Official Luthiers Forum!

Hi! Can anyone shed some light on how to install these.
http://www.lmii.com/CartTwo/thirdproducts.asp?CategoryName=Truss+Rods%2FNeck+Parts&NameProdHeader=Bolt%2DOn+Neck+Inserts
The top ones in the link, part #TNI2.
I want to install them using a neck tenon, not a butt joint. I will be using a hand drill to drill the holes. I know that's not recommended, but I have no choice, and I have used one extensively in the USAF. I'm no slouch with it and don't anticipate any problems.
My question concerns the threaded inserts. Do I need to thread the holes it's installed in, or do they thread themselves? Also, is any epoxy or other adhesive necessary?
Thanks in advance.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

personally i prefer the bolt and barrel nut system, especially since you will be using a tenon instead of a butt joint. I think it is much more resistant to failing. But if you insist on using the threaded ones, Im 99% sure they are self tapping. Just drill a pilot hole and then screw them in. I know arie, forum member, has said he wicks in some thin CA around them after he is done. I would reccomend this since it will make the wood a little more solid and less likely to strip out. I just dont trust wood to hold threads.

I would also recommend installing them in the heel before you cut the tenon.

Are you asking how to screw them into the wood? The ones I have used, not from LMII, have had a slot in one end for a flat head screw driver. That is how I screw them in. However, you could also buy a 1/4 20 half inch long bolt from Lowes or Home Depot and after you screw that into the insert, screw the combo into the wood. Got it?

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http://www.CostaGuitars.com
PMoMC

Everything you need Mottola provides for your question (as often is the case).
http://liutaiomottola.com/construction/Bolton.htm

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Doug

Don't let fear or common sense stop you from trying to build something

Like a Heli-coil

I've used them on two necks (butt joint) and think they work well. They've been used pretty extensively by others as well. I can't remember if there are instructions that come with them as far as the pilot hole goes. I'm pretty sure I just measured the OD of the unthreaded portion and used a drill bit that size. I did wick in some CA on the first neck, but not the second for fear of staining (used a rather thin jazz heel with no tenon and didn't want it to soak through to the other side). I made myself a drill guide and used a hand drill just as you plan. No issues. I would install the inserts before cutting the tenon or clamp the sides of the tenon tightly while installing to avoiding cracking such a thin piece of wood. Not speaking from experience, just thinking out loud. Hope that helps.

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sweat the small stuff.

Actually, the slotted end should be inserted down and this is how the threads get cut. To install the insert, use the proper sized bolt in the insert with a couple of nested nuts to stop the insert from moving up the bolt as it is turned in. When threading into an already cut neck tenon, I tighten a C-clamp on the sides of the tenon to prevent cracks.

The two sets of inserts I've received from LMI did not have the slotted end like the ones from Lowes and Home Depot do. You butt a nut against the insert with the bolt threaded inside. That's poorly worded on my behalf, but I think you get what I'm saying.

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sweat the small stuff.

Some folks use a vertical dowel in the neck (or tenon in this case) to provide a better bite for the inserts. I use the barrel bolts with vertical grain reinforcement on the edges of the tenon and a vertical dowel in the heel of the neck as a general precaution.
Tom

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A person who has never made a mistake has never made anything!!!

Tony's correct, install them BEFORE cutting the tenon, as you are screwing into end grain.

I think reinforcing the sides of the tonon would be a good idea, as in this method: http://www.cumpiano.com/Home/Articles/S ... block.html
even though you are forgoing the KD system, as it may keep the sides from blowing out, and gives the tenon extra strength, which I believe will be necessary in a tenon vs a butt joint, for the type of bolt system you want to use.

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Old growth, shmold growth!

For bolt ons I use the zinc alloy inserts with the interrupted threads like the ones McFeeley's sells. They are about 15 cents apiece and screw in with an allen wrench. The threads are taller than the brass inserts , so bite into the wood a bit more. Zinc is not as strong as steel inserts would be, but the wood gives up first anyway, so they are strong enough. I also like to wick thin superglue into the area around the insert for mahogany or walnut necks.

I use these on butt joint necks with a vertical dowell so they don't screw entirely into endgrain. They work well, and you don't need to thread the hole. I think the recommnended hole is 10mm.

Thanks, all of you, for the information. As usual, I got more than I asked for, with explanations for why each of you do it the way you do.
I love this place!

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

Mike,
You can get the same thing at Ace Hardware if you have one in your area for a fraction of the cost of what Stew Mac charges.
Also, what Tony say, install them before you cut your tenon so it don't split the wood when you screw in the insert. I'd go with the barrel nut if I were you.

Hutch

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"After forty-nine years of violin building, I have decided that the search for a varnish is similar to the fox hunt. The fun is in the hunt."
Jack Batts Maker and Repairer of Fine Violins

+1 ace

Filippo,

Are you using pipe thread taps?

Kevin Looker

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

The LMI insert kit comes with pretty complete instructions and a nut to help install the inserts. They advise the tenon be clamped while inserting to avoid splitting. I found them difficult to get inserted absolutely straight and square. Love the tap idea and that would help get them square. Oh BTW I also popped of a piece of my stacked neck heel by over tightening the screws.

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Thank You and Best To All

Yo, Mike, Every piece of info you need is explained by the previous responses. I will only add four pieces of advice, based on my own experience:

1. Whether buying at the hardware store or at LMII, buy several extra inserts. They are not expensive. You will use these to experiment in test holes on end-grain scraps until you are confident of your pilot hole and your insertion technique. Pilot hole diameter is important.

2. You may cut your tenon first. In fact, this makes it easier to locate the position of the holes for the inserts. But clamp a piece of hardwood on either side before installing the insert. This is to prevent the insert from causing a split and blowout of your tenon. Practice this on scrap, too, while doing your test inserts.

3. If you search a bit at the hardware store, you might find inserts made of a harder metal than brass. Some have sharper, self-tapping threads and can be inserted with an allen wrench. A bit of epoxy applied to the threads will lubricated them during the insertion and will lock the insert in place.

4. Beg or borrow a little time on someone's drill press if you can, and make a little hardwood drill guide to keep your hand drill aligned while doing the pilot hole. This isn't absolutely necessary, but it'll eliminate potential problems with your drilling angle if you can manage it.

Please heed my advice to practice several times on scraps until you get a feel for what is happening as the insert goes in. Then go for it. Good luck with it!
Patrick

My thanks to all, once again.
I'll be looking at my local hardware stores.
Can someone tell me what these are called? I can't very well go looking for "neck inserts" at my local hardware.
As to the barrel nut, I plan to experiment with both of these to see which one is the better choice for my application.
Patrick, you can lay money on the fact that I'll do at least 2 or three run throughs with scrap for each before I choose.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

Some of these inserts have continuous threads their entire length and some do not. I prefer the ones with continuous threads as I had to remove one before and the ones with the interupted threads remove a lot of the wood that one would hope is holding the insert in place. It seems to tare the wood up.

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Formerly known as Adaboy.......

Thanks, Darryl.
Can someone suggest sizes for both fastener types?

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

I use a 3/8" diameter barrel with a 1/4-20 tapped hole through it. I make them myself and make them to be as wide as the tenon. And of course a 1/4-20 bolt.

Thanks, Zeke!
Of course, after I posted that I realized that LMI lists the sizes for each in the link I posted. Was going to edit my post to reflect that, but you beat me to the keypad.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

Haha sorry I beat you to it. I just realized I lied to you about the barrel nut though. I use a 5/8 diameter not 3/8. I don't know how 3/8 got in my head.

I've done these all sorts of ways. I use a butt joint however. I've simply just threaded them in, then threaded them in and wicked with CA, and also drilled the holes the same size and epoxied them in place.

No worries on using a hand drill. If you have a try-square, you know the little square with the steel ruler and the black leveler thing, then take the level off and use it as a guide.

If you use the epoxy method then you can place the inserts in by first screwing a 1/4in x 2 or 3 bolt in flush with the edge of the insert and then dollop the inserts with epoxy and put them in the hole and fudge the alignment using the level square and or just by eye. When dry remove the bolts with a wrench. I like the epoxy method because it doesn't stress the area like threading would (though using a tap would solve that problem nicely) and trust me once they are in they are in, i have tested the strength.