Fabricating an injector

[xo18thfa]

Lately I've been reading up on homemade injectors. LBSC, Martin Evans and a fellow in Australian have articles on making your own. Has anyone tried to make their own injectors? How did they turn out?

Thanks

[LivingLegend]

Barry Hauge (of SuperScale) fabricated the prototype SuperScale Nathan "Simplex" injector body (and other parts) to test the injector internals (cones, valves, checks, etc.) before making the tooling and molds to put the injector into production. You might say, at that point, it was a "homemade" injector.

That prototype injector was installed in Charlie Dockstader's "El Gobernador" for testing. That was over 25-years ago.... To the best of my knowledge, although Charlie no longer owns the "El Goob", that prototype injector is still installed and in use on the engine. PennsyFan..... Can you verify?

I ran Charlie's engine many times with it's SuperScale injector prototype.... The injector always worked flawlessly.

LL

[baggo]

I've made several small injectors (8oz) to the designs by D A G Brown published in Model Engineer some time ago. After a bit of tinkering I managed to get them working well. My Helen Long has two of them fitted. I've also made a 4oz which works but the output is a bit low even for a 2½" gauge loco. 8oz is about right for this gauge. I've got quite a few orders for them!

The smallest commercially available injectors available here are 12oz which are too big for the smaller gauges, taking too much steam from a small boiler, hence the need to make my own.

The critical bits are obviously the cones but once you've made the taper reamers the rest is not too bad. I would imagine larger injectors are quite a bit easier to make.

The commercial ones over here are a bit of a mixed bag, some are good but some won't work straight out of the box and need some adjustment to get them to work.





The bodies above are 7/8" long.

John

[LivingLegend]

Just happen to think....

Were the earlier injectors on Chet Peterson's UP 4-8-4 made from brass barstock? I don't remember for sure.

Maybe Dean Willoughby, who is the present owner of Chet's loco, or David Rohrer, who worked for Chet back in the early days of RRSC, will respond to verify or with a correction.

LL

[Bill Shields]

Baggo:

How do the injectors from Macc and Reeves work out of the bag?

[alanstepney]

Way back, I made a batch of ten to the LBSC design.
About half worked.
Later, I managed to get a couple more working.

The series in Model Engineer on injectors, by D.E.Lawrence was superb, and making a batch of those, I found that 80% worked.

(My "skills" or otherwise, could account for some of the failures.)

So, yes, they can be made, it isnt difficult, but one does need to follow the instructions carefully.

[baggo]

Bill,

I don't know about the Macc ones but the Reeves International injectors seem to be ok. One or two of the lads in our club have fitted them with no problems. The ones made by Gordon Chiverton seem pretty good as well. I used one on Helen before replacing it with one of my own and it worked well.

John

[xo18thfa]

One reference book I have is "The Model Injector" by E.C. "Ted" Crawford. It is from the Australian Model Engineering magazine. I ordered it from TEE Pubs in the UK. Part One is explanation and math. Part Two is step by step to make a 60 oz model.

From that and your inputs, it sounds do-able.

John. Your jig is the answer on how to assemble the body. Thanks for sharing that.


Many thanks, Bob

[dwilloughby]

For Living Legend

The El Goob still has the original injector and it still works.

I remember Chet's engine having what appeared to be a large version of the Engine style of injector. When Cliff and Clarence purchased the engine in 1988 or so, they changed the injectors to the SuperScale Chicago injectors. Still both work great.

[Dick_Morris]

All the published designs I've seen don't have any movable parts except for the check valve. My recollection is that the Ohlencamp (probably missspelled) injectors had a cylinder inside that moved back and forth. I've been told that Superscale used a similar arrangement. Can anyone verify this? Could this be the reason that the Ohlencamp and SS injectors work so well at such a wide range of pressures?

[Fred_V]

the Olenkamp is directly scaled down from a Penberthy. it has a swing check valve and the sliding washer on the output cone which is removable for cleaning the little holes and un-sticking the washer. the mixing and output cones are combined in one unit as compared to the Australian book where they are separate cones.

SS injectors are basically the same as the Olenkamp as far as the steam cone and output cone. i can't remember if it has a ball check or swing check.
Fred V

[B&OBob]

The best design information I have seen was a series in the Model Engineer concluded only a few months ago. The designer used a single tapered reamer for all the parts and arranged for assemby so everything could be pressed in place. Several sizes were described. When I get "out from under" with other projects, I would like to try a batch. Laurie Lawrence wrote a series years ago in which clever alignment jigs were described to hold components for silver soldering.

My experience with Reeves, Kenion, Steam Age and other British small injectors is, they work fine for the first year, performance declining slightly with use. After disassembly and cleaning at the end of every season, successive years are not as good. After that they might or might not ever work again. I attribute that to erosion of the brass components by steam, only because I have no other explanation. Initially they start at the drop of a hat and really "sing", but that doesn't seem to last long before the only remedy I have found is to replace the sagging injector. I now have one from Poly Models made by Gordon Chiverton that is performing well. We'll have to see how it is next season.

The small type illustrated above look terrific. Good luck with them! (Great photography, too!)

Bob