3.5" gauge specification

[Runner]

Hi all,

I have tried to find the answer on the Internet but to no avail. What is the railway or railroad specification for the 3.5" gauge track. I am building a 3.5" gauge LMS Black 5 and measured one axle at being 3.52", the others being 3.5" spot on. Assuming that one day I hope to run it on a track of others making will I have trouble with derailment? I am loathe to correct this oversize axle if I don't have to, but I am at the stage where it is convenient to do. The hesitation to do so is due to problems I had overcoming a slight wheel wooble. Removing the wheels to rework the axle will put the possibility of again introducing wheel wooble. A 4.5" dia wheel seems to accentuate wheel wooble.

Thanks in advance

Brian

 

[chipenter]

Track gage is exact 3.5 , 5 or 7.5 inches , we are replacing the track at Romney Marsh Model Engineering Society and the care and templates are spot on , you wheels need to be measured at the bottom of the flange , sorry but they need adjusting .

 

[cncjunior]

It is funny that this post comes up at this time as I was just at my club yesterday where we were talking about making up wheel sets for our 7.5" gauge track at British Columbia Society of Model Engineers. I volunteered to do a solidworks package for machining out of house/club. Another member pointed me to the standard that was established many a year ago from International Brotherhood of Live Steamers. We found a web site that has a spread sheet with dimensions and tolerances along with drawings for the typical gauges here in North America. I will post a link when I find it again.


Daniel

 

[cncjunior]

The link is http://www.svls.org/ibls.htm it comes from the Sacramento Valley Live Steam web site. The link above doesn't have a tab to go to the club above though.

Daniel

 

[Runner]

Thanks Jeff and Daniel. It appears from the data provided that the wheel gauge should be a tad under 3.5". The dimensions provided in the plans should put the wheel gauge at 3.40625" plus the bit for the radius. I suspect that I made the radius too large, a dimension not specified.

Brian

 

[GWRdriver]

[snip] . . . plus the bit for the radius. I suspect that I made the radius too large, a dimension not specified. - Brian

Perfect timing for this comment as I was about to pass on a bit of advice. I was advised some years ago by a far more experienced runner and track builder (as well as a superb builder) than I am to never skimp on the flange radius. His observations and experiences over many years of running at club tracks (in the USA), and in particular his (our) own track, had shown him that a very large percentage of running and track problems, especially excessive wear of rail and points, were down to poorly formed flanges and in particular insufficient flange radius, followed by incorrect back-to-back dimension. His strong recommendation was always, when in doubt err on the side of a larger radius.

 

[Runner]

Thanks Harry. My radius size was not the problem. A quick measurement of one of the flange thickness's shows that it was 0.125" instead of 0.0625", an eigth instead of a sixteenth. A embarassing senior's moment. Why is it that imperial measurements are specified in fractions when measuring instruments are graduated in decimal? I'll have to produce a fraction to decimal conversion chart, can't depend on memory these days.

Brian