Sirs
I have a model F4 in 00 and the tube supplied for the boiler is a piece of copper tube. It needs holes drilled in the top and part of the lower portion milled away. I have a milling machine, but how do I hold the tube so I can work on it with out crushing it. All I can think of at the present is to fill the tube with plaster of Paris in clean it after I finished work on it. Any thoughts please?
Graham
I suspect a Vee block would help, or something like the machine vice I have (for the Unimat) that can be clamped to the milling table with tee-nuts and had the vees cut into the vice jaws so that they partly surround the tube but leave the top section accessible to a cutting tool.
Filling the tube will help prevent crushing, but with with plaster of Paris I'm not sure how you'd get it back out again.
As an alternative you could try to get something like Cerrobend / Wood's Metal that plumbers use to fill copper pipe when making complex bends. It's a metal alloy that melts at about 70 centigrade (and can also be used a solder for white metal), so can easily be removed by dropping the tube into a pan of boiling water (just be aware to remove all traces of the alloy from the pan as it's not something you want to eat!). The drawback might be that it could melt from the heat generated whilst machining, but that could be gotten around by running the machine al a lower speed, taking finer cuts and maybe using a cutting fluid as a coolant. The other thought would be to fill the tube with molten lead (or scrap white metal) before machining as it has a higher melting point, and leaving it in once finished as added ballast in the completed loco, but may then need to mill out a void for the motor within the boiler.
Julian
Thank you
In the past I have used thin wooden rods or dowels inserted into the thin brass tube that needed to be drilled. The wood inside the brass tube makes a very firm structure. I then secure in my small vice and drill what ever necessary holes are required. I don't know any thing about milling.
Robin.