2" scale TE Lathe Swing?

Hiya,

I was thinking of building a 2" scale Te (undecided as yet) and was wondering what size swing over bed I could get away with on the Lathe?

Cheers Ryan

A 9 inch such as a Boxford is a pretty good size for most model engineering though a smaller 7 inch is adequate.. You should not be looking to swing the rear wheels or even the flywheel necessarily as there are other ways of turning the big bits. Depending on whether you have a milling machine look at how you will turn the underside of the cylinder block to the diameter of the boiler.

Edited By Bazyle on 10/11/2013 23:08:26

9" will allow you to do the flywheel and final drive on all but a ploughing engine in 2" scale as I can't think of any that are larger. This could be done on a myford which has a smaller swing but the gap bed will accomodate these two larger items.

Some designs need the cast rear wheels machining but others are cast to finish so don't need any more work, alternatively they can be fabricated by rolling and welding.

J

This is a question I've been trying to answer for a while. As a beginner I thought my mini-lathe (C3) would do me while I got a few projects under my belt. In theory it is a 7" swing but I've learned that there is more to it than that. I struggled to machine the rim of the 3" flywheel for the S50 I'm making because the cross slide would only just retract far enough. I suppose you could use a LH tool in the back of the tool post but I'm not sure how successful it would be. If I decide to buy something more capable in the future I'd like to be more aware of what its limits were.

Any comments from the more experienced members would be much appreciated.

Gary

Well I did the flywheel for my 10V which is the same size on a Unimat3. Too long ago now to remember what I did but left hand tool is quite likely and you can also get away with using a boring bar upside down while running in reverse if its not a screw on chuck. Thats what I did here as the boring bar was stiffer than my largest L/H tool and I also reverted to the supplied 4 way toolpost rather than the quick change.

Rather than get a big machine just to make one or two flywheels in your life check out evening classes or clubs that have machines you could use. There are also possibilities with rotary tables and a milling machine. Many of the larger items are available part machined too as the suppliers don't want to lose a potential customer so even if they don't list it always ask. If they don't come up with something you have to ask how good they will be on other support issues.

One of the things you might find more difficult is the cylinder block. You will either need to swing it all on a faceplate or be able to mount it on the saddle to use a boring bar between centres. Next you need to be able to swing a boring tool at the boiler diameter over the saddle to machine the curved mounting face. that could be the constraint. Or you do it on a mill. If you don't have a mill nowadays it is probably better to put spare cash towards a mill rather than a bigger lathe.

BTW Jason is the forum No1 TE man.

Jason; Thanks for the reply. It prompted me to go and re-read your Galloway build on MEM. Just shows that even though the WM-280 is capable of swinging it you still have to figure out how to machine it.

Bazyle; Thanks for the reply. I have an SX3 mill which should be good enough for anything I'm ever going to make. The point about machining the cylinder base is the sort of useful information that I as a novice would never have guessed. And I really should go and join Rochdale SMEE. Long term I would love to build a traction engine but I'm building my skills (very) slowly.

Ryan: Apologies for hi-jacking the thread.

Gary

> I suppose you could use a LH tool in the back of the tool post but I'm not sure how successful it would be.

Works every time, as Jason's picture ably demonstrates. Just keep the speed modest and use the 'low' gear. Watch the motor doesn't get to hot, take a half hour break if it does.

Neil

On my 2" Fowler I opted to bore the cylinder on the faceplate but cut the chimney base and cylinder saddle using a tool sticking out the sid eof a boring head on the mill.

For some interesting methods on turning a flywheel on a mill have a look at this guys album, last couple of rows.

Regarding what Neil said about speeds. On the variable speed 280 I found it better to turn those 10.25" flywheels at 250-300rpm and take a lighter cut than loose torque and cooling to the motor at the very low speeds.

J

For anyone else thinking of turning a flywheel on a mil like that make sure you have replacement final drive gear available for it. They may be designed to drive a six inch slab cutter but that's not the same as the energy in a big flywheel. You can do it but better to freewheel the drive and use a belt round the rim.