End Bolt 43tpi die

[Don Taylor]

Another heretical suggestion:

 

'Fuse' the head end of your original screw with its fillister head to the bottom end of a new modern thread and diameter screw to make a new screw long enough for your needs, that still looks original on the outside and that will fit in a modern screw insert or tapped out plate.

 

I have seen this done with larger diameter screws when a long enough screw was not available, but doing it for small diameter screws would be 'tricky'.  I used the word fuse because the big ones that I saw had been mig welded together which I doubt could be done on small diameter screws.  But a Jeweler may be able to do something along these lines.

[Jake Middleton-Metcalfe]

On 9/11/2024 at 11:04 PM, 4to5to6 said:

A source for new bolts would be appreciated.  Preferable a North American source but anywhere is fine.

 

 

C. 1900 bass - 0.0855, 44tpi, 2.218“

1926 Amboyna TT - 0.0850 5BA, 1.240”

1927 ME TT - 0.0860 5BA, 1.162“

 

Thanks.

I think these were all manufactured to 86 thou but perhaps the tolerance was + or - one thou, my reason is the original receipt wheatstone had from the company said "8ba shank 5ba thread or something like that. 5 ba is 43 tpi, perhaps the 44 one was just that the lathe was a bit worn or something, it seems a bit weird to change the spec by 1 tpi when actually the 43 or 44 tpi bolt would be most likely interchangable if the bellows frame nut is only 80 thou thick.

 

Steve Dickinson sells these bolts but I'm not sure what lengths he has. 

Edited September 15 by Jake Middleton-Metcalfe

[4to5to6]

16 hours ago, Jake Middleton-Metcalfe said:

On 9/11/2024 at 3:04 PM, 4to5to6 said:

A source for new bolts would be appreciated.  Preferable a North American source but anywhere is fine.

 

 

C. 1900 bass - 0.0855, 44tpi, 2.218“

1926 Amboyna TT - 0.0850 5BA, 1.240”

1927 ME TT - 0.0860 5BA, 1.162“

 

Thanks.

Expand  

I think these were all manufactured to 86 thou but perhaps the tolerance was + or - one thou, my reason is the original receipt Wheatstone had from the company said "8ba shank 5ba thread or something like that. 5 ba is 43 tpi, perhaps the 44 one was just that the lathe was a bit worn or something, it seems a bit weird to change the spec by 1 tpi when actually the 43 or 44 tpi bolt would be most likely interchangeable if the bellows frame nut is only 80 thou thick.

 

Steve Dickinson sells these bolts but I'm not sure what lengths he has. 

 

Thanks for confirming the specs Jake.  Much, much, much appreciated!!!

 

My original post was to enquire if this special die (0.086” 43TPI, 5BA/8BA) was still available.  It sounds like I will have to custom make my own.

 

All the discussion and advice was greatly appreciated.

.

Edited September 15 by 4to5to6

[Alex West]

On 9/12/2024 at 4:52 PM, 4to5to6 said:

Does anyone know of a source for brand new bolts and screws like these?

I have some.  I think I got them from a vintage screw supplier on ebay

 

Alex West

[Jake Middleton-Metcalfe]

On 9/15/2024 at 8:54 AM, 4to5to6 said:

 

Thanks for confirming the specs Jake.  Much, much, much appreciated!!!

 

My original post was to enquire if this special die (0.086” 43TPI, 5BA/8BA) was still available.  It sounds like I will have to custom make my own.

 

All the discussion and advice was greatly appreciated.

.

If you do this, could you please let us know how you get on? Its very interesting to see how people solve these problems - I did contemplate trying to make the tap and die but was offered the opportunity of adding an extra tap and die onto the order that someone else was making with a tool making company and just decided that it was money well spent and I never tried to do it myself.

Edited September 17 by Jake Middleton-Metcalfe

[4to5to6]

Just completed the design and generated the first CNC tool path. I will machine the holder from both sides then finish it on the lathe.  It will take a few hours of fabricating after machining as a lot of very small holes need to be drilled and taped. 

 

The end result will be an adjustable 5BA die that was cut into three pieces so the diameter can be reduced down to 0.086 (8BA).  6 bolts will align and adjust the depth of cut using an existing bolt as a guide and the cover plate will clamp everything into place after it has been set up.  The two handles will used to turn the die with the bolt blank held in the locked lathe chuck. The center slider shaft will slide into a tail stock drill chuck loosely held or maybe a pipe ??? on the lathe for alignment so threads will cut straight.

 

I'll upload photos of the finished die holder and some sample end bolts when completed.  I'm using AutoCAD to generate the vector files and VCarve to generated the tool paths.  My CNC machine is a highly modified Bravo Prodigy with an 800 watt water cooled spindle and my lathe is an EMCO Compact 5 also with many do-it-yourself upgrades.  Material will be 6061 aluminum 1" thick and 1.75" wide. 

 

This is a quick functional layout only drawing so a lot of the details such as the drilled hole in the slider shaft aren't shown.  Everything may change after I have thought about it over night but I think this will get the job done.

 

 

.

Edited September 18 by 4to5to6

[4to5to6]

Finished tool as planned but no time to set it up and make a bolt today.  I’ll get back to it by the weekend… All this for a few 2.25” long Wheatstone bolts for a single action G Bass.  It’s worth it, he’s a friend.

 

The hardest part was tapping the tiny M2-0.40 threads for the 6 adjustment screws and the 6 clamping cover screws.  All I have is forming taps at this size and they easily break if the pilot hole isn’t perfect.  An exercise in patience.

 

 

The back shaft is held loosely in the tail stock’s Jacobs chuck to keep it in alignment.  This shaft is hollow for the first 90mm to not interfere with the threading.

.

Edited September 19 by 4to5to6
Lathe photo added.

[Jake Middleton-Metcalfe]

really very interesting, looks like the tricky bit might be setting each individual 'chaser' to the correct depth, but there are probably ways around that, so far so good! 

[4to5to6]

The 6 bolts around the perimeter are for adjusting the three chasers and the 6 bolts on the face will then clamp the chasers into place.  I’ll use an existing 5BA 0.086 bolt as a starting place with all parts in the lathe for correct center alignment.  This should be a good starting place then will tweak it to get it perfect.  I’ll find out today.

.

[4to5to6]

Threads are a success.  I ended up redoing the lathe work on the die to line it up better and building a heavier back guide shaft.  I used a dial gauge and good bolt to size and center the chasers.

 

First bolt threads were a 100% success!  Very clean and even threads.  However it took a long time to machine down the brass so I will need another tool similar to the die without threads to size the shaft to 0.086.  I think I have some ideas.  A three point cutter.

 

The bolt cheese head was a challenge and on nearly the last cut, the bit caught the brass and bent the shaft and the head snapped off.  There’s always tomorrow 😄. The good news is that the threads are a success and I was able to try them out on a few concertinas.

 

Ideas to size a 0.086 shaft, 2.25” long with a 0.162” diameter head are welcome.

 

Photos attached.

.

Edited September 21 by 4to5to6

[Tiposx]

Well done so far. I noticed a few things that may help with the sheared head.

-The insert you are using looks like a standard type used for steel. This is 

too blunt to cut brass safely. I use polished insets designed for aluminium, that are very sharp and do not grab. See photo.

-There is too much stick-out from your chuck, hence too much leverage. I push the head right up against the chuck (I use collets actually) for full support.

- it looks like you are making an interrupted cut, You can avoid this by slotting the head after turning it to size.

 

Edited September 21 by Tiposx
Corrected “before turning” to “after”

[alex_holden]

Well done with the adjustable die. Does the thread work in your original nut plates?

 

I almost never turn down long things like bolts with tailstock support because my lathe's tailstock ram isn't long enough to allow the tool to access the full length of the part before the cross slide hits the tailstock. I think what I would try instead is to extend about 15mm of stock at a time from the chuck and turn it down in three or four stages. I found I don't need to do that with standard length brass bolts if I turn them to final diameter in one pass, but I had to do it that way when I made some stainless steel bolts because the cutting forces were much higher.

 

It's surprising what happened to the head. I use a custom ground form tool to cut the fillister profile in one pass and never had a problem with that step of the process. Was it protruding from the chuck jaws like in the photo when you started the cut, or did it get pulled out when the tool caught? It should probably be snugged right up to the jaws (or ideally a collet) so it can't bend. If you need some clearance to turn the outer diameter without running into the jaws you could try adding a washer that is slightly below the finished head diameter.

 

For turning brass I use solid HSS tools, hand honed to a very sharp polished edge. They have a very tiny amount of positive rake, almost zero. I only use carbide inserts for steel.

Edited September 21 by alex_holden
correction

[adrian brown]

6 hours ago, 4to5to6 said:

The bolt cheese head was a challenge and on nearly the last cut, the bit caught the brass and bent the shaft and the head snapped off.  There’s always tomorrow 😄. The good news is that the threads are a success and I was able to try them out on a few concertinas.

 

Ideas to size a 0.086 shaft, 2.25” long with a 0.162” diameter head are welcome.

.

 

Here's a photo of the cutter I mentioned in an earlier reply - it really saves a lot of time in sizing the bolt shanks.

 

The internal diameter is somewhat wider just after the cutting teeth to relieve the friction on the newly cut shank. For the domed head, I ground a parting tool to turn the head and cut off the bolt from the stock in one pass.

 

I hope this helps and let me know if it's not clear.

 

Adrian

 

 

 

 

[4to5to6]

Bass bolt is done!  Thanks for all the great advice.  Milling attachment for my lathe worked perfectly to cut the slot.  I just gently clamped the bolt into a quick change tool holder and had full control in all directions.

 

Photos below.  The new bolt is next to a 2-1/8” bass bolt for comparison.  I made it a bit longer then the requested 2-1/4” and also increased the length of the threads.  It may need to be trimmed but better too long than too short.  I’ll send it off next week.  If it fits, I’ll make the rest of the set.  Threads fit into my Aeolas and a mid 1800s treble as well as a late 1800s Lachenal baritone so 5BA threads on a 0.086 8BA is it.

 

Thanks again for all the awesome advice and help.

 

.

Edited September 21 by 4to5to6

[Jake Middleton-Metcalfe]

Well done

[Chris Ghent]

Nice job