Machining wheels

[Stephen RowleyParticipant @stephenrowley13300]

I have come to the point with my locomotive were I can start to machine the main driving wheels. These are for a Duchess and are 7.9 in by 3/4 thick. I have looked up all the standard dimensions for 5in gauge wheel and the finished thickness of the wheel is 1/2in. So my question is are castings made so thick as to need to take 1/4in off to bring it to the right thickness or have I got the wrong wheels and they are for a 7.1/4in locomotive.

Also I have read 2 books on building a locomotive and both give different ways of mounting a wheel. One said to line up the inside edge of the wheel where the spokes meet the outer rim and the other said to clamp the wheel in a four jaw chuck or face plate and line up the outer rim.

I have tried the face plate and line up the outer rim and tried to line up the inner rim but my wheels must be odd because nether seem to be true.

Any help please.

James K.

[Stephen RowleyParticipant @stephenrowley13300]

[KWILParticipant @kwil]

When running the most obvious defect is if the rim is moving up and down radially so the method of aligning the inner rim where it meets the face of the wheel appears to be the most satisfactory. I hold the tread in an independent four jaw and spend the time aligning the rim and at the same time ensuring the minimum of axial run out. You can now machine the back of the wheel, together with a “clean up” on the tread diameter, which will give you a flat face to hold against spacers on a faceplate when you machine the face, flange, tread and bore the axle. Castings for 7.25″ need to be at least 7/8″ to give adequate “meat” to clean up to the srandard 7.25″ gauge profiles, I cannot comment on your castings.

Edited By KWIL on 12/02/2011 17:22:59

[61962Participant @61962]

Hi James,

 

Correct finished tyre diameter for a Duchess is 7 11/64″ – 7 21/64″ over the flanges, based on 6′ 9″ full size.

 

GL5MLA standards give 1/2″ tyre width, near scale for 5 3/8″ which is accurately 15/32″ at 5″ gauge. The normal standard width for 5″ gauge going back to Greenly and LBSC and perpetuated by Martin Evans is 9/16″. Your castings are generous at 3/4″ but that’s not unusual, and probably reduces the risk of the tyres being chilled.

 

Before machining make sure there are no lumps and bumps on the face of the tyres. True them up with a file. Start machining with a facing cut over the back of the wheel in the 4 jaw. Reverse it and set the visible inner rim as true as you can get it and face the tyre and the wheel centre and bore to size. All subsequent operations should be done on the faceplate with a tight fit mandrel to ensure accuracy. I always do the final tyre profile after the wheels are on the axles to make sure they are true.

 

Hope you enjoy making cast iron cuttings, you’re going to have heaps.

 

Regards

 

Eddie

 

 

 

[Stephen RowleyParticipant @stephenrowley13300]

Thank you for your help. This is exactly what I needed to know.

I do not have a 4 jaw chuck that is big enough so I have spent an 30min lining one wheel up but it will be well worth the effort as I am sure and, the more you do the easer it becomes.

 

James.

[mgjParticipant @mgj]

jsk – are these the Blackgates castings to the plans they sell? If so is there a builders group that you know of, because I intend to tackle a Duchess shortly.

 

Are you doing your own boiler, or are you buying one commercially?

Edited By mgj on 17/02/2011 11:14:32

[Stephen RowleyParticipant @stephenrowley13300]

Sorry I have been so long in replying but I did not notice your reply.

I only started this project because I had the wheels

The wheel casting came from Reeves and I have not as yet had any casting as I have not found a supplier for them. The main frames and other part I have got from the Engineers Laser and the parts I have had are very good and I would recommend them to anyone.

 

I do not know of a builders group and as for the boiler someone tells me I should do it myself and offers all sorts of help and then someone else tells me to buy one as it is not that expensive. My problem is that although this locomotive is based on the LMS Duchess

it is not a 4-6-2 it is a 4-8-2 so any boiler would be 7. 1/2 inches longer that a standard Duchess boiler but apart from that it is a Duchess.

 

If you would like to talk more then send my an email here.

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