Most model locomotives and traction engines use somewhere in their construction half round beading. Cab windows, bunkers, tenders etc. on locomotives and often tenders of traction engines.

Now in the small sizes brass extrusions are easy to come by and relatively inexpensive but in the larger sizes not so easy to acquire and expensive when sourced.

Some time back I was in the workshop of a very well known professional model engineer and through the cigarette smoke I espied strange goings on at his vertical milling machine. Closer inspection revealed that he was making half round beading in steel 1/4” or 5/16” diameter by a purely automatic process leaving him free to pursue other activities, namely using the beading that he had produced. Clever so and so I thought but didn’t tell him so - inflated egos are not my style!

So, how to do it? Well the main requirement is a simple gadget fastened to the milling machine table - drawings below should make it clear.

A block of mild steel drilled and reamed to size parallel with the base, the block fastened to a suitable size base to fit the machine table. The block is then machined away as shown in the drawing to reveal a half round groove, machine a few thou over half way then fix a bridge piece over the half round channel but packed up to make exactly half round. This gives clearance for an end mill that will reduce round stock (easily available) to half round, the bridge piece keeps the metal on the straight and narrow once the process is started.

The positions “A” and “B” indicate screws 6mm, 1/4” whit or what have you. Screws “A” fasten jig to base plate and bridge piece to jig. Screw “B” is only required at the start of proceeding as outlined above.

Modus operandi.

Poke the round bar through the reamed hole into the space between the full hole and the bridge piece, run the mill at a suitable speed and cut away to half diameter having previously locked the bar with screw ‘B’, release the screw and push forward to take another bite until eventually you have about 1” (25mm) projecting beyond the bridge piece. Now for the clever bit, attach a stout cord or similar to the projecting end, arrange for the cord to exert a straight line pull through the milling jig and to pass over a pulley or roller, hang a heavy weight on the cord and set the milling cutter nice and central to the jig. If you now set the machine in motion the weight should pull the bar through the jig automatically. You will need to adjust the weight by trial and error to achieve the desired result - easy really! And so half round beading no longer a problem.

Another thing I noticed through the tobacco fug was his jig for forming the beading to the required shape. He used a bit of plate, about 6mm upon which the centre of curves was marked out and drilled and reamed. Buttons were then made with stalks a close fit in the reamed holes and the extra length threaded to receive a nut. Reaming and making the stalks (shanks) a close fit ensures accuracy in the finished product. The drawing that I have appended shows that left and right can be produced as is but an odd shaped component would require the buttons be placed on the reverse side for the opposite hand.

I hope that this idea (suggestion) is of interest to at least some members.

HAVE YOU EVER BUILT A LOCO? ……..……..NO

WOULD YOU LIKE TO BUILD A LOCO? …….YES

But you don’t know where to start and have not a lot of cash to throw about—well I have just worked out a design for a battery electric loco just for you - simple and easy to build, will NOT cost an “arm and a leg” and should be up and running for next season.

If everything goes to plan, I should be at the Creech site on Sunday 14th June next and will have the outline drawings for the same for your perusal and to answer any questions.

If I have whetted your appetite, your Editor has a preliminary list of some requirements to source to make a start.

Enough for now and I look forward to meeting you at Creech on the 14th June.

Alan