Author Topic: First attempt at scratch building in gauge 3  (Read 1695 times)

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Offline Geoff Nicholls

First attempt at scratch building in gauge 3
« on: Apr 29 2014 08:52 »
elsewhere in this forum you can see a live steam loco being built to the highest standards. In the interests of balance, here's one from the 'kitchen table' end.
This is my first scratch built loco (electric RC not live steam), in any scale,  a J65 (GER E22) 0-6-0T.I originally thought I'd copy the GRS method using laser cut frames with their frame spaces and hornblocks keeping soldering steel to a minimum.

As the J65 was to be the trial run for an eastern Counties Gooch class A 2-2-2WT, I realised it had to be built to the same standards, which meant a more prototypical frame spacing than the GRS 49mm spacers. I'd also started chatting a bit with other G3 types, Mike , Ken Cottle and people on the G3 soc stall at exhibitions. They all assumed I was as good at this as they were at this stuff, so I decided to try and actually be that good, and make the J65 my 'apprentice piece'.
Despite the above comment, I do know my limitations, I can't cut a straight line in metal to save my life.  Fortunately I'm reasonably good at CAD, so drawing frames for laser cutting was easy to do. The frames are 1.5mm steel, because that's what everyone else does. the design was based on the way Mike Williams designed his Manning Wardle frames. the combination of horizontal and vertical spacers with tabs fitting into slots in the frames , creates a stable structure which is easy to hold together while you solder it. Holes were included for rivets to locate the hornblock guides in position while soldering.

As I mentioned earlier, I had originally intended to use GRS brass frame spacers, but they are only 49mm long, I wanted the frames to be as near prototypical as possible. The G3 soc standard wheels back to back is 58mm. Then 2mm for the two axle bushes. Even with 8' 0" radius curves I worked out I'd need very little slack. So I settled on 52mm between the frames. I've adapted Mike Williams' hornblocks kit. They are designed to use a spring underneath, but the E22 had it's real springs underneath, so I turned the hornblocks upside down. At rest the loco will sit of the tops of the screws on the outer axles, there will be 1mm play above the centre axle. The hornblock springs will push the axles down when the track dips.

I bought a rolling road and used it to test the motor/gearbox in situ.
I've tried running it on my track; an 0-6-0 with 13' 6" wheelbase, and 55mm width over the frames will happily negotiate 8' 0" radius turnouts, though there is no slack.

Originally I intended to have the coupling rod fluting ground out, but now I'm planning on etched nickel silver overlays. That means they are thicker, and the brass coupling rod bushes wouldn't be long enough. The original bushes provided by Mark Wood are threaded inside to match the M2 screws.  I thought I could just replace these by longer sections of 3mm brass tube. I was wrong. The tube was too loose on the screw, and it was impossible to tighten the nuts without causing sufficient eccentricity to causing the coupling rods to bind. 

I ordered a new set of threaded bushes.  Having fitted these I tried it out again on the rolling road.  Holding the motor up in my fingers, I could still feel a 'pull' with each rotation.  I found one of the rods was slightly bent during soldering the layers of the steel rods together. (soldering steel is a nightmare!). And the layers were very slightly mis-aligned.

The vice and a file seem to have fixed this.

I cut some lengths of spring and fitted them loose on the hornblocks. It just about floats, but will sit firmly when the batteries are added. I think I will need to glue the springs vertically in place to stop them twisting.

It now runs quite smoothly on the rolling road, and my track, though still not as smoothly as the 'Venture' loco Ken Cottle was demonstrating at the G3 AGM.  Now I need to install batteries and RC and take it to GTG's to get some hands-on advice from the experts.

Offline MikeWilliams

Re: First attempt at scratch building in gauge 3
« Reply #1 on: Apr 29 2014 09:20 »

Ken's Venture ran that smoothly only after testing, tweaking and re-testing, so I'm sure you will get there.

And, can we have some photos please?


Offline Geoff Nicholls

Re: First attempt at scratch building in gauge 3
« Reply #2 on: Apr 29 2014 12:38 »
I only realised after I'd posted the text, that all my photos were larger than the 400K limit. I hope to sort some out tonight.

Offline Geoff Nicholls

Re: First attempt at scratch building in gauge 3
« Reply #3 on: Apr 29 2014 19:52 »
couple of photos attached. I have quite a few showing earlier stages, but they are too large to upload

Offline Geoff Nicholls

Re: First attempt at scratch building in gauge 3
« Reply #4 on: May 07 2014 09:20 »
It works! it actually runs smoothly through my 8' radius turnouts, pulling a couple of wagons. So I now have two locos controlled by my Revolution Train Engineer RC.
The photo shows all the RC bits on a temporary footplate. Now I need to finish off the artwork for the superstructure