Mint gauge for sharp curves

[timbowales]

S7 has much more exact tolerances than Oh! gauge and track building has to have more attention paid to it. Another often overlooked aspect is back to back dimensions on rolling stock wheel sets which can be critical. Often the track is seen as the culprit when it's the wheel sets to blame.

Col.

Col, that advice is actually applicable to all the various gauges that WT-ers use

 

[Stephen Freeman]

The mint gauge does not have grooves. It is machined to provide two thin strips the length of the gauge which are 33mm to their outside edges. These fit between the rails to set the gauge. It will also fit curves. The radius of the minimum curve radius will depend upon its length.

Tim

I should have looked properly. However a small point but as I understand it the strip should fit in the flangeway

 

[Stephen Freeman]

Col, that advice is actually applicable to all the various gauges that WT-ers use

also applies to P4

 

[jc2001]

S7 has much more exact tolerances than Oh! gauge and track building has to have more attention paid to it. Another often overlooked aspect is back to back dimensions on rolling stock wheel sets which can be critical. Often the track is seen as the culprit when it's the wheel sets to blame.

I'm assuming the wheels are correct - it was a conversion by your good self a few years back and I've only recently started to run it.

John

 

[richard carr]

I have to say that my own experience of tight curves is that gauge widening is a waste of time. Even in S7 there is more than enough "slop" in small steam locos and certainly diesels chassis, that it is irrelevant. In P48 I run 39 inch curves and six axle diesels happily go round without any gauge widening. I don't run anything as tight as that in S7 but certainly on my dads layout we had 4 foot radius curves with no gauge widening and things like a jinty went round fine.

Richard

 

[timbowales]

also applies to P4

Stephen, surely my phrase “all gauges” includes P4?

 

[jc2001]

An update. It was still persistently derailing when travelling one way through a curved point. There was a slight tightness with the mint gauge in one place but this was not where it was derailing. I manage to identify the exact spot which was in the middle of switch blades which proved to be a bit over gauge. Narrowing the gauge did not solve it unlike on the hidden track. It would be a major job to rebuild this point so I tried jury rigging a temporary continuous check rail and this seems to have solved it, so I’m now going to add one properly with half chairs etc.

John

 

[Tim V]

An update. It was still persistently derailing when travelling one way through a curved point. There was a slight tightness with the mint gauge in one place but this was not where it was derailing. I manage to identify the exact spot which was in the middle of switch blades which proved to be a bit over gauge. Narrowing the gauge did not solve it unlike on the hidden track. It would be a major job to rebuild this point so I tried jury rigging a temporary continuous check rail and this seems to have solved it, so I’m now going to add one properly with half chairs etc.

John

I would add a temporary check rail by using bluetac to hold it in place. This would be enough to test the concept.

 

[jc2001]

Yes this is what I've done.

 

[jc2001]

An update. After successful tests with a temporary checkrail I have installed a proper one and the Class 42 now traverses it well. It is clear the checkrail is doing its job as I can hear the inner side of the wheels scraping. I used a 3B lead pencil on the inside of the checkrail to help.

I then ran some tests with it pulling & pushing some 4 wheeled wagons. This was a disaster! The overhang on the Class 42 means it either pulls the wagon off by the couplings or it buffer locks. Unfortunately, and very sadly it will have to be relegated to a lone guest model - or my one loco I can take to the annual S7 do at Mark.

I’m now on the lookout for a 1950s-1960s small loco - perhaps an 0-4-0 diesel - that could have been used in the far reaches of the Cornish Clay district.

John

 

[Eastsidepilot]

This was a disaster! The overhang on the Class 42 means it either pulls the wagon off by the couplings or it buffer locks.

John

Not surprising considering a 4'-0" radius curve represents 2.65 chains, min. radius for a cl 42 was 4.5 chains ( 297 ft. ) which equates to 2.08 m (6'-9") in 7mm scale.
Checkrails were usually fitted on curves under 10 chains.

 

[jc2001]

Yes. My aspirations got the better of me.