Author Topic: Motor choice  (Read 2557 times)

0 Members and 1 Guest are viewing this topic.

Offline IanT

Nothing's ever Easy - At least the first time around.

Offline Nick

Re: Motor choice
« Reply #31 on: Jun 30 2020 09:43 »
Chris,

Yes, I see the problem! Mine are indeed old stock, so old that I have no idea where they came from. I can find all-metal pins with heads that appear to be about the right shape at waldon.co.uk and at spentex.co.uk. It's difficult to be sure from the web site photos, but they are cheap enough to be worth a punt (IMO).

Nick

Offline Chris_P

Re: Motor choice
« Reply #32 on: Jul 11 2020 12:14 »
I have just received the pins ordered via IanT's link. The nickel plated brass sounded ideal and they are nicely shaped with a heads of approximately 1.5 mm diameter and around 0.8 mm height. Inevitably there is a degree of variation of about + or - 0.1 mm in these dimensions as I suspect their intended users don't need great accuracy.  :)

I'll leave the experts to debate whether this is a scale size for whatever they are modelling.

Offline Nick

Re: Motor choice
« Reply #33 on: Aug 23 2020 21:00 »
You know those projects where everything that can go wrong, does go wrong? You think three times, measure twice, cut once and still put the hole in the wrong place? This turned out to be one of those. I expected the rear beam to be no more than a plate across the back ends of the frames with a slot for the drawbar, but when I examined the drawings and photos it was apparent that the ejectors, feedwater pipes and cab steps were all hung off the beam and provisions for them were necessary.

With hindsight I probably made it over-complicated, and that may have been the root of the problem. I broke my rule of making things with the fewest number of parts. I see now that with a bit more machining I could have reduced the parts count by half with fewer opportunities for things not to fit and have to be re-made.

Still, it is done now and the rear ends of the running plates are secured. Next up will be the aforementioned bits and pieces. The ejectors look to be a particular challenge.

Nick






Offline Nick

Re: Motor choice
« Reply #34 on: Sep 16 2020 21:42 »
I had Shapeways 3D print the injectors in brass from my solid model. That was a lot easier than machining, and the photo shows them as received. Actually the layering looks a lot worse in the photo than in reality (to my eye, at least). It depends very much on how the light catches them. A little polish on the visible surfaces brought them up really well. I should have thought to include a scale in the photo - they are about 20 mm end to end.

I thought the cost at about £30 the pair was reasonable and competitive with casting for such a small number. Dimensionally they are dead accurate, no messing about with drilling out holes for the pipework. And they had to be brass because the prototype was unpainted, and nothing looks like brass so much as, well, brass.

I will be back to Shapeways for more fittings. Unlike plastics, I don't think we will be 3D printing metals at home any time soon. Apart from the cost of the machine, it requires a high power laser, high temperatures, coolant supply and goodness knows what else. Not something to run in the spare bedroom.

Nick




Offline AshleyW

Re: Motor choice
« Reply #35 on: Sep 17 2020 07:28 »
richard toplis did some injectors, as fitted to my J39, not sure how much he'd charge but could be another source.

Offline Nick

Re: Motor choice
« Reply #36 on: Nov 03 2020 20:57 »
Some more fittings, 3D printed in brass. For the one with the three handwheels, the handwheels and stems were too thin to be printed (I'm learning the limitations of the process as I go on), so I had the body printed, turned the handwheels and soldered them in place.

By the way, does anyone know what it is for? I can identify most fittings but that one has defeated me. It is attached to the side of the smokebox and presumably communicates with the smokebox interior - otherwise why put it there? There are two narrow pipes that disappear behind the smokebox, but unfortunately none of my photos show where they go. Just curious.

Nick





 

Offline John Candy

Re: Motor choice
« Reply #37 on: Nov 04 2020 06:32 »
Very nicely made!
It is a lubricator, most likely feeding the cylinders via the steam chest. It is a common fitting on many early LSWR locos (e.g. Beattie 0298 class 2-4-0 well tanks, the Adams 0415 4-4-2 tanks and 0395 class 0-6-0.... to mention just a few) as well as other locos from other companies (e.g. the LNWR Coal Tank).
Regards,
John.
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.