I Hate Finger Joints

I do.  With every inch of my disliking ability.  I think finger joints were sent by the devil himself to torment me.  I only use them for one thing, guitar amp cabinets.

A little back story to explain my dim view of these simple joints.

As I mentioned in my “About” page, I also built guitar tube amps. I started building amps a few years ago and they actually led me woodworking.  After you build an amp, you need a wooden box for transporting it.  Bam, working wood.

Also, the guy I built the table leaf for is a producer/recording engineer and he wants to use my amps for his next session starting on the tenth of December.  The amp is done but I need a box and in a hurry.

Enter the finger joint.

Traditionally, amp makers (Fender and Marshall) used finger joints for their enclosures.  Simple to batch out (in theory), strong, and very repeatable for the non-skilled worker.  Hey, that’s me, where can I sign up?  Not so fast.

I bought this jig and the Freud box joint blade set from Amazon around a year and half ago.  The jig looked sturdy, fairly simple and wasn’t too expensive.  However, I was duped; either my by own (lack of) abilities, the not great instructions, or a combination of the two.

What’s basically happening is that I run through some test pieces and life is grand.  Then, when I get to the actual pieces of wood, the fingers start moving and instead of being offset they line up.

Let’s look at some pictures for clarification.

I started with 4 test cuts, slightly adjusting the jig away from the blade to close the gap between each finger.

IMG_3252[1]
First attempt.
Not bad but we can do better.

IMG_3254[1]
Fifth test cut.
Number five started out nice but got a little gappy (yes, that’s a word) as the joints progressed.  Still, the fit was very snug and these cabinets will be covered with tolex (a bumpy, vinyl covering) so perfect they do not have to be.

I was happy at this point.  After fighting this problem on and off for a year, I thought I figured it out.  I read up on box joints and jigs, fine adjustments, and really took my time with the test pieces.  The perfect setup.

Sure enough, same problem as before.  There is some kind of drift when cutting the second, mating piece.  I thought labeling the parts to guarantee the fingers would line up would fix this (A to A, B to B) but it did not.

So, after two rounds of cutting, I have this:

Frustration, in unbelievable amounts.
Frustration, in unbelievable amounts.

Trouble starts on the fifth finger on the leftmost piece.  By the fourteenth finger, they are perfectly aligned.  I think this would be slightly less irritating if my test pieces followed suit.

The solution is probably simple and I am just not seeing it but if someone has any suggestions, I’m all ears.

I’m going to built a whole new jig tonight and see if I can get that to work.  If not, then I’m going to make one inch fingers and mark them out like dovetails. I thought about buying the Incra I-Box jig and still might.  For batching out these boxes the Incra jig would probably be best anyway.  The price keeps scaring me away.

Stay tuned, there’s sure to be more frustration than completion in the next few days.  I know I can’t wait.

Eat a peach,

Jonathan

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