Turning a dome for a 009 Peckett saddle tank.

My friend Ben (who sold me my Unimat SL) recently got in touch asking if I could turn a dome for him. He was scratchbuilding a model of 'Oakhill', a 2'3" gauge Peckett used by the Oakhill Brewery to transport raw materials in and finished product out between their brewery in Oakhill in Somerset and Binegar station on the Somerset & Dorset Railway. Ben is a decent guy and a very talented modeller who I'm only too pleased to help out.

The dome is quite unusual being shaped like a normal loco dome with a plate balanced atop, with a hole in the top as the safety valves are enclosed within. This made it an interesting job...

I started in my usual way forming the bottom diameter by mounting a flycutter in the chuck and holding the bar in the toolholder, making sure that the middle of the bar was on centreline;

Then the bar could be held in a collet whilst the flange and main diameter were turned to size, using a forming tool to start off the flange profile. There's a step on the top of the dome where I will mount the separate 'plate', turned with a grooving tool. The bottom was drilled and reamed 2mm for mounting on a length of silver steel rod, and the top drilled through 1.5mm for the 'plate' to locate onto;

Filing the flange to shape is always tricky, a decent smooth needle file, some fine wet & dry and an Optivisor are the tools used along with some Brasso to polish and a fair amount of patience;

In the photo below the left side has been profiled whilst the right side is awaiting attention;

Once the flange is formed the dome was Loctited onto a length of silver steel, and the top profiled using a graver and my watchmakers tool rest, finally being polished with wet & dry and more Brasso;

The 'plate' was turned from brass and had a spigot turned onto its underside which locates in the dome top;

I thinned down the edges with a needle file and a rubbing stick. After parting off I held the bottom spigot in a watchmakers collet and drilled out the top partway using a slot drill;

It could then be glued in place using 24 hour Araldite. A couple of days later the dome was mounted back in the lathe for a final polish;

And the finished item;

This has been quite a satisfying job, I've learn't from it and am pleased with the result. I know than Ben is as well, a nice finishing touch to another of his superb scratchbuilds.

Paul.