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Forum Contributor 2016-17
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Discussion Starter · #1 ·
I’m overhauling my Conn 10m and the pivot screw in the low C# post is stuck. Looks like someone before me mangled the head a bit. I’m going to use penetrating oil etc. but I’m having trouble determining if there is a set/grub screw in the middle of the ‘+’ on the post, since that area is a bit mangled also. Can someone who owns a 10M with a similar post let me know if there is a set screw in there? I know I could just leave the pivot screw but I’d like to try to get it out.
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That's a tough one. If you can free the pivot screw enough to turn by using penetrating oil, heat, tapping with a plastic or rawhide mallet, and lots of patience---if the screw backs all the way out there is no "set screw". If it does not back completely out, it is still in there. Drilling the set screw out is next to impossible. An easier way to remove what's left of it would be to use a very small grinding "burr" in a dremel tool and work very carefully in the area you think it is located. Magnification will help. Another option is to unsolder the post and soak it in "next to boiling" water saturated with alum for several hours in an aluminum pot to dissolve the iron content of the screw. This requires constant tending to replace the water that evaporates.
 

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Yep. My 1932 Tranny has a set-screw there, as do my 1937 and 1949 10Ms. So there definitely should be a set-screw in there. @saxoclese's method of unsoldering the post and soaking it in a hot alum solution is the best course to follow — but you'll still have that cross-cut in the post and other problems, too. So if you're going to unsolder the post anyway, why not just replace it with a post sourced from a junk instrument ?
 

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I can't tell from the photo whether there actually is a "grub screw" in there (it could be because I don't have my reading glasses on), but that appears to be your lower C# post, which normally would need and have a set screw (another name for "grub screw"), and it seems pretty obvious that the cuts in the post you see were part of an attempt to remove a stuck set screw. Whether they got it out or not is uncertain to me, from the photo.

This is possible for a DIYer to address, but you're better off if you have someone familiar with Conn to take it to in order to fully address the existing issue.

If that person gets lucky, they will be able to get an existing set screw out (if there is one in there) by drilling a carefully placed hole in its center and kind of levering it out once the hole is the right size for its remaining remnants to be bent into the center. After that, if really lucky, a replacement screw can just be put in (with some lubricant to prevent future corrosion and crustiness which is likely the cause of all that mess in the first place), or the existing, but now inefficatious threads can be retapped for a replacement screw, with a different threading, to take the old set screw's place.

If you can get a pivot screw in and out without addressing the set-screw question, you don't actually need to repair the set-screw, practically speaking. (A) The C# is a less used fingering, so it is less apt to go out of adjustment quickly than other keys/posts, and (B) you can secure a workable pivot screw with "Loc-Tite" or similar, which is basically how Yamaha student model pivots are held in place when they have basically the same mechanical action as a Conn pivot assembly minus the set-screw.
 

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I’m overhauling my Conn 10m and the pivot screw in the low C# post is stuck. Looks like someone before me mangled the head a bit. I’m going to use penetrating oil etc. but I’m having trouble determining if there is a set/grub screw in the middle of the ‘+’ on the post, since that area is a bit mangled also. Can someone who owns a 10M with a similar post let me know if there is a set screw in there? I know I could just leave the pivot screw but I’d like to try to get it out. View attachment 114070
Thanks.
OK - facts - this post, and I sincerely hope only this post, has been butchered by a fool. The spring to the right appears erroded beyond reasonable service. Time to face the reality - find yourself a VERY good technician, offer to walk their dog every Sunday, wash their car once a month and never speak to their children and you just might find yourself in luck. Seriously - a new post (IMHO) would be the quickest, most simple & drama-free solution - opinion based images supplied.
 

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Someone has really taken to that post with a vengeance. That's a really bad DIY attempt to remove the locking screw. I'd replace the post with one from a wreck, if only for aesthetics.
 

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If the remains of the set screw are still in there, trying to back out the pivot screw will just bugger up the threads on the pivot screw, and it'll probably end up galling in place half way out, unable to back it any further out and unable to put it back where it was.

If the pivot screw is steady where it is (not rocking around) then your best bet is to leave it in place and disassemble from the other end. If it's loose in the post but you can't remove it trying GENTLY with a screwdriver, your best bet will be to clean it up real well to remove residual oil, and then use a wicking Loctite to fix it in place - and disassemble from the other end.

This failure is not uncommon on Conns and it's why every time I lubricate the horn I put a teeny drop of oil on each of the set screws.
 

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Where you going to get a new post from?

MAYBE you can find someone with a junker that a post can come from. Keep in mind it's got to have the correct height and not be one of those with an odd angle to the foot. It would be good if it had the right thread, but my 6M has had a standard post with standard pivot screw in that location since I've owned it (43 years and counting).

Or, you could have one machined up for you. At any rate, you'll need to make good measurements whichever way you end up going.
 

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Discussion Starter · #15 ·
Where you going to get a new post from?

MAYBE you can find someone with a junker that a post can come from. Keep in mind it's got to have the correct height and not be one of those with an odd angle to the foot. It would be good if it had the right thread, but my 6M has had a standard post with standard pivot screw in that location since I've owned it (43 years and counting).

Or, you could have one machined up for you. At any rate, you'll need to make good measurements whichever way you end up going.
Thanks turf3, I agree I may not be able to find a proper replacement so easily. At this point the key is functional, I’ll likely start my search for a replacement post, finish the overhaul, and if need be I can play it as-is until I get the new post.
 

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On a hunch I decided to measure the post on my 10M and check the same post on an old Conn parts horn I have in the shop. The parts horn was one that somebody spray painted and used as a wall decoration before selling it "as is" on Ebay. It turned out that the post was a very close match, including a set screw. It cleaned up quite nice including the spring. Send me a pm with your address and I will send it to you at no charge.


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Discussion Starter · #17 ·
On a hunch I decided to measure the post on my 10M and check the same post on an old Conn parts horn I have in the shop. The parts horn was one that somebody spray painted and used as a wall decoration before selling it "as is" on Ebay. It turned out that the post was a very close match, including a set screw. It cleaned up quite nice including the spring. Send me a pm with your address and I will send it to you at no charge.


View attachment 114103 View attachment 114104 View attachment 114105
Wow, that is extremely generous, thank you so much! Sending you the PM now.
 

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I’m overhauling my Conn 10m and the pivot screw in the low C# post is stuck. Looks like someone before me mangled the head a bit. I’m going to use penetrating oil etc. but I’m having trouble determining if there is a set/grub screw in the middle of the ‘+’ on the post, since that area is a bit mangled also. Can someone who owns a 10M with a similar post let me know if there is a set screw in there? I know I could just leave the pivot screw but I’d like to try to get it out. View attachment 114070
Thanks.
 

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