A Broad Gauge Buffalo

garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Tue Nov 16, 2021 5:59 pm

Don’t judge the Finney/Brassmasters kit from this picture. The first time I put the axle together I bent it slightly pressing the wheels on. The cranks were unrecoverable by the time I had it apart, so I made my own out of steel. The problem here is that when I put it together I didn’t use enough solder, or I removed too much cleaning it up. It should be a pretty straight forward repair, but I thought people would be interested in the whole process.

Jeremy Suter
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Re: A Broad Gauge Buffalo

Postby Jeremy Suter » Tue Nov 16, 2021 6:52 pm

Hi Gareth
Nice work so far.
It might be worth while re-looking at the crank axle.
There is generally no gap between the two sets of eccentrics on the real thing, so if you brought them closer together you may then be able to use thicker sheet to make the cranks from. It might also be worth while making the cranks before fitting to the axle and pinning to the crank and then the axle. I have done it myself making four brass cranks from 1mm sheet brass and pinning all the way through the side, axle and out the other side with a .45mm drill then pinning with .45mm wire and using high melt solder to hold together I also pin the eccentrics together and to the crank on one side.
Anyway best of luck
Tips and tricks in machine tool practice viewtopic.php?f=132&t=6350

garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Mon Dec 13, 2021 3:05 pm

Back to the crank axle. I have four shiny new eccentrics and I have a question about their fitment. The instructions say that they fit together in pairs, but I don't think that's correct. I have a photo I took of the Dean Goods in Swindon, then the two ways of positioning the eccentrics. My main concern is if I put it together as it should be, will it work correctly at the other end?

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garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Mon Dec 13, 2021 4:02 pm

After a bit more research, it will work. I just need to be careful that the eccentric sheaths can pivot on the expansion links. If there is a little play here and between the expansion link and the valve stem everything can move as it should. The kit design allows for the eccentric sheaths and expansion links to be firmly riveted together. If that is done the expansion link will move in and out, rather than wiggle around.

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Winander
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Re: A Broad Gauge Buffalo

Postby Winander » Mon Dec 13, 2021 4:26 pm

The instructions (at least mine do) say to put a washer (etch provided) between the eccentrics. Whilst they may work if you omit the washer, why leave it out if you have the space?

Your first photograph is the correct way to place them and you should put a 0.45 wire through the hole in all 4 parts to align them. I think from the photograph you need to adjust the alignment to do that. You don't solder the sheaves together as each goes either side of the valve spindle. I haven't diverted away from the instructions so that everything is in alignment and runs smoothly, even though it doesn't exactly confirm to prototype.
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garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Mon Dec 13, 2021 5:32 pm

Winander wrote:The instructions (at least mine do) say to put a washer (etch provided) between the eccentrics. Whilst they may work if you omit the washer, why leave it out if you have the space?

Your first photograph is the correct way to place them and you should put a 0.45 wire through the hole in all 4 parts to align them. I think from the photograph you need to adjust the alignment to do that. You don't solder the sheaves together as each goes either side of the valve spindle. I haven't diverted away from the instructions so that everything is in alignment and runs smoothly, even though it doesn't exactly confirm to prototype.


Yes. But if I ignore the instructions and build it as the prototype will there be a problem with the etch geometry? I don't think so, but if anyone knows otherwise it would be good to know before I start. I'm not sure I will have space for the washer. The cranks are going to be much closer to prototypical width.

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Winander
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Re: A Broad Gauge Buffalo

Postby Winander » Mon Dec 13, 2021 6:49 pm

I understand you now.

I venture to suggest the eccentrics would be alright without the washer but if the connecting rods and what's connected to them are too far from a longitudinal axis, then problems could ensue. Modification to the motion plate and the one that locate the 'cylinders' (in the kit pieces of thin tubing) to bring everything more into line would be required. If you are really pushed for space, there is a little sideplay in my eccentrics and I did think of slimming them down.

My major concern is to prevent mine jamming because if it does, the least damaging thing it will do is trash itself.
Last edited by Winander on Tue Dec 14, 2021 3:16 am, edited 1 time in total.
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davebradwell
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Re: A Broad Gauge Buffalo

Postby davebradwell » Mon Dec 13, 2021 8:20 pm

Might it have been Gooch gear on the real thing with the link curving forwards and a radius rod, as in Walschaert's?

DaveB

garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Tue Jan 25, 2022 2:43 am

I have constructed a new crank axle. It’s much sturdier and the mechanism runs well. I also replaced the gearbox. 54:1 is now 120:1 with the expected improvement in slow speed performance.
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I have reworked the brakes in a way that allows them to be installed or removed as a unit, an idea I borrowed from Will L.
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The handrails have been added, although not photographed. The final thing for this update, that I’m feeling rather pleased with, is the injector. I haven’t been able to find anything like it commercially, so I had to fabricate it. The first attempt was about 50% too big. This one looks about right though. I’m using some London Road castings for the bit that goes into the boiler up front. Just need to make the other side now…
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garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Sun Mar 26, 2023 12:45 pm

I have, I think, finished.

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Alan Woodard
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Re: A Broad Gauge Buffalo

Postby Alan Woodard » Mon Mar 27, 2023 9:44 am

Gorgeous.

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Lord Colnago
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Re: A Broad Gauge Buffalo

Postby Lord Colnago » Mon Mar 27, 2023 9:55 am

There's something rather lovely about that, well done Gareth.

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MPR
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Re: A Broad Gauge Buffalo

Postby MPR » Mon Mar 27, 2023 2:05 pm

That is very nice indeed.

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Ian White
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Re: A Broad Gauge Buffalo

Postby Ian White » Mon Mar 27, 2023 6:26 pm

Beautiful model. Excellent work.

splam32
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Re: A Broad Gauge Buffalo

Postby splam32 » Mon Mar 27, 2023 9:30 pm

That is a thing of beauty, the cast saddle tank, even replicates the texture of the iron used, during the period.

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Hardwicke
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Re: A Broad Gauge Buffalo

Postby Hardwicke » Thu Jun 15, 2023 5:28 pm

I'll have to get around to my Sharman (?) kits.
You've done well.
Ordsall Road (BR(E)), Forge Mill Sidings (BR(M)), Kirkcliffe Coking Plant (BR(E)), Swanage (BR (S)) and Heaby (LMS/MR). Acquired Thorneywood (GNR). Still trying to "Keep the Balance".


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