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Dovetail joint fit problems with Incra Jig

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Forum topic by dschlic1 posted 12-10-2014 07:33 PM 1038 views 0 times favorited 5 replies Add to Favorites Watch
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dschlic1

330 posts in 1434 days


12-10-2014 07:33 PM

Topic tags/keywords: question router joining

A while back I purchased an Incra Original Jig and built a fence and set it up on my table saw/router table combination. The problem I am having is that when I adjust the router bit height using the procedure outlined in the manual and also in the reference manual once I mill the actual work pieces they fit way too tight. I am having to produce a very loose fit during the adjustment procedure, so that the finished pieces are able to fit together.

The spacing between the dovetails appears to be correct, it just looks like the bit height is not correct. As far as I can tell it looks like the bit height is not changing. However very small changes in bit height result in large changes in joint tightness. It looks like 1/64” makes a very large difference in the fit.

Has anyone else had this issue, or can offer suggestions as to why I mam having this problem?


5 replies so far

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pintodeluxe

4858 posts in 2278 days


#1 posted 12-10-2014 07:47 PM

Is your stock thickness exactly the same as your test pieces? When I am making dovetails I batch plane some scrap stock along with the workpieces. This helps to ensure that a nice test cut will translate into a nice project.
Other things to check… collet is clean and tight, and the router motor is not slipping in the base.
Good luck with it.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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pintodeluxe

4858 posts in 2278 days


#2 posted 12-10-2014 07:50 PM

sorry double post

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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dschlic1

330 posts in 1434 days


#3 posted 12-10-2014 09:15 PM

All of the stock was thicknessed planed at the same time. So all of the stock should be with 0.01” or less. I did have a problem with the lead screw height adjustment changing, however I solved that with a brake made out of hardboard. But tanks for answering. BTW I am using Whiteside router bits.

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RRBOU

136 posts in 1757 days


#4 posted 12-10-2014 10:29 PM


The spacing between the dovetails appears to be correct, it just looks like the bit height is not correct. As far as I can tell it looks like the bit height is not changing. However very small changes in bit height result in large changes in joint tightness. It looks like 1/64” makes a very large difference in the fit.

Has anyone else had this issue, or can offer suggestions as to why I mam having this problem?

- dschlic1

It looks like 1/64” makes a very large difference in the fit.

That is exactly right. I use the incra system with a lift and an adjustment of 1-2 thousands makes a big difference.

-- If guns cause crime all of mine are defective Randy

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dschlic1

330 posts in 1434 days


#5 posted 12-11-2014 05:50 PM

It may be a learning curve issue. I cut a set of half blind dovetail joints yesterday afternoon and they fit fine. I am using the Shop Notes router lift with a 16 TPI lead screw. So 1/128” adjustment is 1/8 of a turn. I’m not sure my table is that flat!

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