7mm Routemaster [30ft long variety]

[Arun Sharma]

Following on designing in CAD a series of 7mm scale single- and double-decker London buses, I attacked the front end of our 'gate guardian' Routemaster at the London Bus Museum [Brooklands, Surrey] with an Artec Leo 3D scanner.

This was the result. However this is a very early build vehicle and the later 2ft 6in longer vehicles had several detail front end differences which have been reproduced in the 3D CAD file derived from this series of scans.

After about two months of intermittent work, a 'Proof of Concept' aka 'Engineering Prototype' of an entire 30ft RML in 7mm scale has been produced as a CAD file. This has now become hard copy as a series of 3D prints. Some of these prints are rather coarse FDM prints chosen simply because they would likely require modification down the line and FDM prints, whilst dimensionally accurate, are a lot cheaper than high quality/high resolution smooth-surfaced commercial agency Polyjet or SLA prints. Smaller items like the cab and staircase have been printed at home on an Elegoo Mars 2Pro printer and it certainly looks as though the quality of printing bears comparison with expensive commercial agency prints. However, there is a size limit to what can readily be printed on this home printer.

The prints have been assembled and sanded/smoothed where possible and given a uniform coat of a grey primer. Items like accurate wheels have also been produced but only place setter blanks have been used on this prototype model as their sole function is to allow me to check ride height and for that I needed the axle ends to protrude very slightly outside the wheel hub.

 

Anyway, here is the completed model - less seats:

 

This will be on display [on the 7mm Finescale Society stand] at the Guildford 7mm Trade Show in three weeks time. Pro tem, I will get the high resolution prints done and sent off to be cast in resin - The final wheels will be cast in white metal.

In an ideal world, the model will be available as a kit around March next year - price unknown but most likely marketed through Radley Models.

As you can see the FDM process has not been kind to the upper deck front route indicator/destination blind area but this shouldn't be a problem with the high resolution Polyjet parts.

Edited November 3, 2022 by Arun Sharma
addnl info

[Jon Fitness]

Although I'm not a massive fan of RMs, it's 7mm and I'm happy to see it! Could the chassis/underparts possibly be designed with motorising in mind? A robust well engineered steering axle and hubs would be massively helpful. I know a lot of folk seem to be interested in R/C for their 7mm road vehicles but I would be more inclined to the Faller roadway sort of arrangement so that it could operate independently. Another development could be accommodation for interior lighting and illumination of destination blinds.

JF

[Arun Sharma]

Interesting Jon - I've been designing 7mm road [and rail] models for the last 18 years - I don't recall anyone approaching me at a show ever asking about motorising one of my buses or lorries. Certainly something to think about down the line but probably too late in the design sequence for this particular model.

[37114]

Good project Arun. Will be interested to see what you do next as a model, the RM is out of my area but some 1970s buses and coaches would be well received please.

[Arun Sharma]

2 hours ago, 37114 said:

Good project Arun. Will be interested to see what you do next as a model, the RM is out of my area but some 1970s buses and coaches would be well received please.

If I can find a decent set of drawings [or even a prototype in a museum] a Leyland PD3 with the St Helen's front would be a possibility as I have already designed that front end on some LT breakdown tenders viz:

 

The difficult bit was the radiator area. Converting this into a bus half cab would be pretty straightforward.

However, the next model in the list is almost completed and that is the LT 1938 Tube Stock Driving Motor.

 

 

[djparkins]

9 hours ago, Arun Sharma said:

However, the next model in the list is almost completed and that is the LT 1938 Tube Stock Driving Motor.

 

 

 

Hooray!

[Arun Sharma]

3 hours ago, djparkins said:

 

Hooray!

This is the screen shot of the 3D CAD model. All this and more exists in solid form at present. I am currently working on the bogie design but with the aid of the LT Museum, I have all the information I need to complete the design of these although given the requirement for 31-32inch diameter wheels, motorisation might be challenging.

 

Edited November 7, 2022 by Arun Sharma
addnl info

[djparkins]

1 hour ago, Arun Sharma said:

This is the screen shot of the 3D CAD model. All this and more exists in solid form at present. I am currently working on the bogie design but with the aid of the LT Museum, I have all the information I need to complete the design of these although given the requirement for 31-32inch diameter wheels, motorisation might be challenging.

 

 

Arun - will this include intermediate cars?  On a personal level - any luck with the battery loco/wagons we spoke about.

 

David

[Arun Sharma]

2 hours ago, djparkins said:

 

Arun - will this include intermediate cars?  On a personal level - any luck with the battery loco/wagons we spoke about.

 

David

Yes - with the exception of the 18 prototype streamlined DMs which were converted into trailers as these cars retained the three saloon windows at the old cab end. Other than the underframe bits, the trailers and NDMs are essentially the same as the driving cars except that they have a trailing end [less guard's controls] at both ends.

Regarding the 1938 BLs and the 30T flat wagons, I have heard nothing back at all from the resin casters. I will chase them up.

[D6775]

All very interesting, what else is in the back catalogue. Buses suitable for the 80's/90's would be interesting.

[Arun Sharma]

 

On 07/11/2022 at 19:14, D6775 said:

All very interesting, what else is in the back catalogue. Buses suitable for the 80's/90's would be interesting.

80s and 90s buses are complex. Although they tend to have a pretty simple outline, they tend to have flush glazing and windscreens that curve in more than one plane. They are therefore easier to scratchbuild in clear styrene sheet and using vacforming for glazing. Once produced, they don't necessarily lend themselves to being duplicated via silicon moulding as:

a. Transparent resins are difficult to handle sucessfully owing to their propensity to produce bubbles

b. Removal of support pins in transparent resin casting will leave a mark that can be seen through the part [not a problem with opaque resins]

c. Resin casting really requires a wall thickness of 1.5mm as a minimum and that makes scratchbuilding masters more difficult.

 

However, there is a LT Merlin/Swift in the 'back catalogue' somewhere as we have an AEC SMS lurking at Brooklands.

Edited November 17, 2022 by Arun Sharma
clarity

[Jon Fitness]

22 hours ago, Arun Sharma said:

If I can find a decent set of drawings [or even a prototype in a museum] a Leyland PD3 with the St Helen's front would be a possibility as I have already designed that front end on some LT breakdown tenders viz:

 

The difficult bit was the radiator area. Converting this into a bus half cab would be pretty straightforward.

However, the next model in the list is almost completed and that is the LT 1938 Tube Stock Driving Motor.

 

 

There's quite a few vehicles about with St Helens style front ends. Here's a particularly excellent one!

JF

[Lord Flashheart]

Series 3 Bristol VR would be very useful for many layouts.

 

Rob

[pwr]

And a Bristol RE or MW

 

Paul R

[Arun Sharma]

18 hours ago, Jon Fitness said:

There's quite a few vehicles about with St Helens style front ends. Here's a particularly excellent one!

JF

I like that one - I'm guessing that's in the NW Road Transport Museum in St Helens. I think that might be quite a useful kit to design. I will see if there are any plans in the MBF catalogue.

[GRASinBothell]

You seem to have quite a range of kits. Are they listed on a website somewhere?

Gordon

[Arun Sharma]

No, I don't personally have a website.

Most of my kits are small runs and have been sold by Radley Models who do have a website though it can be a pain to negotiate at times. A few kits [mainly trams] are sold directly but they are very limited runs designed to specific orders in the main.

The only notification that usually exists of a new kit coming out is via RMWeb [in the appropriate section], Western Thunder and the 7mm Finescale Society forum. The only hard copy print notifications would be in the journals of the Model Bus Federation or Tram and Light Railway Society.

[Jon Fitness]

6 hours ago, Arun Sharma said:

I like that one - I'm guessing that's in the NW Road Transport Museum in St Helens. I think that might be quite a useful kit to design. I will see if there are any plans in the MBF catalogue.

I think Its an East Lancashire coachbuilders body on a Leyland PD3 chassis.

 

Correction, Its a PD2 so Itll be 27ft 6" not 30 ft.

 

Edited November 8, 2022 by Jon Fitness
Wrong Chassis!

[Hal Nail]

On 07/11/2022 at 20:34, Arun Sharma said:

they tend to have flush glazing and windscreens that curve in more than one plane. They are therefore easier to scratchbuild in clear styrene sheet and using vacforming for glazing. Once produced, they don't necessarily lend themselves to being duplicated via silicon

 

On 07/11/2022 at 21:54, Lord Flashheart said:

Series 3 Bristol VR would be very useful for many layouts.

Sadly this rules out most of the stuff that comes up every time, such as the Bristol, an ergonomic cab for lorries etc.