A beginner's 00-SF, and the ends of wing and check rails

[47137]

I get the feeling I really ought to possess two B2B gauges - one 14.4 and one 14.5, so I can see one goes in and the other does not. On a keyring or similar so they stay together!

 

- Richard.

[martin_wynne]

I get the feeling I really ought to possess two B2B gauges - one 14.4 and one 14.5, so I can see one goes in and the other does not. On a keyring or similar so they stay together!

 

Hi Richard,

 

Much the best solution is to throw your back-to-back gauges away, and use a back-to-flange setting fixture, see:

 

 http://www.rmweb.co.uk/community/index.php?/topic/98904-oo-sf-back-to-back-dimension/&do=findComment&comment=1878333

 

But if you prefer to use back-to-back gauges:

 

The GO back-to-back gauge for 00-SF should be 14.3mm. This is the minimum back-to-back for 00-SF.

 

For setting RTR wheels:  14.4mm.

 

For setting BRMSB / Romford / Markits wheels:  14.5mm.

 

For setting EMGS / Kit wheels:  14.6mm.

 

The wheels should be a close fit on those without play, or closer than those figures providing the 14.3mm gauge fits.

 

regards,

 

Martin.

[47137]

Much the best solution is to throw your back-to-back gauges away, and use a back-to-flange setting fixture, see:

 

 http://www.rmweb.co.uk/community/index.php?/topic/98904-oo-sf-back-to-back-dimension/&do=findComment&comment=1878333

 

But if you prefer to use back-to-back gauges:

The GO back-to-back gauge for 00-SF should be 14.3mm. This is the minimum back-to-back for 00-SF.

For setting RTR wheels:  14.4mm.

For setting BRMSB / Romford / Markits wheels:  14.5mm.

For setting EMGS / Kit wheels:  14.6mm.

The wheels should be a close fit on those without play, or closer than those figures providing the 14.3mm gauge fits.

 

The cynical side of me suggests the fixture will have much the same utility as putting the train on an existing turnout crossing and squinting at the light passing through, but yes I should make one up. But I'd like to see the fixture as complementing the B2B gauges, and not replacing them, because the gauges (the cylindrical ones with an axle slot) do help you keep the wheels square on their axles.

 

I suggest, a lot of the trouble and misunderstandings with wheels and track is there are too many empirical and derived dimensions floating around, and not enough emphasis on the required dimensions. For example a Wrenn wheel 3.3 mm thick fails to run through 00-SF because its flange is too thick, not because its B2B is wrong.

 

The B2B dimensions Martin cites ought to work for most wheels most of the time, but there must be some rogues out there, especially at the coarser end of the spectrum, for which the only guarantee of successful operation is a check with a fixture. The distance between the two points where the tread cone begins to curve out to become the flange is important as well. And that is a required dimension in its own right, independent of B2B, but possible to see with a fixture and a good light.

 

I would like to see some tolerances on all of these B2B figures - perhaps +/- 0.05 mm ? This would allow go/no go checking with a pair of B2B gauges.

 

- Richard.

[martin_wynne]

For example a Wrenn wheel 3.3 mm thick fails to run through 00-SF

 

Hi Richard,

 

00-SF is not intended for Wrenn wheels, and similar old-style RTR models. If you want to run such models you shouldn't use 00-SF.

 

00-SF is a variant of EM and accepts the same wheels as EM, i.e.

 

1. Wheels to the EMGS profile, and the similar RP25/88 profile. These are the wheels usually supplied in kits in the UK.

 

2. Wheels to the RP25/110 profile set to 14.4mm back-to-back. These are the wheels fitted nowadays to good-quality RTR models.

 

3. Wheels which come between those two in profile, such as the Romford/Markits wheels.

 

regards,

 

Martin.

[47137]

Martin - I think everyone who has survived this topic from the beginning knows 00-SF isn't suitable for a Wrenn wheel!

 

Everyone - I offered the Wrenn wheel as an illustration of the inherent difficulty in specifying and setting up a wheel purely on the basis of a B2B dimension and wheel thickness. It's a proprietary wheel.

 

What I am trying to do is to get to the allowable tolerances for the B2B dimension, without too many manual iterations, and to be honest I am wary of accepting three absolute dimensions for use on track with a crossing flangeway spec'ed at 1.01 to 1.04 mm. I am also wary of RTR manufacturers who either invent their own wheel profiles or cannot bring themselves to put what they use on their boxes.

 

I suggest, the B2B dimension has got to be spec'ed to match or better the track tolerance, with a maximum figure as well as a minimum one. My idea of a light sliding fit on a gauge is probably different from those of a professional mechanic and a builder - it's too subjective. How about 14.47 to 14.50 mm as a starter for both the given RTR and Markits wheels? This would be easy to set up using a pair of Markits 14.50 gauges, with one milled or faced down to 14.47. I suggest this because I have used 14.50 (tight) on all of my wheels so far, these wheels are a mixture of both these styles, and they all work.

 

- Richard.

 

 

[martin_wynne]

Hi Richard,

 

It is meaningless to make MAXIMUM back-to-back gauges to a close tolerance unless you know an exact figure for the effective flange thickness. Which varies with different wheels and is determined by:

 

1. the wheel profile, and

 

2. the top corner radius on the rail section being used.

 

The only back-to-back gauge you need is the MINIMUM one at 14.3mm to check that the wheels will clear the 14.2mm check rail span. This gauge must GO between the wheels. This is the gauge which will eliminate older RTR wheels. You might go down to 14.25mm if your track is very accurately made and you are not using sharp curves.

 

Then to check the maximum it's much better to use the setting fixture which I mentioned earlier. This automatically allows for the wheel profile and the top corner radius on your rail:

 

 http://www.rmweb.co.uk/community/index.php?/topic/98904-oo-sf-back-to-back-dimension/&do=findComment&comment=1878333

 

regards,

 

Martin.

[47137]

Hi Richard,

 

It is meaningless to make MAXIMUM back-to-back gauges to a close tolerance unless you know an exact figure for the effective flange thickness. Which varies with different wheels and is determined by:

 

1. the wheel profile, and

 

2. the top corner radius on the rail section being used.

 

The only back-to-back gauge you need is the MINIMUM one at 14.3mm to check that the wheels will clear the 14.2mm check rail span. This gauge must GO between the wheels. This is the gauge which will eliminate older RTR wheels. You might go down to 14.25mm if your track is very accurately made and you are not using sharp curves.

 

Then to check the maximum it's much better to use the setting fixture which I mentioned earlier. This automatically allows for the wheel profile and the top corner radius on your rail:

 

 http://www.rmweb.co.uk/community/index.php?/topic/98904-oo-sf-back-to-back-dimension/&do=findComment&comment=1878333

This post keeps rumbling around in my mind.

 

The point I have failed to make is this: if you want to use gauges to set a dimension (any dimension), you need two gauges of known dimensions. One that fits and one that doesn't. It doesn't matter if you are trying to set a minimum back to back, an optimum one or the largest you can get away with. If you are going to translate any specification of a dimension into practice, you have got to put tolerances on it.

 

I'll see how I get on with a fixture, and report back.

 

- Richard.

[martin_wynne]

The point I have failed to make is this: if you want to use gauges to set a dimension (any dimension), you need two gauges of known dimensions. One that fits and one that doesn't.

 

Hi Richard,

 

This is true, but only IF you know the required dimension.

 

For the smoothest running you want the flange on one wheel just touching the rail on one side, when the back of the wheel is just touching the check rail on the other side. This is the MAXIMUM setting for the back to back. It varies from wheel to wheel according to the effective flange thickness -- which you likely don't know. The setting fixture lets you achieve the optimum back-to-back without needing to know the effective flange thickness.

 

If you are determined to have GO / NO-GO back-to-back gauges for 00-SF:

 

GO gauge is 14.3mm for all wheels.

 

NO-GO gauges are as follows:

 

For RTR wheels:  14.4mm.

 

For BRMSB / Romford / Markits wheels:  14.5mm.

 

For EMGS / Kit wheels:  14.6mm.

 

Best results will be obtained if the wheels are a firm push fit on the NO-GO gauge and a loose fit on the GO gauge.

 

For 00-BF the NO-GO gauges are the same as above. The GO gauge is 14.1mm.

 

regards,

 

Martin.

[47137]

I'm not that determined, because I know RTR wheels run happily with a B2B a whisker over 14.5 mm!

 

- Richard.

[martin_wynne]

I'm not that determined, because I know RTR wheels run happily with a B2B a whisker over 14.5 mm!

 

Not all of them. If you want to use the same gauge for all of them, I strongly recommend that you don't exceed 14.4mm for RTR wheels on 00-SF and 00-BF. Some may be ok if wider, but you are relying on the manufacturer's quality control to maintain a constant flange thickness.

 

regards,

 

Martin.

[Grovenor]

 

Best results will be obtained if the wheels are a firm push fit on the NO-GO gauge and a loose fit on the GO gauge.

Not my idea of a NO-GO gauge!

regards

Keith

[martin_wynne]

Not my idea of a NO-GO gauge!

 

Hi Keith,

 

True if we are dealing with solid metal. But in this case we are dealing with flexible plastic wheel centres or axle bushes.

 

I think practical modellers will know what I mean -- the gauge doesn't fit if held gently against the wheels, but can be made to fit between them with a push.

 

The object is to get as close as possible to the maximum setting without exceeding it. That's why a setting fixture such as I mentioned earlier is more useful than a fixed gauge. The 14.3mm minimum is really only for wheels which can't be set any wider.

 

regards,

 

Martin.

[AndyID]

I use these to measure the B2B. The old-fangled internal calipers are much more sensitive than digital calipers. Measuring the flange thickness is not always so simple

 

 

 

[47137]

I found myself with 20 minutes to spare at Colchester North yesterday and took some photos of the first turnout I saw - this is the one on the dog-leg between platforms 3 and 2. And I remembered this post by Martin, which followed my photos of one of my model turnouts:

 

That looks well made.

 

But by using a Peco template you have got the wing rails one timber too long, and the check rails in the wrong place -- they are barely functional opposite the knuckle:

 

check_extent.png

 

Your choice, but it would be so much better to ignore Peco and work from the prototype. A template of this size could easily have been printed from Templot, see:

 

(cut)

 

 

My model has wing rails on three timbers; Martin says two. But this example at Colchester has four:

 

So I don't think my model is so bad. It was a lot easier for me to copy a Peco template (and arrange the timbers to something near HO spacing) than to set up Templot; though I appreciate Martin's invitation elsewhere to ask for help on the Templot forum.

 

I can post a few more photos if anyone is interested. I will, of course, live with the bent ends instead of flared ends, which is where this topic started :-)

 

- Richard.

 

 

[martin_wynne]

My model has wing rails on three timbers; Martin says two. But this example at Colchester has four:

 

Hi Richard,

 

I said 2 for the crossing angle you were using. It varies with the crossing angle and prototype. The crossing in the photograph is a much flatter angle than your model.

 

regards,

 

Martin.

[AndyID]

I was tempted to "chime in", but I knew Martin would do a much better job

 

Actually, that's a really great photo that shows how the wheel treads are supported all the way through the crossing. The overlap between the shiny bits on the V and the wing rail is very well captured.

 

It also makes me wonder why the wing rails need to be as long as they are. Is it more to do with keeping the various bits on the same plane than anything else?

[47137]

For the record - I am now the proud owner of a Roco 0-6-0 diesel shunter, an English Electric class 11 in Dutch guise. This model is brand new (all of my other HO stock has been second-hand) and it runs through my 00-SF and Peco code 75 turnouts perfectly. I know I should be cautious about writing "perfectly" but it is very smooth indeed. The back-to-backs as supplied are consistent from one axle to another, at 14.5 mm. Well, 14.53 on the micrometer on the callipers.

 

I am not sure whether the wheel profile is RP-25 and I have no way of checking. The wheels measure 2.8 mm wide, but the flanges are visibly thinner than those on recent 00 gauge Hornby and Bachmann. The wheel inserts are slightly proud on the inside of two of the wheels, just about enough to feel with a finger nail. The other four are flush.

 

- Richard.

[MikeH_83]

Out of interest,  How difficult is it to adjust the B2B on steam locos?  With diesel I can see it being rather easy but they don't have any complicated valve gear? in the way.  I am seriously considering 4-sf for my large loft layout but I don't have any current loco stock to "play around with"

[47137]

Out of interest,  How difficult is it to adjust the B2B on steam locos?  With diesel I can see it being rather easy but they don't have any complicated valve gear? in the way.  I am seriously considering 4-sf for my large loft layout but I don't have any current loco stock to "play around with"

I kept a log of all the tests using my locos, but I possess so few steam locos the results are a bit limited:

 

Electrotren GV2004 "TVR" 0-6-0 (H0 scale) - no adjustment needed from factory condition

Hornby R2327 Cadley Colliery (ex-BR) class J94 0-6-0ST - easy to adjust

Hornby R2454 NCB (ex-BR) class J94 0 6 0ST - easy to adjust

Hornby R2920 LNER B17 with fitted cylinder detail - won't go round the curves on my layout, didn't try to set it up

Mainline (Palitoy) BR (ex-LNER) class J72 0 6 0T - easy to adjust

Dapol Sentinel - difficult to adjust - difficult to get access to the wheels - this loco found a gauge narrowing on a point blade which I adjusted by bending the blade

 

At the end of the day, the adjustment is always a tiny fraction of a millimetre. I think I had one diesel loco which was 0.2 mm too narrow on one pair of wheels, and for most of the others it was a hairsbreadth, say 0.1 mm widening needed. For a steam loco with outside valve gear, 00 gauge gives a good amount of spare space for the valve gear, so I don't imagine any great problems.

 

I've never found any RTR with the wheels too far apart.

 

I have some EM gauge wagon wheels re-gauged to 00. Two of these wheel sets have gone out of gauge since adjustment - they now have blobs of superglue on the insides of the wheels and haven't moved since.

 

I don't have a loco with Romford axles but these should be good to go as supplied (14.4 mm) - they would be a real pain to shim out.

 

- Richard.

[MikeH_83]

 

I kept a log of all the tests using my locos, but I possess so few steam locos the results are a bit limited:

 

Electrotren GV2004 "TVR" 0-6-0 (H0 scale) - no adjustment needed from factory condition

Hornby R2327 Cadley Colliery (ex-BR) class J94 0-6-0ST - easy to adjust

Hornby R2454 NCB (ex-BR) class J94 0 6 0ST - easy to adjust

Hornby R2920 LNER B17 with fitted cylinder detail - won't go round the curves on my layout, didn't try to set it up

Mainline (Palitoy) BR (ex-LNER) class J72 0 6 0T - easy to adjust

Dapol Sentinel - difficult to adjust - difficult to get access to the wheels - this loco found a gauge narrowing on a point blade which I adjusted by bending the blade

 

At the end of the day, the adjustment is always a tiny fraction of a millimetre. I think I had one diesel loco which was 0.2 mm too narrow on one pair of wheels, and for most of the others it was a hairsbreadth, say 0.1 mm widening needed. For a steam loco with outside valve gear, 00 gauge gives a good amount of spare space for the valve gear, so I don't imagine any great problems.

 

I've never found any RTR with the wheels too far apart.

 

I have some EM gauge wagon wheels re-gauged to 00. Two of these wheel sets have gone out of gauge since adjustment - they now have blobs of superglue on the insides of the wheels and haven't moved since.

 

I don't have a loco with Romford axles but these should be good to go as supplied (14.4 mm) - they would be a real pain to shim out.

 

- Richard.

 

 

Thanks for that info!  I will give the idea some more thought.  I do like the idea of going with 4-sf though

[hayfield]

I was considering having a copperclad built 00sf turnout that those who are interested in the gauge could borrow, if I did do this what size turnout would be the most appropriate ? My thoughts are for an A5  which is either a 32" (internal radius) or 51" (substitution) radius. I am happy to maintain it but to be quit honest nothing to maintain other than damage

 

My thoughts are, No charge for the loan other than the cost of postage (return the turnout with an additional large letter stamp). I would say that I would expect that the borrowers would return the turnout within 2 weeks and keep a proof of postage which will cover any loss in post.

[MikeH_83]

I was considering having a copperclad built 00sf turnout that those who are interested in the gauge could borrow, if I did do this what size turnout would be the most appropriate ? My thoughts are for an A5  which is either a 32" (internal radius) or 51" (substitution) radius. I am happy to maintain it but to be quit honest nothing to maintain other than damage

 

My thoughts are, No charge for the loan other than the cost of postage (return the turnout with an additional large letter stamp). I would say that I would expect that the borrowers would return the turnout within 2 weeks and keep a proof of postage which will cover any loss in post.

 

This is a brilliant idea!  Those with a fair amount of stock and looking to maybe start again with handbuilt track or anything could test to see what % of their stock works and maybe try adjusting any that need doing,  thus giving them no risk bar postage cost to at least see and try the difference.  Would it not need to be FB rail to match the peco/Hornby flexi track (I think they use FB rail?) for rail joiners so people can very easily join it up to some oo flexi to run the loco's with it?

[47137]

If I was wanting to try out the gauge now, I would ask to borrow a drop-in replacement for a Peco code 75 medium radius right-hand turnout. It could have rail joiners soldered onto the three corners so I would just have to plug in some flexi track.

 

I have written right-hand only because my own layout has ended up with almost entirely right-hand points. The idea of the Peco code 75 with medium radius is because it will be familiar to many prospective new users. Also it is easy to put in a plan drawn in Anyrail. So it would be a FB rail construction.

 

If the turnout was made with a dead frog (by isolating the metal vee) and had some jumper wires already fitted so both routes were always live, the recipient would get a turnout which was already electrically working and not need to fuss around with crocodile clips or similar to apply power to the frog.

 

I suppose there might be an option for the borrower to purchase the turnout outright and keep it :-)

 

- Richard.

[martin_wynne]

If I was wanting to try out the gauge now, I would ask to borrow a drop-in replacement for a Peco code 75 medium radius right-hand turnout.

 

Hi Richard,

 

I would suggest that 4-SF (00-SF) isn't really suitable for such short turnouts, except in small goods yards where main-line locomotives don't go.

 

If you need to use such short turnouts on your layout, it would be better to stick to 00-BF.

 

Supplying an ultra-short turnout for folks to try wouldn't be providing a fair test of 4-SF and is bound to lead to reports of this or that model not running over it.

 

John, I would suggest a B-7 as a reasonable size to properly demonstrate the advantages of 4-SF.

 

regards,

 

Martin.

[hayfield]

This is a brilliant idea!  Those with a fair amount of stock and looking to maybe start again with handbuilt track or anything could test to see what % of their stock works and maybe try adjusting any that need doing,  thus giving them no risk bar postage cost to at least see and try the difference.  Would it not need to be FB rail to match the peco/Hornby flexi track (I think they use FB rail?) for rail joiners so people can very easily join it up to some oo flexi to run the loco's with it?

 

Yes I can do one with Code 82 C&L rail to match their flexi track, I don't think I have any code 75 flat bottom, though connecting bullhead to flatbottom would be just as good

 

The common crossings are dead, no problem in adding a bit of wire