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Thanks for that, Woodie. When do you think that building guide will be available? Also, when you mention assuming end grain threads will fail, does that refer to course v. fine thread (Hillman course v. E-Z fine), or threads screwed into end grain?

Aaron, thanks for that video. Using the T-Wrench through the jig is brilliant.

Thanks, Ed!

George, that's a great, idea, too. I drilled my bolt holes before routing the mortis, then dowel centers (https://www.amazon.com/dp/B0055HPJ22/re ... cyb4G06KRM) to mark the insert locations on the tenon. I could just reverse it by putting the centers in the inserts to mark the locations in the mortis.

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So here is what I got from the enginerds in the shop (we have several...not just the boss):

Because the force required to shear the base of the wood thread is proportional to the length of that base, and because the primary mode of failure for threaded fasteners in end grain wood is failure at the base of the thread, larger, coarser threads are preferred in lower density woods like mahogany, especially when inserted into end grain. In other words, the coarse, deep threads on the Hillman inserts are much better for end-grain installations, while for face grain installations, either type of insert will likely handle any foreseeable level of loading that will not destroy the joint by some other failure mode.

On the building guide...pregnancy and child-birth, which many of us have at least a passing familiarity with, are as nothing to editing several hundred pages of my boss's prose, quick sketches, and poorly lit photographs.

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A constellation only takes shape when one maps the whole.
- Beth Brower

Double post. How do I delete this?

Don't discount opening up the hole 1 step with a step drill. With the slots on the insert oriented the correct way, it's starts cutting straight, right away, even if you don't have the T-handle.

Here's an image from another project, same technique. I could use a standard Allen wrench & it goes in straight. As it is, I used to use a small ratchet & Allen socket.


Many different ways to do this - T-handle Allen wrench into your actual cap screw (if that's what you use).

When using the T-handle driver in the past I found that many times it would stick and I could not get it to back off of the threaded insert (don't know if this has happened to anyone else...). I put a washer between the threaded insert and the T-handle driver and that keeps it from sticking...

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Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

I also like the bolt and locking nut method mentioned earlier, with a LONG bolt 3" of 4", which makes it really easy to keep it aligned. Using open end or box wrenches on the the locknut and the bolt head has always worked to unlock it, so far. A hardwood dowel perpendicular to the fretboard surface embedded with epoxy for the inserts to thread into gives an order of magnitude more strength over neck wood of mahogany or cedar. The wood is harder, and it's not threaded into end grain.

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com