learn

View odie's profile

odie

1602 posts in 737 days


posted 583 days ago

Have you tried a new dovetail bit? I have no problems in the middle cuts … let it plow. When do shatter the wood, on the virgin sides or after you have glued the trim on?

-- Odie, Confucius say, "He who laughs at one's self is BUTT of joke". http://woodstermangotwood.blogspot.com/ (my funny blog)

View TomK 's profile

TomK

504 posts in 772 days


posted 583 days ago

Is the bit very sharp? I have not seen that problem with mine, but have not tried a double double yet either.

-- If you think healthcare is expensive now, wait until it's free! PJ O'Rourke

View odie's profile

odie

1602 posts in 737 days


posted 583 days ago

I have looked at your shop and you are using the old style Incra on a homemade fence … right? What are you using for the carriage? As in …. what are you clamping you work pieces to? I am sorry, but can you give more info? Check my table out and tell me the differences http://lumberjocks.com/projects/3594 .I have never used the old style of positioner.

-- Odie, Confucius say, "He who laughs at one's self is BUTT of joke". http://woodstermangotwood.blogspot.com/ (my funny blog)

View Scott Bryan's profile (online now)

Scott Bryan

20744 posts in 719 days


posted 583 days ago

This is a gorgeous box. I love the double dovetails.

-- With God's help all things are possible- even woodworking. Woodworking is not just a hobby, it is an (expletive deleted) expensive hobby.

View SPHinTampa's profile

SPHinTampa

155 posts in 583 days


posted 583 days ago

Odie and Tom K,

I am working with a new bits (incra kit from MCLS). I have shattered joints on both initial passes and after the trim was glued. Generally it has been a problem for the harder/denser woods. What woods are you working with?

I strongly suspect that I am spinning the bit too fast, especially for the harder woods. Based on RonE’s response and the fact that the rest of you are not running into this problem, I am going to try to slowing the bit speed to see what happens. I will post the results when I have had a chance.

It is extremely helpful to hear both suggestions and results from other people.

-- Shawn, I ask in order to learn

View SPHinTampa's profile

SPHinTampa

155 posts in 583 days


posted 583 days ago

Odie,

Your jig is really cool. I have the same Incra system as you on my router table – the 16” Incra Ultra. I did not show it on my router table picture. The picture that you saw was the older style Incra jig that I found at a garage sale for $15 and decided to use for my bandsaw fence.

I am using the Incra push fence that comes with the Ultra Jig.

-- Shawn, I ask in order to learn

View CharlieM1958's profile

CharlieM1958

7670 posts in 1116 days


posted 583 days ago

Beautiful!

All these Incra jig boxes are making the rest of us look bad. :-)

-- Charlie M. "Woodworking - patience = firewood"

View Blake's profile

Blake

2760 posts in 772 days


posted 583 days ago

Gorgeous box.

I also love using the Incra jig. It’s interesting how you point out that Incra joinery can be a little like “paint by numbers.” I have been resisting the “machined” look of Incra joinery a little lately by trying to incorporate a more natural “flowing look” even when I do use the Incra. That way I get results with the best of both worlds… precision and an artistic feel.

You did a nice job with this one. Great wood selection. I know what you mean about the maple.

-- Check out my new website! http://www.blakeweberwoodworking.com

View jjohn's profile

jjohn

391 posts in 611 days


posted 583 days ago

How that we have seen the beautiful box…let’s see the wife…Just kidding, LOL. A really nice job. I wouldn’t know how to begin the double dovetails. I have to make mine by hand and am very excited if the dovetails work out period. Great job.

-- JJohn

View odie's profile

odie

1602 posts in 737 days


posted 582 days ago

Okie Dokie …. Shawn, I use a 690 Porter-Cable (1 1/2 hp … I think 22000). When I run the first side through I use a backer the same width of pine usually. After the trim is on I place the two face to face and put them through. When I glue the trim, I glue both surfaces and clamp for 24 hours. I used to loose pieces … not any more.

Do you have Perry MacDaniel’s book ?

-- Odie, Confucius say, "He who laughs at one's self is BUTT of joke". http://woodstermangotwood.blogspot.com/ (my funny blog)

View SPHinTampa's profile

SPHinTampa

155 posts in 583 days


posted 582 days ago

Odie,

I have the book, this box design is about 90% stolen from one of it’s projects.

With regards to the double dove tails, I have been using 60 min epoxy to join trim pieces and leaving set for 2 hours (lack of time = lack of patience, or otherwise said I don’t have time to do it right but I seem to have time to do it over)

Based on the feedback I have received, I milled up some popular and some purpleheart test strips tonight and I am going to try a few of the suggestions that you and others have posted (slow down the bit, ensure sharp bit, slow down feedrate, leave trim to set 24 hours) and then post the results. I will be able to test this on the weekend.

I appreciate your assistance.

-- Shawn, I ask in order to learn

View motthunter's profile

motthunter

2079 posts in 696 days


posted 582 days ago

really nice..

-- making sawdust....

View trifern's profile

trifern

7895 posts in 665 days


posted 582 days ago

Great job. I look forward to more projects as you gain experience.

-- My favorite piece is my last one, my best piece is my next one.

View BarryW's profile

BarryW

872 posts in 804 days


posted 582 days ago

nice figure on the wood…looks great.

-- /\/\/\ BarryW /\/\/\ Stay so busy you don't have time to die.

View ND2ELK's profile

ND2ELK

6218 posts in 671 days


posted 582 days ago

Beautiful looking box. You did a great job on it. Thanks for posting.

God Bless
tom

-- Mc Bridge Cabinets, Iowa

View brunob's profile

brunob

1476 posts in 1067 days


posted 582 days ago

Maybe I’ll get my incrajig out againg this weekend. I got frustrated and put it away.

-- Bruce from Central New York

View SPHinTampa's profile

SPHinTampa

155 posts in 583 days


posted 563 days ago

Thanks to everyone for their comments … after some experimentation, it appears that I get the best results from slowing down the router bit speed to 14K rpm.

In addition, for the double joints, waiting longer for the glue to set also helps.

-- Shawn, I ask in order to learn

View Dusty56's profile

Dusty56

3482 posts in 585 days


posted 551 days ago

Indeed a beautiful box !!! Just one question though ….

How much did you have to pay that model to stand next to you ??? LOL … Great project : )

-- You know you're getting old when you know the difference between you're (you are) and your (belonging to you) AND how to use them in a sentence .

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