Triang TT Technical advice

[Il Grifone]

Hi Garry,

 

Very impressive! The 22xx is my favourite but then I'm biased....

 

I find that 3 point suspension is the cure to all wobbly bogie vehicles. The worst in my experience are Athearn box cars and reefers, but it tames even them. One bogie pivot is made free so that the bogie can tilt in all planes and the other is constrained to only rock 'fore and aft'. I fit two pegs (fine screws or nails usually*) to the bogie cross member in line with the pivot and just inside the wheels. (Athearn bogies ('trucks' if you prefer) have a small depression in just the right place.) and adjust them to bear on the floor. (screws are easier to set up but nails are cheaper.) The vehicle is then as solid as the proverbial rock and clings to all but the very worst track.

 

All my bogie stock, apart from 'collectibles', a few fully sprung vehicles and one or two with equalised sideframes** (CCW/HD style) , has this suspension. It's similar to the equalisation for 4 wheel vehicles using etched axleguards, but I only use this for (some) long wheelbase vehicles with fine flanges.

 

* On holiday in Italy, I found some rounded head nails (abour 2.5mm diameter i would estimate) in the local DIY store. They are a nice force fit in a 1.6mm hole. I'm sure something similar can be found here.

 

** This doesn't work in case of track twists (the start of super elevation for example as there is no lateral play. The two methods can be combined however, resulting in a vehicle that is almost derailment proof. (Generally I feel it's not worth the trouble.

 

I'm tempted to copy your 3F!  

 

David

[Golden Fleece 30]

Hi David,

 

Very impressive! The 22xx is my favourite but then I'm biased.

 

Since posting the video I have obtained (yet to collect in a few weeks time) a TT collection which includes 3 brand new kits 22xx, 57xx and a 94xx (I had hoped for a Standard 5 to do in black alongside my green one).  At least now I can have one of each black and green 22xx's.  The collection was good value as my offer made every item UNDER £6.  That included v/good 3 car DMU, Britannia etc in total 11 locos and 3 kits, nearly all boxed items too although some wagons have been weathered.  He wanted to sell as one lot and no dealer was interested so I made a basic offer which was accepted.

 

I think the brass disc is like your 3 point suspension thank you, solid at one end and movement at the other.  I will see how it goes next time I can get the layout set up to try.

 

Garry

[Il Grifone]

Hi Garry,

 

The problem with the brass disc is that it doesn't allow the bogie to rock, which may or may not matter depending on how level the track is. The suggested cure from across the pond for Athearn wobble is to tighten the bogie screws so as to just allow them to turn. Again fine for dead level track, though RP25 wheels do have quite deep flanges to compensate and the short wheelbase of the typical North American freight stock bogie helps too, but the flexibility of equalisation will cope with almost anything.

 

Possibly suggesting a felony, but coins are a cheap source of washer material or you could use 'penny' washers. Wilko sell bulk packs of 'pick and mix' ironmongery which includes the latter. They are 25mm in diameter which is probably a bit wide for a TT coach (I assume it's ¾ of the 00 dimension between the solebars of 28mm), but a decent file will soon sort that. They are 5 M.A. which should fit around the TT bogie pivot. I use them for weighting rolling stock.

 

David

Edited June 16, 2017 by Il Grifone

[NCB]

What you could do with the disc is solder a bit of brass or nickel silver rod across the disc, so the bogie can rock back and fore but not side to side.

[Golden Fleece 30]

Has anyone got any knowledge of the BEC 4-4-0 2P kit when building it? I have started assembling it and in the process of drawing up an etched chassis, but, there seems to be a clearance issue with the rear wheels. This is a later kit that had the two piece whitemetal chassis and you can see that the crankpin is so close to the footplate that the coupling rods/holding washer when fitted would probably short out. This is with the body lifted 1mm by the way so in reality the footplate sits on the crankpin. Obviously I can lower the axle holes but all this is doing, by giving clearance, lifting the body higher. The wheels here did come with the kit and supplied by 3SMR many moons ago to the previous owner. I cannot take much of the footplate insides without fear of coming through the splashers.

 

I know one possibility would be the next size smaller wheels but if the crank throw is the same then it defeats the object unless I then lift the body from the chassis more, partly this would need doing anyway though.

 

I cannot help wondering if I have done anything wrong but I guess this issue would happen for all these kit 4-4-0's built, so, it may have been a design fault and I am not alone with the problem.

 

I am not looking at later 3mm society wheels which MAY have different throws etc as 1) am not a member and will not be joining, and 2) I think the kit was designed before the 3mm society was born (see below) which rules out number 1.

 

I also have a first issue version which has a slightly different chassis fixing and chassis design but the wheels are just as close in its axleboxes.

 

I know the front driving wheels are too far forward but on my drawing I have moved them back to be closer to the splasher centres. Again this was a design fault as the same centres were used on the earlier chassis.

 

Garry

Edited June 17, 2017 by Golden Fleece 30

[Il Grifone]

Garry,

 

The 2P looks promising (more than my 00 Hornby L1 based one - a 10 foot coupled wheelbase when it should be 9' 6" upsets the whole rear end, not assisted by undersize driving wheels, which make it look even worse).

 

I think the problem is that the crank throw is excessive on the Romford wheels. I not sure what the correct throw is on a 2P, but I have the same problem with my (currently shelved) project to motorise a GBL T9. The crank throw on the prototype is only 9", but the 26mm Romford wheels I have are 4mm which would foul the running plate. I could redrill the cranks but, being ham-handed, I'm afraid of not getting all four the same with dire results for the quartering.    Perhaps I should look for some Hornby wheels, but these have 3mm diameter axles I think, would then cause a problem to the drive gears which have a 1/8" bore.

 

Things are never easy! 

 

David

[Golden Fleece 30]

Hi David,

 

Things are never easy!

 

So very true lol.

 

I did wonder about the crank throw but these wheels are already drilled and tapped, plus, in the old days I never managed to do that breaking either the drill or the tap so even if I got non drilled wheels it might be an issue for me. And, as you say getting the quartering right might be a problem.

 

I think I will leave my chassis drawing as a direct copy size wise, just moving the front axle spacing backwards, because if anyone does have smaller throw wheels it will (should) fit correctly.  With mine I may lift the body for minimum clearance and if necessary remove the buffers and drop their height to match other stock.

 

Garry

ps I did not know Hornby etc were using 3mm axles, that will be the 3rd size they have used from 9/64", then 1/8", all these things are sent to try us as the saying goes.

[Il Grifone]

 

Garry,

 

I'm pretty sure I have some Hornby wheels with 3mm axles, but I might be wrong. (The bits boxes are numerous and need sorting out....)

 

Luckily the 2P has quite a large drop at the front from running plate to buffer centre line, which can serve to disguise the former being too high. Hornby made it too small

I'll have to dig out my drawing of a 2P, but am currently going through a wagon phase - the bits of a K's LOWMAC are reminding me to put them together as I type!

 

Yeah I know - Get off the internet!

 

David 

[NCB]

The 3SMR website has some notes on what sort of wheels are required for particular kits. For the 2P it reckons 6'9" 20 spoke with 22" crank throw.  So in theory would need 20.25mm wheels, say 20mm. However, taking the overlarge flange into account something smaller should be OK. Bit suspicious about the 22" throw, think this is diameter not radius, if so should be 11".  Also says 9'6" wheelbase, ie 28.5mm.

[Golden Fleece 30]

The wheels are 20mm diameter with a crank throw of 4mm so there is a big issue there. 1mm throw would make a great difference but unlikely to find any smaller throw ones, cheap anyway.

 

Thinking about it in reality a smaller wheel is no good if the crank throw is the same as it all relies on the distance between the axle centre and the footplate. This means that unless I use a smaller throw than the Romfords I will have to lift the body. I am guessing when Romfords were originally brought out they only had the one crank throw for any sized wheel. I dont remember in the old says being asked anything other than size, insulated or plain. The amount of spokes was immaterial too, which still is today for me.

 

The coupled wheelbase is only 28mm yet too big for the splashers. I may move the rear wheel a little but not much space available at the drawbar, and then possibly an extra 1mm on the front one to align into the splashers better.

 

Garry

Edited June 18, 2017 by Golden Fleece 30

[Il Grifone]

Garry,

 

Romford (and Hamblings) wheels have always had a surfeit of spokes. For instance the 18mm ones have 16, whereas most classes have 14 (exceptions GWR '2721' -16 and LMS 'Jinty' - 15. Crank throw is 'one size fits all'. My thoughts run along 'designed for H0' (like Dublo), but it is only my opinion. (In the case of Dublo, the records apparently show that 00 was always planned - strange how the N2 chassis is almost exactly H0 dimensions!). AFAIK the wheels sold for TT are exactly the same as the 00 ones. Tri-ang TT standards are very similar to 00 scale standards, so they match well.

 

Back in the day, the general rules 'near enough is good enough' and 'if it looks right it is right' held sway*. The later is responsible for some odd 'Matchbox' vehicles. (The Vauxhall saloon is too wide to my eye.)

 

Looking at the 2P it appears that the splashers are too far apart or too small. Without checking, (always guilty!), I think they should be quite close together and maybe larger. The reversing lever not meeting the firebox would suggest this is the case. The Midland Railway couldn't make it's mind up on driving wheel diameter for their 2Ps, but that's irrelevant as this one is an LMS example.

 

The number of spokes always jars for me. Too many and the wheel looks 'busy'. The 'rule of thumb' was one spoke per foot of wheel diameter (obviously approximately and exceptions and any great deviation  is immediately apparent (or perhaps it's just me!).

 

* Both are of very dubious veracity!

 

David

[Golden Fleece 30]

Hi David,

 

Crank throw is 'one size fits all'

AFAIK the wheels sold for TT are exactly the same as the 00 ones. Tri-ang TT standards are very similar to 00 scale standards, so they match well.

Back in the day, the general rules 'near enough is good enough' and 'if it looks right it is right' held sway*

 

This seems to be true although I have a feeling for a short while Romford made a couple of wheel sizes specifically for TT but cannot verify that.  In the old days the 00 sized ones worked well on the Tri-ang, Wrenn, Gem track of the time.

 

The body and chassis castings do not seem to match up, not helped by me not getting the rear splasher/firebox piece up against the footplate but the casting fitted the top parts locating slots so I just soldered it in.  It did allow the saddle part to fit correctly though.

 

I did find in a 3SMR kit a set of Romford wheels supplied by them I guess for the kit which have a slightly reduced flange depth as the photo shows. Why a set of 6'9" wheels were in the kit I do not know as it needs 5'6"/5'3" ones.  Although deceiving the wheel diameter and throw are exactly the same for the old and new versions seen here.

 

Garry 

ps Just obtained a lovely very heavy whitemetal GEM kit for an A4.  When finished that should pull some weight due to its own, it feels heavier than the Dublo diecast one.

[Il Grifone]

Garry,

 

Surely 6' 9" diameter is correct for a 2P? (They should have 20 spokes but never mind!)

It's strange that they supplied an ummatched pair of wheelsets however. One is the later type of Romford wheels which had lost the strange shaped balance weight* and gained a tapped hole for the crank pin rather than a 'drill it yourself' dimple. (IIRC at the same time.) My impression is that the very early ones also had finer flanges?

 

This picture shows the cranks very well - a relatively large diameter wheel boss with the crankpin close to it. I can use it to try and sort my 00 one.

 

https://www.flickr.com/photos/mikealaska/4609560007

 

The A4 will have rather thick castings I think. White metal kits always sem to err on the heavy side. ABS being the only exception I can think of offhand.

 

David

[Golden Fleece 30]

Hi David,

 

The wheels above were from 2 different kits to show comparison only. The larger flanged ones came with the 2P kit, and were tapped. The finer flanged ones without balance weights came from a BR standard class 3 tank which I queried as again they are the 6'9" but the tank loco should have the 5'3" size so either the wrong ones were supplied or the owner bought the wrong size. These were also tapped. I may use these for an A3 sometime.

 

The A4 is far more heavier than any other whitemetal kit even some 00 ones.

 

Garry

[NCB]

Just measured some OO Romfords dating from  the 1970s. These also have a 4mm crank throw.

 

Romford did make some TT wheels a fair while ago, not sure what. However, the last was much later and specifically commissioned  by the 3mm Society and 3SMR (it's on the 3SMR website) to 3mm Society Intermediate standards; it's 16.5mm 18 spoke. Measuring the wheel on the screen I made the throw 3.75mm, but that's approximate.

 

Looking at your pics, reckon the front driver needs to be slightly further back to match the splasher. If the coupling rod bosses foul the flange under the footplate, reckon the only things you can try are filing the flange, raising the body  and/or filing the bosses on the coupling rods. Or use smaller wheels held lower in the chassis.

[Golden Fleece 30]

Looking at your pics, reckon the front driver needs to be slightly further back to match the splasher. If the coupling rod bosses foul the flange under the footplate, reckon the only things you can try are filing the flange, raising the body  and/or filing the bosses on the coupling rods. Or use smaller wheels held lower in the chassis.

 

These are all things I have looked at.  The chassis I have drawn up already has the front wheels moved forwards.  The coupling rods are not drawn as yet but will be drawn with oil boxes that others could file off if necessary.  On my model I am going to lift the loco slightly until it runs without fouling then lower the buffers down to the required height.  Depending on the amount catching I may be able to make a slight groove under the footplate base to give the clearance.  Until I get the chassis though I will not know.

 

David,

Here are the two A4 sides, look how deep the countersunk holes are for the handrail pins. All I have to do is remove most of the valances to make a BR version lol.

 

Garry

[NCB]

More often than not on my 3mm engines I have to raise the body for one reason or another, and that's with using 3mm Society finescale wheels with fine flanges.  The reason is usually, with etched kits is that the prototype has fairly tight clearances, which scaled down become impossible. Also, I tend to use compensation, which needs a bit of space for the wheel to move up and down.

 

This 517 class has a fixed front axle, with compensation on the rear two:

 

 

However, the front wheel was so tight in the splasher I had to raise the body by about 1mm, and also move the splasher sides outwards.

 

This Dukedog  had compensation on both drivers, and would have been too tight even without:

 

 

I used 16.5mm wheels rather than the correct 17mm. By placing them 0.25mm lower in the chassis that gave me 0.5mm clearance with the body at the correct height; I then raised the body by around 0.75mm further, if I remember right, which gave me a total of 1.25mm extra clearance. That gave me confidence I wouldn't get the wheels shorting on the chassis.

 

Nigel

[Golden Fleece 30]

Thanks Nigel,

 

It is reassuring to know I am not the only one who will need to raise a body to get a working loco. Hopefully I may get the chassis drawings finished tomorrow and sent away for etching.

 

Your locos look excellent even though I am not a WR fan. The 0-4-2 looks to have very tight clearances on the front splasher as if the wheel and splasher are the same size.

 

Garry

Edited June 19, 2017 by Golden Fleece 30

[Il Grifone]

Garry,

 

Tri-ang/Hornby did it all the time! The number of bogies and wagon underframes I've scrapped.....

 

The trouble is that the prototype has limited clearances and is made from relatively thin steel plate, neither of which can be scaled down. This inevitably leads to compromises - the most obvious being the track gauge.

 

The art lies in making the necessary bodges as inconspicuous as possible.

 

David

Edited June 19, 2017 by Il Grifone

[Golden Fleece 30]

The art lies in making the necessary bodges as inconspicuous as possible.

 

I do try to David lol.

 

Garry

Edited June 19, 2017 by Golden Fleece 30

[Il Grifone]

Garry,

 

I've just realised that I was looking at the A4 castings the wrong way round. My eyes were telling me that was the outside of the model. It must have been 1. Too da**ed early in the morning and 2. too  da**ed hot (around 30°C already).

 

It should make up nicely. Any idea as to make? It's not something I recognise.

 

David

Edited June 19, 2017 by Il Grifone

[Golden Fleece 30]

Yes David,

 

It is the GEM one.  What is interesting is the tender rear is in the style of the 4 streamlined ones with the curved backs and covered rear cowling, sorry no depth of field on this photo lol.  This will end up as one of the Silver's but not Fox as I already have that.  Originally GEM must have had a deal with Tri-ang as in those days the chassis without motor I think was supplied.

 

It was 34 degrees here on the way to Tesco.

 

Garry

Edited June 19, 2017 by Golden Fleece 30

[Golden Fleece 30]

With the warm weather last night I was laid in bed not being able to sleep and thinking of railways as you do. I wanted to see if I could make a more realistic Tri-ang 08 shunter and came up with the following. First was to see if I could put a wheel assembly in the lathe and drill a 1/16 hole through the axle to put some 1/16" brass rod in as the extended axle, then drill new axle centres closer together without issues of screws etc. Then drill and tap new keeper plate holes as the axles holes removed the original ones. Make a new keeper plate and coupling rods. All this worked so now I will have to wait until I send off another drawing to be etched so I can include the outside return cranks, better shaped rods and the outside frames. Hopefully the return cranks will be to the wheel crank dimensions which should make quartering easy. This will be a while so I will run it as it is, at least it looks better with the shorter wheelbase. Thankfully the overall buffer to buffer distance is very close to scale length.

 

Garry

[Golden Fleece 30]

Can any one tell me the width of the gear used in the 3smr slimline gearboxes? According to the site the gearbox is 6.8mm when folded and if this is correct then Romford cog wheels will not fit unless machined down. I know they supply the gears but I am looking at dimensions only as I am assuming their's are not Romfords? Looking at the photo on the site I cannot see a boss with grub screw so is the cog wheel a press fit?

 

Garry

[Golden Fleece 30]

This is the first test of the "completed" chassis I have made for the BEC TT loco kit. There is the odd little item to address like soldering the bogie pivot inside the bogie frame as the head catches on the body frames over the bogie, and, like most 4-4-0's getting some weight at the rear end. With the body on it does tend to still dip at times. I may be able to to add some weight into the chassis itself after dis-assembly for painting and maybe put some in the cab side sheets. Hopefully this looks like it will also do the GEM LNWR 4-4-0 to save making a new chassis. The tender also has a separate etched chassis fitted as this loco originally was made to take a K's tender drive. As you can see this chassis goes nicely around Tri-ang TT curves.

 

 

Garry