Geoff's G3 Workbench

Ian_T

Western Thunderer
I noticed in Garden Rail that Bachmann had introduced both "G-Scale" and "16mm" figures recently. Not sure exactly what G-Scale is in Bachmann terms - but hopefully it's 1:22.5. The figurines are in both modern and older styles of dress - there are also some cattle and horses. May be worth considering assuming the scale is OK.

G Scale Figures Archives - Bachmann Europe

Regards,

IanT
 

Arty

Western Thunderer
Have a word with Alan Butler at Modelu, I’m sure he could some of his range of figures in 1/22.5.
 

geoff_nicholls

Western Thunderer
A long time ago I acquired parts for one of the Williams Models/John Candy Sentinels. I've finally started building it. The kit is of the loco with a rear bunker, which is in the NRM collection. I have several small tramway style locos on my to-do list, including a Y10 Sentinel, an 04 diesel and a Falcon steam tram. it occured to me that I could build the Sentinel underframe as a motor block which could be swapped into any of these, as the fancy takes me. The photo shows the progress so far, including the new version of the Rx65 receiver I've just bought from Micro Radio Control. I'm using a similar RC in the ECR class A. It's tiny compared to the Revo, and a lot cheaper.

20180912_094310.jpg
 

Ian_T

Western Thunderer
Just for the record Geoff, I did all the original design/CAD work for the 100HP Sentinel. Several false starts were made with less than perfect prototype information but eventually I obtained the manufacturers GA drawings which I re-drew full size before scaling down at 1:22.6 (e.g. it is a true scale G3 model). I also built the mechanicals for the two prototype models (my version is shown below). John made the resin master moulds and from these produced some very nice resin body parts, which he assembled on my frames. Mike sourced the small metal castings and monitored our progress with an eye to any potential 'commercial' future.

Our objective was to make an "entry-level" G3 scale model available at an affordable price. I didn't know any Sentinel 'parts' had been released and as far as I'm aware, this model isn't available at the moment. Mike has apparently had a few other things keeping him occupied.... [trivial stuff like moving house and getting married... ]

Regards,

IanT

P1000599.JPG
 

geoff_nicholls

Western Thunderer
I persuaded Mike to let me have a set of parts, I don't think it's a production kit yet. And John sent me drawings. The Model Engineer 11th Jan 1951 has excellent sectional drawings of a version without the bunker, which I think looks nicer, so I'm building mine like that. I'm using a motor/gearbox from MSC which is for 1/4" axles. They don't make it anymore though. In my opinion the lack of readily available smaller motors with 1/4" axles could be a show-stopper for any entry level G3 modeller considering building this loco. I'm not entry level, but I'd never consider trying build my own gearbox. I didn't like the resin frame spacers, and used some brass ones from bought from GRS. Walsall produce them as well.
I believe both Mike's 'trivial' projects (your words, not mine) were completed on time and running smoothly. However government approval for MW2, the high priority project garden railway was granted some time ago and progress is slow, so the Sentinel kit may be delayed a bit.
 

Spitfire2865

Western Thunderer
Geoff, which MSC gearbox do you mean? I thought their JH motor was quite small already for being as powerful as it is. I wasnt able to stall it under realistic conditions at least.
 

Ian_T

Western Thunderer
I guess John will have sent you copies of my dimensioned PDF's that he used to build the master moulds. We did consider the bunkerless (earlier) engine but John preferred the later (bunkered) version and as we (Mike & myself) didn't have any strong preference - that's the one we agreed to model.

The two prototypes were both built using motor/gearboxes I had previously acquired from Walsall - which I think may still be available. Everything else was designed to be 'off-the-shelf' - with readily available bearings and other listed components. The biggest problem was finding a good (scale) solution to driving the second axle. I originally tried to use a 'Gates' belt - but the tension required to get a good grip proved to be too high. Small scale chain was extortionately expensive (even direct from China) - so we used a simple Delrin chain drive instead (as used in some small 16mm locos). I was concerned about how robust this would be - but in practice it seems just fine.

This is the Mark 1 'Gates' drive - it required too much tension to grip the pulleys sufficiently (resulting in excessive friction). The Walsall motor/gearbox units seemed ideal and were retained in the Mark 2 (final) set-up.

Regards,

IanT

Sentinel Frames #2 A - 200115.JPG
 

Ian_T

Western Thunderer
This is the Walsall motor/gearbox unit we used....

When I spoke to Walsall at Reading ALSRM this year - they still had them available - two reductions available (with either a single or twin start worm fitted) - for about £80 or so - a good deal less than the Slaters unit (but that was back then and this may have changed!)

Regards,

IanT

Walsall Gearbox & motor - Nov 2014.JPG
 

geoff_nicholls

Western Thunderer
which MSC gearbox do you mean?
It was the XL unit, Trevor, though I'm pleased to hear the JH is good enough. I have two of them left over from my 7mm days, perhaps they would provide a 1/4" axle gearbox.
This is the Walsall motor/gearbox unit we used
I'm a bit miffed to hear that. When this project was first anounced on the G3 Forum, I spoke up about the lack of a readily available motor gearbox. I have never heard anyone say or print anything about a gearbox being available from Walsall. I was one of the many people who bought several of those motors from John Candy, they've just sat wasting space in my cupboard because of the lack of a gearbox.
The biggest problem was finding a good (scale) solution to driving the second axle.
I think Arty has answered that one, my post #23 above shows my own method, using a slot for an adjustable tensioning mechanism. I bought my chain drive from motionco> Plastic Chain & Plastic Sprockets>Buy Online from Stock

When Mike provided the frames, they were slotted, once the sprocket and wheels are on the axle, it's pretty near impossible to remove them, so in my opinion it's essential the completed axles are drop-out-able.
 

Arty

Western Thunderer
You can purchase gearboxes from MSC on their own.
The trouble with the Powermaster motors is that the front mounting plate has no fixings and is plastic.
 

Ian_T

Western Thunderer
"I'm a bit miffed to hear that. When this project was first anounced on the G3 Forum, I spoke up about the lack of a readily available motor gearbox. I have never heard anyone say or print anything about a gearbox being available from Walsall. I was one of the many people who bought several of those motors from John Candy, they've just sat wasting space in my cupboard because of the lack of a gearbox."

Well I'm sorry to hear that too Geoff - but a little surprised as my engine has been shown at G3 AGMs, run at GTG's and also appeared in the Newsletter (as has John's version I believe). A simple enquiry to myself (or John or Mike) about the gearbox arrangements could have cleared this problem up very easily.

Personally, I'm now beginning to regret sending my 'working' drawings out without 'signing' and dating them, as I retain rights to them. Frankly I didn't expect them to be distributed beyond my fellow collaborators (or used with any product in their 'raw' state). I'll contact John & Mike privately and offer them a more finished set of drawings should this need arise again. Whilst I'm pleased that our work is finding some use within the G3 community, I would be much happier if after all the effort that went into developing this model, it was finally released. Our original intention back in 2014, was to be able to offer a RTR scale battery-electric G3 loco for about £400. We thought that would be an attractive proposition to anyone thinking of getting into Gauge 3 - and I think that's probably still true.

I'm sorry if I've disrupted your thread Geoff and I'll leave you in peace now. Wishing you well with all your various G3 endeavours. I 've been watching them with great interest and enjoying your progress.

Regards,

IanT
 

Mike W

Western Thunderer
When this project started Walsall would not sell the gearboxes separately and so far as I am aware that is still the case, so Geoff's pile of motors would be unaffected, sorry.

Will contact you about the drawings Ian, but so far as I recall Geoff is using the prototype drawings and just the drawing of the model frames, which have changed a bit and I have now had the frames cut to the new design with slots so the wheels and axles can be dropped out.

Mike
 

geoff_nicholls

Western Thunderer
Gauge 3 Broad Gauge finescale, or BG13.5. A test track with a set of Slaters wheels machined by my co-conspirator Unklian. Shown with an unaltered Slaters G3 narrow gauge axle. And a 50p piece and 6" ruler to give an idea of the size.
In gauge 3 standard gauge is 63.5mm, broad gauge is 95mm
20181020_104118.jpg
 

Spitfire2865

Western Thunderer
Wow!
So what did you decide on for the standards? Using the same flange width as G3 or something a bit more modified? I remember a while ago there was some discussion on it not being as easy as just widening the gauge. But I cant really remember much.
 

geoff_nicholls

Western Thunderer
Trevor, you could just widen the gauge to 95mm, increasing the wheel back-to-back from 58 to 89mm. The G3 society standards are not very noticeable with more modern stock (say after 1880 or so). But once you go back to the 1840/50's the wheels look very chunky, and the narrow back-to-back squeezes the frames, valve gear etc. It's extra work, but I'm not building large numbers of rolling stock, and you can see the difference.
And it's very good exercise for the brain.
 
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