30 April 2020
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Tired of unrealistic gaps between your coaches? We demonstrate how Keen Systems' coupling solution can be installed on Hornby and Bachmann Mk. 1 coaches.
Buckeye couplings were introduced as a safety feature because they help coaches stay upright in the event of an accident, prevent telescoping and attend to other passenger safety issues. Another major advantage is that they allow carriages to be close-coupled, thereby facilitating the movement of passengers from one vehicle to another via end corridor connections. Probably the most obvious issue when viewing a rake of ‘off-the-shelf’ corridor-fitted model carriages is that the stock is too far apart. Look at the gap the small passengers would have to jump between connections! The reason for this issue is that, unless the carriages are placed far enough apart, the buffers lock on curves and cause derailment.
However, this isn’t an insurmountable problem thanks to a clever upgrade made by Keen Systems that allows carriages to be close-coupled in a realistic fashion and still go around the sharpest of set-track curves. Granted, the carriages separate on tight curves, but then again, if your curves cause this to happen it is your curves that are unrealistic. This system is a great example of compromise and since many of us are stuck with tight curves due to space considerations, it is wholly acceptable.
The system is available for a number of different carriages and will, no doubt, fit virtually everything ever made with some adjustment. For this article we have chosen modern rolling stock; a Hornby Mk. 1 and a Bachmann Mk. 1.
Establishing the ride height
1
Make a simple gauge to check the ride height of your stock. Simply cut a 14mm wide piece of plastic card or cardboard using a rule, knife and digital callipers.
2
Place the carriage on some track, then place the gauge on top of the rails. If the ride height is correct, the gauge should reach halfway up the buffer heads. Make a note of by how much the carriage is higher or lower than it should be.
3
If the carriage rides too high, file material off the bogie pivot. If too low, add plastic card washers. We used 10mm and 6mm hollow punches to make this spacer.
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Hornby MK. 1 Coach
Disassembly
1
It is easier if you remove the existing couplings first. Use a small flat-bladed screwdriver to lever these out of their NEM pockets at the end of both bogies.
2
Underneath the carriage, at either end, you will find a clear plastic lug in each corner. Use a small flat-bladed screwdriver to push this inward while applying light pressure on the black underframe.
3
The corner will separate from the body. Do this for all four corners of the vehicle.
4
Now the body is held solely in place by two lugs that project out from the centre of the body on each side. Run your thumbnail along the carriage side and the lugs should snap out. You need long nails for this, but if yours are short then you can use a smooth-edge table knife if you are gentle.
5
Once the lugs are free on each side, the body should lift off. If it is still held in place by stray glue, keep gently tugging at the underframe until you hear a crack as the glue breaks.
6
Lift the coach interior out and place to one side. Note carefully the orientation of this compared to the body. You will need to align this correctly during reassembly so be sure that you are aware of this now. This is also a good time to paint the seats and add passengers.
7
Using a pair of pliers, squeeze the prongs so that the bogie drops out. You can also use a smooth-edge table knife – get this as close to the pivot as you can by sliding underneath the bogie, then use a twisting action.
Fitting the end plates
1
Glue a piece of plastic sheet 0.25mm thick onto the bottom of a fixing plate so that it can be used as a drilling template.
2
Place the drilling template inside the corridor connection and mark the position of the hole in the plate on the end of the carriage.
3
Now drill a 2mm hole through the end of the carriage in the place you marked. Ease the hole by altering the angle of the drill.
4
Turn the carriage over and clean up the hole you drilled from the inside with a file.
5
Temporarily fit the end plate into position and ensure that it slides up and down without any binding.
6
If the hole is in the wrong place, plug it with some 2mm rod and try again. An alternative would be to widen the hole and then to glue a fixing plate on the inside of the carriage.
7
Cut out a fork-shaped spacing tool from 1mm plastic card. The prongs should be spaced so that the tool can be placed over the end plate.
8
Put a spring on the spigot and push the end plate through the hole you drilled. Hold it in position for the next step.
9
Now slide the spacing tool into place between the end plate and the carriage end. Hold the end plate in position.
10
While holding the end plate in place, push a washer fully home. The washer is a tight fit but it will slide down the spigot if you apply even pressure with the aid of some pliers or tweezers. Remove the spacing tool and check that the gap around the end plate is consistent. Push the end plate in and ensure that it moves freely in and out and that the gap remains consistent after this operation. You can alter the position of the washer on the spigot slightly to get the fit perfect.
11
When happy, add a blob of Liquid Poly cement onto the washer to glue it to the spigot.
Fitting the new draw-gear
1
Cut the baseplate and delta plates from the sprue; however, ensure that you leave some of the sprue attachment point in place at the rear of the delta plate.
2
Tidy up any flash and remains of sprue fixing points (except at the rear of the delta plate). Concentrate on the flat face of the delta plate and the finger that protrudes underneath the coupling pocket.
3
In this instance, the baseplate doesn't fit between the solebars. You will need to remove about 0.5mm from each side of the baseplate using a file. To do this, file a few strokes on each side at a time and check regularly to avoid taking off too much material.
4
Temporarily place the body into position using just the central clips. Measure 12mm from the end of the end plate and mark the position on the floor with a scribing tool. Hold the baseplate at the mark and scribe around the rear of the baseplate.
5
Holding the baseplate in the place marked, turn the chassis over and scribe the body securing points on the underframe. Remove the material with a file. Hold in place again to check the fit.
6
Drill a series of holes around the marked area ensuring that you stay within the marks scribed. Now use a knife to cut between the holes. Finally file the edges smooth until the baseplate drops into place.
7
The baseplate needs to sit flush with the floor of the frame. We found that I needed to file away the two steps at the front of the baseplate in order to achieve this. You can also remove the two forward-facing tabs if you need to, although it wasn’t necessary in this instance.
8
Open up the gap under the finger of the delta plate with a fine parallel file. You only need to remove a very small amount of material.
9
Fit the delta plate to the baseplate. We found I needed to raise the front guide up slightly with a finger nail to achieve this.
10
You need the delta plate to slide easily from side to side without it catching in the centre position. At the same time, there does not want to be any fore or aft movement when the delta plate is in the central position. You can achieve this by filing very small amounts off the rear sprue attachment point on the delta plate and checking the fit each time.
11
Glue the baseplate into position with Liquid Poly Cement, ensuring that the rear of the baseplate is flush with the frame.
12
Make a final check of the assembly. You should be able to move the delta plate from side to side over the full extent of its travel with a gentle flick of the finger. If it doesn’t move freely then you need to rectify tight spots.
13
You need to remove material from the bogies to allow room for the close coupling mechanism. Remove the wheels first by pulling out the bogie sides one at a time.
14
Remove the frame material with side cutters and clean up with a file. Ensure that you do this at the correct end of the bogie – it is the coupling pocket end that has to be removed. Refit the wheels.
Bachmann MK. 1 coach
Disassembly
1
Undo the screw that holds each bogie in place. Use a receptacle to hold small parts as you remove them.
2
Lift out the close-coupling drawbar and disconnect the spring attached to the rear. Leave the spring attached to the chassis so that it doesn’t get lost.
3
Use a blunt instrument or pliers to lever the water pipes away from either end of the carriage.
4
Undo the three screws in the underside of the frame. There is one in the middle and one at either end.
5
Use your thumbnails to lever each corner of the carriage and then you will be able to separate the chassis. On this coach the ends were glued and this wasn’t an easy task. You may need to run a knife blade along the end in order to get a finger hold. The floor will then drop away.
Fitting the end plates
1
Inspect the corridor connection and remove flash with a fine file. Ours didn’t require any work at all.
2
Paint the new corridor connections with black paint. Spray is better, although brush will suffice. Don’t paint the surface that will mate with the carriage end. For ease of handling, mount the component on a piece of card using double-sided tape or spray mount.
3
If you wish to swap corridor connections, prise away the old ones and stick the new ones in place using cyanoacrylate.
4
Inspect the corridor connection and remove any flash with a fine file. Mine didn’t require any work at all.
Fitting the new drawbar
1
Place the new drawbar into position and reattach the spring. Check that the operation is smooth and that it doesn’t bind in any position. Ensure that the drawbar is flat to the chassis while you do this.
2
If there is any binding, then file a very small amount of material from the drawbar and try again. Keep doing this until you achieve success.
3
Remove the wheel sets by levering the frame sides until the axle end is clear.
4
Remove the rear of the bogie by drilling a series of holes, then cutting between them. Clean up with a file and refit the wheel sets.
5
Add two strips of 1mm thick 17mm x 1.5mm plastic sheet on the bogie tops, shown here in white. This prevents the drawbars from becoming misaligned at the full extent of their travel.
6
Put the bogies back in place and refit the retaining screws. Pivot the bogies and ensure that the full range of travel can be achieved without binding. Resolve any issues before proceeding.
7
Ensure that all the carriage glass is in place and correctly seated. Wipe away finger marks or stray dust/particles. Proceed to reassemble the carriage going through the disassembly instructions in reverse.
Completion with couplings
1
For trouble-free operation, the manufacturer recommends the use of the flat plate couplings. Check that they mate together easily by easing the holes. To do this, use a 2mm drill and alter the angle of the drill to slightly widen the holes.
2
Ensure that the floor of the coupling pocket is flat and free of any moulding marks by using a file.
3
Glue a male and a female end coupling to each carriage using Liquid Poly Cement or cyanoacrylate ensuring that they are horizontal. You may wish to fit alternative couplings at the end of each carriage rake to match your motive power. Alternatively, why not fit the close coupling system to the tenders of your locomotives?
4
If you wish to fit the buckeyes then they have to be fettled to overcome the constraints of the moulding process. File the couplings slightly so that the sides are parallel and so that they can be separated and joined easily when coupling the carriages together. However, there must not be any pivoting about the buckeye knuckles and you must keep any play to a minimum.
Need more advice? Some of the below articles may help. Also, take a look at the BRM Techniques page for all our latest guides and advice articles.
How to make your model trains grubby
Take a read of our step-by-step guide to weathering a locomotive using paint washes and powders here. Or if you’d like more general tips on weathering a locomotive, see our article here.
