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Convex buffer face

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Ron Laden20/09/2018 09:29:35
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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

Bazyle20/09/2018 09:38:32
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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.

Hopper20/09/2018 09:47:49
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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 Laden20/09/2018 09:48:11
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Thanks Bazyle, that sounds good.

Cheers

Ron

Ron Laden20/09/2018 09:49:27
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Thanks Hopper, that sounds a good approach too.

Ron

Andrew Johnston20/09/2018 10:04:35
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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:

face_profiling_me.jpg

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 Laden20/09/2018 10:07:07
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Thanks Andrew

Ron

JasonB20/09/2018 11:25:31
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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 Wyatt20/09/2018 11:44:37
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I did it the way Jason suggests, and for Norden they are oversize at 1 1/2" diameter in 3 1/2" gauge!

JasonB20/09/2018 12:01:43
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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 Buffersmile p

duncan webster20/09/2018 12:04:24
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2201 forum posts
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Industrial locos ofetn had collosal buffers to cope with sharper curves

Ron Laden20/09/2018 13:12:18
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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 C20/09/2018 13:13:14
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7444 forum posts
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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

dsc00898 (640x480).jpg

KWIL20/09/2018 14:38:49
3111 forum posts
56 photos

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

Brian G20/09/2018 18:25:21
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22 photos

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.

Rochester Castle in Chatham Dockyard

Brian

Edit: Spaces added to kill accidental winking smiley.

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

Mick B120/09/2018 21:46:16
1153 forum posts
64 photos

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 Hughes20/09/2018 22:21:59
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I've posted this in another thread, but might still help, with some interesting methods:- **LINK**

Neil Wyatt20/09/2018 22:23:34
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> Convex buffer face

No relation to Boaty McBoatface?

John Baguley21/09/2018 00:35:56
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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:

buffer2.jpg

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

John

Mick B121/09/2018 08:48:19
1153 forum posts
64 photos

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.

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