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I just wanted to share an exceedingly clever (for me anyways) idea that worked for me when I was installing a strapjack for an LR Baggs i-mix system.

I started by drilling the half inch hole for the strapjack. Then I found that my end block was too thick so the strapjack threads did not come out of the bottom of the guitar when I tried it in place.

My solution was to join two drill bits (a half inch and a three quarter inch) together as shown in the picture below:



The drill bits already had a small hole in their heads and a number six bolt and nut worked nicely. With this bit arrangement I was able to countersink the half inch hole in the end block from the inside to a three quarter inch depth by feeding the shank of the half inch bit through the hole from the inside of the guitar, mounting it in the drill chuck and running the drill in reverse while pulling backwards on the drill. The half in bit kept things centered and the three quarter bit did the countersinking.

When I was done, it all looked planned and the countersink came out very clean. In fact, the countersinking cleaned up the little bit of the exit tear out that I had with only the original half inch hole.

I hope this was clear and is of some use to others at some point.

Pat

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There are three kinds of people:

Those that make things happen,
those that watch things happen,
and those that wondered what happened.

Fantastic tip!!!!!!
I install allot of these and have had some problems with thick end blocks!


Mike

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Mike Collins

There are some reverse counterbore tools available for this, though I'm not sure where a good source is. I have a few of these I've made for various applications including endpin jacks, but just by grinding a flat cutting face on the back side of a spade bit (this way I can also reverse the bevel so I don't have to remember to run the drill in reverse). Keeping the pilot section straight and centered can seem a bit tricky, but with a bit of care it can be done freehand with a bench grinder and a file. I also prefer 15/32" for the main jack hole, as 1/2" just leaves a bit too much clearance for me to feel comfortable with.

Same idea though. I've made them to recess bolts in neck blocks, the occasional mod for an odd potentiometer on electrics, but the endpin hole counterbore certainly gets the most use. It's certainly a handy tool to have, isn't it?

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Eschew obfuscation, espouse elucidation.

Reverse spotfacers work well too although this is a really cool idea. You can get them at aircraft supply places. I think theyardstore.com has them. That's where I got mine. I used it for the same problem.
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.