TromboneChat

So... I am no Conn expert as I think I mentioned in another post somewhere but I do know a little. However I am baffled by this scenario. I acquired, some time ago, a Conn bass trombone slide on its own. I hope to match it up with a single valve 72H bell section I have but don't let that become a red herring - its the slide's identity that is confusing me.

It has engraving on the slide the serial number reads 40392 and is duplicated on both the hand brace and the outer slide tube. It also has 11 on the opposite tube. According to The Conn Loyalist site that makes the slide a 1952/53 manufacture date. As clear as the serial number is there is one digit that I cant quite make out on the model number it clearly say 7*H the missing digit looks like a 0 but could also be a 3 as the only visible bit is the bend at the bottom of the number. It cant be a 2. It does not have a slide lock on it.

Now you would think that it is simple - it must be a 70H slide. But they didn't make a 70H slide that didn't have tuning in the slide (did they?) This does NOT have TIS. Yet again according to The Conn Loyalist in 1952/53 the only bass trombone they were making was the 70H (?) It also appears to be about 1/2" shorter than a 70H that I also already own.

I at one moment decided this must be a 73H slide then - but realised they didn't make a 73H slide until decades later that the 52/53 period this one is made in and probably not without a slide lock either.

I have put my 70H slide alongside this one. (that is to say my existing and definitely 70H slide) This slide has a serial number of 398677 (and a 12 on the opposite tube) which puts it only a little earlier than the mystery slide in terms of production, in fact although lower serial number it is still in the 52/53 years of production. I have taken some photographs in the hope that it will supply some information to those of you who know more than I about Conn trombones. The photos on their own are the mystery slide. There are a couple alongside the 70H for comparison and it shows that the mystery slide is about 1/2" shorter. The Mystery slide has neither cork nor spring and clatters against the brace. I shall install springs in due course but in the mean time I have pulled the slide down a little to where I think it would rest if it did have springs already - its still that half an inch shorter.

Mystery to me but I am hoping someone reading this will know better. Matt - you know more about Conn slides than anyone I know, how about it?... Doug

It'll be a 70H slide that someone converted not to be TIS, hence the markings and the cork barrels without slide lock etc. So the movable oversleeves were removed, and the handbrace reattached to the outers. (I can't quite tell from your photo resolution, but it looks like they added yellow brass sleeves, hence the contrast line with the Conn bronze.)

The cork barrels are cut off above the decorative line (see your stock 70H slide) and everything looks heavily buffed and relacquered. Interesting that the barrels are yellow rather than nickel silver. If I had to guess, the inner slide hand grip was originally chromed like your contemporary 70H, and Conn went over to nickel silver barrels when they started lacquering inner slides in subsequent years (I don't know exactly when, but my 1955 70H is lacquered and all nickel silver).

Not surprised that they made it a little shorter during the conversion. Depends on the bell section it was intended to pair with, of course, but certainly the 70H slide on a 70H bell is pretty long, and A440 can get pretty close on the springs, even with a small mouthpiece.

PS Why's the adjustment nut on your 70H outside of the brace slot?

I think that ithinknot nailed it (that’s almost a tongue twister). The yellow brass oversleeves and the yellow brass cork barrels are interesting. Maybe a tech was able to draw the tubing for the sleeves and turn new cork barrels on a lathe? I wondering why they didn’t just use the original parts.

It appears that some things (overall length of slide, cork barrels) were shortened in order to raise the pitch or create a slide that was not so nose-heavy.

PS Why's the adjustment nut on your 70H outside of the brace slot?

because its two (forgive an Englishmans knowledge of the currency) dimes (?) with a hole drilled in the middle and a small nut soldered on to achieve the adjustment - the cent coins are too thick to fit in the slot. I was wondering if I stood any chance of getting an original fitment but I would think not (excuse the pun) after all this time? It is an effective DIY job and I suppose adds character to the horn! And the serations on the coins act nicely when 'twiddling" it... it came this way to me.

So I hear what you say and there seems to be a concensus between ithinknot and crazy4trombones86, its been re-built then. Rather well I have to say in that case.

So bearing in mind the shorter length of the slide will it be ok with the 72H bell I had it in mind for? I suppose I could answer that myself by getting the tuner out and playing a few notes.

Thanks for your answers... Doug

I've seen at least one 72H without a slide lock. I think it was at Dillon's in NJ. Anyway, they did briefly make some 72H slides that look something like the one in this post, but the 72H had a long slide. Interesting.

Jim Scott

Doug,
A new nut for the TIS adjustment on your other slide could be made very easily. It’s just a disc with knurling and the hole could be drilled and tapped in a just a few minutes. Of course, I am assuming that technicians on your side of the pond have taps that are “threads per inch” in addition to their metric taps.

DougHulme wrote: ↑Sat Feb 12, 2022 6:03 am ...snippet...

It has engraving on the slide the serial number reads 40392 and is duplicated on both the hand brace and the outer slide tube. ..... According to The Conn Loyalist site that makes the slide a 1952/53 manufacture date.

"40392" - seems there's one digit missing.

The original threaded rods are actually a helical thread. Meaning there are 2 threads, one opposite the other, on the thread shaft. That gives twice the distance traveled for one rotation over a standard single thread. There are no commercial dies available for that, as far as I'm aware.

hornbuilder wrote: ↑Sat Feb 12, 2022 12:12 pm ... twice the distance traveled for one rotation over a standard single thread. There are no commercial dirs available for that, as far as I'm aware.

Dies seem to be special order only everywhere on earth, but taps aren't a problem. https://www.icscuttingtools.com/catalog/page_206A.pdf

What did you go with on your TIS mechs? A normal single start thread, but something relatively coarse for the diameter?

crazy4trombones86 said A new nut for the TIS adjustment on your other slide could be made very easily. It’s just a disc with knurling and the hole could be drilled and tapped in a just a few minutes. Of course, I am assuming that technicians on your side of the pond have taps that are “threads per inch” in addition to their metric taps.

Indeed I have numerous 'imperial' threaded taps and dies myself, there are coarse and fine versions somewhere in some old toolboxes. However Matts 'helical' threads I am not too sure about, I will investigate. I dont know if its still true today but until relatively recently all Ford cars made in the UK used to use American Fine threads. I should stop being lazy and sort my workshop out I would know the answers and could make an adjustable wheel myself.

When I see the standard of work that Matt does at M&W it encourages me to leave the tool box closed! very few technicians around of that standard and unless I thought I could do as well, I'd rather leave it to such as they!

Thanks for all your help people - much appreciated... though I'm still unsure whether my mystery slide will work on the 72H bell - laziness or busyness the tuner is still in a draw somewhere in my studio.

Doug

Hope it works. If not...