Friday, 25 April 2014

Cracked it, I think...

OK, nobody grabbed my chance to explain the odd engine in the previous post.
But we don't care about that, do we?  That ain't going to stop me having a go and, whilst observing how revolting the average Mum is at the Grandchildrens' school, it came to me.

Firstly, I was never convinced it was a steam engine. I became more and more certain it was, or was intended to be, an air engine.
With that arrogant assumption firmly in place, I realised that the very reason it was a three cylinder was that it HAD to be to work at all.  A proper three cylinder engine is a 120 degree crank, so that there's always a power stroke going on somewhere.
Secondly it is a cyclical engine.
Thirdly, it is valveless, or at least as we know it, Jim.

The long spigot that pokes out of the piston crown serves in the office of a valve and this is how:-  after getting a nice charge of air, the first piston in the cycle is on its way, first down, then back up the bore. This would normally mean that the higher it gets, the more compression it would cause, thereby sapping power, but just before this happens, the spigot plugs the inlet port allowing the compression to be sent out of the small hole in the cylinder head next to the inlet port, which is the pipe to the next cylinder.  That cylinder is now getting its full charge from the air supply too, thanks to the 120 degree crank.  It is therefore a compression assisted following cylinder, which will do the same as the first and on to the third, whereupon the whole cycle repeats itself.
The presence of an oil pump is clearly because such a machine with brass pistons and cylinders would need some direct lubrication.  The suggestive presence of a war pump is merely that somebody decided this baby could run as a steamer.  I think it could, but I think with so much pipery it will suffer from a lot of condensation. It will also need a lubricator per cylinder because the fine content of oil in a normal steam engine would all be lost with so much transfer of vapour going on.  That aspect is open to conjecture, sure.

As a slowish speed engine in a straight runner it could be a perfectly good steamer.  What it isn't, I am certain, is a high speed steam engine. All that brass would not tolerate the temperatures and pressures of a flash steam plant.

So, what we have is a valveless, compression assisted Uniflow engine, designed for air, workable with steam.......and I claim my five pound voucher.

Tuesday, 22 April 2014

How the Devil does this work?...

And so to a wee puzzle for my hoards of followers.
Anyone into steam here?  Highly skilled mechanical engineers?

A new chum has sent me pictures of this engine.  We assume it was intended to be a steam engine, but I wonder if it might not be a pneumatic engine.
Whatever its original intention, it is...a 3 cylinder, single acting, apparently valveless engine. It ticks over on a lung full of air, is immensely torquey, smooth and powerful.
Beautifully hand made, it has two eccentric sheave driven pumps, one we assume, for water and the other for oil, as it is sump lubricated (more "evidence" of it being a pneumatic?)

Here is the odd internal arrangement shewing pistons With spigots (lovely word, that)

And here is it running on a puff o' wind, sounding for all the world like a Merlin on tickover.

The steam/air goes in the top, the exhaust comes out a little lower.  What the horizontal pipe linking all cylinders does, we don't know.

All ideas as to what it is and how the devil it works would be very much appreciated.
It is due to go in a vintage style straight runner, for the express use of and at the Victoria Park Model Steamboat Club, the world's oldest and of which my Grandad was a founder member back in 1904.
I should also say that it is 1" bore and stroke and about 9" long in all.

Sunday, 20 April 2014

No' many people know dat.....

As Michael Caine would tell you when giving one of his bits of useless information, like "Did you takes eight and one fird seconds to fall from de top of Big Ben to der grand".

But it's not generally known just how much can go into simply correcting certain models before you can even begin to build them.
Take this Spanish kit of a Citroen BX C4 rally car.  I was presented with it to build by a very good customer who collects slot Rally models. He has over 1500 models, all different.  I sometimes build kits that he hasn't time to deal with.
He sent me 5, all made in the same very odd way. Five different cars all mastered in what seems to be CNC cut thin plastic!  That means that every surface is completely free of crown (compound curves) and in fact, after being cast in resin were all suffering from convex surfaces that need to be filled, re-profiled and generally corrected before they could be made up into decent models of rally cars and fitted with running chassis.  In short, they are all appalling and I wonder how the manufacturers get away with foisting them on an unsuspecting public.
As you can see, this has Milliput all over it. Milli is my best modelmaking friend. It sticks to resin well and sets with a little applied warmth to a hard, fine, smooth surface.  Nothing else is as reliable for feather-edging and sharp corners.  This so called "kit" has needed 14 separate applications of Milliput to both correct and thicken a moulding that was paper thin in many areas and horribly wrong on the outside.  This shot shows how thin it still was after some using up of spare Milliput.
Always a good test of a "slush" moulding is to hold it up to the light.  Son Bazz, who both held this AND took the pic on his new DSLR knows this so took this shot as a matter of course.

The corners were all wrong too, so they needed to be loaded with Milliput and the roof, especially had to be given some shape, flat as the real ones look, but that then shows up the cock-eyed nature of the original window opening.  All yet to do.

Then there are the windows to make because none of any use come with the kit and finally the wheel inserts, also absent.
So, if I told you how much this is going to cost, you might not believe it.

"Nah, dare's no' many people know dat"

Wednesday, 16 April 2014

The spice of life...

Nobody can say that the modelmaker's life is boring.
After sending off the two models in the post below for resin moulding, I cleared the decks and got the books out to research a model railway wagon.
The Cordite paste wagons as used on the Royal Armaments Factory's 18" line at Waltham Abbey.
At the last minute I realised from my imperfect photos (best of them shown here) that they were bogie wagons, but which bogie?  Hudson, Fowler, who knows?
The frame could only be guessed at and as I have spent a working life interpolating photos of rare subjects, my guess is as good as anybody else's.
The loco, a Ruston ZLH petrol/parrafin, I have already done in 7mm scale to run on an N-Drive 9mm chassis, thereby representing 18" (ish!)  It was done in resin and photo-etch.  Here's the resin parts master.  The axleboxes were incomplete when this photo was taken.

So, with the drawings done last night, it's full steam ahead for a brass master of the Cordite wagon, to give N-Drive a very nice little train.

Alongside this job, runs a build of a rather nasty Spanish slot rally kit for a good customer (I wouldn't touch it if he wasn't!), a Skoda 130 RL rally car kit master, an H-16 BRM F1 car master and a 4mm kit master of the paddle steamer Kingswear Castle, to be followed by a 7mm scale version.

In between that lot, I am re-veneering my son's Triumph Renown dashboard and helping my wife with her new passion, a Memorial Garden to her Dad, a fenced off, NO DOGS corner of our main plot.  No dogs because they eat everything.  Only today, out little black bugger, Archie, stole a tomato plant seconds after she put it in its grow bag and he ate it!

Sunday, 13 April 2014

The Big Cat...

Back in the 70s, which I have more or less forgotten, if I ever remembered, Jaguar asked the superb tuning company of Broadspeed to prepare a car to beat the Gerries in saloon racing.  Don't ask me which Group or exact series it was, I don't "do" all that nerdy stuff, but anyway, Ralph Broad and his chaps knocked out a huge growling monster, which when it staid the course, was a demolisher of Johnnie Foreigner, the Jaguar XJ Coupe V-12, known immediately as the Big Cat.

A while back a customer gave me one of the ghastly Ocar versions of this as a slot racing shell and asked if I could "correct" it a bit.
Well, of course I could

So I did:-

Seen here with a Ferrari 801 to which I did the same job

These should be new models in Mel Ault's TinTop and PreWing ranges.