One fellows way to make a brass handstrap adjuster screw

[Bob Tedrow]

For your perusal

 

http://hmi.homewood.net/adjusterscrew/

[ben]

For your perusal

 

http://hmi.homewood.net/adjusterscrew/

 

Hello Bob, if I ever need a brass handstrap adjuster screw...I'll know who to turn to...you. Thank you for sharing your knowledge with us. I enjoy the photo essays of the various parts and concertinas you manufacture.

 

By the way, congratulations on the completion of your latest anglo concertina: "The Tobacco Sunburst." It looks stunning!

[TomB-R]

Nice one Bob and thank you for posting it.

 

I'd be intrigued to know the pros and cons that led you to this method rather than turning your own from scratch. Knurling tools don't seem that expensive.

(Apols if this is an ignorant question, I haven't done any metal turning for a good while.)

Tom

Edited June 16, 2009 by TomB-R

[Bob Tedrow]

Nice one Bob and thank you for posting it.

 

I'd be intrigued to know the pros and cons that led you to this method rather than turning your own from scratch. Knurling tools don't seem that expensive.

(Apols if this is an ignorant question, I haven't done any metal turning for a good while.)

Tom

 

gosh, I though I was making my own from scratch!

[TomB-R]

Nice one Bob and thank you for posting it.

 

I'd be intrigued to know the pros and cons that led you to this method rather than turning your own from scratch. Knurling tools don't seem that expensive.

(Apols if this is an ignorant question, I haven't done any metal turning for a good while.)

Tom

 

gosh, I though I was making my own from scratch!

 

Oops, true enough! I meant turning the screw in one piece from solid bar, the whole job on the lathe.

Tom

[Theo]

Oops, true enough! I meant turning the screw in one piece from solid bar, the whole job on the lathe.

Tom

 

I think that many (most?) of the original screws were made from two parts as described by Bob. Its not usually obvious if the screw top is plated or well polished, but when the metal gets tarnished or corroded the join is sometimes revealed. Why would it be done this way? Its much more economical with materials, and probably with time too.

[Dave Lawton]

For your perusal

 

http://hmi.homewood.net/adjusterscrew/

 

Bob, this just raises my admiration of Concertina makers... I appreciate you sharing your art!

 

Dave

[TomB-R]

Oops, true enough! I meant turning the screw in one piece from solid bar, the whole job on the lathe.

Tom

 

I think that many (most?) of the original screws were made from two parts as described by Bob. Its not usually obvious if the screw top is plated or well polished, but when the metal gets tarnished or corroded the join is sometimes revealed. Why would it be done this way? Its much more economical with materials, and probably with time too.

Fair enough, thanks Theo, the "from solid" route would mean a lot of swarf! (though we're looking at brass here?)

Tom

[Theo]

And its also tricky to turn brass down to the small diameter required for the threaded part without it snapping off. I'm particularly aware of this as I've recently been trying to make endbolts which are at least as thin and even longer.

[Chris Ghent]

Theo,

 

this will not be a problem if you find "free turning" brass. This brass contains small amounts of lead which lubricates the tooling. Even so, cut only the threaded portion to size and thread it before cutting the rest of the shank to size. I use a hand held die and thread at around 100 RPM.

 

If you are using cartridge brass, which is good for forming and press tools, you will have trouble with turning and drilling. It can be done, but needs much more precise tool sharpening and speed setting, and the resulting thread will not be quite so clean. You might need to help the threading process with a little tapping fluid.

 

regs

 

Chris

[Jack Bradshaw]

But, where to find dies for the threads used in the restoration of concertinas ????

 

 

Theo,

 

this will not be a problem if you find "free turning" brass. This brass contains small amounts of lead which lubricates the tooling. Even so, cut only the threaded portion to size and thread it before cutting the rest of the shank to size. I use a hand held die and thread at around 100 RPM.

 

If you are using cartridge brass, which is good for forming and press tools, you will have trouble with turning and drilling. It can be done, but needs much more precise tool sharpening and speed setting, and the resulting thread will not be quite so clean. You might need to help the threading process with a little tapping fluid.

 

regs

 

Chris

[Theo]

Theo,

 

this will not be a problem if you find "free turning" brass. This brass contains small amounts of lead which lubricates the tooling. Even so, cut only the threaded portion to size and thread it before cutting the rest of the shank to size. I use a hand held die and thread at around 100 RPM.

 

If you are using cartridge brass, which is good for forming and press tools, you will have trouble with turning and drilling. It can be done, but needs much more precise tool sharpening and speed setting, and the resulting thread will not be quite so clean. You might need to help the threading process with a little tapping fluid.

 

regs

 

Chris

 

My solution, give to me by the ever helpful Geoff Crabb, is to make a hollow cutter which goes in the tailstock. Its basically like an endmill with a hole up the centre. The diameter of the hole being equal to the diameter of the shank of the bolt. It is very quick and easy to use, and in one cut forms the whole shank. The cutter took me about half an hour to make.

 

I've still not worked out how to cut the slot in the head. I could use a slitting saw in the lathe, but my lathe (Boxford) does not give me any easy way to hold the bolt head under the saw.

 

But, where to find dies for the threads used in the restoration of concertinas ????

 

The threads used on old concertinas are all non-standard threads, Indeed there were no generally accepted standard threads until the 1860s. I suspect you would have to make your own taps and dies if you wanted to make an exact match of the original threads.

 

There are similar size thread for which taps and dies are available and if you choose a size that is slightly larger than the original then you can make a new bolt, and retap the nutplate to match. Lachenal endbolts I've measured recently are around 2.2mm in diameter so a possible replacement size for them is M2.5, or 3/32"Witworth(2.38mm) or no3 UNC. These are all available from tool suppliers.

[Chris Ghent]

My solution, give to me by the ever helpful Geoff Crabb, is to make a hollow cutter which goes in the tailstock. Its basically like an endmill with a hole up the centre. The diameter of the hole being equal to the diameter of the shank of the bolt. It is very quick and easy to use, and in one cut forms the whole shank. The cutter took me about half an hour to make.

 

I've still not worked out how to cut the slot in the head. I could use a slitting saw in the lathe, but my lathe (Boxford) does not give me any easy way to hold the bolt head under the saw.

 

 

I use a slitting saw and made a jig to hold the new screw that fits in the normal tool holder in the place of the tool. It is basically just a tube with a locking screw for the shank of the new screw. Getting it to centre height took longer than making the tube.

 

But, where to find dies for the threads used in the restoration of concertinas ????

 

The threads used on old concertinas are all non-standard threads, Indeed there were no generally accepted standard threads until the 1860s. I suspect you would have to make your own taps and dies if you wanted to make an exact match of the original threads.

 

There are similar size thread for which taps and dies are available and if you choose a size that is slightly larger than the original then you can make a new bolt, and retap the nutplate to match. Lachenal endbolts I've measured recently are around 2.2mm in diameter so a possible replacement size for them is M2.5, or 3/32"Witworth(2.38mm) or no3 UNC. These are all available from tool suppliers.

 

Another approach to make a screw to match on old one is to use a geological microscope and grind a threading tool to match the exact profile of the old thread. You then use a vernier to calculate the pitch of the thread by measuring peak to peak, or measure a set distance and count the peaks. It then becomes like creating any other thread on the lathe, providing you have a change wheel that will run your lathe at that TPI.

 

I'm told but have never tried it, you can make a tap by creating a screw from silver steel, then grind the side of the screw twice or three times up its length in the same way as a normal tap is formed. Then taper the tip by grinding and harden it. You then have one taper tap. You would want to have a clean front edge on the grind. Free turning brass is very forgiving...

 

Chris