Slender rod turning for 8BA Studs

[David HaythornthwaiteParticipant @davidhaythornthwaite90386]

I have to make some 8BA studs for a steam engine that I am making.

I see there has been discussion about 8BA studs on this forum back in October 2012 and a regular contributor called NJH showed a picture of a thin piece turning tool which carried a bush to support the turned rod next to the actual cutting tool.

I would like to know where to obtain such a tool – or even know the correct name for it. I seem to remember one being detailed in MEW many years ago, but cannot find it in the index.

Can anyone help? If NJH reads this I would be interested where he bought it from.

David H

[David HaythornthwaiteParticipant @davidhaythornthwaite90386]

Tool for turning 2.2 mm rod for making 8BA studs

[Neil WyattModerator @neilwyatt]

Hello David,

Its a steady rest, but I think you will search along while if you seek one that works like that.

Alternatives include a box tool and making one yourself – which shouldn't be too difficult. It can be as simple as a bar clamped to the toolpost with a hole drilled in it. The difficult bit is setting the point of the tool to get the right cut.

This is my box tool:

Neil

[David HaythornthwaiteParticipant @davidhaythornthwaite90386]

Thanks Neil,

It was most interesting to see that, I particularly liked the way it uses a V steady to stop the piece from both lifting and from pushing away whilst being adjustable for many diameters without having to make bushes.

I was thinking of making something to go in the toolpost, so you could use it for long lengths and I am now wondering about a tool in the top (compound) slide, therefore finely adjustable for diameter, and providing the support from the back toolpost. I like making tools equally to making models, and despite my current resolution to "get on with the steam engine", it looks like a tool project may be on the way.

Thanks for your help. Have a great Christmas and a Happy New Year. MEW is coming along just a treat. – well done.

Thanks again.

Kind Regards

David

[JasonBModerator @jasonb]

Chronos used to sell one but not seen it listed for a while, have a search on some of the other forums like MHEM, MEM and MECH the subject has been covered on them all. Not too hard to make one either.

HMEM thread

Edited By JasonB on 17/12/2014 20:55:00

[NJHParticipant @njh]

David

I have sent you a pm – however I see that Jason as supplied a picture of the beast! By all meant though contact me if you think that I can help.

Regards

Norman

[Maurice Cox 1Participant @mauricecox1]

I needed to turn down a long slender rod some time ago. I made a similar device to that shown, by making a replacement jaw for my travelling steady, Bored a 1/4" hole in it when fitted to the lathe, and reduced this with a bronze bush, drilled to the size of the rod. After the right amount of cut was determined by trial and error, the rod was turned down at one pass.

Regards

Maurice

[David HaythornthwaiteParticipant @davidhaythornthwaite90386]

Thanks Jason, Norman and Maurice.

I think I shall make something along the lines of the photo Jason posted.

I have also wondered whether to have the rear toolpost (QC) carry the supporting bush, swivelling my topslide round 90 deg. so that it carries my tangential tool right up to the back of the bush. The bush would then be centralised to the lathe centre by the cross slide feed and the diameter i.e. the cut would be controlled by the top slide feed.

We shall see – but thanks everyone.

David

[NobbyParticipant @nobby]

Hi David
I suppose the next problem will be threading the 8ba ?
Nobby

[David HaythornthwaiteParticipant @davidhaythornthwaite90386]

Hi Nobby

"I suppose the next problem will be threading the 8ba ?"

No problem with that. The ends of the studs will be threaded by holding the stud in an ER25 collet and using a die in a tailstock die holder. (yes they are long enough, – I think). If not, for the short ones, I shall thread them, one end, whilst they are on the parent material, cut off and screw them into a threaded mandrell in the chuck (or collet). For the tapping I have a home made pillar tool.

David

[NobbyParticipant @nobby]

Hi David
Thats what I thought . I also use a tailstock die holder and cut 8 Ba in steel . I did wonder as well as you if using the back toolpost to support to the bush Then rotate the topslide round square with the X slide so the X slide does not move when you put a cut on to final size for 8BA
Nobby

[Gray62Participant @gray62]

There was a small roller box described in MEW October 2002 (Issue 85) Neat little device but a little OTT if you are not going to use it much (mine hasn't seen light of day for a few years now.

[Bob Unitt 1Participant @bobunitt1]

You could try a 'rose bit' – a hollow end-mill held in the tailstock through which you pass the workpiece to reduce it to the diameter of the hole. Advantages are that it always cuts to the required dimension, and applies no lateral pressure to the workpiece as it cuts. I don't know if they're commercially available, I made my own years ago to produce some 8ba bolts in stainless.

[john jennings 1Participant @johnjennings1]

Interested to know that a rose tool works on (free cutting ?) stainless.

They are (were?) a traditonal clockmakers tool so apart from brass (running down small screw blanks) would also cope with pivot steel a part hardened carbon steel.

Worth a try as easy to make and set up

John

[Bob Unitt 1Participant @bobunitt1]

Posted by john jennings 1 on 18/12/2014 12:54:46:

Interested to know that a rose tool works on (free cutting ?) stainless.

They are (were?) a traditonal clockmakers tool so apart from brass (running down small screw blanks) would also cope with pivot steel a part hardened carbon steel.

Worth a try as easy to make and set up

John

I can't remember the stainless steel I used, probably something I scrounged from a friend who was company secretary of a steel distributor (a really useful guy to know ). It was for the 'wet end' of a steam engine. The cutter was most likely hardened & tempered 'silver steel', and I doubt that it ever produced more than the half-a-dozen bolts I needed for that engine. I just went into the workshop to see if I still had it, but it's disappeared somewhere in the intervening 20 years and 2 house-moves.

[David HaythornthwaiteParticipant @davidhaythornthwaite90386]

Thanks Bob,

An interesting way round the problem.

David

[UJ NewtonParticipant @ujnewton33659]

For a steady I use a knurling tool with the knurled rollers replaced..

[David HaythornthwaiteParticipant @davidhaythornthwaite90386]

What a good Idea. I would not be able to get the support quite as close to the cutting point on my setup, but I shall investigate. Thanks

David

[NobbyParticipant @nobby]

Hi David and guys
I know this is bigger than 8ba this is 5/32 whit thread i am useing a traveling steady I made for my S7

Nobby

[David HaythornthwaiteParticipant @davidhaythornthwaite90386]

Thanks to all who contributed to this thread.

I finished up turning lengths of silver steel down to 2.2mm diameter to cut into 8BA studs.

I used the rear tool post to hold a Phosphor Bronze bush round the rod, and set my topslide at right angles to the lathe bed (almost 90 deg – full right angles is impossible on a standard ML7 top slide.) The cutting tool (tangential) was adjusted by the top slide feed screw.

I attach a photo of my setup.

The finish was not as bad as it appears.

Thanks – David

Edited By David Haythornthwaite on 19/01/2015 19:32:13

[Nick HughesParticipant @nickhughes97026]

Hemingway kits do a nice casting, that you machine and fit to the traveling steady mounting point on the Series 7 lathes:- **LINK**

[thomas oliver 2Participant @thomasoliver2]

I think you will find that the round stays of the average umbrella are 8BA size exactly – if you can find one on the local scrap dump. 2.5mm MS welding rod is the correct size for 7BA studs which are widely used on the smaller Stuart Steam Engines.

[David HaythornthwaiteParticipant @davidhaythornthwaite90386]

Thanks for that. Yes – I have no problem with 7BA as you say. Interesting about the umbrellas, I shall keep my eyes open.

Mugging little old ladies to measure their umbrellas with a micrometer seems a bit extreme. I am sure a hunt through the cupboard of SWMBO will turn up something !

Kind Regards

David

[Ian S CParticipant @iansc]

Some time ago I had an idea, I don't know if it is practical, or some one has done it before. A tool in the form of a button die, but without the thread, an external reamer. I think there was mention of a tool similar to this, with a taper, for making the tapered plug in a plug cock in Model Engineer a good few years back.

Ian S C

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