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Discussion Starter · #1 ·
OK, so here's the sitch.

I'm working up a Mexi-Conn tenor.

The neck fits into the receiver with what seems to me a normal amount of snugness. When it's in there it doesn't wiggle around. Cursory inspection indicates the neck tenon is decently round. If you rotate the neck in the receiver it seems to have no tight or loose points, it's about the same all the way around.

Yet the neck will not tighten up with the screw.

The slot in the receiver looks normal, the sides are still well apart, not crushed together or unusually distorted. It looks like there is no "stuff" in the slot that might keep it from closing up on the neck. I replaced the slightly bent and stretched brass neck screw with a steel screw, well greased.

Yet the neck won't tighten up with the screw. I have used more than usual force on it.

If the neck tenon were worn too small it seems that it would be loose in the receiver before attempting to tighten. If it were out of round it seems that there would be some looser and tighter places as you rotate it round in the receiver.

Any ideas? I know I could get it to tighten up by cutting the slot deeper but that compromises the sealing. I have had a lot of saxophones with detachable necks and this one looks (to me) just like all the others through the years that worked fine.
 

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Have you checked to see if there is a taper on the tenon? What you describe sounds like the end of the tenon is the correct diameter, but the upper end (away from the opening) is smaller.

I usually measure tenons at three locations along the length to see if a taper exists.
 

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Good thought.

Another question (sorta stupid, sorry): with the neck off, when you tighten the thumbscrew can you see the two sides of the receiver come closer to one another (i.e. the slot getting narrower) ?

then: is there any sign on the receiver that it may be cracked anyplace ?
 

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Discussion Starter · #4 ·
Good thought.

Another question (sorta stupid, sorry): with the neck off, when you tighten the thumbscrew can you see the two sides of the receiver come closer to one another (i.e. the slot getting narrower) ?

then: is there any sign on the receiver that it may be cracked anyplace ?
The slot gets a little bit narrower when tightening the screw, but it seems stiffer than I would expect. I'll take a look at one of my other horns this evening to get a subjective comparison.

I'll also measure carefully and as noted that might reveal the problem.

Receiver looks good, definitely not cracked (my baritone has a crack that's been there since I got the horn in 1984, so I think I would recognize). The tenon had a crack in it and I expected that was related to the issue, but yesterday I soldered that crack closed and there was no difference whatsoever - which is why I started asking.

Do you know off the top of your head the diameter of the tenon (roughly) so I can borrow the right ID mike?
 

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I use a caliper for quick troubleshooting measurements such as this - accuracy to 0.001" is plenty for the application.

While you are at it, check also for roundness at each of the three diameters along the length.
 

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The slot gets a little bit narrower when tightening the screw, but it seems stiffer than I would expect. I'll take a look at one of my other horns this evening to get a subjective comparison.

I'll also measure carefully and as noted that might reveal the problem.

Receiver looks good, definitely not cracked (my baritone has a crack that's been there since I got the horn in 1984, so I think I would recognize). The tenon had a crack in it and I expected that was related to the issue, but yesterday I soldered that crack closed and there was no difference whatsoever - which is why I started asking.

Do you know off the top of your head the diameter of the tenon (roughly) so I can borrow the right ID mike?
There are only a pair of Georges here, I regret to inform you ....:( :bluewink:...but on the flip side, we make great drinkin' buddies.

The two 16M necks I have here have tenon diameters of 27.9 and 27.95, FWIW...one is an older wire brace neck, the other appears to be a sheet metal brace neck (I say 'appears' only because the brace is gone, but the solder points still present).
 

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Discussion Starter · #7 ·
I use a caliper for quick troubleshooting measurements such as this - accuracy to 0.001" is plenty for the application.

While you are at it, check also for roundness at each of the three diameters along the length.
Calipers are fine for the tenon OD but I want to check the receiver ID at different depths. I don't have a set of telescoping gauges, but I can borrow 3 point hole-test mikes. (Actually, I think we might have a set of telescoping gauges in the shop which would allow better checking for out-of-round on the receiver. If that's so, I'll grab them too.)
 

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Calipers are fine for the tenon OD but I want to check the receiver ID at different depths. I don't have a set of telescoping gauges, but I can borrow 3 point hole-test mikes. (Actually, I think we might have a set of telescoping gauges in the shop which would allow better checking for out-of-round on the receiver. If that's so, I'll grab them too.)
Absolutely!
 

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You may need to expand the tenon at the top depending upon the measurements you get. I might add that if you don't yet have a "neck leak isolator tool" it is a good idea to get one if you work on saxophone neck fitting. It is the only way to be sure you have an airtight seal. Tenons or receivers that are slightly out of round can feel snug, but still leak.

A trick my mentor showed me for working on older saxophones that seem to require really torquing the screw to keep the neck from turning is shown in the illustration below. Filing the portion where the screw makes contact so that it puts more pressure on the outside gives a bit more mechanical advantage which often makes a big difference.

neck tenon receiver modification.jpg
 

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Discussion Starter · #11 ·
Double-forked calipers...but I guess you don't have those handy ?

https://musicmedic.com/digital-caliper.html
Those are just ordinary calipers. I have those in metric and English, vernier, dial and digital, practically coming out of my ears. They are slightly better than useless for ID measurements. First of all, the ID prongs are only about 15 mm long, and the actual contact surfaces are about 10 long. So you can get a "sort of average" ID for the area from an opening to 15-ish deep. You can't measure deeper than 15. If you have a local out of cylindrical area, it'll show the hourglass shape as if the whole thing were the smallest diameter, and a barrel shape won't be picked up at all, because the ID contact edges are too long.

If you want accurate ID measurements, regular calipers are not the best way to go. A three point hole mike will give you the best average measurements; the length of their contact edges varies with manufacturer, but you can typically go several inches deep into a hole. They are also very expensive. Telescoping gauges require some technique to get good results because they give you transfer measurements, but you can get the most localized measurements. The telescoping gauges are not expensive. You can buy actual ID micrometers, but I think the smallest hole is probably around 1.5". Of course there are hole gauges based on expanding sectors and a dial gauge, but those are typically production gauges each with a head for the specific hole being measured. They're not really universal measuring tools.

Don't even get me started on air gauges and CMMs.
 

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Discussion Starter · #12 ·
On the other hand, have you ever considered the advantages to the saxophone repairman of owning a really nice CMM?

"Honey, I think I know what I want for Christmas..."
 

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On the other hand, have you ever considered the advantages to the saxophone repairman of owning a really nice CMM?

"Honey, I think I know what I want for Christmas..."
I just got one of these: https://www.nikonmetrology.com/en-us/product/modelmaker-h120

Great fun - not quite up to characterizing the entire bore of a saxophone though. But if one were satisfied with assuming constant thickness of the body, the exterior scans are excellent.
 

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Discussion Starter · #14 ·
I just got one of these: https://www.nikonmetrology.com/en-us/product/modelmaker-h120

Great fun - not quite up to characterizing the entire bore of a saxophone though. But if one were satisfied with assuming constant thickness of the body, the exterior scans are excellent.
Well, certainly you could assume constant thickness (or close enough) for all the conical body tubes since they're just rolled and seamed. Given the size of the parts, the bow and bell are surely close enough (there is stretching and thinning in the stamping process, but it's going to be a tiny fraction of the bore dimensions). That just leaves the neck and some careful measurements at selected areas would probably give you enough to decide how much to take off the OD where. Of course drawn tone holes have a lot of thinning but you can measure the ID and height of these directly.
 

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OK, so here's the sitch.

I'm working up a Mexi-Conn tenor.

The neck fits into the receiver with what seems to me a normal amount of snugness. When it's in there it doesn't wiggle around. Cursory inspection indicates the neck tenon is decently round. If you rotate the neck in the receiver it seems to have no tight or loose points, it's about the same all the way around.

Yet the neck will not tighten up with the screw.

The slot in the receiver looks normal, the sides are still well apart, not crushed together or unusually distorted. It looks like there is no "stuff" in the slot that might keep it from closing up on the neck. I replaced the slightly bent and stretched brass neck screw with a steel screw, well greased.

Yet the neck won't tighten up with the screw. I have used more than usual force on it.

If the neck tenon were worn too small it seems that it would be loose in the receiver before attempting to tighten. If it were out of round it seems that there would be some looser and tighter places as you rotate it round in the receiver.

Any ideas? I know I could get it to tighten up by cutting the slot deeper but that compromises the sealing. I have had a lot of saxophones with detachable necks and this one looks (to me) just like all the others through the years that worked fine.
Size up the tenon until it fits in the loosened collar well enough to be played without moving around. Then when you tighten the screw it will get tight without squeezing the two sides of the clamp together.
My tech does not get this. I have to talk to him again. The first thing he does is to sand the tenon! Then he might size it up just a hair but it basically falls into the collar and I have to tighten until the clamp bottoms out to be marginally good to play. All my life techs have sized up the tenon to be actually hard to put in. When its that tight, its going to play great and last a long time.
The player has to do his part and always loosen the screw before putting the neck in, turning it to one side to lay the horn down or removing it.
 

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OK stupid but I have to ask. Did you take to screw all the way out and check that somebody has added a shouldered screw? It could be bottoming out on the shoulder long before it had a chance to tighten. Should almost be all thread.
 

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Measurement taken with screw completely loose & 1/4 turn past initial contact. Neck is completely locked at about 1/8 turn past contact. Nasty way to take a measurement but at least we know it compresses approximately .011.
The neck tendon measured 1.1145 or .0015 less than receiver. This is a 1958 16m
 

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Everything you wrote about the measuring tools is true, but... usually not critical in this case. This is not a very common issue, but I've seen it enough and in 100% of the cases the problem was pretty much what Dr G suggested. The tenon isn't tight only at the top. Either the tenon is too small there, the socket is too wide there, or both.

If there is no change when you rotate the tenon, then at least one of them (the tenon or the socket) is round. Both need to not be round for a noticeable change.
If it seals regardless of the screw, then most likely there is no roundness problem at the bottom.

Of course it could be some other less likely and rare issue, but in every case I've seen the solution was fitting just the top part of the tenon, which doesn't have anything to do with the seal anyway.
This is why you don't (usually) need those "fancy" measuring tool. the quotes because telescoping gauges really are not fancy (not so expensive) and a simple tool once you get the feel. Just make sure you don't have defective ones that give incorrect measurement, like my first set was :)

Regular calipers are generally good enough for this. You can easily find almost anything you need about the tenon, and you can easily see if the socket is wider at the top with them too.
I sometimes use telescoping gauges for this purpose and you can do everything you mentioned with them, but honestly for the usual problem when this happens it's not completely necessary.

A very fast and simple measurement is to just feel if the tight calipers on the tenon are a little loose at the very top of the tenon and vise versa (can't get around the tenon when tightened at the top). Then for the socket, check at a few depths (1mm-2mm depth difference) and see if you suddenly can't get them in farther. Then check deeper and see if they feel loose at the top.
I tend to grab the calipers and not the telescoping gauges first for this because I can check both tenon and socket with them (the gauges are only good for the socket).

One thing I will mention about calipers since some posts are about that (apparently not relevant to you since you have a bunch of different ones). Imperial mechanical (vernier) ones supposedly measure pretty reliably to around 0.001". Metric vernier calipers generally measure pretty accurately to the closest 0.1mm, and give a pretty good idea to the closest 0.05mm (about 0.002"). This is borderline and often not good enough. So dial or digital calipers are preferable. That is if you want to measure, which for the reasons already mentioned, is not a real measurement of the socket anyway. You can do the "feel" tests just the same with vernier calipers.
 

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The neck on my 1949 10M was loose; no amount of tightening of the screw would fix it. I took the horn to a techie and got him to expand the neck tenon. The neck was still loose when he'd finished. He said to me that he couldn't expand the tenon any further for fear he would split it. When I got the 10M back home I examined the neck tenon and receiver closely. It seemed to me that the techy had expanded the tenon at the bottom end only, while the retaining screw gripped the tenon at the other, upper, end (where it was fixed to the neck) which had not been expanded. I wrapped some plumber's Teflon tape around just the upper half of the neck tenon and assembled the sax. Wonder of wonders, the screw tightened, the neck was fixed in place with no movement and no leaks…

I've often thought of replacing the neck tenon and receiver with new parts — but why bother ? The Teflon tape does the trick, doesn't need replacing very often, and is relatively cheap to buy…
 

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Discussion Starter · #20 ·
The neck on my 1949 10M was loose; no amount of tightening of the screw would fix it. I took the horn to a techie and got him to expand the neck tenon. The neck was still loose when he'd finished. He said to me that he couldn't expand the tenon any further for fear he would split it. When I got the 10M back home I examined the neck tenon and receiver closely. It seemed to me that the techy had expanded the tenon at the bottom end only, while the retaining screw gripped the tenon at the other, upper, end (where it was fixed to the neck) which had not been expanded. I wrapped some plumber's Teflon tape around just the upper half of the neck tenon and assembled the sax. Wonder of wonders, the screw tightened, the neck was fixed in place with no movement and no leaks…

I've often thought of replacing the neck tenon and receiver with new parts — but why bother ? The Teflon tape does the trick, doesn't need replacing very often, and is relatively cheap to buy…
Yeah, I had a goober do that to a 10M (not this one) many years ago. It made it hard as heck to get the neck in, but it still wobbled about when tightened.

I don't think this one has the exact same issue, because it doesn't wobble much at all (if you grap the end and pull lightly up and down, there's only the tiniest trace of movement, and that only with the screw loose). It's more that when I tighten the screw, the neck will still rotate. Anyway, actual measurements are required. I've got the relevant measuring tools on my bench, just need the time to sit down and use them, and then think about what the results mean. I'll probably compare to the alto and baritone I also have access to (my other Conn tenor is 2000 miles away).
 
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