Installing Threaded Inserts

[ashcatlt]

So, the upper strap button on my Rickenbacker has stripped out of its hole. I went to the hardware store looking for a dowel with which to fill the hole, then redrill, but I found something that I thought would be a bit better: a hex-drive threaded insert. It looks basically like this one:

I'm a little unsure how to go about installing this thing, though. The existing hole is going to have to get bigger to accomodate the insert, but as you can see above, the thing is tapered, and that's what's throwing me off. Do I need to make the hole tapered somehow? Do I just drill the hole to match the "thin" end of the taper and let it force itself in? (where's the tooth grinding, scared it's going to crack smiley?)

Any advice is appreciated.

[D2o]

Ash, I am with you … maybe it’s a stinky-little-inkling smiley that you seek?

In addition to your stated concerns, that tapered thing just doesn’t strike me as a better solution than the non-tapered screw normally found on a strap button, because I imagine that if it ever starts to loosen it will let go in a hurry.

I may be misinterpreting how this thing is supposed to work but, unless someone else can give you some assurance as to why it may be a superior solution, I think you should pay attention stick with the original plan.

D2o

[ashcatlt]

In case there's some confusion, this thing has threads inside as well, where the original strap button screws in. I figured those metal threads would be more reliable for longer than the wood would.

[D2o]

Yeah, that’s what I thought. I can’t say I’ve ever seen one of these before, by the way.

So there is a very good bond between the strap button screw and the threaded insert, but my thought is that with the traditional strap button screw, you will be more likely to notice if it starts to loosen – i.e. even though the strap button may be in no imminent danger of falling out (because the screw is straight and still threaded to some extent).



If the tapered threaded insert starts to get loose, it looks to me like it would separate from the wood quickly (sort of like two tapered glasses that are stuck together).

Actually, this seems like a generally impractical fastener – regardless of the application, unless the threaded insert actually gets expanded when you put the screw in (sort of like a lead wall anchor). Is that how this works, by any chance?

Otherwise, I am not crazy about it so far.

D2o

[chuck]

it is the same as the machine screw inserts for necks .
i dont know about the taper ... but the concept of an insert should work fine .

if you remove the strap buttons a lot , it might be worthwhile .... but if you dont , a new proper sized hole with fresh threads should last a loooong time

[jcgss77]

For lack of more information, it strikes me that if you drill a normal hole with your drill bit and put it together, the screw from the strap button will spread the bottom of the anchor so that it spreads as wide as the top of the anchor, which will cause the anchor to grip evenly within the hole. Perhaps there is some information from the anchor manufacturer which explains the action of the item, if this is how it works?

I was eyeing something like that up to see if it would work for joining the neck to the body.

[sumgai]

ash,

Short story long, the outside taper is imitating a proper wood screw. Most screws you see in todays guitars are actually made for metal work, not wood.

Wood screws are tapered in order to prevent cracking of the material. As the hole is widened, it gets weaker, and you can guess the rest. As it also happens, there is only 0.5% difference in total surface area between a tapered shank and a straight one. That translates to the amount of thread that's digging into the wood is virtually the same, so it only makes sense to try and not crack the wood, right?

So if that's the case, then why they'd ever use a straight-shank screw in the first place? Good question - ranks right up there with why do voters believe that their vote counts?

I suppose one answer might be that long-shank wood screws are harder to come by in a quality steel. (Read that as "more expensive".) Usually wood screws are meant to hold together pieces of... wood. Which don't move around very much.   Such screws are tightened down all the way, with nothing exposed below the head.

Compare that to the strap being jerked about in all directions, and where those forces are collected - that's right, at a single point of the screw, just below the head. Perhaps the thinking goes that "if we can't get wood screws that are strong enough to withstand abuse right below the head, then maybe we should use metal screws instead, 'cause they're made of quality steel instead of soft zinc.

I dunno for sure here, I'm just guessing.......



OK, so now we're down to the real nitty-gritty, and that is, do these inserts work as intended? I'd bet yes, they're a good thing. I've used them (or similar) in the past, although my current Strat is something I'm trying to keep fully stock. (Yes, I've changed out the pickguard, and mounted a hex-pickup. But all of that can be reversed and restored, I've kept all the original parts - no one would be the wiser for it.)

Beyond the very short pickguard screws, which usually are wood screws, there are only three places I can think of that have longer, and probably metal, screws - the neck, the strap posts, and if so equipped, a vibrato tailpiece/bridge butt'y. (If you'll look carefully, Leo's original Strat 6-screw unit did use wood screws! I think their reproduction models do too, but it's hard to tell from the outside, and I'm not gonna go buy one just to take apart and give you all a report!)

Early Fender basses also come to mind. When first introduced, and for about a decade afterwards, Leo used wood screws to hold down the tail pieces. Not so, in the later editions. Not sure if that was a CBS thing or otherwise, but it makes no difference - for the last 40 years, perhaps a bit more, everyone of these that I've worked on had straight-shanked screws in the tail pieces, not tapered ones. And that goes for both MIA and off-shore units too.

But when all is said and done, it's been at least 50+ years that things have been the way they are now, and no one's made a fuss over it so far, so I'm pretty sure that I'm not gonna start a revolution now, at this stage of the game. Still, I have to approve of your intentions here. I say do it! ;D

HTH



sumgai

[ashcatlt]

The Rick strap button is more like a bolt (even described as such) then the screw that D2o pictures, which is what you'd find on most other guitars.

The "locking" strap I use actually requires that you remove the strap button screw and insert it through a hole at the end of the strap, then screw it back in. So it will probably be going in and out a few times here and there. I think this is what has caused the problem to begin with.

So, SG, you've given your stamp of approval but not really told me HOW to install it. Are you saying that the hole should be about the size of the thin end, and that the insert will expand the hole as necessary when I screw it in? Should I use a powered driver to get it in there, or just go slow with a hand-held hex wrench?

[lpf3]

Ash-

I dunno about that tapered insert, I would be worried about forcing it in & cracking also- but I've had good results from these for a lot of different applications (Including guitar).


Same idea, only straight.

You can see the slot at the top for the flat screwdriver- the thing is the brass is pretty soft & it's easy to bugger up a little; but not bad.

They're also readily available at your local home centers or mom & pop place.......

Just drill your hole the same size as the shaft- (the part without the threads) just like any other pilot hole & you should be in business.

-lpf3

[D2o]

FWIW, the insert that lpf3 mentions has my vote - all my concerns would be alleviated with that.

Cheers,
D2o

[sumgai]

ash,

Straight, as in lpf3's example is one way to go, particularly in view of your anticipated future needs. But I wouldn't call it a cure to the problem, only a different way to do things.

If you're going to stick with the tapered insert, it should be installed as a wood screw is supposed to be installed - you turn it in 1/2 rotation, then back it out 1/4 rotation, then in again, then out again, lather, rinse and repeat until the screw (insert) is fully seated. That's how I was taught to avoid cracking/breaking the work piece.

In fact, I've probably broken more wood screws with a power driver than I've ever damaged any wood at all. But then again, I did say that most wood screws are made of zinc, a soft metal to begin with - no torsional strength to speak of......

Pilot holes are, of course, mandatory, regardless of which shape shank you end up using.

HTH



sumgai

[lpf3]

Ash-

I don't think one shape insert is any better than the other, but sumgai has a good point........

If you're going to stick with the tapered insert, it should be installed as a wood screw is supposed to be installed - you turn it in 1/2 rotation, then back it out 1/4 rotation, then in again, then out again, lather, rinse and repeat until the screw (insert) is fully seated. That's how I was taught to avoid cracking/breaking the work piece.

If you drill the pilot hole the size of the narrowest part of the insert & then use SG's method of 2 steps forward, 1 step back- the insert will act as it's own drill bit, in a way. You have the added benefit of using the hex key instead of a flat screwdriver & that'll give you better traction.......

It's on you

-lpf3

[gumbo]

...and then there's the other time-honoured (yeah, ok, "honored") woodworking trick of putting a tiny wipe of soap on the thread before you screw it in....in the manner that SG proposes, of course..

...never split a bit of wood in many years of screwing around ;D when using this method..

[sumgai]

Heh, forgot the soap bit.... no wonder my wood projects always end up looking so dirty.........

;D

More likely to be beneficial in a hard wood, but still a good idea in soft woods too.



sumgai

[ashcatlt]

Okay, cool. Thanks all, my mind is very much eased by this. I'm gonna go ahead with the one I've got. Looks like I'll need a little liquid courage so I can actually take a power tool to my old friend here, then maybe a little artificial patience to screw the thing in good and slow and safely and I'll be bouncing around the stage with it again!

To be clear, I don't expect to ever remove this insert once installed, it's just the strap bolt which might be removed and replace every once in a while.

[D2o]

Just another day in the life of Dr. Ash Cat, L.T.

"Beer!"

"Scalpal!"

"More beer!"

Go to it ash, and good luck - based on what I've read from others (here), I'm sure it will work out just fine.

[gumbo]

FWIW...
...I don't use inserts, but when I 'update' my guitars (on purchase) to straplocks, I install the supplied (Schaller) screw with good ol' SuperGlue...that cryo-whatever stuff that sticks elephants to the sides of 10-storey buildings.....because I never plan to be continually removing them.

FWIAW...
...on the odd occasion that I have had to remove a component so-installed, it hasn't been that much of a hassle...but at no time (in the meantime) have things worked loose in the middle of a gig like they once did before someone got me onto doing this.....

[chuck]

thats a great idea gumbo ...
the sooperdooper glooo will soak into the wood and harden the threads

[newey]

I also have used Superglue™ on strap peg screws. Be careful not to use overmuch, especially if you have a nitro finish!

While I've never experienced a problem wiping away any excess oozing out around the hole (must be done quickly!), all my finishes are poly. I imagine the methyl methacrylate cement would probably attack nitro, though.

[sumgai]

newey,

For that reason alone, it's a good idea to use painter's blue tape to mask off the hole. And still clean up any spills, like mosh-kosh!


As it happens, I don't use any "lock-tite" wannabe products, but then again, I don't seem to feel the need for them. Perhaps my stage presence is too meek?

I have both kinds of straplocks, Dunlop and Schaller. The latter is nice, it came with my Fender Strat AmDlx, but after awhile, I find that I prefer the Dunlop units. Not to mention, the Dunlop unit can be fully recessed into the body - nothing sticks out at all, yet the strap is just as secure as if you'd mounted the "button" normally. All it takes is a "counter-bore" hole, leaving the screw-sized portion the same diameter as before, though a bit deeper. The down side of course is that you can't mount a normal strap for temporary purposes.......

HTH


sumgai

[chuck]

Schaller strap locks = guitar happiness

[ashcatlt]

I completely forgot to come by and report that I actually did install this thing last weekend. I don't have tools of my own, and had trouble coordinating a time when I could get it to somebody who did.

After all the worry and two pages of thread it was so stupid easy! I drilled it out to just a little bigger than the thin end and did the forward and back thing the sg recomended and it just worked.

I even got to play it at our gig on Monday. Unfortunately, there was some issues re: tuning stability which I have to narrow down.

It was all nasty sticky gummy on the back of the neck, which made it difficult to play. I think I've got that cleaned up after some pretty intensive rubbing with a cloth and some lemon oil, but it's been an on-going problem for a while. The guy I bought if from said that something about the carnuba wax that they use on it, and...something...

For these reasons it will have to sit as backup for our "big" gig tonight. It's more reliable and sounds closer to what I want then the LP right now, but I'm kind of hoping I don't break a string.

[D2o]

Good stuff, ash!

I think you are taking too much of the blame for the length of this thread, though.

To be fair, I think that as much of those two pages was debate about the long term stability of the tapered insert, as it was about the actual installation.

Sounds like you (and/or your friend) did a good job.

By the way, what do you think of the idea of mineral spirits on the goopy neck? It's always worked well for me.

D2o