Author Topic: Assembled Cylinders  (Read 7999 times)

Offline Yorkshireman

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Assembled Cylinders
« on: July 30, 2009, 01:04:19 PM »
As requested, pictures for you addicts.

The BR74 Project at Berliner-Eisenbahn is using assembled cylinders, no castings, built up from plates, turned parts and some castings.
The exact detail is a little secret... All nuts and bolts visible from the outside are to scale.

This is for a 5" loco in 1:10 scale. The cylinders are quite large, larger as some the cylinders of some 7,25" locos, see the ruler.
The cylinders have pistonvalves with inside admission. The exhaust from the rear end is routed by an extra channel through the cylinder block to the front. This system was used in many of the Prussian designs.

Today, I completed the assembly of the cylinders, almost. The cover around the cylinders was made from some copper sheet which was handy. The draincocks are like the originals.

Have fun
Yorkie














bogstandard

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Re: Assembled Cylinders
« Reply #1 on: July 30, 2009, 02:26:10 PM »
Hi Yorkie,

Was the original design of the cylinder like you have produced, using tubes and endplates?. Or was the original a complete casting, and you are just replicating the outside detail?

Whichever way you look at it, it is a very innovative design, to produce a locomotive cylinder from just tubes and plates.

I was just asking because during the war years and immediately following, producing castings I think would have been rather difficult, and the tube plate method might have been used on the full sized loco because of supply problems. I am sure it would have worked just as well in full sized.

Bogs

Offline Yorkshireman

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Re: Assembled Cylinders
« Reply #2 on: July 30, 2009, 02:52:19 PM »
Hallo Bogs
It is a cost saving method. Of course the design of the KPEV (Royal Prussian Railway Authority) of 1912 was using solid cast iron cylinders. This approach avoids any complex milling operation e.g. for the steam channels, as these are now tricky holes in the sandwiched plates.

Some modern (reconstructed) locos at the small railways in Wales now have been built using exactly this approach! In case the old wooden patterns of the cast cylinders are lost, than this is the method of choice.

Yorkie

bogstandard

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Re: Assembled Cylinders
« Reply #3 on: July 30, 2009, 03:09:00 PM »
Thanks for the fast reply Yorkie.

I had guessed it was a way to make it cheaper, castings nowadays cost the earth.
 
Your reply has confirmed to me that it is a viable proposition in full sized as well.

Maybe the stalwart model loco builders in this country should be looking at methods like this, rather than being ripped off by the usual suppliers who sell awful castings for top end prices.

Bogs

Offline sbwhart

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Re: Assembled Cylinders
« Reply #4 on: July 30, 2009, 05:06:02 PM »
Hi Yorkie

Thats very interesting thanks for showing.

I've seen a similar fabrication method for cylinders employed by a chap in Sweden (i think), but he silver soldered the parts together, from your pics it looks like you've bolted the parts together with liquid gasket seals is this correct?.

Cheers

Stew
A little bit of clearance never got in the road
 :wave:

Location:- Crewe Cheshire

Offline Yorkshireman

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Re: Assembled Cylinders
« Reply #5 on: July 31, 2009, 01:32:41 AM »
Hallo Stew
The sealant is Loctite 5920, what is also used to fix oldtimer cars.
There is a possible drawback: After years, I may need to change pistonrings. When I unscrew the nuts on one side, the cover on the other end may come loose when there is no more tension on the studs. Then the reassembly of the cylinder on the locoframes, under the runningboard, will be a little difficult.
Yorkie

Offline sbwhart

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Re: Assembled Cylinders
« Reply #6 on: July 31, 2009, 01:56:30 AM »
Hi Yorkie

Thanks for the reply its amazing what you can fabricate if you try, I'm with Bogs when he says you get bad castings in the UK had one or two problems with them myself and I'm determined to avoid their use with the rest of my loco build.

Cheers

Stew
A little bit of clearance never got in the road
 :wave:

Location:- Crewe Cheshire

Offline Yorkshireman

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Re: Assembled Cylinders
« Reply #7 on: July 31, 2009, 03:51:51 AM »
Stew

You mean cylinder castings from the 'established suppliers', do you?
Friend of mine made his own wood patterns for cylinders of a fairly common loco, took the patterns to a foundry in Huddersfield and had them cast. The people there accepted the job as a non-urged way to use left-over material in their regular operations. The price was a tiny fraction compared to those at the 'established suppliers' and the quality was better.
On my cylinders here, the steam channels, covers, valve guides on the piston valve were made by a bronce foundry in the Midlands. Again, the price was right. We delt with the foundy directly!

Bottom line is, the 'established suppliers' have to survive too, but they are like an oligopoly, where the market is dominated by just a small number of sellers.

Yorkie

bogstandard

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Re: Assembled Cylinders
« Reply #8 on: July 31, 2009, 04:59:27 AM »
Yorkie,

Quote
Bottom line is, the 'established suppliers' have to survive too

I totally agree with you on that point, but it has now got to the stage that the customer is paying good money for a product that isn't up to the mark.

Imagine having put a lot of hours into machining a casting, then you hit an insurmountable problem of say a large inclusion or blowhole.

All you get from the suppliers is, send it back and we will send you a new one. Postal costs back to them and your wasted time are never reimbursed in any way. No gestures of goodwill, nothing.

If they had the castings made by a reputable foundry, rather that the cheapest one they can find, then this sort of thing would be a rare occurance.

It seems at times, if the castings look to be about the right shape, they class it as 'that'll do' and pass it off onto the unsuspecting customer.

There is a fine line between a good supplier and a rip off merchant, and the larger suppliers are usually the worst, as they seem to have the attitude that because they are the only supplier, they can charge whatever they like, even for very substandard goods, in the knowledge that they have already made a load of cash on the initial sale, and it will cost them very little to replace a defective part.

In other words, 'I'm Ok Jack', and 'the customer will always keep coming back, because he has to'.


Bogs

Offline Darren

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Re: Assembled Cylinders
« Reply #9 on: July 31, 2009, 05:07:00 AM »
I wonder how many kits are machined up, instead they stay sat in their packaging for a year or longer.

By then the customer thinks it's too late to make a complaint if they ever actually get to start the machining process.



The "satisfied" customer No' could be quite high
You will find it a distinct help… if you know and look as if you know what you are doing. (IRS training manual)

Offline sbwhart

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Re: Assembled Cylinders
« Reply #10 on: July 31, 2009, 05:32:31 AM »
Stew

You mean cylinder castings from the 'established suppliers', do you?


Yorkie

Hi Yorkie

Yes its established suppliers I'm on about  in my case Reeves I've built/building two models using casting from them and have had to return castings to them three times at my expense and I've replaced a US casting with a fabricated part rather than returning it. I also visited Reeves with my wheel castings as the driving and driven wheels didn't quite match, by the look of them they'd come from two different suppliers, the attitude although they were very nice about it was thats what we've got take it or leave it.

One thing that suprises me is that suppliers don't seem to have taken advantage of CNC machine tools in the supply of part, if you look at some of the castings it would be a easy job for them to be roughed out from a chunk of continuous  cast material by CNC to a stage where the customer/modeler could finish them off, perhaps there is something in the economics I don't understand in this.

Cheers

Stew
A little bit of clearance never got in the road
 :wave:

Location:- Crewe Cheshire

Offline Yorkshireman

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Re: Assembled Cylinders
« Reply #11 on: July 31, 2009, 08:20:47 AM »
Stew

The CNC approach would imply that 'the suppliers' would be run by engineers, and that is not the case. It is also an enormous initial investment. Throwing a pattern together and having it cast again and again is easy and should indeed drive the costs DOWN when producing larger batches. With CNC each and every piece does require the same amount of costly machine time. The quality is orders of magnitude better, though. It depends how modelers would value their own time.

At Berliner-Eisenbahn they introduced spark eroded loco wheels, beautiful and correct in every aspect: oval and tapered spokes even with little webs at the ends, made from tough steel. One could even have the year of manufacture carved into the back. Such a wheel is quite expansive, but if one would just take the minimum wage for producing a wheel like this from a casting (assuming it was possible), then it becomes resonable again. Last year I showed a driver wheel for a 7.25" loco like this on my club's stand in Harrogate. Most people wondered why the wheel was tied to the table, only some guys realized what it was, and only then the wheel caused some commotion.

I agree that producing parts from continuous cast material should be feasible. But how many modellers would rather just a 'cheap' casting?

Yorkie