Bad Joints - no, not the smoking kind

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Blog entry by RusticElements posted 04-16-2009 03:49 PM 1706 reads 0 times favorited 5 comments Add to Favorites Watch

I started having trouble with loose finger joints in my beehive boxes. My finger joint jig just wasn’t doing what it did when it was new. I now have a couple good size stacks of “seconds” :(.

In trying to figure out what was wrong I went through several scenarios. First, the front box felt a little loose and on closer inspection I found the holes in the aluminum sled spacer were worn. I replaced it with a new steel one.

That helped, but not much. I now have another stack of “seconds” :(.

things still felt a little loose so I replaced one of the wood runners with steel. That tightened things up considerably.

But I still had problems. There was virtually no play in the system but the joints were still loose. Fortunately, this time I learned my lesson and only did a single run of boards instead of a whole batch. And still no good. I decided to measure the pins and spaces to try and get a clue as to what was going on.

As you can see, these are not the measurements I wanted. But this gave me a clue. If the spaces were too big, that means the dado blade is too wide. But how? It’s the same setup I’ve always used. So I looked at the blades:

Shown here is the inside of one of the outer blades caked with pine pitch and sawdust. The other one was actually worse, but I didn’t think to take the pictures until after I had cleaned it.

I cleaned all the blades, put everything back together and tried again.

This is better:

Much better!!

-- Michael R. Harvey - Brewster, NY - - -

5 comments so far

View PurpLev's profile


8536 posts in 3675 days

#1 posted 04-16-2009 03:58 PM

good catch on the dirty blades… when you work with such small tolerances those gunk that accumulate on the blade counts..

I guess your sled uses preset spacers on the top? that means that your spacing is rather permanent, and you rely on dado thickness to be precise.

Another approach is to use the single-spacer design for a sled, with that one, you adjust the spacer to the dado thickness, so it’s always dynamic, if your blade thickness changes, you can adjust the sled to it.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View RBWoodworker's profile


441 posts in 3378 days

#2 posted 04-17-2009 05:00 AM

it’s funny how gunk and pitch can really throw a project..I made it a habit of cleaning my blades with believe it or not.. easy off oven it takes the toughest resins right off in no time and the blades look but be careful.. easy off is a mild acid which WILl burn your skin if you leave it on for a minute..and,, wear a respirator too..

-- Randall Child

View DocK16's profile


1184 posts in 4113 days

#3 posted 04-17-2009 05:16 AM

I cut my bee boxes using a 3/4 inch straight bit and an Incra router fence. Very little tear out.

-- Common sense is so rare anymore when you do see it, it looks like pure genius.

View Karson's profile


35125 posts in 4427 days

#4 posted 04-17-2009 05:55 AM

Great tip there and some great pictures to show the problem

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware soon moving to Virginia †

View Grumpy's profile


23997 posts in 3877 days

#5 posted 04-19-2009 01:13 AM

Well spotted Michael. A bit of dust can make life difficult. I am taking up tiles in the toilet for a refurb a my wife is complaining about the dust through the house.

-- Grumpy - "Always look on the bright side of life"- Monty Python

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