r707
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Post by r707 on Sept 21, 2016 12:21:56 GMT
I'll second that - Although a frequent reader - I rarely comment - but I'm moved to post an encouragement; this loco build is by far one of the most interesting and accomplished I've seen. To include the rather unique LNWR design features (ie simpling valve) is impressive enough - but the quality of fabrication / machining speaks for itself. Eagerly awaiting the next instalments! best regards, ~ Phil
PS Dumb question #1: Explanation as to why no coupling rod between driving wheels? In this configuration it sems to me the LP cylinder / rear wheelset will always be playing "catch-up" with the HP oustide cyls / front wheelset. Or have I missed something?
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miken
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Post by miken on Sept 21, 2016 13:25:26 GMT
PS Dumb question #1: Explanation as to why no coupling rod between driving wheels? In this configuration it sems to me the LP cylinder / rear wheelset will always be playing "catch-up" with the HP oustide cyls / front wheelset. Or have I missed something? Thanks Phil, You are correct. This is one of several hilarious features of this design. When the loco is in motion the HP engine provides a conventional, 4 small power strokes per wheel revolution. Meanwhile there are 2 random (and completely out of phase) large thrusts per rev coming from the LP. When pulling away this caused an unpleasant surging motion for the passengers, up to about 20mph when it would smooth itself out. Also, when the driver had to reverse back to couple up to a train, If, when he put the engine into forward gear (remember, he has a screw reverser to control the HP engine only). When he tries to drive off (using the tiny HP cylinders to try and get the train moving) , if the HP/rear wheels slip before the loco moves (and there isn't much weight on them). Then the 2 sets of wheels could theoretically, rotate independently and in opposite directions because the engine needs to move about 10 foot forwards before the slip eccentric decides which way its going to go! To paraphrase a well known model engineer. This, while impressive, would serve no useful purpose. If the loco did refuse to start forwards in this position then the driver could sometimes make it start, if he had room, by driving the entire train backwards a bit and then trying forwards in a more favourable staring position. Or if against buffers at a station he might be able to reverse and compress all the buffers down the length of the train and get a bit of a spring push start. Or he could try deliberately spinning the wheels before coupling up before backing up to the train to try and hope to achieve a better starting position.
As a last resort, someone would have to get down between the frames with a pry bar and lever the slip eccentric into forward gear I bet the drivers hated them. Imagine trying all these tricks with a crowd of people watching. Later engines like mine were fitted with a by-pass valve to help starting. This is different to a simpling valve. It just bypasses the LP cylinder completely by blowing the HP exhaust straight up the chimney. As Bob Youlden said to me. "Ive never seen a trombone folded up inside a smokebox before". I hope to be able to reproduce all these features. Especially the contra-rotating trick. Coupling rods would spoil all this fun as either nothing would revolve at all or something would probably break. Also its a bit pushed for space to fit them. Francis Webb persevered with his compounds for over 20 years and they built loads of them in different classes but all basically similar layout. He was either very determined or didn't like to admit he had made a mistake. When he retired, his replacement quickly scrapped the lot .
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miken
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Post by miken on Sept 30, 2016 15:42:39 GMT
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Post by Roger on Sept 30, 2016 15:56:41 GMT
Hi Mike, Can't you just anneal the angle, bend it a little, straighten out the flange, anneal again and repeat? The bends don't look that extreme so I would have thought it could be coerced into that shape. You could turn a couple of disks, one with a recess round the edge just under the thickness of the angle and nip the flange lightly in the vice as you bend it a little. Another thought would be to use a pair of registered disks such that when clamped in the vice they were not quite biting on the flange thickness. You could then get the angle red hot, insert it in the groove and just bend the angle round the outside diameter of the discs. I guess it all depends on how much time you're prepared to spend on making little bits of tooling and experimenting. I really enjoy that sort of thing, so I don't mind doing that sort of thing.
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miken
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Post by miken on Sept 30, 2016 19:21:05 GMT
Hello Roger, Thanks for the suggestions I have tried bending brass angle and round rod in the past when its red hot and it has immediately snapped. I have found it best (as you say) to anneal and bend a bit,cold, then re-anneal. But ive always found that with angle the 90deg either opens up or closes depending on which way you bend it. I was once lent a set of miniature bending rolls with a groove turned in one roller, supposedly to do just this sort of thing. But it didnt work and just distorted horribly. My other problem is that I dont like making tooling. I think I'll stick with what i know.
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Post by Roger on Sept 30, 2016 19:29:01 GMT
Just one final thought, I suppose you could use a very fine 'razor saw' so that the cuts were as narrow as possible. That would make less work in the following stages.
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miken
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Post by miken on Sept 30, 2016 19:33:02 GMT
Yes, that would help
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Post by Deleted on Sept 30, 2016 21:04:34 GMT
nice work Mike, it's not easy curving right angle, even harder when doing it in opposite curves that have to fit in between straight sections...Having done this myself I know how difficult it is to stop the angle from twisting just as much as getting it to the correct radius. I like your approach...looks great...
Pete
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jma1009
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Post by jma1009 on Sept 30, 2016 21:52:18 GMT
By all accounts the Teutonics were the best of the Webb compounds, so I dont expect Mike's loco to exhibit the characteristics of the worst Webb compounds. I dont think I have seen such an interesting build since Roy Amesbury described his 5"g GWR 'President'compound in ME circa 1982
An old friend of Don Young's was Rodney Weaver who was a devout LNWR Webb devotee and expert. I met Rodney once. Quite a character!
I think, Mike, you got the making of the splasher angle spot on, and is probably how I would have done it as like you I hate wasting time making jigs and fixtures.
Cheers, Julian
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Post by 4fbuilder on Sept 30, 2016 22:03:38 GMT
Good evening Mike,
A couple of ideas: a method I've used in the past is to remove the vertical section in the area of the bend, bent the angle to the required shape, the area to be bent is now just a piece of flat, when bent silver solder in a piece of flat material then trim back to size; another method the late Bill Carter used was to solder in a section of square brass say 1/4" square into the root of some well annealed 5/16" brass angle, pop the whole lot through the rolls then simply melt out the soldered square material, I think he used that method on his GNR atlantic.
Congratulations on your success at the Model Engineer exhibition with Bessborough.
Regards,
Bob
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miken
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Post by miken on Sept 30, 2016 22:17:34 GMT
Thank you Bob. It was a genuine surprise. I like the idea of soldering a square section. I can see that would work well. Maybe next time.
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Post by arch1947 on Sept 30, 2016 23:07:54 GMT
Hi, I have tried using a piece of bar the right ID for the curve with a grove machined for the flange. The angle was annealed as suggested by others and gradually pulled around the bar with one flange captive in the groove. This helps keep everything square. Cheers, Arch
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r707
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Post by r707 on Feb 16, 2017 13:07:32 GMT
Hi Mike - I might be so bold as to ask if there's been any updates of late ? I'm dead keen to see any progress on your fascinating loco build ... :-) ~ Phil
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Post by 4fbuilder on Feb 16, 2017 16:29:24 GMT
Hello Phil,
Mike's probably waiting for the paint to dry this very moment knowing the speed he works at!
Bob
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miken
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Post by miken on Feb 21, 2017 15:13:21 GMT
Hello all, Im still here, but I've had to take a bit of a break from the compound as my 1927 Morris Cowley has recently decided it doesn't want to go any more and im busy doing a rebuild on the engine, gearbox, clutch brakes etc. Lots of parts to fabricate. Normal service will resume when im back on the road. Keep busy Mike
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miken
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Post by miken on Oct 18, 2017 15:15:23 GMT
After a year off from this project ive struggled to get motivated and start on it again. I'm now keen to see this engine in steam so have forced myself to resume and have made a start on the boiler dome and safety valve thing (whatever its called). So far, I have not used any castings and have fabricated everything. So, continuing this theme I made the following items from bronze bar and a bit of bronze cored bar that I had. I rough turn them. (Very) rough mill them and finish to shape with files and emery cloth. I felt a bit grumpy when I started them, but as they took shape under the file it became much more pleasant and Im now keen to press on.
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miken
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Post by miken on Oct 18, 2017 15:20:02 GMT
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r707
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Post by r707 on Oct 19, 2017 5:33:54 GMT
Delighted to discover work has resumed Mike - There is an eager audience waiting (me) to see this project steaming in compounded anger ...! > Oh, and the hand fettled dome and safety valve bonnet are terrific. Cheers, ~ Phil
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Post by Jim on Oct 19, 2017 19:44:16 GMT
Add me to the audience Mike. The skilled workmanship you are demonstrating is great to see and something we can all learn from and be inspired by. As to running out of energy to keep going, we all encounter that at times, these projects are labours of love and take a long time. As someone once said, 'You really have to love the chosen prototype because you're going to be withit for a long time'. Looking forward to you next update.
Jim.
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miken
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Post by miken on Oct 21, 2017 19:35:24 GMT
Today was supposed to be a public running day and I had planned to take Bessborough for its last outing of the year around the track at Hove Park but it was cancelled due to bad weather. So I continued with some more work on the compounds safety valves. The prototype had the sort with a central spring and a lever that spans the 2 valves. I dont know what this type is called. Has anyone made a working version in this scale? Is it possible? I made one when I built my traction engine but that was 6" scale. Anyway I opted for the easy solution and made a couple of simple loco style valves that will have a very light central spring to hold the lever. I will tin the shiny brass tops of the valves with solder so that they dont show up so much and hopefully resemble cast iron which is what the original valve body was made from. Just noticed that the valves look like they are leaning apart! Must be a trick of perspective or something. They arent. More filing
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