Convex buffer face

[Ron LadenParticipant @ronladen17547]

I am about to turn a set of alu buffers for the 0-4-0 loco.

The buffer face is convex, can you tell me a way of producing that on my mini-lathe.

Ron

Edited By Ron Laden on 20/09/2018 09:36:26

[Ron LadenParticipant @ronladen17547]

[BazyleParticipant @bazyle]

Ron,
Draw the curve you want much bigger on graph paper with a scale of about 10 thou per square and make up a table of distances from the edge for each square in from the front face. ie a series of steps.
Then just smooth off with a file (insert lots of safety advice for half wits here).

Crude maybe but much quicker than faffing about with any kind of template tracing or curve generating systems unless you want to do something like that as a challenge/interesting project in itself.

btw I'm impressed with your rapid progress and ingenuity so far.

[HopperParticipant @hopper]

Or just turn a flat surface and then put the curve on with a file. A 10" single-cut millsaw file, fitted with a handle for safety of course, would work well. You'll need a good stiff wire brush "file card" to keep the teeth cleaned out. Rubbing chalk on the file first helps stop metal getting stuck between the teeth.

Run the job at moderate to fast speed and keep the file moving at all times, using long strokes as if filing a normal job held in a vice.

[Ron LadenParticipant @ronladen17547]

Thanks Bazyle, that sounds good.

Cheers

Ron

[Ron LadenParticipant @ronladen17547]

Thanks Hopper, that sounds a good approach too.

Ron

[Anonymous]

Posted by Bazyle on 20/09/2018 09:38:32:

Crude maybe but much quicker than faffing about with any kind of template tracing or curve generating systems unless you want to do something like that as a challenge/interesting project in itself.

Been there, done that; 18.75" radius on an 8.25" diameter part:

In the absence of the above setup I'd be with Hopper and use files and wet 'n' dry until the curve looked about right.

Andrew

[Ron LadenParticipant @ronladen17547]

Thanks Andrew

Ron

[JasonBModerator @jasonb]

You can save a bit of filing time by making a tangental cut or two and then just blend the flats into a curve with the file

[Neil WyattModerator @neilwyatt]

I did it the way Jason suggests, and for Norden they are oversize at 1 1/2" diameter in 3 1/2" gauge!

[JasonBModerator @jasonb]

Posted by Neil Wyatt on 20/09/2018 11:44:37:

I did it the way Jason suggests, and for Norden they are oversize at 1 1/2" diameter in 3 1/2" gauge!

That's a snow plough not a Buffer

[duncan webster 1Participant @duncanwebster1]

Industrial locos ofetn had collosal buffers to cope with sharper curves

[Ron LadenParticipant @ronladen17547]

Thanks guys,

Looking at the pics of 08,s they dont seem to have particularly large buffers, I thought they would have been larger.

Of course the 0-4-0 is not scale just pinching features from the 08 and I am guesstimating the buffer diameter to be around 15 inches so going with 1.25 inch.

Ron

 

Edited By Ron Laden on 20/09/2018 13:14:21

[Ian S CParticipant @iansc]

I'd go the file way, but I'v got a long angle lathe file (well 3 actually), these don't tend to clog up, and they must be ok on the lathe 'cause it's stamped on the file beside the makers name on at least one of them.

Ian S C

[KWILParticipant @kwil]

See MEW 45, DAG Brown showed a setup (on a S7) for turning large radius curves such as Buffer Heads. Works a treat.

[Brian GParticipant @briang]

Not just colossal buffers on industrial locos, but frequently a 5-link chain carried on the footplate for when the three-link won't reach. A long-wheelbase (11'8"  ) 0-6-0 like an 08 wouldn't be able to round the curves that needed these, but industrial locomotives (and a few BR locos like the 02) with a wheelbase around half of an 08 that could have massive buffers to avoid buffer-locking on extremely tight curves. Rochester Castle shown here operates on curves of 2 chains or less in Chatham Dockyard.

Brian

Edit: Spaces added to kill accidental winking smiley.

Edited By Brian G on 20/09/2018 18:29:05

[Mick B1Participant @mickb1]

I've never actually done this, but an experienced turner showed me a method using a pointy rod the length of the required radius located in deep dot-punches below spindle centreline on headstock and crossslide chuckside face.

You use the saddle handwheel to keep the radius rod in contact both ends, whilst traversing a tool across the workface. The saddle moves away from the chuck to generate the radius. You arrange the tool so that it reaches centre when the radius rod's parallel to the bedways.

It's fiddly, but it's simple, accurate and I've seen it work.

Edited By Mick B1 on 20/09/2018 21:49:23

[Nick HughesParticipant @nickhughes97026]

I've posted this in another thread, but might still help, with some interesting methods:- **LINK**

[Neil WyattModerator @neilwyatt]

> Convex buffer face

No relation to Boaty McBoatface?

[John BaguleyParticipant @johnbaguley78655]

Posted by Mick B1 on 20/09/2018 21:46:16:

I've never actually done this, but an experienced turner showed me a method using a pointy rod the length of the required radius located in deep dot-punches below spindle centreline on headstock and crossslide chuckside face.

You use the saddle handwheel to keep the radius rod in contact both ends, whilst traversing a tool across the workface. The saddle moves away from the chuck to generate the radius. You arrange the tool so that it reaches centre when the radius rod's parallel to the bedways.

It's fiddly, but it's simple, accurate and I've seen it work.

Edited By Mick B1 on 20/09/2018 21:49:23

That's how I do mine:

The method was described by Tim Coles in ME Issue 4277.

John

[Mick B1Participant @mickb1]

You can of course use a similar method for concave radii, with the radius rod held between the tail side of the crossslide and a locked tailstock.

The turner I was talking about was using it to make the mushrooms on the end of full-size locomotive superheater tubes and, I think, a mating concave component too.

[paul rushmerParticipant @paulrushmer83015]

I hand tool mine using a file ground smooth on the end and sharpened like a wide parting tool, the tool rest being a round rod held in the tool post. Check the profile by eye and feel polish with emery to finish. This method is quick simple and easy. Just be carful.

Paul

[KWILParticipant @kwil]

Pointy radius rod and the DAG Brown approach produce identical items so there is no guess work to make them look OK.

[Ron LadenParticipant @ronladen17547]

Posted by Mick B1 on 20/09/2018 21:46:16:

I've never actually done this, but an experienced turner showed me a method using a pointy rod the length of the required radius located in deep dot-punches below spindle centreline on headstock and crossslide chuckside face.

You use the saddle handwheel to keep the radius rod in contact both ends, whilst traversing a tool across the workface. The saddle moves away from the chuck to generate the radius. You arrange the tool so that it reaches centre when the radius rod's parallel to the bedways.

It's fiddly, but it's simple, accurate and I've seen it work.

Thanks for this idea Mick, I gave it a try on a test piece and it works really well and is easy to do. The only problem I have is the four blanks which I have for the buffers are 70mm long and the radius needs to be around 200mm. A 200mm guide rod keeps the cross slide too far way from the workpiece even with the top slide fully wound in, I,m using a mini-lathe by the way. The blanks need to be around 125 mm long and then it will work, however all is not lost.

A machinist friend supplied me with the 70mm blanks (FOC) which was very good of him, I dont know the grade of aluminium but it is the hardest I have come across. The 3.2mm parting tool I have works really well as a groove tool (well on good machining aluminium at least) but it doesnt like the material my friend supplied. So I need to get a softer grade and longer blanks and then I think it will be fine.

Thanks again

Ron

 

Edited By Ron Laden on 21/09/2018 15:26:45

Edited By Ron Laden on 21/09/2018 15:28:14

 

Edited By Ron Laden on 21/09/2018 15:53:52

[Ron LadenParticipant @ronladen17547]

Sorry, dont know why my above reply is in miniature, cant seem to change it..?

Ron

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