Brake shoe radius

Hi,

I need to produce a set of brake shoes on a 5" tender, what method would you use to produce the radius, which is 2 1/8"R.

Would you file the radius by hand or would you machine the radius?

I thought of a boring tool but worried about the sudden shocks on each revolution.

Many thanks

Les

Clamp the work to a rotary table and mill the arc.

Hold the work in a vice on the mill and use a boring head to swing the arc

If you only have a lathe then hold work in teh toolpost or vertical slide and make a cutter holder that fixes to teh faceplate and use that to flycut the radius.

J

Edited By JasonB on 03/01/2015 09:59:36

Why not bore out a ring of metal and then cut them from the ring as required? It is likely that they will never be used for the purpose of braking and then only to keep the tender stopped. Thats all I use my braking for to stop it rolling off the bench!

Clive

There's no reason not to clamp them on a face plate, and bore them on the lathe, if you are worried about shock, use HSS, use a low speed. Mount them on a disposable sheet of metal such as aluminium, or even a bit of MDF, take light, but positive cuts.

Ian S C

CNC mill - Andrew

Good evening Les,

I suppose you could invest in a CNC mill if you want six hundred brake shoes or more, but for six then the simple way is as previously mentioned, that is on the faceplate. An alternative may be to get a steel stockholder to cut a ring from which you could machine the shoes. Another method, draw up the shoe and get them water jet cut. If you are into CAD, you could draw them up, send the drawing off for 3D printing as a pattern then have them cast, again alright if you need dozens, but by the time you've done all that you could have almost finished them from stock material!

On the tender they can be made from steel stock as they are generally only used as a parking brake and probably steel would be suitable for those on the locomotive.

Regards,

Bob Youldon

Don't forget that the machined surface of the shoes needs to match the taper on the wheel tread, otherwise the shoes will not sit square when the brakes are applied.

John

Good evening John,

The advantage of water jet cutting, if you ask the nice man will set the head over to cut at the required angle. mind you if we did the jop properly the brake hanger pin etc would be at the correct angle to match that of the tread.

Regards,

Bob Youldon

I think turned the braking surfaces with the embryo brakes attached to the faceplate with the topslide at the same angle as when I coned the wheels, but I may be mistaken... I know they only fit the wheels one way round!

Neil

Bob,

Not all brake systems have the pins etc. at an angle to match the wheel, just looking at GWR if the block number has an A on the end it is for angled pins, most compensated braked engines had these, but panniers, tenders etc. had the angles on the block not the pin.

Baldric