[Johanj]

Hello,

I am repairing a 1924 Conn New Wonder and wish to replace some axles by making them myself. I need then some thread cutting tools and have to know what the exact dimensions are before I order them. The problem is that in Europe we have metric sizes and I am not sure about the right American size.

For the main axles I measured a diameter of 2,67mm which is 0.105 inches.
The thread has approx. 20 thread per cm or 50 per inch.

For the axis used for the motherofpearl rollers I measured 1,96mm or 0.077 inches.
The thread is also approx. 20 thread per cm or 50 per inch.

What type of thread should I use and what size of steel rod?

Kind regards,
Johan Jonker
The Netherlands
(sax.jonker.co)

 

[shootingstar]

Off the top of my head I'd be guessing. Your best bet is to buy a thread gauge and measure one of the rods you have on hand. After you have your answer you will have a good tool for your toolbox.

 

[Koen88]

Hey Johan,

maybe this `ll help??
http://dl.dropbox.com/u/19536871/draad_tabel3.jpg

groeten uit NL

 

[shootingstar]

One thing to consider is that they might not all be the same size. From personal experience I know that a horn that old has been through a lot of repairs and sometimes thread sizes will be changed (for a lot of different reasons). I think your best bet is a pitch gauge I suggested earlier. I have both the pitch gauge part number T1714 and screw checker part number T1616 from Allied Supply. Good luck.

 

[Graysax]

If memory serves me correctly, I believe it is SAE 3-48

 

[Johanj]

Thanks everyone.

According to http://en.wikipedia.org/wiki/Drill_and_tap_size_chart SAE 3-48 means 48 threads per inch and a clearance of 0.11, that can certainly be the right size.

 

[Johanj]

Hello again,

I have an additional question. I was wondering why the diameter of the axles is so exotic: 0.105 inches (2.65mm). Or is/was that a quite usual size?
Another thing is that I cannot find material in the Netherlands fot that. So I am afraid I have to use lathe to make ot myself.

 

[Gordon (NZ)]

From "Machinery's Handbook", that 2630-page reference of everything engineering:

0.1055" is "Steel Wire Gage (U.S.)", size #12.
(This system also called "Washburn & Moen", "American Steel & Wire Co." & "Roebling Wire Gages")

0.106" is "Music or Piano Wire Gage", size #35

0.104" is "British Std. Wire Gauge", Size #12

Nothing straight forward in those exotic countries that don't have a history of metrics!
No doubt Google knows how these mysterious measuring systems came about.

 

[Johanj]

Ha thanks Gordon. With your help I found a shop selling 0.104 in the UK. I hope they will send to NL.

 

[Johanj]

I received 20 pieces 40cm of 0.104 inch wire and the diameter matches within 0.01mm with the existing axles. Perfect!

 

[Gordon (NZ)]

You're most welcome. I'm glad it worked for you.