Jubilee

[Steambuff]

Hi,
I am after a bit of advice on machining oval buffers for a 31/2" 2-6-4 Jubilee. I know Martin Evans advocates doing the heads in two sections, but I would like to know if any member has any other solutions to providing a nicely finished oval buffer head

[Phil Sutton]

Hi,I hate to state the obvious,but someone wrote an article in M.E.sometime back(Within the last 3 years)about machineing oval items on a lathe.I rather think it was Steve Eccles,but unfortunately I no longer have the copies to hand.i suppose the only other method that immediatly springs to mind,is to rough them out as if they where circular,and then finish to size by filing.

Good luck,

Phil

[Steambuff]

Thanks Phil,
like you said sometimes the obvious is the least thought about. I shall have a go and see how I get on. Hopefully my hand skills are up to it.

[Phil Sutton]

HI.I'm glad I was of some help.No doubt the difficulty will be how complex the shape of the rear side of the buffer is.I would imagine that the plunger part of the buffer will be round,though.
I haven't any Jubilee pictures to hand at the moment,but if they similar to the Dutchess,they look like a large circle,with the top and bottom arcs cut off,which I think would be quite a simple exercise with saw and file,or even a quick job in the milling m/c.
I rather think ,having thought about it,that Steve Eccles' idea required some complicated parts adding to the lathe,and when all is said and done,then KISS - or Keep It Simple,Stupid.is by far the easiest way to go.

Phil

[SteveW]

Steambuff,

I saw this one a while back but the old fashion way of filling has already appeared.

It occurs that the really hard bit is getting the shape correct and symetrical. If the buffer face is faced but leaving a tit a piece of paper (maybe sticky backed) of the correct shape and with a centre marker hole can be stuck on the tit. A small hole in the buffer face can also be used.

Then its back to filling or an angle grinder for roughing out (eye, ear and breathing protection of course).

Profiling the face is just a question of a couple of shallow shamfers and a file.

Re eye protection: I find, being a glasses wearer, a poly-carb visor is loads better than goggles. Goggles steam up my glasses. I also find the visor (see ScrewFix cat (UK readers)) stops the hots bit getting down my shirt collar when fly cutting.

[Steambuff]

Thanks Steve,
Looks like I will have to get my angle grinder out. That should at least speed things up.

[chameleonrob]

if you have access to a rotary table then this might help, it is an isometric circle constructed out of four arcs, each arc flows into the next one and all you need to draw it on paper is a 30 60 set square and a compass. with a rotary table just mill round the arcs, hope this helps

rob

[Steambuff]

Hi Chameleonrob,
Thanks for your reply unfortunately I don't have a rotary table or a milling machine. But your drawing and explanation helped, as I now know how to mark out and obtain symetrical oval buffer heads. It does mean a bit of hand work, but thats what the hobby involves.

Steambuff

[steammadman]

Cheers Cameleonrob,been trying to remember how
my old maths teacher taught us how to draw an elipse,
for weeks ,now ican make a name plate for my latest
creation. WELL it is getting on for 60 years since my school days,and the old brain aint what it used to be,
(a bit slow),any wa6y thanks,i'll have a go in the shed
tomorrow. (watch out ufo's if it dont work for me)
Brian the steammadman

[SteveW]

Re producing an elipse:

I recall a method based on a construction from two concentric circles, one of the major diameter and one the minor.

A radial is drawn to the major circumference and a vertical drawn from the intersection towards the centre line. A horizontal is drawn out from the same radial where it crosses the minor circle.

The intercection of the vertical and horizontal is a point on the elipse. Repeat the process of radials and horz/vert construction lines to complete the elipse of points.

Join the dots to form the elipse.

QED.

[Garry]

Re Ellipse

Usually the radials you mention are lines drawn at 30 and 60 degree intervals in each quadrant. 1, because it divdes the quadrants equally and 2, because you can use a 30/60 degree set square. You can put more radials in in required as the more you put in the more accurate you line between the points will be. Another method is by using a template with the major and minor radius marked on and placing this with the marks on these raduises. It is a little difficult to explain on here ( I will try if you wish) but you will get an accurate line depending on how many positions you place the template on the radius quadrants.

Garry