Bolt-on neck for f-hole mandolin

[WoMando]

Ran across this in my searches. What are the pros and cons of using a butt joint like this?

http://www.dunwellguitar.com/BuildMa...ildMando15.htm

[peter.coombe]

I can't think of any significant pros, a dovetail is not all that difficult. Is quite a different story for guitars, and looks like this guy is a guitar maker. It is rare for a mandolin to need a neck reset, but it is a common repair job for a guitar so a bolt on neck on a guitar has significant advantages, not so for a mandolin.

As for cons, extra mass of all that extra hardware, need specific tools, may be more likely to fail, not traditional. Maybe someone else can think of more.

Why do it?

[rcc56]

I don't think I would be thrilled about pulling and reinstalling allen bolts through an endpin hole if it ever did need a neck set.

[pops1]

Breedlove mandolins are done this way.

[Tavy]

As Graham correctly points out this is a real pain for f-hole mandolins. I have done this for oval hole mandolins and there it works much better.

There is a significant "gotcha" compared to guitars though: the neck heal is so short on a mandolin that the lower bolt has significantly less leverage to withstand the pull of the strings. That means there's way more force on the bolts - not an issue they are plenty strong enough - but also more force on on the wood where the bolts press down on it, and more force on the top edge of the butt join. You need to be very careful to over-reinforce those areas.

[fscotte]

The inevitable lacquer crack at the neck to body connection, if not done well.

With a dovetail, the pull of the strings will make the joint tighter. You dont get that with a bolt on butt joint. If it isnt precisely fitted and very tight, it will likely open up ever so slightly with time.

Personally, I see this taking longer than a dovetail. I can fit one in about 30 minutes.

[Ivan Kelsall]

Both Weber & Summit mandolins have a 'bolt on neck' (sort of). The bolts are used to correctly adjust the neck angle prior to gluing.
So they're not a true 'bolt on' neck,which to me implies NO glue - as per Fender guitars,
Ivan

[multidon]

As stated above, American made Breedloves had the bolt on butt joint. I used to have one and it seemed perfectly fitted. There was no lacquer over the joint so there would have been no cracking. If it ever moved it could be easily reset. I think that joint was at least part of the reason they were able to keep costs down on a USA made mandolin compared with other makers. Of course we all know what happen to them, ultimately. It seems most mandolinists are willing to pay a hefty surcharge to get “traditional” construction, and just say no to innovation.

[lenf12]

So they're not a true 'bolt on' neck,which to me implies NO glue - as per Fender guitars, Ivan

Or Rigel mandolins.

Len B.
Clearwater, FL

[WoMando]

The course I purchased uses a pinned mortise and tenon, which I predict may be a problem if the neck ever needs to be removed.

[Joed]

Just ran across this https://www.youtube.com/watch?v=8pRjZggay2w. That's pretty much like a Stratocaster sort of joint.

[j. condino]

The bolt on system shown in post number one is very similar to what the original Breedlove necks were like (I have no idea of their current system). I built a couple of hundred mandolins using this method while getting verbally abused by the production managers daily for only making 2 1/2 mandolins per day before lunch while being paid $7 per hour while some other guy in the past who quit made 3 per day for $6 per hour ( I subsequently found out that he made up for lost time by not installing any tonebars or braces of any kind!!!!!!!!!!!!!!!!!!).......

The method is secure, positive, and actually works quite well. If you know what you are doing it is very easy to work on. When you are trying to produce hundreds if not thousands of mandolins a year in a production setting, it has purpose. It also is in alignment with the design & philosophy that they use with their guitars, so it makes sense for them. I'd estimate that they have made close to 20,000 mandolins and 100,000 guitars with this system since the introduction circa 1992, so it is well tested and proven.

I can comfortably say that I've made an equal number of traditional dovetail neck joints since then. Neither one is superior to the other, just different approaches. I will say that I can resent a neck with that bolt on style in about ten minutes and go back to stringing it up, whereas a traditional dovetail takes about ten times the total effort and requires additional finish work. There are many well known manufacturers who have use bolts and other hardware on 1000s of mandolins that are working fine out in the trenches. There are better areas to worry about on your mandolins....

I have not used that system in about 20 years and only use a traditional dovetail design with hot hide glue on my own instruments, but I do feel that it is important to give honest feedback about the system from someone with a lot of actual hands on experience, not just internet speculation by people who have never used or worked on this design.....

[Brian Evans]

I've built a number of guitars with a very similar bolt on joint. I use a mortise and tenon to locate the neck, but the rounded face that the neck sits on with this mandolin joint would do a similar thing. Resets are simple, you just loosen the bolts (you don't need to actually remove the neck, although of course you can), slip your sand paper in and finesse the fit. Reinstalling the bolts is simple, even with an F-hole. The body holes are oversize by a trifle, you tape a piece of 1/32" wire to the bolt and fish it in through an F-hole and through the neck block. The O-ring idea works well to keep the bolts in place. The bolts are usually 1/4", the axial force of a 1/4" threaded bolt with 12 inch-pounds of torque (super little torque, thumb and one finger on the tee of the wrench) is 250 lbs per bolt, so for two bolts 500 lbs. It goes up from there, most people will do it up "tight", and probably 1,000 lbs of clamping force per bolt. This is the weakness of the joint - that degree of force squashes the wood, as the wood ages and loses it's springyness it relaxes and the bolts becomes loose. As the wood gets bigger and smaller through seasonal humidity changes, the bolts become loose. You need the ability to retighten the bolts once a year or so. Belleville washers (actually tapered disc springs) can retain force preload through seasonal changes in the wood. My take on it, anyway.