Search found 818 matches

by Russ Elliott
Tue May 09, 2017 12:12 pm
Forum: Track and Turnouts
Topic: P4 vs S4 - Pro's and con's
Replies: 164
Views: 40212

Re: P4 vs S4 - Pro's and con's

I think someone got their wires crossed in compiling the Clag table. I'll gladly plead guilty to that one, if it helps. I think the subtlety between a 'maximum variation' and a 'tolerance on the basic dimension' was, and is, somewhat superfluous to the purpose of our P4 standards Digest sheet. It i...
by Russ Elliott
Tue May 09, 2017 9:10 am
Forum: Track and Turnouts
Topic: P4 vs S4 - Pro's and con's
Replies: 164
Views: 40212

Re: P4 vs S4 - Pro's and con's

The 1/32" each side of the nominal 4' 5 5/8" BB came from contemporary wheel specs. In modern parlance, it is called the 'run out error', or 'run out tolerance'. It relates to the as-manufactured condition, as a means of checking conformance for contracts. (Keith is right, it is not a 'wea...
by Russ Elliott
Sun May 07, 2017 1:39 am
Forum: Track and Turnouts
Topic: Re: Track and Wheel Standards
Replies: 35
Views: 10870

Re: Track and wheel standards

Yes, the MRSG table given in the January 67 MRC was faulty. The standards published by the Scalefour Society however did not repeat the error, i.e. the Society version never needed to state where 18.15mm was derived from because it never stated a value for 'BB + EF'. This caused me to look at the st...
by Russ Elliott
Fri May 05, 2017 4:17 pm
Forum: Guest Book
Topic: Flexi Chassis an Appreciation
Replies: 467
Views: 84321

Re: Flexi Chassis an Appreciation

I assumed that any such chassis would have (per each wheel bearing) 2 bent out mounting brackets with holes supporting the sliding wire at each end, with little right angle bends on the ends of the wire to stop it going all the way through the mountings. Making little right angle bends on both ends...
by Russ Elliott
Fri May 05, 2017 4:02 pm
Forum: Guest Book
Topic: Flexi Chassis an Appreciation
Replies: 467
Views: 84321

Re: Flexi Chassis an Appreciation

Bill's sprung wagon units are discrete for the good pragmatic reasons (IMO) that they would need extra brass real estate if they were not discrete, they can accommodate different wheelbases, and a central fulcrum would get in the way of plastic kit brake mouldings. Seems eminently sensible to me.
by Russ Elliott
Fri May 05, 2017 3:02 pm
Forum: Tools and Techniques
Topic: Self-healing cutting mat recommendations
Replies: 21
Views: 7292

Re: Self-healing cutting mat recommendations

I've used the card back of A4 pads for general cutting. Not self-healing of course, but they last a sufficient time, and good for soldering on. When they get a bit used, I get a new one from the stash.
by Russ Elliott
Sat Apr 29, 2017 12:50 pm
Forum: Exhibitions
Topic: Scalefour Society AGM, 17 June 2017
Replies: 29
Views: 9130

Scalefour Society AGM, 17 June 2017

The North London Group is hosting this year's AGM. Details are here.
by Russ Elliott
Thu Apr 27, 2017 2:43 am
Forum: Guest Book
Topic: Flexi Chassis an Appreciation
Replies: 467
Views: 84321

Re: Flexi Chassis an Appreciation

Our beams do not stretch. It would take about 1.5kg to stretch a 100mm length of 0.012" guitar string by 1mm. We don't have those kind of longitudinal forces in our models. Our beams merely bend. All our beam curves are cubics. Taking the simple case of a single point load F midway between two ...
by Russ Elliott
Tue Apr 25, 2017 9:12 am
Forum: Guest Book
Topic: Flexi Chassis an Appreciation
Replies: 467
Views: 84321

Re: Whoops - small maths error

proto87stores wrote:The up/down sliding resistance for CSB's was 4 times higher moving upwards than downwards.

???
by Russ Elliott
Thu Apr 20, 2017 3:28 pm
Forum: Guest Book
Topic: Flexi Chassis an Appreciation
Replies: 467
Views: 84321

Re: Flexi Chassis an Appreciation

Andy - friction between the beam and the fulcrum points, and between hornblocks and hornguides, will influence the attainment of any equilibrium state, but this process does not fall into the phenomenon classed as hysteresis. We simply have a bunch of moving bits, and it is sensible to give them a s...
by Russ Elliott
Wed Apr 19, 2017 2:37 pm
Forum: Guest Book
Topic: Flexi Chassis an Appreciation
Replies: 467
Views: 84321

Re: Flexi Chassis an Appreciation

If I'm interpreting the photo correctly, it doesn't look to me as though the CSB is actually continuous. I think that configuration reduces to a rigid equalizing beam for the two driving axles with a virtual sprung fulcrum to the body/chassis and a separately sprung trailing axle. Andy - Ted's 'liv...
by Russ Elliott
Mon Apr 17, 2017 9:19 pm
Forum: Guest Book
Topic: Flexi Chassis an Appreciation
Replies: 467
Views: 84321

Re: Flexi Chassis an Appreciation

Interesting and useful figures, Zeb. The difference seems to be due to the deflection of the spring of the weighing pad. Yes. Manufacturers of scales (particularly pocket ones) never seem keen to state what their FSD distance is, or realise that the figure might be useful. Typically, as far as I can...
by Russ Elliott
Fri Apr 14, 2017 6:40 pm
Forum: Track and Turnouts
Topic: Conductor Rail Supports Kit
Replies: 51
Views: 11095

Re: Conductor Rail Supports Kit

I'm not sure one can draw a distinction between mainlines and secondary lines as far as conductor rail is concerned, and I've never been able to determine a rationale on what gets used and where. There's still plenty of 100lb/yard conductor rail on mainlines. Conductor rail doesn't wear much, but a ...
by Russ Elliott
Fri Apr 14, 2017 10:09 am
Forum: Track and Turnouts
Topic: Conductor Rail Supports Kit
Replies: 51
Views: 11095

Re: Conductor Rail Supports Kit

the price of the print would not change significantly and the etch must cost something I think we got 77 (an 11 x 7 array) of ear etch frames on a single sheet of 10 thou nickel. Each frame was sufficient for a CRS support pack. (Not quite sure exactly how many ears we got on each frame - I don't h...
by Russ Elliott
Fri Apr 14, 2017 9:11 am
Forum: Chassis and Suspensions
Topic: Articulated beams?
Replies: 84
Views: 17983

Re: Articulated beams?

I suggest that my style of loco building might have sufficient for purpose stability, and validity...? Of course, Julian. There are hundreds maybe thousands of 3-point (or 4-point, still quite popular in some 7mm kits) compensated locos which perform perfectly adequately, and which are stable, and ...
by Russ Elliott
Fri Apr 14, 2017 8:37 am
Forum: Track and Turnouts
Topic: Conductor Rail Supports Kit
Replies: 51
Views: 11095

Re: Conductor Rail Supports Kit

the rail must exert some kind of force on the clips and the reversal of stress which this causes on the glued joint must lead to failure eventually. Yes, I accept that there will be friction between the rail and the ear, depending on how tightly the ear is nipped up over the rail foot - the bond be...
by Russ Elliott
Thu Apr 13, 2017 10:41 pm
Forum: Chassis and Suspensions
Topic: COG and suspension calculation 4-6-0
Replies: 22
Views: 4511

Re: COG and suspension calculation 4-6-0

Jon, the HL TendeRiser etch is shown on the High Level site. Here's an extract from the drawing I did of Steve Duckworth's drive, as featured in a recent Snooze:

tenderiser-part.png
by Russ Elliott
Thu Apr 13, 2017 6:11 pm
Forum: Chassis and Suspensions
Topic: COG and suspension calculation 4-6-0
Replies: 22
Views: 4511

Re: COG and suspension calculation 4-6-0

It's (a), Jon.
by Russ Elliott
Wed Apr 12, 2017 11:06 pm
Forum: Chassis and Suspensions
Topic: COG and suspension calculation 4-6-0
Replies: 22
Views: 4511

Re: COG and suspension calculation 4-6-0

Most of the CLAG examples appear to avoid the issue of bogies. Any 0-6-0 solution can't posibly be valid. Yes, it can, Jon. Jol is correct. See http://www.clag.org.uk/beam-annex3.html#weight-relationships-between-CSB-and-non-CSB-sprung-components Changing tack completely, and in response to your OP...
by Russ Elliott
Wed Apr 12, 2017 10:48 pm
Forum: Chassis and Suspensions
Topic: Articulated beams?
Replies: 84
Views: 17983

Re: Articulated beams?

Yes, I think we are in furious agreement, Keith. I wasn't suggesting Andy's proposal was the 3-point principle. (Pivots on both sides are functionally equivalent to a torsion bar admidships.) Andy's proposal, as I understand it, is an equalised one: springy-equaliser3.png Not recommended for 4-wheel...
by Russ Elliott
Wed Apr 12, 2017 10:23 pm
Forum: Couplings
Topic: Alex Jackson couplings and Brassmasters CCUs
Replies: 8
Views: 3350

Re: Alex Jackson couplings and Brassmasters CCUs

I'm a big AJ fan, but one thing has always troubled me a bit - bogies on curves getting unwanted yaw moments. On wagons, with AJs at both ends, the turning moments tend to balance out, but observation of coaches, regardless of coupling type, has convinced me that bogie yaw freedom is crucial. aj-tur...
by Russ Elliott
Wed Apr 12, 2017 10:02 pm
Forum: Track and Turnouts
Topic: Conductor Rail Supports Kit
Replies: 51
Views: 11095

Re: Conductor Rail Supports Kit

For info, here is a comparison drawing of the positive supports for LT using heavy conductor rail and an SR support using lighter 100lb/yard section. (The Society does not do the lighter rail section, and the SR pots in the CRS pack are for the heavier rail section.) 3rd-rail-comparisons-LT-SR.png I...
by Russ Elliott
Wed Apr 12, 2017 9:36 pm
Forum: andrewnummelin
Topic: A railmotor or two - using the skills of others - etching
Replies: 13
Views: 5820

Re: A railmotor or two - using the skills of others - etching

Yes, sorry, by 'standard' (thickness) I meant common. And, as Howard himself noted, a thicker material can give decent half etch relief. A working drawing of the cross-section between wheel and cylinder centre will indicate what kind of thickness might be best.
by Russ Elliott
Wed Apr 12, 2017 12:34 pm
Forum: Chassis and Suspensions
Topic: Articulated beams?
Replies: 84
Views: 17983

Re: Articulated beams?

For a 2-axle chassis, this is an alternative configuration to the traditional fixed + rocking axle configuration. a-3jaa0p3u.jpg My impression from limited testing is that this alternative is more stable and requires less weight to stay on the track. I agree. It's like an MJT torsion-bar CCU, for e...
by Russ Elliott
Wed Apr 12, 2017 10:25 am
Forum: Chassis and Suspensions
Topic: Articulated beams?
Replies: 84
Views: 17983

Re: Articulated beams?

I wonder if you consider we have dealt with the issue of stability sufficiently? Probably not. In qualitative terms, lateral stability is easy to explain (we know a CofG towards the left improves lateral stability but gives a silly axle weight distribution, whilst one towards the triangle apex impr...

Go to advanced search