Lowdown on EM - how much is it just a case of easing out RTR wheels?

[Lacathedrale]

I've had alot of fun building my first P4 turnout, but I'm worried about the overhead of wheel (and sometimes chassis?) replacement on every otherwise perfectly fine RTR model to facilitate it in a layout context. Current and forthcoming RTR represents about half of the stock I wish to run on the layout - the Hattons Genesis and Hornby generic pre-group coaches and the two Bachmann LNWR locomotives: the coal tank and the forthcoming improved precedent.

 

I have heard that modern 00 wheels can often be eased out to a 16.5mm B2B, though It looks to me like the average DOGA Intermediate/RP25-110 wheel is 0.4mm wider than an EM wheel, 0.25mm of which is in the thickness of the flange. Given the 1mm EMGS flangeway, I don't suppose this would be a problem - but I have no meaningful experience.

 

Basically, if I have to re-wheel everything for EM or P4, I may as well go with P4 and at least have the satisfaction of really nice looking track, or 00 for the expedition of getting it done. However, if rolling stock and particularly those locomotives can just have their wheels eased out instead - that puts EM in a separate consideration. Any thoughts?

[ikcdab]

Having read extensively on here, I believe that wagons and coaches can just have the wheelsets modified as you suggest or new EM wheelsets dropped in.

Locomotives can be more problematic because of the space available behind cylinders etc. Obviously, inside frame locos would need new axles.

Not sure if that's any help, it's looks as if wagons and coaches are straightforward, locos more difficult.

 

[Lacathedrale]

Ah thank you - presumably because bogies and wagon frames are scale width, with correct length pinpoint axles - whereas locomotives have narrower chassis and corresponding axles.

 

Is simply a case of replacing the axles with longer ones, or does one need to also replace the wheels? Again, specifically talking about inside frame, inside cylinder/valve Bachmann locomotives.

[PMP]

There’s no one size fits all answer unfortunately. Each one will have variables such as the width between the rear faces of the splashers for example, this may preclude widening the wheelsets with sufficient clearance.  I’ve known some models that have been regauged using their existing wheels but those have primarily been D&E prototypes. Quite a few coaches and wagons can have replacement wheels fitted, again it depends how easily on the design of the chassis. Some are designed for OO and the axle guards are too close to allow replacement wheels of wider gauges to fit. Some of the more recent smaller manufacturers are accommodating the wider gauges by including different brake mounting positions, but they are few in number and again primarily for D&E era types. 
The short answer is decide which gauge you’re going to model in, and then adapt any RTR if necessary, to fit your chosen gauge. Some may be an easy fix, others impractical or a PITA. You can reasonably assume that the larger RTR manufacturers won’t be designing gauge widening into their releases as a matter of course, it’s not worth their while, and steam prototypes are the most difficult to accommodate.

[Lacathedrale]

Thank you PMP - I guess I really was speaking about the hattons/Hornby pre-group coaches and the Bachmann coal tank/precedent rather than as a generic question.

 

Honestly I'm seriously considering modelling 'authentic' late 19th century practise of ballasting over the sleepers and just doing it in bloody 00 at this rate

[DCB]

I have bought a fair bit of EM stock because its cheap and rewheeled it or regauged it to OO. Some was 3 rail EM gauge.  Quite a lot of OO was / is derived from HO  Hornby Dublo, Lima etc and can't be regauged, quite a lot of OO is seriously over width, Triang, pre 2000 Hornby much of which is 40mm over cylinders and valve gear.   You can get a huge improvement in OO appearance by narrowing the track spacing to 43/44mm  which works in EM as you can't  get the locos round sharp curves.  The real advantage of EM/P4 is decent size motors fit down between the wheels in locos,  converting steam RTR or OO kits to EM/P4 is a huge hassle with either superb workmanship or worse appearance, fabricating N/S or brass splashers mainly.   To me I would stick with OO with EM radii unldess you are scratchbuilding pre 1900 stock you will need for a LNWR layout.  If you are scratchbuilding, that extra space between loco chassis sides makes life a lot easier

[mike morley]

Would agree entirely with PMP and would add that while some - repeat some - locos can be regauged by simply spreading the wheels there is a definite knack to it that not everybody has.  I don't have it: a friend of mine does. 

He has also discovered that even if there is enough clearance within splashers, behind brake shoes etc to widen the gauge to 18.2mm it does not necessarily mean it will run on EM track.  For instance, the Hornby Black Motor might have the space where it's needed but it doesnt have the wheel profile and dislikes the checkrails on EM pointwork.

[martin_wynne]

29 minutes ago, mike morley said:

For instance, the Hornby Black Motor might have the space where it's needed but it doesn't have the wheel profile and dislikes the checkrails on EM pointwork.

 

Hi Mike,

 

If regauging 00 RTR wheels for EM, the correct back-to-back should be 16.4mm max.

 

If you widen them to 16.5mm they will likely bump on the crossings.

 

The minimum for all wheels on EM is 16.3mm min.

 

For more info, see:

 

 https://85a.uk/00-sf/setting_00_wheels.php

 

And add 2.0mm to all the figures for EM.

 

cheers,

 

Martin.

Edited December 12, 2021 by martin_wynne
link added

[PMP]

8 hours ago, Lacathedrale said:

Thank you PMP - I guess I really was speaking about the hattons/Hornby pre-group coaches and the Bachmann coal tank/precedent rather than as a generic question.

 

Honestly I'm seriously considering modelling 'authentic' late 19th century practise of ballasting over the sleepers and just doing it in bloody 00 at this rate

My overview on the Hattons Genesis range is here

https://albionyard.com/2020/10/27/transformation-tuesday-genesis/

 

They may be one of the types where a straight drop in doesn’t work, (they do have standard 26mm axles) particularly if you’re aiming to retain their lighting system. When I was working in EM I took the thought that if  a replacement was straightforward that was a Brucie Bonus, otherwise expect varying degrees of challenges

[philsandy]

12 hours ago, Lacathedrale said:

Ah thank you - presumably because bogies and wagon frames are scale width, with correct length pinpoint axles - whereas locomotives have narrower chassis and corresponding axles.

 

Is simply a case of replacing the axles with longer ones, or does one need to also replace the wheels? Again, specifically talking about inside frame, inside cylinder/valve Bachmann locomotives.

 

I have converted steam locos to EM using the original wheels, but using longer EMGS shouldered axles, 3mm x 2mm. (5905 R5D2).

I reduced the wheel flanges by 0.2mm/0.3mm to give a flange width of 0.5mm, (but check first, Bachmann flanges do vary in width). 

I found this an easier way of converting, especially for locos with valve gear, although with some locos there can be a problem with there not being enough clearance between the front wheel crank pin screws and the valve gear.

 

METHOD I USED:

I reduced the wheel flange by placing a good flat file on a work bench, placing the wheel, flange side down on the file and sliding it back and forth. Regularly checking the flange thickness with a digital vernier.

It's easier rather than to keep trying to measure the flange width to first take a measurement of the overall wheel width and keep checking that, till you have reduced it by 0.2mm/0.3mm.

eg, overall wheel width is 2.9mm, so reduce it to 2.6 or 2.7mm.

 

I rolled a small flat file around the 2mm dia. axle stubs to put a knurl on to give a tighter fit in the plastic wheel bush.

 

Used Araldite to glue the plastic bushes in to the wheel hubs.

 

The problem then was because these bushes have a shoulder (about 0.5mm thick) and the 3mm dia. part of the axle is 16mm long, this would give a B2B of about 17mm.

I filed the bush shoulder thickness down to 0.25mm, This is done with the bush being in situ in the wheel bore, and using the method described above, re. reducing flange thickness.

So if the wheel width measured at the axle bore is say 2.7 mm, when the bush in place it should then measure 2.95 mm, and if the 3mm diameter part of the axle is 16mm long, when both wheels are pressed home up to the shoulders, this will give you a B2B of 16.5mm.

Hope this makes sense.

 

[Enterprisingwestern]

4 hours ago, martin_wynne said:

 

 

 

If regauging 00 RTR wheels for EM, the correct back-to-back should be 16.4mm max.

 

If you widen them to 16.5mm they will likely bump on the crossings.

 

 

Martin, I am not crossing swords with you, just pointing out that technically it's the root profile to opposite rear face of the wheel which is the critical dimension for passing smoothly through pointwork and that a blanket/standard "OO rtr wheel" doesn't exist. Having bodged rtr wheels to EM for some 50 years now, (a first issue Mainline Peak being an early challenge using the existing wheels!), I inspect and measure all rtr wheels closely to judge by rule of thumb what needs doing to them, and to that end have at least 3 b2b gauges depending on findings, because if you come across a RP25/88 wheel it is to all intents and purposes to EMGS standards and will require a 16.5mm b2b gauge, (and that's before we start on the thorny issue of gauge accuracy.

As I say, not a criticism of your comments, just a clarification.

 

Mike.

[t-b-g]

I would agree that RTR wheels have varied so much over the years that laying down a blanket dimension for setting the back to backs is just not realistic. Even wheels from the same manufacturer can vary from one model to another.

 

The Bachamnn L & Y 2-4-2T and LMS Crab are two that have really thick flanges. I had to re-wheel them both to get them to run on a finescale OO layout, which had 1mm flangeway gaps. There was no back to back setting that would get them through without bumping and lurching.

 

A friend of mine has a simple system. He has converted some RTR locos to EM by simply pulling the wheels out a bit at a time until they just clear the checkrails on an EM point. If they still fit between the rails at that stage, then it seems to work. If they bind between the rails at that point, then the flanges are too thick and the wheels need replacing. He had to re-wheel a Bachmann Crab but the Midland Compound from Bachmann worked OK.

[DCB]

If you want good appearance and reliable running you need a consistent wheel profile, both flange and tread.  RTR OO will never have good running  while we insist on running all sorts of wheel profiles. Likewise you won't get reliable running simply by widening the gauge of RTR OO by a couple of mm  A lot of OO wheels have a truly awful tread profile.  Absolutely flat across the tread. Even some Markits look absolutely flat across the tread, and their B to B isn't wonderfully consistent either.. Ready to use OO track has to cope with Hornby "Silver Seal" 13.8mm B to B and Hornby Dublo  14.2mm B to B, as well as massive variation in flange depth. Basically I reckon you need to do all the same mods to OO wheels for good running that you need for EM.  The worst wheels I have suffered are a 2020 Dapol Mogul pony truck.  I had to reprofile their treads to a conical profile to keep them on the rails, that's bog standard RTR on Peco code 100.   The P4 Bumf seems to bang on about the 1 in 20 coning on the tyre but it doesn't seem to get mentioned much and yet is crucial.   My modified Dapol wheels run through pointwork just loose.  As standard they get sideways on the first curve.  

The other problem with random wheels is flange depth. Hornby Dublo3 rail arranged their wheels and points so the flange supported the wheel through crossings, and the running is extremely smooth and reliable considering they are 15" radius, many heritage  (1950s) point frog assemblies also had limited depth between crossing components so fine scale wheel flanges were also supported and they also work well with nothing like the crashing and banging of modern Hornby over code 100 Peco streamline points. Those old wheels had some very fine flanges, even the 1960s Romfords had much nicer thinner flanged and tyres than 2000 era.  Just saying in a very long winded manner that just pushing the wheels out  2mm risks missing out on the improvement in running you might be looking for.

[The Johnster]

Don't forget the brakes, another potential problem area.  If you convert by moving RTR 00 wheelsets out to the wider gauge, you have to move the brake blocks that have been positioned (wrongly) to align (correctly) with the wheels, so that they continue to be aligned with the wheels after the conversion.  Many RTR wagon, and coach/wagon bogie, chassis featured the brake blocks and linkage moulded in a position outboard of the wheels, clawing uselessly at fresh air, which were an obvious anomaly and which I disliked; some older toolings from Hornby and Dapol are still on the market like this.  Irrespective of my dislike of them, they were in fact more correctly positioned than the usual current 00 RTR and kit models that have the brake gear mounted too far inboard too line up with the wheels, part of the 00 compromise.  Varying amounts of difficulty may be experienced in moving them outwards as part of your EM conversion.

[KeithHC]

If you go on the Ultrascales web site there is access to several data sheets on converting various manufacturers locomotives. This will give an idea of what is required. There has been a recent post about a conversion of an M7 using the Hornsby wheels however although it works the poster will be changing the wheels in due course. Also I have heard that Bachmann wheel sets are quite easy to change gauge with. Hopefully in the new year I will attemp to adjust three Bachmann older Bullieds.

 

Keith

[martin_wynne]

2 hours ago, t-b-g said:

I would agree that RTR wheels have varied so much over the years that laying down a blanket dimension for setting the back to backs is just not realistic. Even wheels from the same manufacturer can vary from one model to another.

 

Well yes, but you have to start somewhere. A back-to-back gauge is the simplest to use, if imperfect. But there is a better way.

 

The object of the exercise is to set the back-to-flange dimension to 17.2mm for EM, or 15.2mm for 00-SF. A better way to do that than using a back-to-back gauge is to make yourself a simple wheel setting fixture. This will set any wheels to the required back-to-back allowing for differing wheel profiles. For a simple way to make and use such a fixture, which costs next to nothing, see:

 

 https://85a.uk/00-sf/index.php#fixture

 

cheers,

 

Martin.

[t-b-g]

1 hour ago, martin_wynne said:

 

Well yes, but you have to start somewhere. A back-to-back gauge is the simplest to use, if imperfect. But there is a better way.

 

The object of the exercise is to set the back-to-flange dimension to 17.2mm for EM, or 15.2mm for 00-SF. A better way to do that than using a back-to-back gauge is to make yourself a simple wheel setting fixture. This will set any wheels to the required back-to-back allowing for differing wheel profiles. For a simple way to make and use such a fixture, which costs next to nothing, see:

 

 https://85a.uk/00-sf/index.php#fixture

 

cheers,

 

Martin.

 

Quite right and there are certainly minimum and maximum back to backs that will or won't work with certain thicknesses of wheel and flange.

 

My own solution to a variety of wheel standards was to go EM and as I have very little RTR, their variety of wheels doesn't bother me greatly. When I have helped others with OO layouts and RTR, I have a very unscientific way of setting the back to backs. If they are tight over check rails, I open them up until they just go through. If they are then tight between the rails, I narrow them slightly. If there is no "sweet spot" where they work, it means the flanges are too thick and I change the wheels. After you have set a few, you get a good feel for what will work and what won't.

 

I find that any wheels that don't catch on the check rails but still fit between the running rails work just fine. I couldn't even tell you what the measurement is. It really is a case of "just big enough but not too big".

 

Edit to add:

 

I have measured some RTR back to backs on new stuff straight from the factory that is really quite a long way out, so any RTR being added to the layouts I am involved with gets checked before it is put on the track. 

Edited December 12, 2021 by t-b-g
To add content

[Jeff Smith]

William - having a P4 turnout in your possession it would be a good idea to run some P4 wheels through it to demonstrate how smoothly they negotiate the frog gaps.  You could just re-wheel a short wheelbase wagon but better would be to make one of the axles rock.  There are quite a few simple etches to do this. 

 

My first P4 conversion was a drop-in wheel-set for a Lima GWR diesel rail-car, no compensation but runs perfectly through turnouts.  A more recent RTR conversion was an Ultrascale set for the Bachmann GWR 8750 Pannier Tank.  The centre axle is sprung so a type of compensation.  I had to cut off and replace the outside brake pull-rods but there was plenty of room in the splashers.  The Ultrascale wheels are expensive but come ready quartered with a replacement drive gear already fitted.  The Gibson wheelsets are cheaper but you have to mount and quarter them.

 

I use OO wheel and track standards for O-16.5 so am familiar with them.  I admit to never having tried EM but if it is effectively wider OO, with all it's problems - wheel-drop through frogs - then, to get back to my original point, you need to try P4 running first.

[Il Grifone]

The success or otherwise of regauging wheelsets for EM depends  on the wheels.

 

EM gauge originally used the BRMSB wheel (2.5mm thick of which 0.5mm is flange)  on eighteen millimetre gauge (hence the name) with 17mm check gauge. An extra 0.2mm track gauge and finer wheels were improvements added to the specification later. The flangeways  were set at 1mm which precludes some of the more rubbish wheels from running. (I had  Bachmann wheelsets allergic to my trackbuilding. Proper wheels were fine - investigation showed the Bachmann (allegedly NMRA) wheelsets had a flange of around 0.8mm....

 

The 1mm flangeway combined with 2mm wheel treads ensures there is no problem with wheel drop at crossings as the wheel is supported all the way through.

[Lacathedrale]

Well @Jeff Smith I do have a P4 turnout and a Ratio Iron Mink running through it without a problem, but I have neither the patience of Job nor the years of Methuselah to re-chassis in addition to re-wheeling stock for my forthcoming layout.

 

I'm pleased with the appearance and it was enjoyable to build - but part of my layout journey (as opposed to track or locomotive-building) is leveraging RTR where feasible, and there is just no way I'm going to spend £hundreds on an RTR loco and then throw most of it away to convert it to P4.

 

It's becoming clear that EM's ability to use 00 gauge wheels is as @PMP has mentioned, a 'brucie bonus' rather than a given - which is quite reasonable.

[martin_wynne]

On 11/12/2021 at 22:49, Lacathedrale said:

I have heard that modern 00 wheels can often be eased out to a 16.5mm B2B, though It looks to me like the average DOGA Intermediate/RP25-110 wheel is 0.4mm wider than an EM wheel, 0.25mm of which is in the thickness of the flange. Given the 1mm EMGS flangeway, I don't suppose this would be a problem - but I have no meaningful experience.

 

Hi William,

 

Have a look at the numerous topics on here about 00-SF. It was previously known as "EM minus 2". In other words it is exactly the same as EM, same dimensions, same flangeway, same tolerances -- but with 2.0mm subtracted from all the dimensions.  i.e. 16.2mm gauge for 00 models.

 

It was invented in the 1970s by the late Roy Miller of the EMGS.

 

Many folks have tried it in recent years. Invariably with favourable results. They have found that the vast majority of modern 00 RTR models run on 00-SF with no problems.

 

It follows that exactly the same models with the same wheels will run on EM if you widen the wheels by 2.0mm. And they do.

 

The back-to-back for 00 RTR is 14.4mm, see:

 

 http://doubleogauge.com/standards/commercialwheels.htm

 

So just widen the RTR wheels to 16.4mm, and off you go on EM. Don't use your usual 16.5mm EM back-to-back gauge on them.

 

Here's an 00-SF layout to prove the point. Widen this track by 2.0mm and it would be EM. Widen the wheels by 2.0mm and they would run on it:

 

 

The significant word in the above is "modern" RTR. Obviously you are not going to have any joy in EM with the wheels on ancient Tri-ang and Hornby-Dublo models.

 

cheers,

 

Martin.

[t-b-g]

1 hour ago, martin_wynne said:

 

Hi William,

 

Have a look at the numerous topics on here about 00-SF. It was previously known as "EM minus 2". In other words it is exactly the same as EM, same dimensions, same flangeway, same tolerances -- but with 2.0mm subtracted from all the dimensions.  i.e. 16.2mm gauge for 00 models.

 

It was invented in the 1970s by the late Roy Miller of the EMGS.

 

Many folks have tried it in recent years. Invariably with favourable results. They have found that the vast majority of modern 00 RTR models run on 00-SF with no problems.

 

It follows that exactly the same models with the same wheels will run on EM if you widen the wheels by 2.0mm. And they do.

 

The back-to-back for 00 RTR is 14.4mm, see:

 

 http://doubleogauge.com/standards/commercialwheels.htm

 

So just widen the RTR wheels to 16.4mm, and off you go on EM. Don't use your usual 16.5mm EM back-to-back gauge on them.

 

Here's an 00-SF layout to prove the point. Widen this track by 2.0mm and it would be EM. Widen the wheels by 2.0mm and they would run on it:

 

 

The significant word in the above is "modern" RTR. Obviously you are not going to have any joy in EM with the wheels on ancient Tri-ang and Hornby-Dublo models.

 

cheers,

 

Martin.

 

That is sound advice Martin but I would add one caveat. Even with modern RTR you do sometimes get the odd rogue wheel flange that is so thick that it can't get through a 1mm flangeway gap. I do some work on a layout which used the DOGA Fine standards. For those that haven't come across this, it is 16.5mm gauge with a 1mm flange gap (the same as EM Gauge). There were a couple of locos that I have already mentioned, the relatively modern Bachmann L & Y 2-4-2T and the LMS Crab by the same firm and no matter how much I tried getting the back to back exactly right so they would go through, they bumped and rode up because the flanges were 1mm thick and with the best engineering in the world, a 1mm flange will not run smoothly through a 1mm flangeway. They ended up being re-wheeled, even for OO.

 

Two Bachmann locos, the LNWR G2 and Midland Compound, have been converted to EM by just pulling the wheels out and run through 1mm flangeways easily with no bumping.

 

Thick flanges are very much in the minority but there may be some others around.

 

So if you get a wheel that won't run through on a 16.4mm back to back, that may be the reason.  

[martin_wynne]

22 minutes ago, t-b-g said:

There were a couple of locos that I have already mentioned, the relatively modern Bachmann L & Y 2-4-2T and the LMS Crab by the same firm and no matter how much I tried getting the back to back exactly right so they would go through, they bumped and rode up because the flanges were 1mm thick

 

Hi,

 

Those locomotives were faulty and should have been returned to the supplier for replacement.

 

I don't know why 00 modellers put up with poor quality control which they wouldn't accept when buying anything else.

 

Martin.

[Jeff Smith]

2 hours ago, Lacathedrale said:

Well @Jeff Smith I do have a P4 turnout and a Ratio Iron Mink running through it without a problem, but I have neither the patience of Job nor the years of Methuselah to re-chassis in addition to re-wheeling stock for my forthcoming layout.

 

I'm pleased with the appearance and it was enjoyable to build - but part of my layout journey (as opposed to track or locomotive-building) is leveraging RTR where feasible, and there is just no way I'm going to spend £hundreds on an RTR loco and then throw most of it away to convert it to P4.

 

It's becoming clear that EM's ability to use 00 gauge wheels is as @PMP has mentioned, a 'brucie bonus' rather than a given - which is quite reasonable.

Well, I'm glad you have run P4 wheels through a P4 turnout.....

 

I would not buy a new RTR just for the body either!  I'd rather build a kit body although they can be expensive too.  The point I was making about drop-in wheelsets was that you don't need to throw away anything except the wheels.  EM drop-in wheels are also available.

[Lacathedrale]

I have decided to throw my lot in with EM for now - maybe P4 can come by as a second (third?) layout in future - but the idea that I can buy the track RTP from the EMGS and re-gauge the various coaches or swap out the wheels is a real winner. I appreciate there will be a learning curve for locomotives, but given that I only have a need for half a dozen at maximum, none of which will have outside cylinders or valve gear, I think it should be manageable.

 

Thank you all for the help and advice.