Present your club with a globe as you are leaving, it will prove that the earth is round.

 

John S.

Axel,

It may have been done before  but like the Disney films that are re-released every 7 years it will play to a fresh audience.

 

Anyway if David is building one he needs all the help !!  [ apology is in the post ]

 

John S.

As one who has built a Minnie, I confirm that it was a great engne to build and gave me lots of pleasure to do so.  I have steamed it and it runs like a dream. 

The only problemt that I have had is that, I cannot in spite of many different attempts, get the water pump to actually put water into the boiler against the steam pressure. Even at 20lbs air pressure the return valve in the pump body cannot resist and the water is recycled back into the water tank. But it was great fun to have a go at.

 

John

Howard,

 

Picking up on the other comment in your first post – the one about precision.

 

I’ve had real problems with too-close fits in stationary steam engines. If you have any misalignment, no matter how tiny, things will bind. It’s amazing how a little bit of easing of a fit will make it all more tolerant, without necessarily adding knocks or clicks!

 

Neil

Is the Tich a scale model or a freelance?

Apologies for going off topic. 

I have just read the comments regarding problems with the 1″ scale “Minnie” boiler pump. I have not yet made the pump for my own Minnie but would I be better to make and fit an injector to feed the boiler instead of spending a lot of time making a pump that may not function effectively? Has anyone fitted a Minnie with an injector?

  

I haven’t built either Minnie or Tich, but I have the books for both and have been through them with a fine tooth comb. My two cents below – your mileage may vary.

 

Minnie in my opinion is a better quality design. Mr Mason has included many diagrams and photos of layouts and work holding/machining ops, rather than just word descriptions and the very few sketches of such items in Tich plans. (other feature related reasons – see Tich issues below). Lots of very small parts, but that should not put you off if you are patient. The pump issues mentioned above should be resolvable with some fooling around with spring force and ball/seat size and travel, but lots of experimentation may be required to zero in on optimum sizes/lengths. Heat could be a factor too – reciprocating pumps will not easily pump hot water, and the pump being stuck to a hot lump of copper boiler means it surely will be warm. Maybe a thermal isolating mount for it somehow could be implemented. The only major thing that would make Minnie easier would be building the engine on an engine frame and using a separate steam dome rather than the cylinder block, like USA traction engine practice. This would simplify things considerably, but it wouldn’t be an English design traction engine anymore. As I recall there are several bushings called out as brass, in my opinion only good bronze should be used for bushes on rotating shafts. Also cast aluminum T rings are called out for the rear wheels, I would say built up steel wheels from rolled steel rings and waterjet cut steel disks, all silver soldered up, will be much better and maybe cheaper than aluminum T rings.

 

Tich is a very small locomotive. I have seen people struggle mightily to coal fire it with success. In addition the throttle / regulator is one of the worst designs I’ve ever seen for one. There are also many known published plans errors for Tich on Alan Stepney’s site. The regulator issues could probably be solved by installing a smokebox throttle. One good and proven such throttle is a Swagelok ball valve (high temp rated model) but space is small for this in Tich so it might take some fiddling on a CAD system to shoehorn it in. If it won’t fit, a screw down needle style throttle would be easy and will work fine. If I were building Tich, I’d go with the Baker valve variant for easier build, and the open cab variant, for easier firing. Speaking of firing, maybe a two slotted tube or ceramic element gas burner as used in gauge 1 models would be easier for a beginner to make and use rather than coal firing. After all the firebox of a gauge 1 big loco like a 4-6-2 or 2-10-0 is around the same size as a Tich firebox, and the gas burners work fine for the big gauge 1 models. Check out Roger Thornber’s locos in ME for details on these gas burners.

 

It’s too bad someone hasn’t done a design for a narrow gauge open cab outline loco, like Terry Aspin’s Charles 0-4-0, for 3 1/2″ gauge. (or have they?) This would give an equally simple to build and low material cost loco for beginners but the boiler would be just that much bigger as to have more room for a simple smokebox throttle and would be easier to fire on coal. Food for thought. Doesn’t need to have a saddle tank, either, it could be a tender loco for simplicity.

 

JD

Reciprocating pumps used in hot conditions or which are infrequently used are usually fitted with priming valves . These are just simple manually operated valves fitted on the output side of the pump which when open allow initially air and then cold water to pass through the pump and overboard to waste . This allows any trapped air to clear and the initial flow of water cools the pump . Priming Valve is closed once pump is working .

It is indeed out of print but keep your eye out, I saw one a few weeks ago for less than £10.

 

It is also possible to make the model with just the book and no drawings so paying a bit more for the book is not so bad, I made mine with just the book.

 

Back to Jeff’s point about alloy rims, I feel this is one of the better options for the 1″ Minnie as most builders may have only done a stationary engine or two before so will not have facilities to roll a decent round ring from 3mm plate. They would then have to cut 4 rings for the tees or use disks as Jeff suggests which would need a good welding ability to be able to achive a wheel that is not distorted as the weld cools not to mention disc wheels making it look like a Simplicity roller

 

Jason

Here you can see a 1″ Minnie with a revised pump on the horn plate

 

And this is the same builders 2″ Minnie with an even mor ediscreat pump low down on the hornplate

 

You can also pick up whole volumes of ME for about £6 each on ebay so should be able to cover the build for about £20 if it was spread over 3 volumes.

 

Jason