Neck joint question.

[multidon]

Would anybody here be at all leery of a mortise and tenon neck joint that was glued only, with no bolts? A traditional dovetail requires no bolts, of course, because the design of the joint creates its own mechanical strength. But a straight mortise and tenon seems to me to be inherently weaker, and more dependent on the glue. Which is why most makers use some sort of reinforcing bolt system. Some makers claim the joint without the bolts would be fine, and they use the bolts only as internal clamping until the glue dries. But they do not take out the bolts. Most mortise and tenon joints I have seen include bolts. Most use two. Martin guitars with that type of joint have one. But if a maker claimed that his mortise and tenon joint used no bolts (screws) at all, and was glued only, would that set off any alarm bells for anyone here? Should I walk away from purchasing such an instrument?

[sunburst]

When buying an instrument, it is hard to tell how good the joint is.
For a glue joint to be strong, the most important things are good design, good surface preparation, and good fit. If the design of the mortise and tenon joint is good, if the wood surfaces were well prepared and freshly prepared, if the fit of the joint is good, the joint should be plenty strong... until the instrument is subjected to excessive heat (like a hot car in summer) or to extremes of humidity.
Bottom line, there is nothing inherently wrong with a mortise and tenon joint, but as you say, it is not a mechanical joint (like a dovetail) and thus is somewhat more dependent on the strength of the glue joints. In a well-cared-for instrument, that's not a problem.
The difference in strength and stability between a good mortise and tenon and a good dovetail is not as much as we may think, however. I've seen well fit, well glued dovetails released by the heat of a car in summer, so good treatment of the instrument is important regardless of the type of joint.
We have some control (usually) over the treatment the instrument receives, but we have no control over the design and execution of the joint itself, so when buying an instrument, we simply have to trust the maker to have done a good job.

[Marty Jacobson]

Based on that information alone, no. Bolts are not necessary on a mortise and tenon joint which is properly sized and well executed. I would trust the builder on that decision as well as all the other details which are just as important and which can be approached many ways in the construction of an instrument.

[HoGo]

All classical violins have simple (and rather shallow) mortise and tenon joint. It's the back button that actually carries most of the load - it's pretty much the same as on mandolins but those have even more gluing surface and stronger button. If joint is tight (really tight) and HHG is used the joint will be nearly indestructible. But very often I see these joints with rather thick gap (if you can see it it's already too thick IMO) filled with titebond glue and in that case I would rather see a bolt through heel of neck so things won't move...
On the other hand, dovetail joint, even if not 100% perfect wood to wood fit will be much stronger as most of the load is carried by the contact surfaces of wood inside the joint and you really need just several good areas holding it together without wiggling to get quite safe joint even with white glue. Of course 100% fit would be great but it's almost impossible (especially with straight dovetail) to attain. I do it much like Frank Ford in his guitar neck reset procedure undercutting the very inside surfaces and concentrate on good fit of the most important parts (these spaces allow ecape for the glue and help creating tighter joint where needed).

[MikeEdgerton]

I thought Roger Siminoff had something about these joints but he really doesnt. He does have pretty much everything else here.