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My Tenon will be too short. Bolt-On Question
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Author:  Dan K [ Fri Mar 21, 2014 8:54 am ]
Post subject:  My Tenon will be too short. Bolt-On Question
First time poster, First time builder.

I'm following the Natelson and Cumpiano book while building my Dread kit from LMII. I just glued up the heelblock to the neck and trued all surfaces on the large sanding board. As I reread the section for the fifth time, I realized instead of leaving 15/16" behind the 14th fret for the tenon, I only left 3/4" [headinwall] .

I've researched the forum, I've done some critical thinking, here are my questions:

1) Will a 3/4" long Tenon be strong enough to house the 3/8" barrel bolts?

2) I know the Tenon should not butt up to the Mortise, but is this too much space?

3) I would like to get the experience of crafting a fine mortise and tenon joint, however, if this weak tenon may cause a huge problem in the future, is it better to just use a butt joint on this guitar?

Thank you OLFer's, I'm taking this as a lesson in patience and humility.,

-Dan
Author:  johnparchem [ Fri Mar 21, 2014 9:26 am ]
Post subject:  Re: My Tenon will be too short. Bolt-On Question
There is no issue with the gap. I do not have enough experience with the barrel nut to say if there is enough wood left under the barrel nut to hold. I can say that the 3/4 tenon is just fine for https://www.lmii.com/products/mostly-not-wood/truss-rods/neck-parts/bolt-on-neck-inserts. Lot of guitars have these inserts.
Author:  Dan K [ Fri Mar 21, 2014 9:35 am ]
Post subject:  Re: My Tenon will be too short. Bolt-On Question
Thanks for the quick reply John,
I ordered the CDN inserts for this tenon, but I will take a look at the TNI2. I guess it just comes down to what I'm comfortable with.
Author:  Glen H [ Fri Mar 21, 2014 10:14 am ]
Post subject:  Re: My Tenon will be too short. Bolt-On Question
Hey Dan
1) I've been making mine 3/4 of an inch forever, didn't know better. no problems

2) There is no need IMO for the tenon to butt up to the mortise. I leave a gap.

3) It is not too weak. There is no need to crank down real hard and tight on the barrel nuts/bolts. Just snug it up.

Good luck
Author:  Freeman [ Fri Mar 21, 2014 10:32 am ]
Post subject:  Re: My Tenon will be too short. Bolt-On Question
As others have said, the length shouldn't be a problem. The only issue might be the barrel bolts. If you don't have enough wood they might blow out. Here is a picture of a friends neck where that happened

Image

If you want to use barrel bolts I would consider laminating a piece of veneer on the end of the tenon - make it cross grain with the grain running up and down. That should strengthen it considerably. Also consider using the threaded inserts - I have had very good luck with them and you can see that my friend converted to them after having his problems. Good luck.
Author:  Dan K [ Fri Mar 21, 2014 11:02 am ]
Post subject:  Re: My Tenon will be too short. Bolt-On Question
Thank you all for the advice. I was thinking of adding bulk to the tenon for the barrel bolts, but I feel like the threaded inserts will be a better fit. Any idea if these are readily available in hardware stores?
Author:  Quine [ Fri Mar 21, 2014 12:15 pm ]
Post subject:  Re: My Tenon will be too short. Bolt-On Question
I get threaded inserts from Rockler. I've seen them at Home Depot and the True Value...but not every time
You could glue on a 1/16" shim to your tenon if you're worried. Gluing on a piece of maple would make it stronger with the grain running vertically along the tenon.
Author:  Freeman [ Mon Mar 24, 2014 11:12 am ]
Post subject:  Re: My Tenon will be too short. Bolt-On Question
Cap'n wrote:
Thank you all for the advice. I was thinking of adding bulk to the tenon for the barrel bolts, but I feel like the threaded inserts will be a better fit. Any idea if these are readily available in hardware stores?


They should be available at any hardware store. You can also buy the complete kit with bolts and washers from LMI. A couple of tricks - first when you make your neck block drill two 1/4 inch holes at right angles to the face thru the mortise. Best to do this in a drill press - you want the holes perpendicular. Build your box putting either the top or back on, but not the other. Build your neck and but don't install the inserts. Take the body out of the mold and do a rough fit of the neck - make a dummy fretboard or take careful measurements and set the neck angle close to the final angle (there are several ways to do this - we can talk you thru that).

Now lightly clamp the neck in place and drill thru the holes in the neck block with a 1/4 inch bit into the heel. The blue tape on the bit is a depth stop so I won't go too deeply into the heel, the fretboard is clamped onto the neck for reference

Image

Now carefully drill out the holes in the heel - LMI recommends a 10 mm bit 9/16 deep. Put a 1/4 nut on one of the bolts and thread it into the insert, then lock the nut down tight against the insert. Use this to carefully thread the insert into the heel - the locked bolt will let you turn it in and out of the wood without the bolt coming out of the insert. Go very slowly, it is possible to split the wood. When you get it nicely threaded, remove the insert and put a little medium CA on it, that keeps it from ever coming out as you tighten and loosen the neck bolts.

Image

Last step, you may need to ream out the holes in the neck block slightly to get a little wiggle room with the bolts as you do the final neck angle setting. Remember that the bolts will be going thru the block at a very slight angle, you don't want them to bind (one advantage of the barrel bolts is that they will rotate to allow that angle)

I've had very good luck with this neck attachment method and use it exclusively now.
Author:  Dan K [ Mon Mar 24, 2014 12:54 pm ]
Post subject:  Re: My Tenon will be too short. Bolt-On Question
OK, well I realized why I cut my tenon short. I'm following Cumpiano's and Natelson's procedures, but using the measurments provided by the Scott Antes plans in my kit, which calls for a 3/4" Tenon. Now I just need to keep these two things straight. Procedures = Book, Measurments = Plan.

Freeman, thank you for the in depth toot on setting the neck with that hardware. I may still try the barrel and bolt method because I have them handy. I also have plenty of maple from the cam clamps I made so I may try the cross grain veneer on the side.

Thanks everyone for taking the time to reply, and making this a great experience for a first time poster.
Debating on posting this on the Doc-u-Build forum, maybe I'll wait and see how the rosette installation goes.
Author:  Freeman [ Mon Mar 24, 2014 9:20 pm ]
Post subject:  Re: My Tenon will be too short. Bolt-On Question
Cap'n wrote:
... using the measurments provided by the Scott Antes plans in my kit, ....


I haven't seen the Antes dread plans but I have built a parlor from his plans for that size. Most plans are drawn as tho you were looking at the inside of the back but at least the parlor plans are kind of an X ray of the top. If you are used to looking at the back from the insides it is very easy to put the two tone bars (the slanted braces between the X) backwards - in other words to make a left handed braced guitar. Just make sure that your braces look something like this (this is an 00, yours will look a little differently)

Image
Author:  Dan K [ Tue Apr 01, 2014 9:20 am ]
Post subject:  Re: My Tenon will be too short. Bolt-On Question
I did worry about that when I first received my kit and the plans. It must've taken me 3 or 4 in-depth passes until I saw the very subtle perforated pickguard orientation. The only reason I knew to look for that was your post on an earlier topic. Thanks Freeman

Dan
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