A Broad Gauge Buffalo

garethashenden
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A Broad Gauge Buffalo

Postby garethashenden » Thu Oct 08, 2020 4:16 pm

Despite this technically being EM, I'm going to post this here as it may be of interest to some of you.

I don't remember exactly when I started this project, but the first photograph I have of it is dated 20 September 2018, so it was probably a few days to a week before that. But lets go back to the beginning and discuss just what is being built and why. My friend Duncan decided, as one does, that the ideal thing to build for the Cameo Layout Challenge was a mixed gauge Great Western layout set in Cornwall c. 1890-1892. There's nothing wrong with that per-say, we're all welcome to model whatever odd things appeal to us, but there was a distinct lack of Broad Gauge rolling stock to hand. Existing EM gauge rolling stock could be put to use, and goods wagons are straightforward to build, but something was needed to pull them.

Various options were discussed and I, somewhat foolishly, agreed to build a 1076 class Buffalo saddle tank in its Broad Gauge form, starting with the Alan Gibson kit. Some of these 0-6-0 tanks were built to Standard Gauge, some were built to Broad Gauge, some were converted from Standard to Broad and all were eventually converted to Standard after the end of Broad gauge. They were designed for this from the outset, hence the double frames.

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It seemed like a straightforward job. Long axles, change the valance, build the rest of the kit as designed. If only. The problems I have encountered have mostly been of my own making, I'll admit that. I started with a fairly normal build, CSB suspension with High Level hornblocks on the inside of the inner frames. The desire to keep the motor/gearbox out of both the cab and the space in front of the firebox while driving the rear axle was eventually satisfied by a High Level gearbox and drive stretcher. The real headache arrived when I decided to do something about the empty space between the frames under the boiler.

The lack of inside motion was quite obvious and something needed to be done about it. I thought that, since I'm adding inside motion, I may as well make it work right? I'd never done that before but I have had an interest in doing it for a while. A kit for a Dean Goods inside motion was obtained from Brassmasters. It went together quite smoothly, although fitting it to the locomotive proved challenging. The first problem was that the motion plate and the hornblocks wanted to be in the same place. So farewell to the Continuous Springy Beams, replaced instead with hornblocks riding directly in the frame cutouts and some compensation beams. It wasn't as good, but it worked. The inside motion was fitted and everything spun around impressively. I fitted the wheels, the quartering was out, but I wasn't worried.

I probably started the body before this point in the story, but that's not too important. The kit's footplate wasn't really suitable for use as all the wheel openings needed to be on the outside, rather than the inside. Still, it did provide some basic dimensions and is still happily sitting in the bottom of the kit box. Aside from the gauge, the most distinctive feature of these locomotives is the nice curvy valance. Its not as curvy as some, but it isn't straight either. Not the hardest thing to make, although I seem to have got it wrong. The front arch on both sides needs to move forward and the middle on one side is far too high, both inside and out. But that's fixable. At some point everything got put away, the table I was working on was needed for Thanksgiving and it was at least six months before it surfaced again.

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On to the main problem and the reason this has spent so much time half built in its box: The Quartering. I pressed the wheels on the axles with a GW wheel press, which in the past has resulted it nearly perfectly quartered wheels every time I've used it. Not the case this time! I kept tweaking things, the quartering, the crank pin holes, the quartering, and it got better but it still had a bind that I couldn't find. Eventually I started over, pulled off the wheels and pressed them on again. But this time I used three plain axles, I set the crank axle aside. And the bind was gone. Well, buy this point the crank pin holes were way too big, but it ran in a different manner. So I had a look at the crank axle. This was constructed, following the instructions, from a steel axle, brass eccentrics, and bronze cranks. These were silver soldered together, then the axle was cut out from the inside of the cranks. It started out as a single piece of ground steel rod, but while examining it I discovered that the two ends were no longer concentric. My best explanation is that pressing the wheels on bent the cranks. Not so far that it didn't work, there was enough slop in the hornblocks that the inside motion moved smoothly, but enough that the connecting rods couldn't take up the slack. If I build another locomotive with inside motion I'll use an all steel axle, and press the wheels on before cutting the axle. I had found the problem, but wasn't sure of the solution, so back in the box it went. For another year or so.

I knew I needed new connecting rods and over the summer I had a suspension brainwave: put the CSB hornblocks on the outside of the frames. That would leave all the space needed for the motion plate but give the sprung character I was hoping for. I tried making a set of rods and failed miserably, so I ordered two sets of Bill Bedford's Pannier Tank rods from Eileen's. I thought it would be a good idea to have a spare on hand, given how this project has gone. I disassembled the chassis, made the rods and put the chassis back together again. It went pretty well but I was unsure how to fix the crank axle. I had been planning on unsoldering it and making new cranks out of steel before putting it back together, but unsoldering silver solder isn't the same as unsoldering soft solder. So I thought I'd try to straighten it. it might work, if it doesn't I'm not in a worse place right? Well it did work. I put it in my lathe and turned it by hand. Gave it a few pokes here and there and the eccentricity went away. Which makes me very aware of just how soft the cranks are. I must have annealed them while putting the axle together.

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The chassis is now together, the wheels are gauged and quartered and it runs. I will admit that there is a slight hesitation, but I've traced that to the crank rods hitting the top of the slidebars. The pesky motion plate is just a fraction too low. A straight forward fix. Then I need to build a 36" curved test track. If it doesn't get around that I have problems, but it should. Then back to the bodywork.

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Paul Willis
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Re: A Broad Gauge Buffalo

Postby Paul Willis » Sun Oct 18, 2020 9:38 am

Hi Gareth,

Can I just say that regardless of what the standards are that is being built to, that's a fascinating looking project, and very nicely modelled.

I would certainly be very interested in seeing more of this as the build progresses. Thanks for sharing.

Cheers
Paul
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www.5522models.co.uk

garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Mon Oct 26, 2020 6:37 pm

Slowly making progress. I had the brainwave of using my CAD skills to make templates and sticking them to sheet metal, rather than trying to draw out the shapes I need on the metal. It worked really well and I now have two valances with the right wheelbase and radius curves, and a footplate to match. I took my time shaping them, I know I usually regret it when I rush. Splasher tops and backs next.

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Terry Bendall
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Re: A Broad Gauge Buffalo

Postby Terry Bendall » Tue Oct 27, 2020 4:55 pm

Just looked at this thread and certainly no problem that it is EM. My view is that fine modelling can be done in any scale/gauge combination and we can all learn from each other.

garethashenden wrote:My best explanation is that pressing the wheels on bent the cranks.


That could well have happened. One way to avoid it might have been to put a spacing block between the faces of the cranks so they could not close up.

garethashenden wrote:Which makes me very aware of just how soft the cranks are. I must have annealed them while putting the axle together.


Given they were made of bronze this could well have happened. Annealing is the process of heating metal and allowing it to cool slowly to make it easier to form.

garethashenden wrote: I had the brainwave of using my CAD skills to make templates


Using CAD is one way but the technique is of course not new. i was using hand drawn templates glued to the metal 40 years ago! CAD just makes it easier and probably more accurate. :)

Terry Bendall

garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Mon Nov 16, 2020 6:32 pm

Since the last post the footplate has largely been completed and the cab added. I've also reworked the bunker to the correct shape. Very easy with a small course file. i'm pretty much back to where I was when I picked up this project again a couple of months ago.

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The other thing I've been working on is the wheels. The ones I had were fine, I guess. Gibson wheels, I don't remember which code. But they've been on and off the axles too many times to really be useable. They're a little loose, but don't go on the axle squarely. So I could just buy more, but the spoke count is wrong and they should be pin-in-line not pin-between-spokes. Then there are balance weights.So I 3d printed some. Using the tires from the Gibson wheels, I designed new centers. I started with just the spokes, boss, and rim, then saved this into two files, one for the center axle and one for the outer axles. Then I added the balance weights and printed them. I had to do a revision or two, but I'm happy with them. The rivets will be added with transfers. So far only one has been fitted to its tire, the rest will follow soon.

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andrewnummelin
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Re: A Broad Gauge Buffalo

Postby andrewnummelin » Tue Nov 17, 2020 12:24 pm

garethashenden wrote:....So I 3d printed some. Using the tires from the Gibson wheels, I designed new centers. I started with just the spokes, boss, and rim, then saved this into two files, one for the center axle and one for the outer axles. Then I added the balance weights and printed them. I had to do a revision or two, but I'm happy with them. The rivets will be added with transfers. So far only one has been fitted to its tire, the rest will follow soon.


A fascinating project that I'm enjoying following.
Because of some existing and planned projects, I'm particularly interested in your 3D printing of the wheel centres. Were these commercially printed or done "at home"? Which material was used? How are you fixing them to the tyres?
Regards,

Andrew Nummelin

garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Tue Nov 17, 2020 4:13 pm

andrewnummelin wrote:
garethashenden wrote:....So I 3d printed some. Using the tires from the Gibson wheels, I designed new centers. I started with just the spokes, boss, and rim, then saved this into two files, one for the center axle and one for the outer axles. Then I added the balance weights and printed them. I had to do a revision or two, but I'm happy with them. The rivets will be added with transfers. So far only one has been fitted to its tire, the rest will follow soon.


A fascinating project that I'm enjoying following.
Because of some existing and planned projects, I'm particularly interested in your 3D printing of the wheel centres. Were these commercially printed or done "at home"? Which material was used? How are you fixing them to the tyres?



They were printed at home using an Anycubic Photon printer and their black resin. So far the one I've mounted is a tight push fit, but I had planned on using a drop of superglue. That may not be necessary, it depends on how the other printed.

andrewnummelin
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Re: A Broad Gauge Buffalo

Postby andrewnummelin » Wed Nov 18, 2020 8:48 am

garethashenden wrote:
andrewnummelin wrote:
garethashenden wrote:....So I 3d printed some. Using the tires from the Gibson wheels, I designed new centers. I started with just the spokes, boss, and rim, then saved this into two files, one for the center axle and one for the outer axles. Then I added the balance weights and printed them. I had to do a revision or two, but I'm happy with them. The rivets will be added with transfers. So far only one has been fitted to its tire, the rest will follow soon.


A fascinating project that I'm enjoying following.
Because of some existing and planned projects, I'm particularly interested in your 3D printing of the wheel centres. Were these commercially printed or done "at home"? Which material was used? How are you fixing them to the tyres?



They were printed at home using an Anycubic Photon printer and their black resin. So far the one I've mounted is a tight push fit, but I had planned on using a drop of superglue. That may not be necessary, it depends on how the other printed.

Thanks - I suspect my shopping list is going to grow...
Regards,

Andrew Nummelin

garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Sun Mar 21, 2021 2:24 pm

Picking this up again, some progress has been made.

The cab has been changed again. Looking through the etches I found a taller cab which is the solution to the cab/tank height discrepency. I had overlooked it because it was drawn as the full cab front and sides, with long roof supports. The work of a moment to trim those and slightly longer to file the cab sides to match the splashers. Once this was fitted I revisited how to align the cab and boiler. I had been using two substantial rods on the inside corners of the tank, but its difficult to get them in exactly the right spot. So I came up with a system of four small pegs. Two mounted vertically in the footplate going into holes under the smokebox, and two horizontally in the cab, going into the back of the tank. This gives quite secure repeatable locationing, with one 10BA bolt holding the smokebox to the chassis.

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I have removed all the detail from the tank. It had a three course tank and I'm modelling an engine with a six course tank. It seemed easier to do all the rivets at the same time, rather than trying to match the existing ones. I need to rearrange the holes in the top of the tank. I think the dome and filler need to move, the dome a little, the filler a lot. Buffer beams have been made and fitted, ready for the cute pointy Dean buffers.

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Finally, the crank axle has had new cranks made. Unfortunately the eccentric sheathes didn't survive the disassembly process, so reassembling is on hold until a new etch arrives.

garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Sun Mar 28, 2021 12:38 pm

Further progress, it rolls! Unfortunately the tires aren't square to the wheel centers, so they're very wobbly. I'll need to print new centers and redo them. Oh well.

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Andy W
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Re: A Broad Gauge Buffalo

Postby Andy W » Mon Mar 29, 2021 8:16 am

Looking good!
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Philip Hall
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Re: A Broad Gauge Buffalo

Postby Philip Hall » Mon Mar 29, 2021 12:13 pm

Re the wheels: I don’t know about how accurately you can make printed centres, but it might be an idea to have the centres a fraction bigger than the tyres and then skim down the centres to fit the tyres. That way you can also skim the front face of the centre to ensure it is at right angles to the axle hole, removing the possibility of wobble as well.

All this assumes you have a lathe of course, so apologies if you don’t!

Philip

garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Mon Mar 29, 2021 2:42 pm

Philip Hall wrote:Re the wheels: I don’t know about how accurately you can make printed centres, but it might be an idea to have the centres a fraction bigger than the tyres and then skim down the centres to fit the tyres. That way you can also skim the front face of the centre to ensure it is at right angles to the axle hole, removing the possibility of wobble as well.

All this assumes you have a lathe of course, so apologies if you don’t!

Philip


That’s what I was doing yesterday. I had a bit of trouble with the printer but eventually got enough useable wheels. I have a couple of Alan Gibson OO axles kicking about, they’re very slightly smaller than the rod I used for these long axles. I used my GW wheel press to mount the wheel in the OO axle, then I turned the wheel on the lathe, taking off about .15mm. Then the tire was pressed on and the wheel returned to the lathe to check that it was close up true. I should really get an indicator for the lathe at some point. With the wheel in the lathe I polished the tread slightly to remove a bit of rust and some roughness from its manufacturing. Finally, the wheels were twisted off the axle. I have a M1 tap out for delivery at the moment. I’ll actually tap the crank pin holes instead of hoping the screw goes in straight. I may ream the axle hole in the wheel before final assembly. This isn’t the most brittle resin I’ve used but it’s not nearly as forgiving as the AG wheel centres are. I don’t want to break the wheels at the last moment.

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Re: A Broad Gauge Buffalo

Postby davebradwell » Mon Mar 29, 2021 3:02 pm

As it will be difficult to drill small holes in your wheel truly (unless you're following a printed hole) and as a tapped hole is a poor reference for a critical dimension - the crank throw, anyway, have you considered using other types of crankpin? The Ultrascale relies on a plain hole and flat wheel face for accuracy, for example, or you might just stick plain pieces of 1.5mm tube through holes in the wheel. Of course getting the holes in the right place is another matter.

DaveB

garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Mon Mar 29, 2021 9:12 pm

There is a printed hole. It will need opening up to tap drill diameter, but it should be straight through. The wheels were printed flat on their backs and the hole is clear, so it should be in the right spot.

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Re: A Broad Gauge Buffalo

Postby davebradwell » Tue Mar 30, 2021 8:36 am

With recent talk of loose and eccentric bushes your thread just seemed an opportunity for a reminder that there are other ways. It's subtly better to locate the actual pin accurately and leave the screw to just hold it all together rather than locating the screw first. My own take on the Gibson crankpin (and the Exactoscale was similar) is to open the hole in the wheel up to a tight clearance - 0.9 or 0.95 - so that the screw can't get enough bite to take it off course, even if I start it at an angle. Tapping the wheel seems an unnecessary risk (you've got to get it square) as the screw head takes the clamping load. Mind the head can't catch the axlebox corners!

I'm watching with amazement as you transform that whitemetal lump. Never could get on with the stuff.

DaveB

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Re: A Broad Gauge Buffalo

Postby garethashenden » Sun Apr 04, 2021 4:19 pm

Managed to get the inside motion working. There is a little tight spot I need to iron out, but overall I'm feeling quite pleased with myself.

https://www.youtube.com/watch?v=2g6YHv2CleE

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Winander
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Re: A Broad Gauge Buffalo

Postby Winander » Sun Apr 04, 2021 4:42 pm

Gareth,

Looking good, did the motion come with the kit or separate?

thanks,
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garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Sun Apr 04, 2021 4:48 pm

Winander wrote:Gareth,

Looking good, did the motion come with the kit or separate?

thanks,


No, its a Martin Finney kit for a Dean Goods. Same size cylinders as a Buffalo so it seemed like a good starting point.

garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Sun Oct 10, 2021 12:03 pm

Having spent the summer doing other things, mostly in the shape of a Jaguar XJ-S, I have returned to the Buffalo project. I gave the boiler/saddle tank a coat of etch primer a couple of days ago. Last night I had a truly riveting evening with some Micro-Mark rivet transfers.

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garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Mon Oct 25, 2021 11:51 pm

Its amazing how a chimney makes an engine come alive! This one I turned from copper rod this afternoon. The upper rim should be copper, so it seemed like the easy thing to do. The flare at the bottom still needs work, particularly on the other side.

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garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Sun Nov 14, 2021 6:40 pm

I have fitted pickups. I find it very tempting to paint it now, but I wanted to test its operation before I mess it up with paint. Its got a slight hesitation at slow speed that I need to sort out, and its a bit growly as well. But overall I'm pleased.

https://www.youtube.com/watch?v=yHq5UfxjzzE

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Re: A Broad Gauge Buffalo

Postby garethashenden » Tue Nov 16, 2021 12:32 am

I have found the source of the hesitation! It is, as I feared, the crank axle that is at fault. One of the solder joints on the crank has failed. Between the web and the pin on the right hand side. Probably not soldered well enough initially. Will need to disassemble, clean, and resolder it. It will be interesting to see if the 3d printed wheels can survive being removed and reinstalled on the axles or if I'll need to print another set.

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garethashenden
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Re: A Broad Gauge Buffalo

Postby garethashenden » Tue Nov 16, 2021 1:48 pm

Well that escalated quickly! Actually broken in two places.

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Winander
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Re: A Broad Gauge Buffalo

Postby Winander » Tue Nov 16, 2021 4:47 pm

garethashenden wrote:Well that escalated quickly! Actually broken in two places.

That's disappointing as the cranks are supposed to be cast, although they do appear to be in three pieces. I have one of Finney's on the go at the moment but haven't got to the stage of cutting the axle. I used lead free soft solder and although the reel doesn't have any ingredients on it, I believe all of them are over 200oC melting point. I used a blowlamp, Powerflow flux and fastened strips of solder where I wanted it, much like the technique for silver soldering. I did have a concern that the eccentrics wouldn't solder as they are at the centre of the lump and it is difficult to direct solder where is is required for fear of soldering the sheaves to them. It seems to be alright but time will tell.

Did you cut your axle out before fitting the wheels? I think Dave Holt's epic build highlighted the need to leave it until after the wheels were fitted as the cranks are not sufficiently strong to withstand the force. The castings look like they are made around a crank axle where the big end fits, so any stress would weaken that joint. Stress could also come from the manner in which you cut the axle - a carborundum disk in a mini drill is recommended but I don't have one, so will carefully use a piecing saw.

I hope all goes well in the reconstruction.
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