Imperial Lyre Box Screw

Discussion in 'The Rehearsal Room' started by 2nd tenor, May 5, 2017.

  1. 2nd tenor

    2nd tenor Well-Known Member

    I have a Boosey and Hawkes instrument that came to me without a screw in its lyre box. Thinking that it might be handy to have a functioning box I contacted a couple of spares suppliers who assured me that their part would fit and work in my B&H. The supplied parts didn't fit so I measured a couple of things (thread diameter and pitch) and used the information to identify the thread type used. I now have a (roughly 1/2" long) 4 BA screw in the Lyre box (sourced it off of eBay), I couldn't get a knurled head head Screw but plain slotted will work for me - assisted by some small handy tool, be careful not to over tighten. The British Association or BA standard for threaded parts is something that was commonly used in the past, it is no longer in common use - expect older instruments to have Imperial (inch based) rather than Metric (millimetre based) threads on them.

    I hope that the 4BA size details above are a help to someone who finds themself in a similar situation and, of course, that this post actually shows up when someone searches for the deatails in a few years time. What worked for me might not work for someone else, but it's a start.
    Last edited: May 5, 2017
  2. Jack E

    Jack E Active Member

    With motor bikes, 2T, I think they didn't start switching away from Whitworth and BA threads until the 1970s - and plenty of smaller and more specialist companies stayed with them well after that. The good news is that model engineers still use BA screws, and screws, washers and nuts are still readily available in steel, stainless steel and brass in sizes down to 12BA - which is 1.3mm diameter. It's also worth bearing in mind that, if your lyre screw is a BA thread, your water valve screws and nuts are probably BA threads, too.

    If any of the threads get damaged, model engineers' suppliers also sell BA taps and suitable tap wrenches.

    With best regards,
    2nd tenor likes this.
  3. 4th Cornet

    4th Cornet Member

    This is an interesting thread...


  4. 2nd tenor

    2nd tenor Well-Known Member

    :) . I didn't realise that my interest in all things engineering was contagious. The original post was more intended to be a statement of information for those who might at some time need it rather than anything else, a way of giving back something to the on-line community and potentially helping some future reader. A while back someone started a thread about valve alignment. That's a subject of limited interest but by using it, and further developing some of the ideas in it myself, I've worked on a couple of instruments and improved how they play - some topics don't appeal to the majority of members but they still have value.

    tmp seems a bit quiet at the moment, I guess that there comes a point when existing members have said what they want to about any particular subject. However, if anyone has repair expertise to share and wants to start a thread on keeping older instruments in good working order (ready for playing) then I'd follow it with interest.
    Last edited: Jun 13, 2017
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  5. 4th Cornet

    4th Cornet Member

    It is indeed a useful post. I hope mine wasn't taken as being sarcastic as that wasn't the intention :S
  6. MissBraz

    MissBraz Member

    hahaha love this !!! Much appreciated from this engineer!!
    4th Cornet likes this.
  7. Tom-King

    Tom-King Well-Known Member

    It can never hurt to have information out there - good on you for sharing.

    I would, personally, have not bothered searching for that and simply used a lyre that clips onto the bell (and I do anyway - my Bb and Sop don't have a lyre box, by choice - I prefer the music that little bit further away) but I'm sure it'll come in useful to someone at some point in the future - this is where forums like this are much better than facebook, it's easier to search back and find information like this.
    Jack E, 2nd tenor and 4th Cornet like this.
  8. 2nd tenor

    2nd tenor Well-Known Member

    Update, for the record.

    By chance a friend's Besson (maybe 1990's? maybe UK built?) ended up with me for a bit of basic maintenance. I noticed that the Lyre Box screw was missing, to my surprise it too takes a 4BA by 1/2" screw.

    Thanks, I'm happy to share information; in the past others on tmp have been kind enough to answer my questions so offering a bit of data back to the forum seems an appropriate thing to do.

    On a Cornet, Flugelhorn or Trombone ( :) ) that off of bell mounting is an option, but if you happen to play a Tenor Horn, Baritone, Euphonium or Tuba then a different route is needed.
    Last edited: Aug 12, 2017 at 10:47 PM
    Jack E likes this.
  9. Jack E

    Jack E Active Member

    I would imagine the reason they stuck with the BA thread is that it greatly simplifies the stocking and supplying of spares, so your customer can just order "a lyre box screw for my Besson tenor horn", and be sure to get a part which fits.

    Also, if you already have the necessary drills and taps to produce a BA thread, why throw them away to buy metric replacements, and incur the cost of modifying all the production drawings, parts lists, and arranging for the stores to stock both items? With its small thread and large, knurled head, the lyre box screw can't be bought off the shelf from bulk suppliers of threaded fasteners, anyway - just like the water key screws with their long shank and short thread, it's not used anywhere else in industry, so even if you switched to a metric thread, it would still have to be specially made.

    One of my favourite points about the Land Rover I used to own was the way they didn't change any part unless there was a damn good reason for doing so, but worked on the lines of, "If it ain't broke, don't fix it." Mine was a 90, built in 1986 - but some spares for it were compatible with models dating back to the late 1940s!

    With best regards,


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