Threaded Inserts

[Bruce Johnson]

How much more force? Do you have a torque target?


Socket heads in the final assembly too? I would guess the driver ‘camming out’ of Phillips-head screws sets the practical torque limit in conventional Fender-style neck joints.

I've never established an actual torque value for how much I tighten the neck "bolts" (machine screws, actually) on my basses, but it's quite a bit higher than I would tighten the wood screws on a Fender. I use stainless steel 10-32 Socket Head Screws, and tighten them with a T-handle Allen Wrench. Not enough to start crushing the wood, but close.

My neck plates are 1/4" thick aluminum, recessed into the body, with counterbores for the heads of the cap screws.

 

[Bruce Johnson]

Mmmmm....

Yeah I'm sceptical!
The inserts I've used in my current build are put in from the underside, but they stop short only just under the fretboard so I can't see how it's physically any different which side they are put in from.

T-nuts and BruceBars have flat surface area on the top side of the neck wood. They push down on the wood, squeezing it. Likewise, the neck plate on the back of the body provides surface area. Tightening machine screws between them can allow much higher clamping force than you can get with wood screws threaded into wood, or cylindrical inserts set in from the bottom. That's the whole point: higher clamping force holding the neck and body together.

 

[Fingerz]

First attempt at Bruce bars. Feels like a really solid join where the pressure is really evenly spread. Thanks so much for all the advice and information.

 

[Snert]

^^ That looks great. It's good to read others doing this as as soon as I saw the first ones, I thought 'what a stonkingly great idea'. My first build is still a few months away and I'm going to incorporate them too.

 

[Roxbororob]

First attempt at Bruce bars. Feels like a really solid join where the pressure is really evenly spread. Thanks so much for all the advice and information.
View attachment 4685488

Im a mechanical designer by day and was one of the first to reply with a source for good inserts.

I can emphatically say that these are so much better. Its good you took the time (and advice from T_Bone_TL and Bruce) to make these. Nicely done too!

Edited...

 

[Bruce Johnson]

First attempt at Bruce bars. Feels like a really solid join where the pressure is really evenly spread. Thanks so much for all the advice and information.
View attachment 4685488

Nice work! It looks like you even chiseled the corners of the slots square? I usually don't even go to that trouble. I either rout the slot a bit longer than needed, leaving the rounded end of the slot empty. Or I use a belt sander to roughly round off the ends of the bars.

You generally want just a light sliding fit of the bars in the slots. Don't make the fit so tight that you have to press them in. That could cause the heel to split later. It doesn't matter if the bars are a little loose in there. As soon as the screws are in and tightened, they will be locked down.

You'll find that these bars, combined with some structural improvements in the neck, will significantly improve the clarity of the deep bottom end. The low fundamentals will stand out. Not really louder, but clearer. More like a piano.

 

[Fingerz]

Nice work! It looks like you even chiseled the corners of the slots square? I usually don't even go to that trouble. I either rout the slot a bit longer than needed, leaving the rounded end of the slot empty. Or I use a belt sander to roughly round off the ends of the bars.

You generally want just a light sliding fit of the bars in the slots. Don't make the fit so tight that you have to press them in. That could cause the heel to split later. It doesn't matter if the bars are a little loose in there. As soon as the screws are in and tightened, they will be locked down.

You'll find that these bars, combined with some structural improvements in the neck, will significantly improve the clarity of the deep bottom end. The low fundamentals will stand out. Not really louder, but clearer. More like a piano.

Thanks. In the future I fancy making a template I can route to, but I didn't go for routing this time as to use the fence just felt a bit risky. I chose to Forstner out the meat, then chisel everything square and flat, it's enjoyable and necessary for me to improve my hand skills!

They're snug but no too tight, great advice again on that front, all taken on board for the future. I didn't want them to move too much incase any glue got in there when I laminated my fingerboard on, then fixed the thread off centre from the clearance holes. I've really enjoyed implementing this element of the design and feel like I've learnt a great concept as well as some new skills along the way. Really appreciate it.

 

[dazmond]

Invalid Link Removed (1/4"-20 square brass nut)

Anyone have thoughts on using a square brass nut (or stacked pair) as the neck inserts/Bruce bars? Would be reasonably easy to chisel some corners into a forstner hole before the fretboard goes on, and being that the nuts are square, they shouldn't spin.

 

[Bruce Johnson]

Invalid Link Removed (1/4"-20 square brass nut)

Anyone have thoughts on using a square brass nut (or stacked pair) as the neck inserts/Bruce bars? Would be reasonably easy to chisel some corners into a forstner hole before the fretboard goes on, and being that the nuts are square, they shouldn't spin.

Hey dazmond;

If you are installing them from the top side, under the fingerboard, they would be pretty good. Not as much clamping surface area as a BruceBar, but it should be enough to get some increased clamping force. Square is good to keep it from spinning, and brass is good to keep it from seizing.

But, if you are going to do that, maybe just make the bars? Buy some brass bar stock, drill and tap some holes, saw them off. It's not that hard.

1/4-20 bolts are kind of overkill for neck bolts. I've never seen the need for anything larger than 10-32 on electric basses.

 

[dazmond]

I didn't enjoy the last bit of machining I did that much, so I am maybe trying to avoid it.... it's kind of fun trying to find an off the shelf solution too. Brass stock is $$ locally or getting shipped, so it's even better if I can find a solution where the work is already done for me. I also stumbled across M6 brass hydrofoil track nut that might be worth a try for me too. The big screw size is mostly about the aesthetic/availability of using furniture bolts. UP100 10pcs M8 / M6 Hydrofoil Mounting T-Nuts for Water Sports Surfing All Hydrofoil Tracks (M6 Thread) : Amazon.ca: Sports & Outdoors for an image. Can find them cheaper on aliexpress.

 

[frets4ever]

I didn't enjoy the last bit of machining I did that much, so I am maybe trying to avoid it.... it's kind of fun trying to find an off the shelf solution too. Brass stock is $$ locally or getting shipped, so it's even better if I can find a solution where the work is already done for me. I also stumbled across M6 brass hydrofoil track nut that might be worth a try for me too. The big screw size is mostly about the aesthetic/availability of using furniture bolts. UP100 10pcs M8 / M6 Hydrofoil Mounting T-Nuts for Water Sports Surfing All Hydrofoil Tracks (M6 Thread) : Amazon.ca: Sports & Outdoors for an image. Can find them cheaper on aliexpress.

Before Bruce provides alternatives, you may want to look at 20 series t nuts they are steel and plated to prevent rust and seizing. They have smaller dimensions and different screw sizes.

https://www.amazon.com/JCSPBYL-Sliding-Hammer-Aluminum-Profiles/dp/B0BK75LJNF/138-2633788-0094916?pd_rd_w=MTt7r&content-id=amzn1.sym.751acc83-5c05-42d0-a15e-303622651e1e&pf_rd_p=751acc83-5c05-42d0-a15e-303622651e1e&pf_rd_r=GZWR459BAANAV0WM6N3X&pd_rd_wg=ex3fr&pd_rd_r=0c77c6df-e5f4-4073-882c-344c33391452&pd_rd_i=B0BK75LJNF&th=1