Chuffer's Workbench

[Bulwell Hall]

16 hours ago, Chuffer Davies said:

Building a locomotive chassis to a specific brief is different to building one for yourself.  The 'Brief' was to build a chassis that was capable of hauling the long mineral train on Pendon's Vale Scene.  Whilst this train is normally hauled by Guy William's famous 28xx, currently Pendon has no suitable substitute loco if the 28xx needs servicing. I had tested the ROD as far as I could on both my test track at home and on the club's Clayton layout but eventually it needed to be tested on the train for which it is being built.  On Tuesday morning I set off to drive the 190 miles to Pendon Museum. Fortunately the weather was kind to me, the sun was shining, the traffic on the M1 was for once moving freely, and I was able to enjoy the four hour drive to Pendon's car park in the beautiful Oxfordshire Village of Long Wittenham. 

 

After a private tour of the museum, including a look around the back of the layouts to see those areas that the public don't normally get to see, Tony Sheffield (the Pendon locomotive CME) invited me into the fiddleyard of the Vale Scene to give the ROD its long awaited test run.  I was first given a demonstration of the 28xx hauling its famous train.  You need good sight to see the back of the train sitting in the fiddle yard.  The train is well over 20 feet long and its back stands under the scenery of Pendon Parva village.  The power was applied and after a slight slip of the driving wheels the 28xx dug in and started its train.  The 3 link couplings remain taught when the train comes to rest in the fiddleyard and so the 28xx doesn't have the luxury of picking up the train one wagon at a time, it starts the whole train at once. 

 

After this amazing performance by a locomotive that is now over 50 years old, Tony removed the 28xx from its train and invited me to place the ROD in its place.  The controller was turned and ------ the ROD polished the track.  Tony gave the train a slight helping hand and after a couple of feet the ROD dug in and away it went.  It then hauled the train all the way around the Vale back to the fiddle yard only slipping momentarily as it went up the short gradient at the entrance to the fiddle yard.  Tony explained that the fiddleyard has another slight gradient at its exit, just where the locomotive stands, and this is why the ROD couldn't get the train started.   He then went to his work bench and returned with some offcuts of lead flashing.  These were incrementally placed on the boiler of the ROD until there was sufficient additional weight to enable the ROD to start the train. 

 

This is how much additional lead is needed to allow the ROD to meet the Brief:

 

  

I now have to find a way of hiding this lead in various crevices of the chassis and/or Guy's loco body.  Once installed I will then return to Pendon to try once more.   So close but no cigar! (yet).

 

 

Many thanks to the Pendon team for their hospitality and for their kind words of encouragement.  Better luck next time, hopefully.

 

Regards,

Frank

Absolutely wonderful Frank - well done!

 

Gerry

[sej]

That's astonishing, and quite beautiful Frank, congratulations. Do you use any side control or springing on the front pony truck? Cheers Simon.

 

[Chuffer Davies]

13 hours ago, sej said:

That's astonishing, and quite beautiful Frank, congratulations. Do you use any side control or springing on the front pony truck? Cheers Simon.

 

Hi Simon,

In the case of the ROD I've used two devices.  The first is my universal solution for pony trucks and comprises a simple coil spring made from fine phosphor bronze wire wrapped around the shank of a drill to form the coil.  Crude but effective.  The top of the spring is soldered to a chassis spacer directly above the body of the pony truck.  I then solder a brass washer to the bottom of the spring to act as a skate that presses down onto the top of the pony truck.  this provides downward force only but does not have any impact on side control.

In the case of the ROD I noticed that the wheels were getting very close to the front drain cocks on the cylinders and might cause a short if they touched.  The loco's chassis is live to the nearside and so the offside pony truck wheel would be where the problem could occur.  For this reason I have also added a side control wire acting on the back of the pony truck below the axle’s centre line to avoid any adverse tipping action when the truck deflects on a curve.  Hopefully the following pictures will better illustrate this:

 

 

 

Frank

 

Edited August 7, 2023 by Chuffer Davies
Missing apostrophe

[sej]

Thanks Frank, love the spring and washer cobo; looking forward to fitting one of those on this!

Cheers

Simon

[Chuffer Davies]

1 hour ago, sej said:

Thanks Frank, love the spring and washer cobo; looking forward to fitting one of those on this!

Cheers

Simon

Now that’s very pretty.  I’m confident the springing will work on this model. I’ve used it on many models without issue.

Frank

[Chuffer Davies]

Having managed to conceal the additional lead flashing in the remaining unused space in Guy William's ROD superstructure I have today revisited Pendon for a second test of the ROD's haulage capacity.  The first task this morning was to clean the wheels because I hadn't had time to do it before setting off from Yorkshire.  We used lighter fuel as the solvent to clean the wheels, but when the loco was first coupled up to the train the wheels slipped even more than they had done previously without the additional ballast.  After a couple of circuits of the layout any remnants of the lighter fuel had been rubbed off and at last the loco had enough grip to successfully start the train.  Unfortunately the model had developed a new fault in the interim and was shorting out at one specific location right in the middle of the scenic section of The Vale. After several attempts to cure it the problem was eventually tracked down to a brake block on the tender.  

 

I should mention that the loco has to be capable of starting the train with all the couplings in tension.  The automated control system at Pendon is unable to set back the train after it comes to a stop in the fiddle yard.  In this video the train sets off at a fair rate of knots.  This is because the computer controlling the train is configured for Guys 28xx which uses an older and larger motor requiring a higher voltage than that needed by the 1320 High Level coreless motor in the ROD.  If and when the ROD is used in front of the viewing public the computer's parameters will be adjusted so that the train runs at a more appropriate speed.      

 

The loco's test has now been signed off and I can turn my attention to Guy's superstructure.  The loco looks rather shabby and we have agreed that it would benefit from a repaint.  This will also allow me to replace the damaged whistles (my fault) and to repair some loose handrails and handrail knobs without being concerned about causing further damage to the existing paintwork.

 

I will also be stripping the chassis down as far as is possible, giving it a thorough clean and degrease before it too gets painted.  The next time it runs on Pendon should be when it is handed back to recommence its revenue earning service.

 

Regards,

Frank  

[Chuffer Davies]

This weekend just gone we had a now rare opportunity to play trains on our Hungerford (EM) exhibition layout which had been invited to appear at Abingdon's 50th Anniversary show.   I say rare because the previous time w exhibited was at Gaydon in 2019.  Hungerford has been on the circuit for 22 years and has been to almost all the shows that might want to invite it.  Most of the time it is packed away in a dark attic flat in the top of the building that hosts the Shipley Model Railway Society.  Despite its age the old girl performed well with only a handful of problems coming to light on the Saturday morning.  Fortunately almost all faults were 'round the back' so did not impact the viewing public's pleasure.

This event at last gave me the opportunity to run the GWR model locomotives I have built since Gaydon, these being the modified Heljan 47xx, the Dapol Mogul for which I designed and built a replacement Motor-In-Tender (MIT) chassis, and the MIT converted Mitchell Mogul acquired from the estate of my late friend Tony Stoker.  The Moguls operated faultlessly.  The 47xx ran almost faultlessly but occasionally exhibited a 'shudder'.   I am not convinced the Heljan R-T-R chassis is man enough to haul a heavy train of metal kit built rolling stock.  It was pretty much on its limits and if I had time I would be very tempted to design and build a new chassis similar to that I built for the Dapol Mogul. 

 

I took the opportunity to shoot some videos of the layout which included shots of the 47xx and Dapol Mogul both of which still require weathering (apologies).  I hope that those unable to attend Abingdon, or have never seen Hungerford in the flesh, will enjoy these very amateurish shots of the layout.  I have also included a photo of the well stocked fiddle yard where the 22 trains that run in the layout are stored .   Enjoy!

 

 

 

 

 

 

 

[1466]

36 minutes ago, Chuffer Davies said:

This weekend just gone we had a now rare opportunity to play trains on our Hungerford (EM) exhibition layout which had been invited to appear at Abingdon's 50th Anniversary show.   I say rare because the previous time w exhibited was at Gaydon in 2019.  Hungerford has been on the circuit for 22 years and has been to almost all the shows that might want to invite it.  Most of the time it is packed away in a dark attic flat in the top of the building that hosts the Shipley Model Railway Society.  Despite its age the old girl performed well with only a handful of problems coming to light on the Saturday morning.  Fortunately almost all faults were 'round the back' so did not impact the viewing public's pleasure.

This event at last gave me the opportunity to run the GWR model locomotives I have built since Gaydon, these being the modified Heljan 47xx, the Dapol Mogul for which I designed and built a replacement Motor-In-Tender (MIT) chassis, and the MIT converted Mitchell Mogul acquired from the estate of my late friend Tony Stoker.  The Moguls operated faultlessly.  The 47xx ran almost faultlessly but occasionally exhibited a 'shudder'.   I am not convinced the Heljan R-T-R chassis is man enough to haul a heavy train of metal kit built rolling stock.  It was pretty much on its limits and if I had time I would be very tempted to design and build a new chassis similar to that I built for the Dapol Mogul. 

 

I took the opportunity to shoot some videos of the layout which included shots of the 47xx and Dapol Mogul both of which still require weathering (apologies).  I hope that those unable to attend Abingdon, or have never seen Hungerford in the flesh, will enjoy these very amateurish shots of the layout.  I have also included a photo of the well stocked fiddle yard where the 22 trains that run in the layout are stored .   Enjoy!

 

 

 

 

 

 

 

Thanks for posting , Frank .

I was “treating” my wife to Abingdon and we left in sufficient time but roadworks delayed us so much , we had to abandon .

So your posts are some solace to our disappointment.

I was particularly interested to see the Mogul and 47xx running . 
BTW Hungerford  was a  big factor in going to Abingdon. 
PS I know how to treat the Sheilas!

[richbrummitt]

Good to see you and Hungerford on Saturday. Always a joy. Loved the videos. Thanks for posting!

[Chuffer Davies]

I am currently servicing three locos that unexpectedly misbehaved at the Abingdon exhibition and couldn't be used over the weekend. One of these is a Malcolm Mitchell 517 class auto tank.

This is a rather unique model having been built by Guy Williams for a Model Railway Journal article.  Shortly after the article was published the model was put on sale and I was fortunate enough to purchase it. Guy built the model in P4 but as our Hungerford layout is built to EM gauge Malcolm sold me the etches so that I could build a second chassis in EM.

On the Abingdon weekend the loco ran perfectly at low speed but when trying to run it at main line speed it ran erratically. 

 

Once I got the chance to investigate the problem properly I initially concluded that the motor was to blame so I swapped it out only to discover that the problem remained.  I was certain that it was an electrical problem because there was a faint smell of ozone when I ran the chassis.  I then tried connecting wires from the controller directly to the chassis and turned the loco upside down to examine it closely.  Low and behold I could see sparks emanating from between the gearbox and one of the horn blocks.

 

I have always had a dislike for wire pickups for current collection.  Most of my tank engines are built with split frame current collection whereby the rims of the wheels are shorted to their axles.  The axles in turn are made with a paxillin bush to isolate one end from the other so that the current can pass from the axle through the horn blocks into the frames. 

The frame spacers are made from double sided printed circuit board with the copper track cut through so that the frames are electrically isolated from each other.  The motor’s leads can then be soldered directly to the frames.  Whilst an amount of extra work is required to machine the axles the end result is a simple and reliable means of current collection. 

 

The position of the paxillin bush in the axle on which the gearbox is mounted is critical because it has to sit in a very small gap between the gearbox and one of the hornblocks.  A fibre washer is inserted over the axle between the gearbox and the hornblock to stop the gearbox from shorting against the hornblock.

 

In the case of the 517 the gearbox is mounted on the middle axle.  This axle requires a small amount of side play to help the loco negotiate curves.  This creates a further complication when obtaining the correct position for the paxillin bush in the split axle.

 It appears that I hadn’t quite got the split in the correct place on the 517 and the end of the axle running through the gearbox was coming into contact with the horn block on the other side of the fibre washer.  I had no option but to remove the axle from the chassis and using my lathe I removed a small amount of metal from the split end of the axle so that it could no longer make contact with the horn block.

The fix appears to have worked and the loco is now running smoothly once more.  Why this problem suddenly manifested itself after many years of trouble free running I have no idea but at least its now resolved and the loco will once more be seen on Hungerford the next time it is exhibited.

[richbrummitt]

Is it possible it previously only ever ran such that the central axle was moved away from the potential short? Equally it could be that the smallest amount of wear caused the situation. Whatever it is/was it is pleasing to hear that it is no longer causing any frustration. 

[Chuffer Davies]

I have now serviced/repaired another of the Hungerford locomotives that had to be retired at the start of the Abingdon Exhibition earlier this month. This time it is model of a City class locomotive that must be well over 40 years old. It was originally built from a Nu-Cast kit in OO gauge by the late Michael Bradley of the Wakefield Model Railway Society. Michael later converted it to EM by simply changing the Romford driving wheel's axles to an EM pair and then pulled out the bogie and tender wheels on their axles to EM. In this guise it first ran on Wakefield's Kingsbridge layout which featured in several 1982 Model Railway Constructor articles.

When this model was first exhibited on our Hungerford layout is 2002 we experienced a problems with the Romford gears stripping. Michael died in 1997 and so it fell to me to deal with the issue. I decided that the best option was to dismantle and fully rebuild the chassis. The modifications introduced at the time were:

• Ultrascale (Beuler) motor and gearbox replacing the XO3 type motor and Romford gears that came with the kit. 
• Compensation: Simple compensation of the leading driven axle and a new functional set of compensated frames for the tender.
• American pickup - All 4 wheels on the offside of the loco and all 3 wheels on the nearside of the tender.
• Ultrascale wheels with modified Markit outside cranks.
• Replacement Coupling Rods - Made from a set of Gibson's Universal Rods.

Rather than use Ultrascales' plastic outside cranks I decided I'd prefer to experiment with a set of Markit's metal cranks.  I drilled out the threaded axle holes in the cranks to 2.5mm.  I then rebated the ends of the Ultrascale extended axles reducing their diameter to 2.5mm to a depth of 1mm matching rge dimensions of the modified cranks.  I know that the 3 jaw chuck on my Unitmat lathe does not run perfectly true and so the axles were held in a home made brass collet inserted in a 4 jaw chuck.  The positioning of its jaws were then adjusted using a Test Dial Indicator resting on the axle's end to ensure that the axle was running dead true before turning.  The cranks are fixed to the axles using Loctite 603 which I can confirm provides a rock tight fixing. 

  

This loco has now run reliably in its rebuilt form for 20+ years but recently the motor has started to fade and at Abingdon it could do no better than crawl when attached to its train of parcel vans. The loco was retired for the duration of the show and I have now had a chance to repair it.

 

Rebuilt chassis with the Ultrascale Motor and Gearbox as installed in 2002:

 

Rather than just replace the motor I took the decision to replace both the motor and gearbox with a superior High Level 1230 coreless motor and RoadRunner gearbox. This necessitated removing the outside cranks from the rear axle in order to release the wheels and axle from the frames which in turn allowed the gearbox to be released. I was amazed how little the coupling rods and frame bearings had warn so repairs could be limited to the replacement power unit.

 

Chassis with replacement High Level 1230 coreless motor and 60:1 RoadRunner gearbox:

 

The model is now reassembled and runs even better than when first rebuilt in 2002. The High Level drive system is silent with the 60:1 gearbox ratio providing excellent low speed control under analogue operation. With 6' 8" driving wheels the top speed is more than adequate for Hungerford's main line running.  Whilst the model is crude when compared to modern etched brass offerings I still think the model is a fair representation of its prototype and worthy of appearing on our Hungerford layout.