7mm Dikitriki's Dark side: A WD 2-8-0

Dikitriki

Dikitriki

Flying Squad
Hi

I have some spare time today - the rest of the family have gone to visit the in laws while I catch up on some work....:)

So, if my modelling goes well, I reward myself by preparing a draft tax return......:confused:

Anyway, it's the turn of the radius rod. Here are the components...

P1010035.JPG

I have thinned down the slides on the left, losing the etched oiler, so I have filed a replacement from scrap etch. The bearing and washer serve to reduce the dianeter of the expansion link bearing hole and strengthen it, as well as reducing side play. The forked end is from the now redundant eccentric rod, and will be filed to match the shape once it is soldered on - the fork is behind the rod.

Now to fire up the soldering iron.

Richard
 
Dikitriki

Dikitriki

Flying Squad
OK

The radius rod has been completed, as has the expansion link. It's actually 4/5 of an expansion link as the top part is running inside the Gladiator valve gear support frame and under the valence and is not modelled. The top hole is the support bracket bearing, the middle one is for the radius rod bearing (slight forward gear) and the bottom hole is merely a hole on the original. Scale Hardware bolts at the bottom. I have shown it next to the Gladiator expansion link for comparison.

P1010040.JPG

Now to unite the 2 components and add the eccentric rod.

Richard
 
Dog Star

Dog Star

Western Thunderer
Hi Richard,
As you are illuminating so much of the art of building motion parts for steam engines might you consider changing the thread title to more accurately reflect the content? Something like:- "Dikitriki's Bright side"....

Cue for Python jokes?

regards, Graham

BTW - for your encore, may I suggest the Flaman drive for an A4?
 
Dikitriki

Dikitriki

Flying Squad
Dog Star said:
"Dikitriki's Bright side"....

Not after I've finished blackening it:)

BTW - for your encore, may I suggest the Flaman drive for an A4?

Before my period I think, but nice of you to issue another challenge. Clive, of the Heyside Group, is planning a Caprotti Standard 5 with all rotating gear/joints, and I believe has already sourced miniature gears from the States.
Click to expand...

Last pic of the day. I have made the various joints as shown in the photo, so I'm well on with the valve gear. The eccentric rod has had the big end doubled in thickness at the back to ensure that the rod doesn't catch the projecting bolts on the return crank as it rotates.

P1010046a.jpg

Richard
 
Jordan

Jordan

Mid-Western Thunderer
Dog Star said:
Hi Richard,
.... might you consider changing the thread title to more accurately reflect the content? Something like:- "Dikitriki's Bright side"....
Click to expand...
I agree - it's been confusing me from Page 1 - not a single sign of any North American trains or models at all...??!!??:confused::D;)

Absolutely tons of respect for all this mucking about with steam connecting rods though....:bowdown::bowdown::bowdown:
...could the original designers not have made the real things any more complicated..??:rolleyes:
 
Dog Star

Dog Star

Western Thunderer
OK Richard... if you feel that a Flaman drive is below you, then how about oil pipes and connectors to the tops of A3 slidebars? (and yes, it can be done - Mr Paul Penn-Sayers has made some).
 
Dikitriki

Dikitriki

Flying Squad
Hi

It's the turn of the reversing arms tonight.

This pic shows the components....

P1010047.JPG

I showed the making of the arms from scrap etch earlier - 2 matching pairs. They were joined together with a thicker bit of scrap etch in the middle - so that the radius rod can slide easily between the 2 arms - and all 3 pieces drilled through and tapped 12BA. The trunnion, either cast (MOK) or filed from etch must slide freely in the radius arm slides.

One point I forgot to mention earlier. The radius arm will be supported on the trunnion in the reversing arms and effectively on the valve crosshead slides at the front end. If it is to move linearly, the bearing in the expansion link must be fairly sloppy as this moves in an arc, and if there isn't this play, the radius rod will bind or move up and down at the front.

And here's the finished other side...

P1010049.JPG

I chemically blackened the trunnion and rear part of the radius rod before soldering the bearing pin through.

Cheers

Richard
 
Dikitriki

Dikitriki

Flying Squad
Right, continuing the saga....

(Sing along to 'dem bones') The eccentric rod's connected to the return crank....

P1010055.JPG

with a nice cast pin courtesy of a DJH spare.

The radius rod's connected to the combination lever....

P1010056.JPG

with a 14BA bolt, head thinned down to almost nothing at the back.

Altogether now....

P1010054a.jpg

A couple of pics showing the mounting method....

P1010051a.jpg

P1010052a.jpg

The kit provides only the 4 nickel silver arms on the left through which a rod is inserted and the reversing arms soldered on. This would not enable the valve gear to be removable.

I enlarged the holes, ran a tube (to clear a 12BA bolt) all the way through to ensure alignment, added cast weighshaft bearings (MOK - though Laurie Griffin now does some), and cut back the tube so that with the bolt in place, the unit still fits into the chassis. Exact alignment of the reversing arms and radius rod etc. is achieved by filing back the front of the tube until such time as , when the bolt is fully tightened, the reversing arms and radius rod are in a straight line, and all move freely. You can alse see clearly the valve cross head slides on the right.

Next is to install the valve gear on the support bracket, attach the bracket and cylinders to the chassis and see how accurate the holes on the combination lever and drop link are for the union link. I genuinely don't know at this stage, and while I think I'm OK, fiddling around with valve gear can lead to unanticipated problems.

Back shortly.....gulp.....

Richard
 
Dog Star

Dog Star

Western Thunderer
[typing this at roughly 12.30pm... ten minutes after Richard's previous post]

Are you back yet? Has Doctor Diki prescribed some medicine?

Being serious... tubes with clearance for 12BA, bolt fully tightened... into what does the bolt tighten?

Being more serious, after the time and effort to make all of the joints moveable, where will you attach the servo drive to link up as the engine moves away from a stop?

regards, Graham
 
adrian

adrian

Flying Squad
Dog Star said:
[typing this at roughly 12.30pm... ten minutes after Richard's previous post]
Being serious... tubes with clearance for 12BA, bolt fully tightened... into what does the bolt tighten?
Click to expand...
My guess - Previous post #333 says reversing arms drilled and tapped 12BA.

Edit 1: just realised this means, as they are independent, you could have one side in full forward gear and the other side in full reverse!
 
Dog Star

Dog Star

Western Thunderer
adrian said:
Previous post #333 says reversing arms drilled and tapped 12BA.

Edit 1: just realised this means, as they are independent, you could have one side in full forward gear and the other side in full reverse!
Click to expand...

Well, I did not want to be so rude as to suggest anything like that.... :rolleyes: . I am more interested in how Richard intends to link up the gear!:)
 
Dikitriki

Dikitriki

Flying Squad
I'm back.

That was a faff putting it all back together.

P1010059.JPG

OK, I don't think I'm going to have any problems with the union link attitude, though I shall have to look at lots of photos showing the extreme of the travel to see whether I need to adjust the centres slightly. I'm also pleased to say that the valve crosshead does not lift at either end of the travel. Nor do I think I shall have to kink the combination lever.

Adrian is right, the end of the bolt can be discerned in the reversing arms.

The next 2 photos show the construction and clearances. All the lines are pretty parallel to the frames and I have to say I'm pretty chuffed with that. I've left the photos at full size and I shall be free to answer any questions after (3-line whip) the WI soup lunch.....

P1010061.JPG

P1010060.JPG

Cheers

Richard
 
3 LINK

3 LINK

Western Thunderer
Hi Richard,

Just a quick line to say how much I am enjoying this thread, especially the way you have explained your technique as you go along, a bit like a Haynes manual for locomotive valve gear :thumbs:.

ATB,

Martyn.
 
Len Cattley

Len Cattley

Western Thunderer
Hi Richard that looks great your modelling is something I wish to aspire to :) . There is one question I wish to ask in post 335 you make a 12 BA bolt to pass through a tube and bolt into the reversing arms, how do you stop it from tightening it to the tubes as well?

Regards

Len
 
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