EM wheels on P4 track

[John Fitton]

Unfortunately, Martin has not proved the concept publicly, merely postulated it. Burford is a permanent layout, so we cannot see the layout perform under exacting exhibition conditions.

Perhaps a demo at Scaleforum/the AGM where it can be properly scrutinised by a number of other modellers (step forward Terry)?

This all seems a bit silly to me. We must have all moved to P4 because the track and wheels look so much better than OO/EM. I know I did. Since I can buy virtually perfect P4 wheels from the few remaining manufacturers to run on my less than perfect track, why the heck would I abandon my original premise and switch to EM wheels, and suffer such an incredible hassle of re-inventing my own set of standards?

No answer required of course. P4 is tops with me - not interested in using coarse scale wheels on finescale track.

John

[martin goodall]

As I have clearly stated in the past, if you are perfectly happy with P4 standards and your stock never falls off the rails, then you don't need to consider making any changes.

I was not entirely satisfied, so I started experimenting.

[jim s-w]

I have always believed in the old adage "Horses for courses", which basically means that rolling stock should be built or adjusted for use on a specific layout.

Hi Martin

I prefer the goal of all stock goes all places. My stuff has run on our test track, Amlwch, Mostyn and Moor Street. Add in Calcutta sidings 2 (underconstruction but to go on the road before new street) and some of my stock will be on thier 6th layout by the time New Street hits the road. Provided everything is built to a consistant standard it should work regardless. Indeed, by the time new street is properly tweaked I would expect any stock built to p4 standards to work on it. Your stuff (as, if I read correctly, is less tollerant than normal p4 stock. Especially with regards to check rails etc) would possibly help debug my point work just that little bit more than normal p4 stock.

Ultimately my invite is just an excuse to play trains!

Cheers

Jim

[martin goodall]

[Your stuff (as, if I read correctly, is less tollerant than normal p4 stock. Especially with regards to check rails etc) would possibly help debug my point work just that little bit more than normal p4 stock.

My EM-profile wheels have never had any problem with P4 check rails and wing rails, for the simple reason that these wheels are set to the P4 back-to-back. It slightly puzzles me (and is the source of some amusement) that everyone who queries whether there might be clearance problems with these wheels focuses on the backs of the wheels - the one place where no problem can occur, because the wheels are set to the same BB dimension as any P4 wheelset.

Where a problem could possibly arise is on the outside of the flange. I have proved to my own satisfaction that there will be no problem in practice, provided that the track really is laid to a minimum gauge of 18.83mm. I thought mine was, until I start testing these wheels and found several tight spots. Re-checking with a roller gauge confirmed that the track was under-gauge in some places, and this was readily remedied. The reason that this had not shown up previously is that the BB setting for P4 wheels is actually slightly under-gauge, and so they are quite forgiving of track which may be slightly less than 18.83mm gauge, whereas EM-profile wheels do require the full 18.83mm to run smoothly on P4 track.

[martin goodall]

P.S. I forgot to say that I am seriously tempted by the invitation to play trains on BNS at Scaleforum!

[Russ Elliott]

Martin - you forgot to mention the other crucial reason/condition why your wheels work on P4 track - namely that their flange thicknesses are in the close vicinity of 0.5mm.

[craig_whilding]

Where a problem could possibly arise is on the outside of the flange. I have proved to my own satisfaction that there will be no problem in practice, provided that the track really is laid to a minimum gauge of 18.83mm. I thought mine was, until I start testing these wheels and found several tight spots. Re-checking with a roller gauge confirmed that the track was under-gauge in some places, and this was readily remedied. The reason that this had not shown up previously is that the BB setting for P4 wheels is actually slightly under-gauge, and so they are quite forgiving of track which may be slightly less than 18.83mm gauge, whereas EM-profile wheels do require the full 18.83mm to run smoothly on P4 track.

Which B2B do you mean as its quite a large range specified and not one value. I think it is widely recognised now though that 17.75mm is the one to aim for and not use the earlier 17.67mm b2b gauges. S4 obviously needs you to aim for the 17.87mm maximum..

Its always worth checking with a nice one piece roller gauge though where you know a b2b can't be affecting the test.

[Philip Hall]

Craig Whilding wrote:
I think it is widely recognised now though that 17.75mm is the one to aim for and not use the earlier 17.67mm b2b gauges.

I've always thought that in setting the B-B to the maximum value, it's important that wheels don't wobble, but we all know that with the best will in the world, they do sometimes. So I feel a bit of play between the wheels and the track helps no end. When I started in P4, I experimented a little, and worked out that if I had wheels set to the maximum B-B, a slight wobble could put the outer edge of the flange in contact with a crossing nose, so I had a gauge machined up at 17.7mm and have used this dimension ever since.

Philip

[craig_whilding]

Craig Whilding wrote:
I think it is widely recognised now though that 17.75mm is the one to aim for and not use the earlier 17.67mm b2b gauges.

I've always thought that in setting the B-B to the maximum value, it's important that wheels don't wobble, but we all know that with the best will in the world, they do sometimes. So I feel a bit of play between the wheels and the track helps no end. When I started in P4, I experimented a little, and worked out that if I had wheels set to the maximum B-B, a slight wobble could put the outer edge of the flange in contact with a crossing nose, so I had a gauge machined up at 17.7mm and have used this dimension ever since.
Philip

Indeed which is why I said the mid point is the normal for P4, Exactoscale sell their gauge at 17.75mm now which is pretty much the middle of the P4 range so people can just use that now. I guess if you were working to S4 then the wheel wobble is something you'd need to pay more attention to as its all tighter tolerances again.

[Terry Bendall]

I have always believed in the old adage "Horses for courses", which basically means that rolling stock should be built or adjusted for use on a specific layout.

Jim added

I prefer the goal of all stock goes all places. My stuff has run on our test track, Amlwch, Mostyn and Moor Street. Add in Calcutta sidings 2 (underconstruction but to go on the road before new street) and some of my stock will be on thier 6th layout by the time New Street hits the road. Provided everything is built to a consistant standard it should work regardless. [/quote]

Jim is of course quite right. P4 is a set of standards and if a vehicle is built to those standards, and the track is built to those standards then any item of P4 stock should run on any piece of P4 track. (This of course assumes that other viables such as concentric wheels and appropriate suspension/compensation are "working2.) Like Jim, stock that I have built has run on other layouts and we have borrowed stock to run on ours.

So. if Martin's idea is viable, his stock with EM wheels set to the P4 back to back should work on Jim's track. So let's see it happen at Scaleforum. If there is a problem with couplings, I am sure that Jim or Martin can use modern prototype practice and use a barrier vehicle with Martin's coupling on one end and one suitable for one of Jim's locos on the other. If it works, we will all be interested, but if it doesn't ..... ?

Terry Bendall

[Tim V]

Of course, there is always a test run on Clutton, 3' radius curves, challenging twists in the track.

Martin should bring a complete train - engine and stock.

Happy hour is at about 16:00 Saturday

[HowardGWR]

You don't have to wait until then Tim and Martin. You only live about 3 miles away from each other as does Robin Gay and a load of other P4 adherents. Why not have a joint NWSEMGSAG / Scalefour Bristol AG meeting? I'd go all the way up to Bristol for that one. Better hire the Colston Hall.
All the best, Howard

[martin goodall]

Martin - you forgot to mention the other crucial reason/condition why your wheels work on P4 track - namely that their flange thicknesses are in the close vicinity of 0.5mm.

Yes. That's absolutely right. EM wheels from Ultrascale, Kean-Maygib and Alan Gibson would all appear to have a flange thickness of about that value. Clearly, you would begin to have problems with wheels having a flange thickness significantly greater than 0.5mm.

I think I have done the sum before, but assuming a flange width of 0.5mm the overall width of one of these EM wheelsets set to the P4 back-to-back gauge is 0.5 + 17.7 + 0.5 = 18.7. Those who set greater store by technical theory than I do get worried about the reduced running clearance compared with an orthodox P4 wheelset, but my own experience with these wheels is that this is not a problem. This is where actual experiment with real models on a real layout wins out over theoretcial calculations - my 'suck-it-and-see' approach, which clearly makes some perople rather unhappy.

[martin goodall]

Which B2B do you mean as its quite a large range specified and not one value. I think it is widely recognised now though that 17.75mm is the one to aim for and not use the earlier 17.67mm b2b gauges. S4 obviously needs you to aim for the 17.87mm maximum..

Its always worth checking with a nice one piece roller gauge though where you know a b2b can't be affecting the test.

Provided the B2B is within the P4 tolerances (17.67 to 17.75mm), there shgould be no problem. According to my vernier gauge, the P4 B2B gauge I use (supplied by Studiolith more than 35 years ago!) is 17.7mm wide.

Interestingly, if you do the sum I did earlier, but applying it to P4 wheels set to the "Scale Four" B2B gauge, you get 0.4 + 17.87 + 0.4 = 18.67mm. This, again, ought to give the theoreticians palpitations, but Ray Hammond and others can confirm that they have used the "Scale Four" standards with complete success for many years.

[Tim V]

You don't have to wait until then Tim and Martin. You only live about 3 miles away from each other as does Robin Gay and a load of other P4 adherents. Why not have a joint NWSEMGSAG / Scalefour Bristol AG meeting? I'd go all the way up to Bristol for that one. Better hire the Colston Hall.
All the best, Howard

Are you paying for the hire of the hall Howard?

Much better at Scaleforum, in front of a large (?) crowd.

[grovenor-2685]

Google translate renders this as

I apologize. Sorry that is not the topic, only registered, but where to read the rules for the creation topics?

Just go back to 'Guestbook' and click on 'New Topic'
Regards
Keith

[martin goodall]

Might the 'mistaken' post in Russian possibly be some kind of spam?

I am not well-versed in viruses and Trojans, but whoever looks after web security might like to run a scan.

[Andrew Ullyott]

You don't have to wait until then Tim and Martin. You only live about 3 miles away from each other as does Robin Gay and a load of other P4 adherents. Why not have a joint NWSEMGSAG / Scalefour Bristol AG meeting? I'd go all the way up to Bristol for that one. Better hire the Colston Hall.
All the best, Howard

Are you paying for the hire of the hall Howard?

Much better at Scaleforum, in front of a large (?) crowd.

Ah yes, I can picture the scene... bit like a fistful of dollars, but with trains. Better make that 'a fistful of flanges' then
cue music
two skilled modellers with a steely eye staring at each other from opposing ends of a piece of track
It's 18mm plus, but plus what?
the crowd will scuttle for cover behind associated trade stands, where Mr Lewis will probably catch the the unwary and try to sell them something
time slows... (logarithmically or in linear proportion or does it?
the combatants place their chosen implement
the crowd gasps

...cor exciting or what?
Can't wait!!
p.s can you cheer on both sides at the same time?
p.p.s really had to resist the urge to go bananas with the smilies
p.p.p.s probably shouldn't have had that last bottle of Thatchers Old Rascal

[martin goodall]

I assumed you had been drinking Strangler's Old Misty, Andrew.

Joking apart - as I mentioned before, I am not out to prove anything, so any 'High Noon' scenarios really aren't my thing.

I might take up Jim's kind offer to try out some EM-wheeled stock on BNS, although I have been known in the past to turn up at Scaleforum having left intended stock behind 150 miles away!

[P.S. In case anyone is not aware, Howard, Andrew and I are all members of the same area group - er, of the EMGS, that is. Hence the ribaldry.]

[jim s-w]

Hi Martin

As its just a demo you cant run very far I am afraid, But if anyone wants to bring things for a play of just to pose for a piccie or two they will be welcome. Only proviso is that locos are DCC and P4 (obviously)

Cheers

Jim

[Wenbridge]

Just as an irrelevant aside (I'm good at those) this tickles me as in my 1/32 G1 world I am for the moment largely looped in to the "Goodall compromise" (if I may call it that) as the best wheels generally available are G1F profile (equivalent to decent EM) which I am running over P4 equivalent track albeit with their back to backs suitably tweaked.

It does work but it doesn't look anywhere near as good as the "genuine article". Oh for a supplier in G1 which was the equivalent of so many that serve the 4mm modeller.....

Simon Castens

[martin goodall]

Thanks, for joining in, Simon (and best wishes to the Titfield Thunderbolt in your new shop).

I can well understand that you can see the difference in the size of the wheel flanges in Gauge 1.

However, in 4mm scale the difference between a modern EM wheel flange and a P4 flange is hardly noticeable, unless the viewer is one of those people who goes in for 'nose-grinding'. 'Coarse-scale' 00 wheel flanges are a different matter, of course.

I often think that we tend to look at our models far too closely, and should see rolling stock as an integral component of the layout as a whole. So the visual appearance of wheel flanges should be judged from 'a normal viewing distance' (i.e. a couple of feet away as a minimum) in the context of the entire modelled scene.

(Discuss !)

[jim s-w]

Hi Martin

This is the era of digital photography. Most layouts are seen online now not at shows and 'normal viewing distance' is closer to a few inches these days than a few feet.

Cheers

Jim

[martin goodall]

I take Jim's point, and Birmingham New Street is an excellent example of what he is saying, with some really stunning photos which have appeared on this forum.

But Jim's note prompted me to bowse through his BNS photos again, paying particular attention to wheel flanges, and I have to say that even in these fairly close and very detailed shots (which really do capture the true character of the subject), I could not really see the wheels in sufficient detail to be able to tell what profile they are. I suggest that identical photos of EM-wheeled stock would look no different.

(I suppose Jim's photos probably still come within my definition of 'normal viewing distance', although clearly taken from rather closer than the 2-foot distance I mentioned earlier.)

[jim s-w]

Hi Martin

Diesels are the best case scenario for hiding wheels though. If it was steam locos, Hydralic locos such as a western or Warship or something like a voyager (220) then the difference would be very much more obvious. Having said that given the clearances people mention on P4 steam locos with outside valve gear I would imagine an EM wheel at P4 back to back would make life even more difficult.

Cheers

Jim