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GWR Bird class - running trials


Barry Ten

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With the major work on the loco complete, the Bird has temporarily borrowed City of Truro's tender for some running trials:

 

bird6.jpg.a78d7c8525acd41e74a681f4c003047a.jpg

 

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Initial results are quite encouraging from a haulage and general smooth-running point of view, but one thing I'm  struggling with is the outside cranks tending to go out of quarter if I handle the model. They were a very loose fit on the extended axles and the usual Loctite retainer I've used in the past quite successfully doesn't seem to be creating a firm enough bond. I remember the cranks on the City being quite a tight fit on their threads and almost not needing to be retained - they certainly took a bit of brute force to shift - but that's not the case with the Bird.  The City's cranks were of the usual type where you have to solder a retaining washer on, whereas these ones are the sort where a bushed washer has to be screwed on, and I must say I prefer the former.

 

I'd be grateful for any suggestions as to how I can get the cranks to stay in quarter - araldite, perhaps? I presume soldering is out of the question  due to the different alloys but perhaps I'm wrong.

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Hi Al,

 

The issue with loctite (cyanoacrlyate, I'm assuming) is it is designed for a very fine gap (e.g between tightened screw thread and nut) and sets rock hard but can be sheared under force. The original stuff is not gap filling. My guess is your gap is too large and the forces under driving conditions shear the adhesion, not the handling.

 

If it were my problem I'd try epoxy, warming the cranks to approx 50C so the glue becomes reasonably fluid to aid spread over the surface. Epoxy will gap fill and has a shade more flexibility than Loctite. Araldite is an epoxy I think, I just buy generic quick set from Daiso! Good quality Japanese I'd add.

 

Colin 

 

 

Edited by BWsTrains
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  • RMweb Gold

Thanks, Colin!

 

The stuff I have is in a small bottle that an aeromodelling mate gave me about ten years ago; I think it's Loctite 601 gear retainer, basically some green stuff, and that's about all I know. It's been suggested that I might be able to solder the cranks after all, so that's another option besides the epoxy.

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  • RMweb Gold

2nd vote for epoxy resin Al.  The 5 minute types are nowhere near as strong as the original which takes about 12 hours to set.  If you can roughen the ends of the axles and the inside of the cranks to create some mechanical retention that will also help retention.

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Also, your Loctite will have gone "off" by now, whereas fresh superglue might work OK for your needs.

Cyanoacrylate is one very reactive monomer, catalyst water, of which "the Sceptred Isle" has more than its fair share in the atmosphere. I store unopened tubes in the freezer in a glass jar. See here:

 

 for a mini topic. No point in me rehashing that again.

 

IMO as cyanoacrylate is now generic there's little value in paying for a "name" brand, i.e. much like pharmaceuticals.

I go to Daiso buy 4 * 1g for $2, their products are made in Japan and they've not let me down over several years.

 

Colin

 

 

 

 

 

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I use a nut threaded on before the crank. When the crank is in the correct position, back turn the nut until it is tight against the crank and it should be locked.

 

Mike Wiltshire

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DCB

Posted (edited)

Looks to be sitting too high.  I have been struggling with a Dukedog with the same issue. The frames of 5' 8" locos and 6'8" locos are the same but the buffers are 6" / 2mm higher on the buffer beam locos (and the running plate 6" or 2mm lower.) The footsteps at the back of the 5' 8" locos are the same distance from the ground as the 6'8"  wheel locos but shorter between top step and running plate.  If you use City of Truro bits and don't trim 2mm out between top step and running plate then the loco ends up 2mm too high when tender and loco steps align. 

Edited by DavidCBroad
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  • RMweb Gold

As I said in my previous reply to your point about the buffers. the running height is determined by the need for front bogie clearance. The tops of the wheels must clear the front frame extensions on curves, which they won't do if the running height is any lower. It's nothing to do with the rest of the body.

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Over on Wright Writes it was suggested that soldering the cranks should work, provided all is clean. I gave it a go (first cleaning off the all the gunk from oil and Loctite residue) with alcohol, then used 145 solder and Carr's Green Label flux, and it worked very well. I don't know where I'd got the idea that I couldn't solder to steel, but it turned out to be one of those fallacies. I'll know in future.

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7 hours ago, Barry Ten said:

Over on Wright Writes it was suggested that soldering the cranks should work, provided all is clean. I gave it a go (first cleaning off the all the gunk from oil and Loctite residue) with alcohol, then used 145 solder and Carr's Green Label flux, and it worked very well. I don't know where I'd got the idea that I couldn't solder to steel, but it turned out to be one of those fallacies. I'll know in future.

 

Regardless of the actual bond, it should presumably be an effective filler, thereby creating an interference fit??

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  • RMweb Gold

All I know is that once soldered, I couldn't shift the cranks by normal finger pressure. I didn't try any harder than that!

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