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 Post subject: Treaded inserts question
PostPosted: Tue Oct 21, 2025 8:49 am 
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Repair situation, converting a dowelled neck joint to a butt joint.
Also, epoxy in, or wick in thin ca glue?

Are these suitable for a butt jointed neck?

https://www.amazon.co.uk/Z-LOK-400-M6-Threaded-Internal/dp/B002WC8TRA/ref=sr_1_6?crid=2RPLGBLR03BJ3&dib=eyJ2IjoiMSJ9.VKpbT326RL7jIgjD2Fsyg9l67EtyRMytxYHclGi5bAxsUDsPko2WvpUXaSlMzIVyd3KmiIiqb5JZ8dmEC9swjZLhA6UbLtmnPxiczE3OKlMId9Q_gkl6oXPYV7iJLhbTrRkbAJvutyn5MJll-bDpnOecxa8b8E-ver6hLZSw32CVDlzEemKvqTSHgGAxDE-yoJR1gtfQy0JeUp3J2UwIbSSID24k8GUlilQRAkGfKs_q_aFbifLmR6_aAeKFT2pUHSWncbQ0BWz0I4Z5WbZGee02cYIFwC9yE1GMY7M7MYA.nmuEN7pEHKVltVWUy39zfhoLW87eHEUppZXBJQaZLT4&dib_tag=se&keywords=threaded%2Binserts%2Bez%2Blok%2Bm6%2Bfor%2Bwood%2Bbrass&qid=1761054051&sprefix=threaded%2Binserts%2Bez%2Blok%2Bm6%2Bfor%2Bwood%2Bbrass%2Caps%2C152&sr=8-6&th=1

Or should I use steel ones?

https://www.amazon.co.uk/Z-LOK-400-M6-Threaded-Internal/dp/B002WC8TRA/ref=sr_1_6?crid=2RPLGBLR03BJ3&dib=eyJ2IjoiMSJ9.VKpbT326RL7jIgjD2Fsyg9l67EtyRMytxYHclGi5bAxsUDsPko2WvpUXaSlMzIVyd3KmiIiqb5JZ8dmEC9swjZLhA6UbLtmnPxiczE3OKlMId9Q_gkl6oXPYV7iJLhbTrRkbAJvutyn5MJll-bDpnOecxa8b8E-ver6hLZSw32CVDlzEemKvqTSHgGAxDE-yoJR1gtfQy0JeUp3J2UwIbSSID24k8GUlilQRAkGfKs_q_aFbifLmR6_aAeKFT2pUHSWncbQ0BWz0I4Z5WbZGee02cYIFwC9yE1GMY7M7MYA.nmuEN7pEHKVltVWUy39zfhoLW87eHEUppZXBJQaZLT4&dib_tag=se&keywords=threaded%2Binserts%2Bez%2Blok%2Bm6%2Bfor%2Bwood%2Bbrass&qid=1761054051&sprefix=threaded%2Binserts%2Bez%2Blok%2Bm6%2Bfor%2Bwood%2Bbrass%2Caps%2C152&sr=8-6&th=1

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.


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PostPosted: Tue Oct 21, 2025 9:44 am 
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Both links go to the brass kind which I hate furiously with the burning passion of a thousand suns.

These are my jam. https://www.mcfeelys.com/1-4-20-x-591-i ... y-100.html. You can find matching bolts everywhere.

The hex key insert makes getting them in there so much easier. I have not felt the need to glue or epoxy them in for a long time now. Unless you’re using some soft wood like Spanish cedar, they will hold nicely. The actual ones I use are only 1/2 deep but I didn’t find them on a cursory search, but I wanted to show the type.

Thanks for the reminder that I need to buy more!



These users thanked the author meddlingfool for the post: Colin North (Tue Oct 21, 2025 5:06 pm)
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PostPosted: Tue Oct 21, 2025 9:47 am 
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I prefer these inserts: https://www.amazon.com/Hillman-Group-30 ... C88&sr=8-8

They require a smaller hole (5/16”) than the ones you cite and the coarser threads are less likely to turn the end grain into particles. I like the brass because is less likely to spall with a steel bolt. I also like to have a 1/2” vertical dowel in the heel with the center set back 1/2” from the edge for the insert to bite into. The insert is being set into end grain in the heel and has the possibility of pulling out. I use thin CA wicked in after the installation of the insert. If anything goes wrong on the installation, you don’t want glue holding it in the wrong place.

My experience on the inserts is only on new builds. I have never done a retrofit like you describe. I imagine you would have to remove the heel cap to install the vertical dowel.

Here’s a hint on the insert installation: if you have the neck clamped in the drill press to drill for the insert, after drilling a hole, without changing the alignment, replace the drill bit with a bolt with the insert on the end and turn the insert in by hand using the drill press to keep it aligned. It’s a lot easier than trying to free hand it in.



These users thanked the author bobgramann for the post (total 3): Dave Rickard (Thu Oct 23, 2025 9:31 am) • Colin North (Tue Oct 21, 2025 5:06 pm) • Bryan Bear (Tue Oct 21, 2025 9:58 am)
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PostPosted: Tue Oct 21, 2025 2:51 pm 
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bobgramann wrote:
Here’s a hint on the insert installation: if you have the neck clamped in the drill press to drill for the insert, after drilling a hole, without changing the alignment, replace the drill bit with a bolt with the insert on the end and turn the insert in by hand using the drill press to keep it aligned. It’s a lot easier than trying to free hand it in.


This is a great tip for general use of threaded inserts in anything, not just for neck inserts. Cut the head off a bolt and chuck it, thread on two nuts and jamb them together as a stop, thread on the insert under the nuts, then turn/lower the chuck by hand (no power!). The inserts cannot help but go in straight. I use this all the time for making jigs.



These users thanked the author doncaparker for the post: Colin North (Tue Oct 21, 2025 5:06 pm)
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PostPosted: Thu Oct 23, 2025 10:04 am 
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I use a tenon on my necks and had an old dowling jig. Beau Hannam put up a video on Youtube using that dowling jig to both drill the hole in the heel and screw in the insert and this works great

Kent



These users thanked the author kfish for the post: Colin North (Thu Oct 23, 2025 4:06 pm)
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PostPosted: Thu Oct 23, 2025 4:08 pm 
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kfish wrote:
I use a tenon on my necks and had an old dowling jig. Beau Hannam put up a video on Youtube using that dowling jig to both drill the hole in the heel and screw in the insert and this works great

Kent


Yes, I've seen it. That would be nice, but I don't have the possibility if making this repair with a tenon.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.


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PostPosted: Fri Oct 24, 2025 7:08 am 
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I use a butt joint with M6 steel inserts in my builds and have had no problems. I do not use adhesive on the inserts but I do glue in a 12mm hardwood dowel so that almost the whole of the inserts are in cross grain.
In your repair circumstance that will be difficult.
I took this method from R.M. Mottola and as far as I could tell these were the type of fittings that he recommends. Also it is worth noting that the slot is there to cut the thread, not to use a screwdriver. I made up a driver from threaded bar so that the inserts can be driven slightly below the surface of the heel to give some leeway to use a chisel when fitting. The tape is there to shim to size for the dowel jig.
Apologies for the picture quality, that is how it turned out after size reduction.


You do not have the required permissions to view the files attached to this post.



These users thanked the author stumblin for the post: Colin North (Fri Oct 24, 2025 8:20 am)
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PostPosted: Fri Oct 24, 2025 8:40 am 
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Thanks Roy, 12mm dowel all lined up.
I plan to go up through the heel cap area, then replace it - I have removed it anyway to facilitate clamping of the heel break.
I checked the website for the inserts you show, they seem to be for metal, with fine external threads - with this being a 12 string, I aim to get everything as solid as possible.
I already have some other inserts which have coarser. deeper threads for wood.
Link to a post about the guitar involved here - http://www.luthiersforum.com/forum/viewtopic.php?f=10137&t=57388

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.


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PostPosted: Fri Oct 24, 2025 11:05 am 
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this is a case of a lot of misinformation
most of the inserts shown were not for wood
this one is the one you want to use.

https://www.amazon.com/hz/mobile/missio ... MX8QM1MCCF

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These users thanked the author bluescreek for the post: Colin North (Fri Oct 24, 2025 11:20 am)
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PostPosted: Fri Oct 24, 2025 11:22 am 
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Got that John, my first post was suggesting the E-Z Loks.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.


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PostPosted: Fri Oct 24, 2025 11:33 am 
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Encourage you to try the zinc for hardwood with Allen key that I linked at least once. It’s great misinformation.


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PostPosted: Fri Oct 24, 2025 1:58 pm 
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I use the ones that are in the link that John shared. I should not have to say it but I have seen people using the slot as a screwdriver slot. It is not as it is a thread cutter.

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PostPosted: Sat Oct 25, 2025 7:36 am 
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Good point John
these are sharp and cut into the block very well the Zink ones are not as sharp and like I said Martin used these for 30 years and I have never seen one fail . The fine threads for plastic don't work in wood.

I use a should bolt to set them into the tenon

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