Deepen hole for thumbscrews?

[RWL]

My Wheatstone TT Aeola has protruding thumbscrews for wrist straps.  These are rubbing against the case lining when I insert and remove the instrument from its case leading to a hole in the lining.  Of course I could just remove them, but then they'd likely get lost, so I'd prefer to just screw them the whole way in a leave them there.  Is there any harm in drilling the holes a little deeper to allow the thumbscrews to sit flush?  To the best of my knowledge, these should be outside the pressure side of the padboard / reed pan, so I don't see why I couldn't just drill the holes deeper, and possibly the whole way through.

 

 

 

[Chris Ghent]

Do they thread into a brass captive nut? If so you will need to remove that and deepen the hole in the wood behind.  And check they won’t foul any action parts if they protrude into the action box.  Have you considered shortening the threaded part of the screws? Sometimes they have more length than needed…

[Chris Ghent]

Another thought, you could create holes in a solid part of the case to thread them into for storage.  

[fred v]

Have you ever tried wrist straps? I won't play without them now that I've used them.

[RWL]

9 hours ago, Chris Ghent said:

Do they thread into a brass captive nut? If so you will need to remove that and deepen the hole in the wood behind.  And check they won’t foul any action parts if they protrude into the action box.  Have you considered shortening the threaded part of the screws? Sometimes they have more length than needed…

They do thread into a brass disk held in place with a small screw.  It would not be easy to shorten the screws and make it look professional, and that might make some of them a little short if the next owner wants to use wrist straps.

[RWL]

10 hours ago, Chris Ghent said:

Another thought, you could create holes in a solid part of the case to thread them into for storage.  

That's an interesting thought I hadn't considered.  The tops of the corner blocks may not be padded and might serve; the rest of the interior is padded.  I'll probably go with deepening the holes though because at most I need to go 1/16" [~1 mm] deeper, the brass discs are covered in verdegris and the instrument looks nicer [at least to my eye] with the small chromed thumbscrews or at least I've gotten accustomed to seeing it with those chromed thumbscrews.

[RWL]

1 hour ago, fred v said:

Have you ever tried wrist straps? I won't play without them now that I've used them.

I did try the wrist straps.  To me it made it more difficult to get to the lower notes.  Since this is a tenor treble I go down to the C in the bass clef staff and I use the lower notes quite a bit.  In the group I'm in, they wanted / needed a bass, so I usually my box to do that and play the chords.  It would have been nice if they'd worked because in theory it would make the instrument easier to hold when playing unsupported by a knee.  Some day I will make a neck strap and use the upper set of thumbscrews for that.  I just haven't needed to play standing so necessity hasn't prodded me.

[SteveS]

Any alteration to the depth of the blind drilled holes for the captive nuts (sometimes called receiver plates) may well cause a load of trouble to some restorer in the future.  Pulling out the captive nuts can damage the instrument by pulling veneer away with the nut.  You may even affect the potential resale value, since putting right any alterations is an expensive process.

 

As a repairer, I would caution against any alteration to a vintage instrument.

 

Looking at the photo, have you tried turning the instrument through 45 degrees in its case?  The wrist strap thumbscrews shouldn't then touch the inside of the case.

Edited September 27, 2023 by SteveS

[RWL]

27 minutes ago, SteveS said:

Looking at the photo, have you tried turning the instrument through 45 degrees in its case?  The wrist strap thumbscrews shouldn't then touch the inside of the case.

Tilting it one flat toward the rear causes the thumb straps to hit the corner blocks and be stressed when the lid is closed.  Rotating it one flat the other way makes it harder to get the instrument out of the case.  

[RWL]

A 3/32" drill bit fits through the threaded hole in the plates/nuts and bottoms out well beyond the length of the screws.  It seems the wood is being "form threaded" by the ends of the screws but some pieces of wood are hard and won't allow the screws to thread in very far.  The easiest thing to do would be to remove the receiver plates/captive nuts and just drill the holes out a little, but they're so tight in the wood that it wouldn't be an easy job to remove them to do this.  The threads on the thumb screws are SAE 4-48, a standard but uncommon size.  Not something that I'd find at a local hardware store.  If they were 4-40 I have taps that would clean out the wood.  The metric M3 taps are larger in diameter than these screws and the thread pitches don't match well, so I can't substitute a metric tap to clean out the wooden holes.   I do have some 4-48 screws so I may be able to make a tap good enough to work in wood.  I'm off to the N.E. Squeeze In in a couple of days.  Time to ponder.  I probably won't do anything until I'm back from the event.

[SteveS]

Rather than adapt an instrument to suit the case (and risk damaging a vintage instrument), look at making (or acquiring) a slightly larger case.

[Theo]

6 minutes ago, SteveS said:

Rather than adapt an instrument to suit the case (and risk damaging a vintage instrument), look at making (or acquiring) a slightly larger case.

 

Or modify the case.  The original photo shows thane screw has enough space, just need to remove some padding to clear the other.

[d.elliott]

Are you sure that the screws are original? It may well be that they are off a machine of a different period or manufacture and that they are binding in the threads in the nuts.

[RWL]

39 minutes ago, d.elliott said:

Are you sure that the screws are original? It may well be that they are off a machine of a different period or manufacture and that they are binding in the threads in the nuts.

Of course with a 100 year old instrument one never knows, but the chrome finish and knurled edges match the larger thumbscrews for the thumb strap so they appear to be from the same manufacturer.  Whether they were there when the instrument was constructed or added later, I don't know.   I admit that I was surprised that they were 4-48.  The instrument was made prior to screw dimension standardization so I was anticipating something proprietary as was the case with a previous Lachenal I owned.  That would be a point favoring that they were of a more modern manufacture. This was one of David Cornell's instruments.  He was a well known participant of many years at the Northeast Squeeze In and his collection was sold upon his death a few years ago.  I believe his custom was to have his instruments serviced at the Button Box in Massachusetts.  I had a conversation with the BB's main repair person / restorer several years ago about screw threads and my recollection was that they would retap some nuts to an SAE [American] size.  What their criteria were for when to do this and how frequently they would do this I don't remember.  My speculation would be that it was done when no original screws were available. 

 

I don't believe that the screws are binding in the nuts.  I can swap two screws and the side that binds still binds at about the same distance.    Hmm.  That's an interesting concept though.  I think I'll gather up one of my micrometers and  measure the proximal and distal ends of the screws and see if there's a substantial difference.

[fred v]

A 4-48 tap is readily available in the US, just google it

 

[Moll Peatly]

On 9/28/2023 at 10:36 AM, SteveS said:

Rather than adapt an instrument to suit the case (and risk damaging a vintage instrument), look at making (or acquiring) a slightly larger case.

 

On 9/28/2023 at 10:44 AM, Theo said:

 

Or modify the case.  The original photo shows thane screw has enough space, just need to remove some padding to clear the other.

These, a thousand times over. Even if the lining is vintage/original, it is of paltry value financially and of zero value musically. The case is supposed to look after the instrument, not vice versa.

[chris rowe]

Simple solution, remove the screws, drill a couple of undersized holes in the lining padding and screw them into that.

[d.elliott]

On 9/29/2023 at 1:55 PM, fred v said:

A 4-48 tap is readily available in the US, just google it

 

It is not just the pitch (TPI) of the thread, or it's O/D out side diameter, but also the thread form I doubt that an American or modern metric tread form would be a comfortable fit with a 1850's British thread form. If you are tapping out then you are removing some metal before you hit the wood below. I might consider inserting a hot darning needle to poke out and burn back any wood that's in the way. However I would first try to remove the plate nut (disk) using a scalpel to ensure that the polish is not encroaching around the disc circumference. I would also be prepared to wax in once the plate nut is replaced. 

 

Finally, with the plate nut out and in your hand, you can test to see if the screw will fully enter the nut, or whether there is thread binding problem rather than a wood interference problem.