Outer shape of Cylinders

[Johannes GrabschParticipant @johannesgrabsch91508]

Hallo

If one would create the cylinders of a loco from block-material and having the bore completed – what is a smart way to make two edges of the block 'round' using common machinery in an average workshop?

Thanks

Johannes

[Johannes GrabschParticipant @johannesgrabsch91508]

[Martin CottrellParticipant @martincottrell21329]

Hello Johannes

Depending on the equipment you have available in your average workshop, there is an easy way and a hard way! If you have a milling machine and a rotary table it should be a fairly simple job. If not, you could turn up a couple of stepped steel plugs with the smaller diameter machined to fit the cylinder bore and the larger diameter at the size you require the outside diameter of the cylinder to be. You can then use the plugs fitted into both ends of the cylinder bore as filing buttons, grinding then filing the surplus material away until you reach the outer diameter of the plugs.

That gives you a couple of ideas, no doubt others will come up with better ones!

Regards, Martin.

[Jeff DaymanParticipant @jeffdayman43397]

You could also make an "axle" plug to fit the bores, with flats halfway across the end diameters outside the block. The block is held in the mill vise with the axle in the bore, flats resting on the tops of the mill vise jaws. Then many light mill cuts are made on the block to round it, a few degrees rotation, re-clamp, mill, rote a bit, mill, etc. If you make enough cuts the flats forming the rounds will be small enough to file smooth.

I have used this method hogging cast iron cylinders from solid many times. JD

[Boiler BriParticipant @boilerbri]

You could have them spark eroded?

Bri

[Nick_GParticipant @nick_g]

.

This guy youtube 'Mr Crispin' shows it here in this video of loco cylinders he is making.

That one is part 6 of him making cylinders from a block. – Go forward or backwards in the series in needed but I think that is the one you want.

Nick

[John OlsenParticipant @johnolsen79199]

I would do it between centres in a shaper myself. Of course, not everyone has a shaper, and those that do may not have a between centres setup for it.

John

[JasonBModerator @jasonb]

Rotary tanle is the easiest way, rough out most of th ewaste in the mill vice then starting with cylinder vertical shape the two ends

Then set upo with a tailstock to remove material to create the lagging space, you can leave any bosses for drains etc

Simple method as Jeff descrobes if to do it in the vice with a pin down the middle and rotate the work in stages

[Neil WyattModerator @neilwyatt]

There's my long-forgotten Cylinder blog:

http://www.model-engineer.co.uk/forums/postings.asp?th=36393

Admittedly a small cylinder, but the same principles apply.

Neil

[Phil H1Participant @philh196021]

There seems to be quite some effort expended to create a lagging space. With a cast iron cylinder for a model locomotive (say 1 1/4" bore) – Is a lagging space really necessary?

Phil H

[duncan webster 1Participant @duncanwebster1]

It reduces the mass of the cylinders, so they warm up more quickly, which reduces condensation

[Phil H1Participant @philh196021]

Thanks Duncan – I hadn't thought about the mass but again – is it really significant? I would imagine another couple of minutes and the additional mass will be heated through. Opening the cylinder drain cocks for a couple of additional seconds would empty the condensation. Have you any experience with solid wall cylinders with no lagging space?

PhilH

[Neil WyattModerator @neilwyatt]

Fine if you want to maximise the adhesion of your loco. For a stationary engine, my choice would be to do it properly as I'd know it wasn't right under the lagging – plus some stationary engines aren't lagged

Neil

[Brian OldfordParticipant @brianoldford70365]

Having been in the trade and now semi-retired I'd be inclined to knock up a simple pattern and have them cast at one of the jobbing foundries I know. If you have the means to machine a cylinder out of solid you could do similar to other materials.

Edited By Brian Oldford on 14/10/2016 17:22:49

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