Post
by Abiogenesis » Tue Aug 22, 2017 7:42 pm
Hello.
This is my first post here. At the end of May this year, I started to watch many videos on YouTube about garden railways & thought of having some kind of a layout myself. After watching Roly Williams fire up his Hornby G100 “Rocket”, I persuaded my eldest son to relinquish his 34 year old G100 (bought when he was born) from its pride of place on his sideboard. I was prompted to resurrect my Mamod ST1 as well, which I had purchased from Hamleys in 1962, as a 20th birthday present to myself.
Some years ago, I replaced the G 100’s original gas tank & at the same time I also lagged the boiler with Rockwool, but didn’t run it & it became only a display item. I placed it on chocks & fired it up three times & discovered that the burner on WOT did not generate enough heat to produce the results I saw in Roly’s video. I disassembled the gas line & fittings & they were all clear. I was left with the burner & so, purchased a preowned spare from Tony Green. Before its arrival, I erroneously concluded that the boiler had a leak, because further dismantling revealed that the glass fibre insulation was wet. Prudence dictated that I should seek professional advice, so I sent the boiler to Western Steam for examination. Geoff tested it hydraulically to 100 psi & it will be back soon, fitted with their 40 psi safety valve.
Meanwhile, I turned to Ebay & successfully bid for an SL1 with only one cylinder. It came with an oval of Mamod track & a Mamod open coal wagon. I was delighted. Having already completed some research, I concluded that Roy Wood Models had the upgrades I desired, so a pair of his upgraded cylinders with “O” ring fitted pistons were ordered, together with steam turret, needle valve regulator, displacement lubricator with drain, water top-up valve, a 40 psi safety valve & a number of decorative embellishments. Here I must praise Roy Wood for his valuable & constant help, whilst I struggled to climb the learning curve of Mamodification.
The plastic sight glass ruptured & led me to reducing the loco to only its running chassis, whilst I figured a way to replace the drilled out rivets on the boiler. Copper wire enabled me to position two bolts, but how to seal them? I salvaged a piece of Rubbaseal roofing from the skip (my youngest son is a bricklayer & is building himself a loft conversion in our roof space) & cut small washers to place on each side of bolt, where it passed through the boiler. This enabled me to secure the brass backhead in place. It worked very well.
About six days ago, loss of steam pressure led me to suspect that the sight glass had failed again. I had to remove gas tank & ceramic burner, the displacement lubricator & reposition the regulator, before I could gain access. I then realised that the sight glass had not leaked, nor had the Rubbaseal washers given way. It was the work of only about fifteen minutes before I had the loco in steam again. It was the steam dome insert that was the culprit. Back when I had the boiler out of the chassis & had substituted the RWM regulator & steam pipe for the Mamod original, I had also cut off & soldered the steam pipe where it exited the bottom of the boiler & had plugged the pipe with solder beneath the steam dome fitting, but I had not noticed that the insert was loose. I used a gas fired torch to effect a permanent repair, then sprayed the SL1 with heat resistant, red brake caliper paint.
I should also mention that a few days ago, a Mamod trainset with a guards van, a log carrier & an open coal wagon appeared on Ebay. Again, I was fortunate. Another gas burner from Forest Classics was fitted to Loco No 2 & I have a set of similar motive power upgrades for it on order from RWM. More rails & two sets of points have also been purchased & attempts to run two trains at once, have resulted in moments of high drama & downright panic.
This morning, I fitted the RWM cylinders to Loco No 1 again, after first deciding to solder the bolts that secure the brass backhead. I also soldered the steam dome fitting to the boiler, because of the constant leaks. It does not take long to reassemble Loco No 1 because I have cut down the cab. The safety valve lifted within 5 minutes & with three wagons heavily loaded with shingle & timber, plus a guard’s van with 1lb of lead sheet on the floor, Loco No 1 raced away with three full turns on the regulator. It got to the curve before I did & derailed disgracefully. I then attached Loco No 2 dead in tow & the added weight made little difference. Is it possible for an SL1 to be too powerful for its own good? After a few 50 feet circuits the loco stopped abruptly & would move in neither direction when pushed. An inspection revealed that the hind pair of wheels had shifted on their axle. Judicious work with pliers rectified the problem & I levered the triangular tabs with a steel punch to tighten the wheels.
Continuing to blow off, the loco hauled its load for more uncounted circuits & I failed to take account of the increased steam consumption. The train halted & it was the smell of burning paint that alerted me; that & the ruptured water sight plastic. AArrrggghh! No useable spares! What to do?
Tesco sell boxes of 100 white interdental sticks (toothpicks), labelled Pro Formula. These boxes are semi-transparent & very tough. I cut out two strips & shaped them & tried them both at the same time under the brass backhead. Too thick. Swapping “O” rings enable me to try one piece of plastic & it did not leak at 40 psi hydraulic pressure. Placing the boiler on the gas stove, the safety valve soon lifted. I viewed the plastic sight glass from afar with binoculars. No leaks. After four minutes, I turned off the gas & let the boiler cool. I have just removed the backhead & inspected the plastic. There is the very slightest impression of the rectangular slot on the surface of the plastic, but it’s considerable less that the imprint on the Mamod items. I could only just see it with my forger’s headset. Those are my findings. Make of them what you will. I’ve no idea what type of plastic was used in China to manufacture these boxes. It’s tough as old boots. I'll send samples to those who would like to repeat the experiment.
Regards,
Perry