Notes on Flippems (also relevant to Dinghams)

[John CutlerParticipant]

After struggling for a solid day and a half to assemble a pair of Flippem couplings and install them for testing, I thought I should share my experience.

1.       The attraction of the Flippem over the Dingham is its wider loop allowing coupling on tighter radius curves down to 36” radius. The loop is apparently stronger at 0.4mm thick;

2.       No coupling hook baseplates (drawgear endplates) are included on the Flippem etch (see below): I soon discovered a need for them. Fortunately Wizard can supply these but there is not the variety contained on the Dingham etch.

3.       The Flippem instructions, on video, are pretty dire. I ended up referring to the EMGS Manual 9.1.1(7) supplemented by sources on the web and elsewhere.

4.       Unlike the standard Dingham, there are 4 different hook heights included on the Flippem fret. There is no indication of which one equates to the standard height; you have to work that out. There are 8 standard long hooks and 8 standard short hooks on the fret.

5.        Take care not to remove the small protrusions on the hooks; these have a function.

6.       Do not open up the pivot holes in the hooks or you will regret it. If the wire is a loose fit, it will flop about as you try to solder it.

7.       The Flippem is supplied with 0.4mm brass wire for the pivots; the Dingham specification is for 0.5mm brass wire. Note the smaller diameter wire makes sense in terms of achieving a looser rotation about the pivot.

8.       Assembling the pivot wire at a right angle to the hook is a pain to achieve. A recommendation is to make a jig out of a small wooden block with a 0.4mm slot for the etched hook and another very shallow 0.4mm one at 90 ̊  for the pivot. One wants the minimum of solder applied so as not to interfere with the operation of the pivot; I used solder paint (from London Road Models) as this can be applied strictly where needed. A problem with this operation is that the wooden jig gets scorched and can become unusable quite quickly. I suspect 0.5mm brass wire might be easier to use. Mark Davy, who installed Dinghams on 100+ vehicles on Tetbury (P4) for Brian Lewis, states it takes him several attempts to get this assembly right. A plastic hook incorporating the pivot would avoid this issue and soldering altogether.

9.       Even worse, as far as I am concerned, is the difficulty in fitting the hook or latch to the pivot. I discovered that there is no way these would assemble unless the wire protrusions were less than 1.5mm. I set the lug angles at 45 ̊  and engaged one lug with tweezers. Then madly holding it so it would not drop out, that lug was bent (with difficulty) to the correct 90 ̊. Then the other lug was slowly bent over the opposite pivot wire with tweezers, carefully ensuring it lined up at each stage. I used a vice to hold the tail of the hook in place whilst attempting this (and mostly failing!). This is very fiddly and needs a good magnifying glass to be sure of what is going on. The lugs need to be loose enough to allow free pivoting; but this creates a problem with the latch on the Flippem.

10.   I followed Mark Davy’s advice to bend the tail of the loop 90 ̊ down before bending the pivot lugs upwards. This bend needs to be as close to the pivot lug as possible.

11.   The latch etching is very small. Sure enough, one sprang off wildly whilst attempting to fit the latch to the pivot, into the Carpet Desert never to be seen again. Budget for losses.

12.   The Flippem video instructions promote the use of a gauge to set the height of the hook in relation to the buffer beam. The EMGS Manual states “the centre height of the coupler slot should be 14mm above the railhead.” I am afraid that whilst these are useful guides, the critical measure is that of the bottom of the end of the hook above the railhead (assuming that all the hooks are dimensionally identical). On assembly the hook is prone to droop due to gravity. Mark Davy recommends (July 2023 Scalefour News) a jig set at 12mm above the railhead to support the hook in position but Tetbury uses 12.5mm. The South Hants layouts successfully use a height of 13mm. The hooks of my test RTR wagons ended up at 13mm height by default so I would recommend that. The Flippem hooks have variable heights in relation to the buffer beam so allowing a vehicle with a lower (or higher) buffer beam to be coupled without having to drill a bigger hole for a recentred hook.

13.   Do not follow the EMGS Manual instruction to drill a 2mm diameter hole at the correct height in the buffer beam. This is needlessly oversize and might cause unwanted damage. The tail of the Flippem hook is 1.3mm high. Drilling to that diameter gives a reasonable fit before fixing further at front and back of the buffer beam.

14.   On my test RTR vehicles (ancient Airfix & Dapol wagons), the ends of the short hooks ended up in line with the buffer faces. This accords with the EMGS instructions. Mark Davy sets the hook with the latch 0.25mm back from the buffer faces. This reduces the risk of the loop catching under the latch when uncoupling; but may cause problems on curves.

15.    The Flippem has a design fault. The Dingham has a prominent tab underneath the hook. This is bent up to create an end-stop for the tail of the latch. The tail is bent so as to prevent the latch from rising so far that gravity will not allow it to fall. On the Flippem this is a very short protrusion, so small that one could easily mistake it for flash and file it off. It will bend to 90 ̊ OK and can properly function as a stop. The problem is that in order to do so, the pivot lug must rest very close to the hook body and the same is true of the opposite lug. This inhibits the looseness of the pivot required for the latch to return under gravity; I spent a lot of time adjusting the lug bends to achieve both pivot freedom and the end-stop effect. Otherwise the delayed uncoupling feature will not work.

16.   The default height of the coupling loop is also critical; it is suggested the bottom of the loop should be 14mm above the rails and a jig would be useful for checking and setting this. Fortunately it is easy to gently tweak the height of the coupling loop. Even at the correct height, I found an occasional tendency for the hook to hit the loop and bounce back rather than the loop rising over the hook to couple.

Pros

1.       The Flippem and the Dingham are visually unobtrusive. Most of the couplings are hidden by the buffers at normal viewing angles when vehicles are coupled up. Even uncoupled, they do not jar visually, being small and hooks where one expects to see hooks anyway.

The Flippems are mostly hidden behind the buffers. Compare to the bulky (but drooping!) Winterley coupling on the left. (Note no dropper fitted to the Flippem loop).

2.       My limited testing leads me to believe that coupling and uncoupling reliability is slightly better than for average AJs or their derivatives but not as good as regularly maintained and precision-set AJs as found on the best P4 layouts e.g. St Merryn.

3.       Testing on my awful track suggests they are less prone to unintentional uncoupling than AJs.

4.       No unprototypical “auto-shuffle” is required for uncoupling.

Cons

1.       These couplings are unbelievably fiddly to assemble. A magnifying glass is a must. This makes them time-consuming as well. Making AJs is a doddle by comparison. I could build at least 2 (if not 3) wagons’ worth of Winterley couplings in the same time as for one wagon of these.

2.       Fitting the Flippem/Dingham hooks is pretty much a one-way process. Martin Brent would turn in his grave if I fitted such a hook to the front of his T9’s buffer beam and I cannot bring myself to do it. Other coupling devices can easily be changed by comparison.

3.       Sprung buffers need to be glued up solid or be replaced.

4.       Free-running vehicles need to have brakes applied otherwise the couplings are likely to bounce off each other; I had experience of that in testing. This seems counter-intuitive.

5.       The coupling heights seem to be as critical as for AJs for them to work properly. This suggests maintenance could be an issue, especially for the height of the loops.

6.       Rolling stock cannot be turned end for end. Note that locos can be fitted so as to be turned but at the cost of coupling reliability; refer to the EMGS Manual.

7.       Coupling up may not be possible at curves of less than 36” radius.

8.       The consensus seems to be that reliable uncoupling is only possible on straight or near-straight track.

9.       In some cases, buffer beam details may need to be removed in order for the coupling loop to operate.

10.   Fitting to some RTR locomotives is impossible. I suspect the Dapol B4 and the rear end of the Hornby Adams Radial tank fall into that category.

11.   Flippems are available from pregroupingrailways.com but 4mm scale Dinghams can now only be purchased from the O Gauge Guild or the Scalefour Society by members. That makes them expensive for EM non-members (try buying them at one of their exhibitions?).

Conclusions

If these were available ready-assembled, I would be sorely tempted to fit them for an exhibition layout but probably not for home use; that would mean segregating my rolling stock. They look good and are reasonably reliable. But I am afraid that assembling them in bulk would drive me mad and damage my eyesight.

Anyone looking to convert a quantity of RTR rolling stock should consider whether the appearance of the drawgear endplates (hook bases) matters to them. If so, you may need to purchase the Dinghams coupling etch just for them. Likewise if you want to run on curves below 48” radius, you will need the Flippem loops; the good news is that these are separately available from pregroupingrailways.com as a retrofit.

• This topic was modified 1 year, 4 months ago by John Cutler. Reason: Misnaming

[Author]

Posts