Machining buffer heads

[benlmaggi]

I am about to start machining the buffer heads for my Sweet William engine. I plan to make them in two pieces: a shaft that will go into the buffer castings, and a "head" or strike plate surface. The head will have a recess cut into the back that the shaft will be Loctited into.

I have never machined a convex surface before. However, there are thousands of British and European model locomotives out there with them so someone must know how. Here in the States, we dodge the issue by using couplers!

Thanks for any help anyone can provide.

[ejparrott]

If you just push the shank into the head Loctite will not hold it for long. Suggest adding a screw thread between the two to take the load.

[Deleted]

Why not do it in one? Shaft and head together? Have a look at the V2 thread, there is a brief description on there which I can expand upon if needs be?

[uuu]

I removed the screw from the top slide, so it was freed off. Then constructed a link, the length of the target radius (5 inch, in my case), clamped in the opposite side of the four-way toolpost, so the as the cross slide was moved, the top slide followed the correct curve. A bit harder to describe than to do! This was cutting a stainless bar, head and shank from one piece.

Wilf

[jma1009]

i think ive silver soldered the buffer heads to the shanks on most of mine, though the first loco i built had them machined out of BRIDGET castings in CI, plus the stocks. i wouldnt use loctite for heads to shanks.

as to the curve on the faces of the buffer heads, im a bit old fashioned and turn them in the lathe and get them 'by sight' or template near enough. the faces either side are slightly stepped as a result as i wangle both feed screw and topslide handles at the same time. with a bit of practice this works out ok for me though i expect others may be horrified! then i wait for a nice sunny day and sit in the garden and file the surfaces to a nice curve taking out all the machining marks. then i polish up with various grades of wet and dry paper.

ive seen all sorts of complicated set ups and jigs for doing the curves but all end up 'not quite right' and not as per prototype. hence sitting in the garden filing away and judging these things by eye.

i suppose it also helps if you know what the buffer heads in fullsize actually look like and their shape! photos can be quite deceptive and you really need to look closely at the real thing.

cheers,
julian

[Ruston92]

Make a template then machine it by eye, quick to set up and simple to do.

[Ruston92]

Make a template then machine it by eye, quick to set up and simple to do.

[davebreeze]

Also, do they need to be curved? Flat buffer heads are not uncommon, the LSWR B4 I'm building has them. I've seem German coaches which have 2 flat and 2 curved buffers, arranged so that a flat one is always up against a curved one on the next vehicle.

[Deleted]

Dave, the real LSWR B4s have curved heads, I know No. 96 Normandy very well indeed

[ejparrott]

Think Talyllyn buffers are currently all flat. We did at one stage have one flat one curved each side, the curved bearing against the flat on the opposite vehicle. Our No. 4 is modeled that way.

[uuu]

Here's the setup described above - as best as I can recreate it. You see it's very simple.

I couldn't find the proper pivot pin that would have gone in the lower hole in the link in the picture (nearest the chuck, which is our of shot at the bottom)
The picture has the link at the position of the centre of the work - the end of the cut. As you withdraw the cross slide - moving to the right in the picture, the link will pull the topslide towards the chuck. You always get the same radius - set by the spacing of the holes in the link.

And here's the result


Wilf

[Roger]

It's the perfect job for CNC of course, maybe there's someone in your club that has one? It doesn't have to be a lathe either, I'm going to make mine on the CNC mill. Programming could be fiddly without a decent CAM program though. I'll get the curve looking right on the screen using spline curves and produce the path from that. It sounds complicated but isn't when you have the right software.

[vulcanbomber]

CNC programming the curves on buffer heads is dead easy, just needs the correct use of G01, G02 and G03 in a G71 cycle.

[Roger]

Mar 13, 2014 13:16:38 GMT vulcanbomber said:

CNC programming the curves on buffer heads is dead easy, just needs the correct use of G01, G02 and G03 in a G71 cycle.

Agreed if it's a simple curve, but I doubt if it is.

[Deleted]

HI GUYS---------------DO YOU NEED SOME HELP WITH THOSE "COMPOUND CURVES ??"...............

[gwr7800]

Always liked Hooters! They do nice chicken! Will now look and think buffers! Thanks Hagley!! HeHe regards chris

[Rex Hanman]

How did you manage to get all my ex's in one shot??

[jma1009]

bromide being sent to alan (Hagley)!

[Deleted]

-------Ah !!, that's better....just tested my new, COLD-ONLY shower....and it's worked, I'm glad to say.LoL !...REX, second row, 4th from the right says she wants to make-up !! --------- OK, let's get back to Buffers then}--- www.buffersmodelrailways.com/ ------------ Sorry BENLMAGGI, we've gone off your thread somewhat.....

[Deleted]

Mar 12, 2014 10:28:17 GMT uuu said:

Here's the setup described above - as best as I can recreate it. You see it's very simple.

I couldn't find the proper pivot pin that would have gone in the lower hole in the link in the picture (nearest the chuck, which is our of shot at the bottom)
The picture has the link at the position of the centre of the work - the end of the cut. As you withdraw the cross slide - moving to the right in the picture, the link will pull the topslide towards the chuck. You always get the same radius - set by the spacing of the holes in the link.

And here's the result


Wilf

--------------------------------------So the tool would be in the empty section of the tool holder on the immediate lower, right ?? and describes an arc as the cross-slide is moved ??