Member postings for SillyOldDuffer

No flaw really, the apparent paradox is caused by ignoring other factors - the weight of the train and the rolling resistance provide a load even when there are no passengers.

If the bearings had zero friction and the train was in a vacuum then there would indeed be no drawbar pull unless the train was accelerating. Once moving the train would carry on at the same velocity for ever.

Personal experience of measuring 'work' is counter-intuitive. When I hang by my arms from a climbing frame, the maths says that I'm not doing any work because I'm not moving. Why do I get so tired then? It's because muscles don't simply take my weight as a rope would. Instead they constantly tighten and relax slightly, doing work even though I think I'm still. No work is done when I sit on a swing suspended from the same climbing frame.

Dave

Edited By SillyOldDuffer on 03/09/2016 18:19:15

As we don't know exactly what was said to Russell or what Paypal's motives are the truth remains elusive.

I take your point about anti-fraud precautions and can confirm that a friend who lives abroad has been told that is exactly why his UK card was frozen - nothing to do with Paypal and/or Brexit, just tightening up.

However, in the US PayPal Holdings have said that Brexit will have some effect on its regulatory environment, so my suggestion wasn't pure speculation.

If Russell's change had been due to an anti-fraud precaution that's probably exactly what Paypal would have told him. Why shouldn't they? Saying it was something to do with the EU when it wasn't seems an unlikely fib for a Call Centre to invent.

My point however was that, good and bad, the Brexit snowball is already rolling. Assuming that nothing will change because we are still formally in the EU feels a bit like telling the wife you want a divorce and then expecting normal domestic services until a Court has confirmed you are single again.

On the whole I worry about the risks and cost of achieving Brexit. Perhaps I'm wrong. There's been some good news this week. British industry has done unexpectedly well since the referendum result. Long may it last!

Apologies to Russell for veering off his original question.

Dave

My ME hasn't arrived yet so I can't look at the numbers, boo hoo, but could the cause be due to bearing differences?

Regards,

Dave

This is how they they did things 50 years ago before CNC confused us with ethical concerns:

Severn-Lamb are an interesting discovery, new to me anyway. They still exist - shame their goodies look to be a bit beyond my means...

Cheers,

Dave

Perhaps some of the heat is because people may have very different motives for model engineering.

If your object is to demonstrate your personal skills, perseverance, craftsmanship and talent using classic methods, then techniques like laser cutting and CNC aren't for you.

If your object is to create the best possible model, then anything goes. CNC is just another tool in the armoury.  (Unless there are rules that forbid it.)

I find much to admire in both approaches, even though I don't aspire to either.

Dave

Edited By SillyOldDuffer on 02/09/2016 17:08:03

Hi Jim,

Is this what you are trying to produce? If so, how deep in mm is the head that needs to be gripped?

Ta,

Dave

Don't worry. If you're banished to the outer darkness over this I shall start a "Free the Fizzy One" campaign!

Best Wishes,

Dave

Thanks to Neil for taking the time to summarise his take on this.

Apologies if I missed a point already made in his two-part post but I would add that it's only cheating if you do it in a competition AND you deliberately break the rules of that competition.

Curiously enough my breakfast read today was the September 19th 1966 issue of Model Engineer. In it there is strong reaction to a claim by K.E. Wilson that: "the vast majority of prize-winning locomotives cannot even raise steam and haul their own tenders: I would make it compulsory for every engine that qualified for a prize of any sort to demonstrate its working powers before receiving any award". Presumably he felt there was a bias against his work in competitions.

The same issue contains the article "My Purley Locomotive Works" by LBSC. In it he describes his workshop. No CNC of course but I have to say LBSC was exceptionally well equipped. For instance he mentions three machines "which are the sole examples in this country, to the best of my knowledge and belief." I don't suppose anyone would suggest that LBSC owning and using better tools than average meant that he was "cheating".

Dave

Why do I only spot mistakes after hitting the button?

Edited By SillyOldDuffer on 02/09/2016 11:01:45

Many thanks for Stuckism - my latest word of the day.

Cheers,

Dave

I think fizzy started an interesting and informative debate. Surely he has the right to express his opinion about a technology of interest to Model Engineers without being accused of gross insensitivity, insolence, and contemptuous rudeness? Especially as he raised the issue in a way clearly intended to allow others to disagree with him.

Dave

This isn't a new idea. I read somewhere that the original lathe cross-slide was disparagingly called 'Maudsley's Go-cart' by the old timers of his day. They felt that use of a cross-slide devalued the skill they applied to the job and that quality was reduced. It was cheating.

I think it depends on what you're doing and why. I admire and respect craftsmanship but it isn't my main goal not least because it's time-consuming. And I think learning how to apply CNC is itself a significant skill. I wouldn't knock either approach.

I suppose it would be possible for judges to weight competition scores according to the tools used, e.g

• Model made with hammer and cold chisel : x10
• Model made with hacksaw, file and hand drill: x8
• Model made with Chinese lathe: x7
• Model made with Western lathe: x4
• Model made with British Lathe: x3
• Model made with British Lathe and Mill: x2
• Model made with CNC: x1
• Model made using industrial machine centre: x0.5

Cheers,

Dave

Although we haven't left the EU yet the intent to do so has been clearly stated.

There is no doubt that all the organisations who will be effected by the change are adapting to the impact of the announcement as well as preparing for the formal exit . Even though we have not even started the exit process, the fall in the value of the pound, the rise in the rate of inflation, and the most recent reduction in the bank rate are all issues that businesses have to manage immediately.

Paypal is registered as a bank in Luxembourg. EU financial regulation applies to all this bank's operations in the EU. Leaving the EU means that the UK will no longer be covered by this regulatory arrangement so an alternative will have to be set up. It is likely that the process to do this has already started, and that it might well include tidying up customer arrangements that cross the future border, which is what Russell has been doing.

No-one should be surprised that Brexit is already starting to make a difference or that some of what happens next will be painful.

Dave

Edited By SillyOldDuffer on 31/08/2016 20:48:05

I can't resist a thought experiment.

Say the test track is 1000m long from start to finish and rises 10m over that distance.

If the engine pulls the dynamometer and train up the incline, the engine will have to:

1. overcome the rolling resistance of the train,
2. lift the mass of the train 10m up,
3. lift the mass of the engine itself up 10m.

I suggest that because the dynamometer measures drawbar pull it won't 'see' the work done by the engine lifting itself up the incline. If that's true (?) then the dynamometer will read low because part of the total work being done by the engine is invisible to the dynamometer.

Moving on, what happens when the engine pulls the train down the same incline?

Once again the engine has to overcome the rolling resistance of the train but, as seen by the drawbar, the rolling resistance will be apparently lower. This is because the train now has 10 metres worth of potential energy available. I suggest that in this case the dynamometer reads true but we get a result lower than the engine is actually capable of.

An extreme downhill scenario is that the potential energy of the train is high enough to push the engine down the track with the engine's wheels skidding. Dynamometer readings wouldn't mean much if that happened.

Going back to my "is that true" question, I remember getting confused at school about 'every force has an equal and opposite reaction' when applied to a train or horse and cart in motion. I'm very happy to be corrected if my assumption about what the drawbar 'sees' is wrong, which it could well be.

A nice level track would eliminate these questions. How sad that we live in the real world and have to work with what we've got!

Dave

I think it would depend on how accurate you want the result to be, and whether the refinement is justified given the other sophistications that would be needed to maintain accuracy. (For example, Duncan's comment about oscillation is interesting.)

One problem with a dynamometer towed by an engine is the track. Curves, up gradients, down gradients, track condition, and points will all have an effect that could be allowed for.

I'm not sure it's worth it though, and in the case of running round a loop the effect of uphill and downhill sections would tend to cancel out.

If the test were run on a straight track it might be easier to survey the rise and fall of the track and use the data apply a correction to the dynamometer results.

The GWR had a rolling road dynamometer at Swindon for which they claimed great things. The rolling road made it possible to eliminate most track variables to get more accurate results. It's not the whole story though, although a rolling road gives cleaner data, it is still useful to measure locomotive performance on a real journey where a wider range of conditions might show something else up.

With a steam engine, the fuel, skill of the stoker, and skill of the driver are an awkward set of variables. You might have fixed the track and built the ideal dynamometer only to find that the driver is a badly hungover clown. (Surely not!)

Analysing the reasons for wanting a dynamometer in the first place might help. For example:

• A requirement to measure output and efficiency for design purposes implies good accuracy for which a standardised track or rolling road might be essential
• A dynamometer that can be pulled by any engine on any track at any time and still give accurate results at all times is a worthy challenge.
• Comparing the power output of two engines or two runs of the same engine on the same track is much less demanding.

Please let us know how you get on. It's an interesting subject.

Cheers,

Dave

PS Meant to say, if you can easily capture both pull and push data you might as well.  Post-processing would let you ignore it or take it into account, or both. 

Edited By SillyOldDuffer on 30/08/2016 12:08:58

Edited By SillyOldDuffer on 30/08/2016 12:12:59

Edited By SillyOldDuffer on 30/08/2016 12:13:50

The ways of the internet defeat me sometimes. I'd searched before. Definitely no 6mm button oilers to be found anywhere. I'd bet the farm on it.

Just tried again,. Guess what - ArcEuroTrade do them.

Perhaps it's me...

Ta,

Dave

Just read the other good ideas which came in while I was typing. I'm almost tempted to put the ball back to see if they work too!

Cheers,

Dave

Neil and Roy,

My heroes!

Neil's rod and grease trick wasn't quite sticky enough to lift the ball cleanly out, but I was able to get the bearing out of the narrow oilway and into the oiler well. Grease dislodged whilst fishing about stopped the ball bearing falling back and then I was able to get it with the magnet.

I think my earlier magnet only attempt failed because a ball deep inside an oilway is surrounded by iron which also gets magnetised.

Many thanks,

Dave

By applying excessive oil pressure to a 6mm button oiler on my cross-slide I pushed the oiler's ball bearing past the spring and out the other side of the casing. I shall be pleading guilty at the court-martial.

After removing the button oiler I can see that the ball bearing has fallen into the top of the oilway, which leads straight down to the ways. The ball rotates in the hole so it's not jammed solid but, so far, I can't get it out.

I've tried levering the ball with a needle, attracting it with a magnetised rod, flushing with WD40 and blowing compressed air from underneath. No luck.

I would prefer not to remove the cross-slide until all else has failed. Can anyone suggest a solution please?

Secondly, can anyone suggest a source of 6mm diameter button oilers? RDG and various ebay suppliers don't seem to stock that size.

Thanks,

Dave

Another thought, sometimes it's useful to calculate the geometric mean. On the dangerous assumption I got the sums right, the geometric mean of 1+2 is 1.414 (-ish)

So depending how you do it, the mean of 1+2 could be 1, 1.414, 1.5 or 2

I think it was muzzer in another thread who warned against over thinking things...

Dave

Edited By SillyOldDuffer on 28/08/2016 17:22:50

Edit It was a dangerous assumption that I'd get the sums right: the square root of 3 is 1.732, not 1.414.  Serves me right for trying to be a smarty pants.

Edited By SillyOldDuffer on 28/08/2016 17:26:40

I hope 'not done it yet' explains because he's set me wondering too!

I guess he may have been thinking about rounding when he wrote " The simple maths principle". In that case 1.5 would round up to 2.

After repeatedly being caught out by BODMAS as a programmer I started to use brackets galore. Colleagues good at maths were always annoyed by unnecessary brackets but it reduced the embarrassing numeric accidents I kept having!

Dave