Vehicle Chocks for 4mm scale Carflat, Lowfit, Tierwag and Cartic 2

7 Oxford E-Type Jaguar, Mini Saloon & Van

E-Type Jaguar

Recessed chock required, greater diameter and width tyres than the Jaguar Mk2.




Mini Saloon & Van

The saloon has a good shoulder, but the van has a very poorly moulded cone unsuitable for mounting a chock so, in this case clipping to the axle was necessary, makes for rather wider chocks than I would like but functionality has priority, normal viewing angle does not show the chocks being rather wide.

CAD for the van








Result




Remaining Oxford Models

The remaining models all had good shoulders to design the clips for.

Morris Minor Van, Ford Anglia Van, Viva Mk2, VW Beetle all share the same chocks.

Volvo P1800 and Amazon share the same chocks.

Renault Dauphine, VW T1 Van, Land Rover all have differing tyre and shoulder parameters compared to any other models so have unique chocks.


Next, Minix - Common Wheel Various Wagons

Jim

 

8 Minix - Common Wheel Various Wagons

These models originated as an accessory to Tri-ang trains as discrete scenic items. The cars were also used as loads for their Tierwag and early Cartic 2 car transporters, the vans three to a bogie flat wagon, some even teetering toy style on a short bolster wagon. Eventually sales of the individual vehicles ceased and then only the cars and vans were available in the UK as loads on those wagons.

The early versions with the chrome wheels even became collectors’ items in their own right which was a real pain when I was trying to buy the wagons with cars in the mid noughties on eBay. The wagons were stripped and sold off empty, eventually the common cars re-entered the marketplace in job lots which allowed me to re-populate the empty wagons I had bought earlier.

Later versions of these vehicles with the black plastic wheels had a much cruder body moulding, very poor in fact, cheap and nasty, but, back to the business of wheel chocks.

I will now address the needs of 'chocking' Minix chrome wheeled cars and vans; this required a variety of designs for different wagons to meet the design requirements.

Minix - Lowfit & Carflat

Simple chocks as in the video are suitable for the Tri-ang Hornby and Oxford Carflats and Mainline/Bachmann Lowfit as there are no restrictions presented by all three of them.

The chrome plated wheel models are what I work with here, the few black wheel models I have reside on the lower deck of Tierwags with a different arrangement to the top deck which is covered in part 11.

The chromed wheels have a convex coned rear face to which it is not possible to clip onto. I believe that all the Minix cars, van, bus and trailer/caravan had the same wheels, the coach or bus appearing to be somewhat smaller than 1:76 scale.

However, making life a little easier the wheels are a straight push fit on to plain axles with quite a consistent B2B between them which allowed a semi-clip fit arrangement.

Chocks fitted on both wheels of an axle allows them to be retained by acting as wedges between the chassis plate and the wheels.

The conical face of the chock clip acts against the convex rear face of the wheel to lock them in position.

The only downside is that if one falls out, they both do, however this has not become an issue due to the consistency of the build of these cars, only a very few have needed dismantling and the B2B opened out, any reduction can be performed in situ.

So, the clip became the shape shown below, the coned part being only a few layers thick but has proven to be sound even though a few may have slightly incomplete first layers.

I have added an extra version of this CAD model, one with a 0.2mm thicker clip which prints 0.1mm thicker to use on some Minix models with slightly larger B2B than the norm, they can be used either paired with a standard thickness clip or two thicker ones together.

CAD Design

The following images show the CAD models, from wheel, matching clip and an assembly.











Result

As printed.




Fitted to a car and a van.




Two vans on Lowfits.




Now it's time to move on to the specialised double deck transporters which provided many hours of fun, they were rather more difficult to create clip on chock designs that were effective and discrete.

Next - Minix Tierwag - Upper Deck.

Jim

 

9 Minix - Tierwag - Upper Deck

This all got fairly involved requiring a different design for both decks, it was made easier by dismantling a Tierwag to remove the central lifting deck section. This is easily removed by lifting it half way such a finger may be placed under a static upper deck part between the lifting section and the loading ramp and gently easing the static part up to unclip it from the main body of the wagon.

Once this part is removed the lifting deck part may be easily unhooked from the static upper deck at the other end.

Then it was much easier to measure up and test printed parts for both decks which are very different in profile. As an aside it allowed me to replace a missing end ramp on this wagon with a printed one, (Ref 9.1)

Design

It was not possible use the discrete clip-on chocks on a Tierwag due to a lack of clearance between the differing raised central guides on both decks and the backs of the wheels so two different parts were required which clipped to the car underside using a central hole present on all but a few of my Minix cars to which the 4 sets of chocks were linked by a frame. It will become clearer shortly.

Stage 1

The initial development was as below, where a set of 4 chocks are linked together with a central frame that sits in the channel between the longitudinal deck wheel guides.

CAD





This general arrangement allows the central frame to grip the upper deck guide rails but not the vehicle, the next stage was to address this design requirement.

Stage 2

This stage makes the wheel chock set specific to a particular vehicle wheelbase by linking two stage one parts by a longitudinal frame with a central barbed spigot. All but a handful of Minix cars had a central hole in the chassis in which this barb could anchor the frame, thereby fulfilling the other design aim, the chocks stay attached to the vehicles.

CAD



Result

As printed.




How it clips to the top deck.




Clipped to the underside of a car by the barbed post.




Cars clipped to the upper deck.




Summary

Of the eleven different Minix cars I currently have, nine different wheelbase variants were required for Tierwag top deck use.

The longitudinal frame becomes hidden in the channel between the guides so an excess of bright yellow is not easily visible.

However, the equivalent for the lower deck was much more difficult to design.

Next - Minix Tierwag - Lower Deck

Jim


References

9.1 3D print of a Tierwag End Ramp

https://platform1mrc.com/p1mrc/inde...an-oap-vs-3d-printers.6395/page-2#post-115527

 

10 Minix - Tierwag - Lower Deck

The problem here was that the central guide between the wheel backs on the lower deck is solid so that the chock frame can only grip the sides of it.

This created other issues.

The frame needs to bridge the raised central portion and fit between it and the underside of the car avoiding detail such as the gearbox on all cars except the transverse engined Morris 1100, Austin 1800 and the rear engined Hillman Imp.

Up to this point I could avoid the use of printing supports, only modest bridges were required across the rails, supports for filament printing can be problematic as by default they do not actually support the print but catch drooping layers.

I went into a lot of detail on this problem in my Conflat P project, eventually it proved too difficult with my Raise3D E2 printer.

Filament printing supports rely on a minimal contact between the support and the model by leaving a single layer gap.

Problem, when a corner is navigated by the first layer of a model above the default 'support' it prints in the air so, the extruded plastic takes a short cut. When printing larger models with a 0.4mm nozzle this becomes insignificant but, when printing a model that is 2 or 3 layers thick with a 0.2mm nozzle it is significant and leads to a malformed unusable part.

So, an alternative method was developed whereby delicate parts could be supported properly, this is detailed in my 3D Printing thread (Ref 10.1) which shows the initial style of the chocks shown here.

With this issue solved the following design was adopted and modified to suit the various car wheelbase lengths.

Chocks could only be placed between axles as there is insufficient clearance for any frame to pass behind the wheels as for the top deck, they are barely visible in the shadows of the lower deck but at least they stop cars rolling fore and aft, which is a design aim.

CAD

Initial style

Grip marginal due to the lack of chocks compared with the upper deck designs.




Revised style

Added the longitudinal side bars and their inboard bulges which spring them outwards slightly, creates greater grip on the solid centre longitudinal guides of the lower deck.



Result

As the chock frames are more visible than the top deck versions, they are printed in grey which is less visible in the shadows of the lower deck.

Morris 1100 version: Left - underside with printing supports removed (ref 10.1) and right - topside with printing supports still in place.




Checked for fit on a Tierwag lower deck.




In use these chocks are clipped to the car by the central barb engaging in a hole already present in 95% of my Minix cars, their original purpose is unknown but where present it is midway between axle centres in all cases.

The car is then slid into position on the lower deck.

Next - Minix on a Cartic 2

Jim

References

10.1 32 - Supports for Delicate Parts when Printing with a 0.2mm Nozzle

https://platform1mrc.com/p1mrc/inde...an-oap-vs-3d-printers.6395/page-2#post-115575

 

11 Minix - Cartic 2

These are cut down versions of the Cartic 4.

Minix - Cartic 2 - early Version - Tri-ang

Those I have are marked on the underside as "Made in England" without chocks moulded in place. Two of these sets are in blue, one in Silcox Express orange, one of the blue sets has damaged surfaces where cars were previously glued in place.

Minix - Cartic 2 - later Version - Hornby

These are marked on the underside as "Made in China Hornby" with chocks moulded in place, these appear to be for the crude black wheeled Minix, the later crude cars including I believe a Ford Sierra. Later still, versions came with only 8 Skaledale cars, the quantity of cars diminishing over the years probably to keep down costs.

The 3 sets of moulded chocks on each deck will not accept my chrome wheeled Minix cars, their wheel B2B is just too narrow and besides from photographs of Cartic 4 wagons particularly on Paul Bartlett's site (ref 11.2) show they could be loaded with at least 7 cars, e.g. 4x Ford Anglia on the lower deck and 3 larger cars on the top deck on a Ford factory train.

Whether from a manufacturer like Ford or on a Motorail service for carrying private cars they were packed on almost bumper to bumper on the lower deck, maybe 3 on each deck, not just 4 to a Cartic unit.

Chocks

What I have found in YouTube videos (e.g. Ref 11.1) and Paul Bartlett photographs is that the chocks were generally yellow when new but became grey and rusty as time passed.

As an example, here is a snippet from a Paul Bartlett (C) Cartic 4 photograph (Ref 11.2) which shows some littering the ground and a few in position on the lower deck: -




Once again, the upper and lower decks require different chock designs, and of course, the centre guides on the decks are of slightly different dimensions to a Tierwag, however the core design of the upper deck parts are the same as for the Tierwag upper deck.

The lower deck parts for the Cartic are very similar to the upper deck, visibility of them is greater on the Cartic although the deck skirts do limit how much of the chock frame is visible from the side. So, they are all printed in yellow PLA.

To keep the quantity of designs manageable, some hope, I have decided that long vehicles especially if they have tow hooks will be top deck only, with a maximum of three cars.

Most other vehicles can have chocks suitable for both decks, i.e. a set for each deck, however I have ample long cars for all the top decks which can accept Minix cars so I don't really need many upper deck chocks for the small cars.

Here are examples: -

CAD

Upper Deck - Ford Anglia & Vauxhall Viva (same wheelbase) - almost identical to that for the Tierwag upper deck.




Lower Deck - Ford Anglia & Vauxhall Viva (same wheelbase) - hybrid of the design for the Tierwag designs, somewhat more complicated than those for the Tierwag. These would also be printed with my support technique described earlier.




Upper Deck - Ford Corsair a longer version of the that for the Anglia/Viva, the common central hole for the central barb has proved to be invaluable. Keeping these deck frames flexible enough for the vary levels of the decks was tricky as front and rear chocks could be on different angles of the deck.




Results

Loaded Cartic 2 - typical unit formation 3 longer vehicles on upper deck, 4 shorter vehicles on the lower deck.




Summary

So, more challenging than the Tierwag designs particularly as the decks are not flat, fitting e.g. a long car on the top deck was more a case of clipping the chocks to the deck and then clipping the car to the chock frame.

Next - Project Summary

Jim

References

11.1 Motorail Letting the train take the strain

Relevant time of interest at 7 minutes 10 seconds, and 25 seconds



11.2 Cartic 4

https://paulbartlett.zenfolio.com/brcartic4

 

Thanks Phil.

Just corrected the reference numbers within the text of this post (11), the ol' brain ain't what it used to be , who am I kidding

Jim

 

12 Project Summary

I can call this a successful project as the design aims were met without too much loss of hair or sleepless nights.

This was another exercise in pushing the limits of what can be done with a filament-based printing system.

There were a few trials of patience designing parts which fit more than just one example of a particular model due to the varying quality and fitment of wheels on many of them.

There have been a few early failures where the arms were not strong enough allowing plastic deformation of the PLA to weaken their grip after a week but that can be addressed further, if need be, may just be a print batch issue, some are only are only a few layers thick in places.

A quantity of spares has been printed of each so hopefully that will avoid the need of printing more in the case of loss or damage in the next 10 years.

It became obvious mid-way through that key dimensions (e.g. wheel dimensions, wheelbase and barb heights) had to be recorded on a spreadsheet so that I could easily check to see whether an existing design would fit another model or not.

I have yet to decide what to do with the China made Cartic 2 wagons with their massive moulded on the deck chocks which will not accept chrome wheeled Minix cars and severely limit the quantity of contemporary models that can be loaded using them.

Storage

With some 19 variants of the individual chocks where many look the same with only subtle dimensional differences file naming and storage of the spares had to be taken seriously, storage of spares was proposed using a set of small locking or screw capped containers that are well labeled.

Plus, the chocks with joining frames, further 24+ for the Tierwag and 14+ for the Cartic needed further labelled containers, in the end 45 containers were required, as luck would have it the perfect container was found on Amazon, 45 lidded boxes with catches contained in one larger box with latches.

Operation

In practice empty and loaded sets of Tierwag and Cartic 2 wagons will just be swapped over in fiddle yards rather than actually emptied and loaded, similarly at the Minix Motor Works.

Export/import vehicles from/to other destinations on the un-modelled national network and Euroferry port can easily be swapped in the fiddle yards which represent them as they will be carried on Carflats and Lowfits. Typically, these vehicles will be contemporary models by Corgi, Oxford and EFE fitted with individual clip-on chocks which grip the wagon deck by friction and the dimples on their extremities engaging with the deck planking grooves.

Vans from the Minix Works will also travel by Lowfits or Carflats.

Carflats with cars making up Motorail and unbranded travel by train services will vary between having Minix cars or contemporary cars but the two eras of models will not be mixed. Tri-ang Hornby 'Carflats' will only carry Minix & EKO cars.

How long will these chocks last in use, hopefully at least 10 years!

Jim

Summary in Images

Minix vans on Mainline/Bachmann Lowfits




EKO and Minix cars on a Tri-ang Hornby Carflat




Minix cars on a Tierwag




Minix cars on a Cartic 2




Oxford & Hornby Vans and Corgi Mini saloons on Bachmann Carflats






Postscript:

Loading a Cartic

Did you wonder how the cars were loaded on to the top deck of a Cartic, well once again converted coach chassis e.g. Mk1 coach and car body carrying wagons such as a Bocar, both had metal frames added with ramps. The Mk1 conversion is easy to view in the PB photographs below, lower deck was side entry and exit, the Bocar conversion looks partially wrecked, difficult to make out it's structure properly.

Paul Bartlett photographs: -

https://paulbartlett.zenfolio.com/brmotorail

RCTS Photographs :-

https://features.rcts.org.uk/carria...artic-ramp-mystery/mystery-dover-cartic-ramp/

Straps and chocks in later times

Also, amongst those PB photographs it is shown that Carflats were also coupled to Cartics for conveying vans e.g. Ford Transit vans. Also, sometimes straps were used as well the chocks in later years even for smaller vehicles, chocks missing by then?

Heavier vehicles such as lorry chassis, were strapped to the guard rails at the sides of the Carflat wagons.

The quantity of chocks per vehicle also varied from two per wheel to just both ends of a car, presumably on both sides.

 

P.P.S Further photograph link to the RCTS site added.

Oh dear, why do I get the urge to create a ramp for my motor works, there are so many variants on a variety of ex-coach and Carflat chassis, and many a Carflat was an ex-coach chassis too, I think the white one on a BR Mk1 chassis (PB photo) has the most detail to make at least a plausible, semi-fictional and representative example

Jim