24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

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Knuckles
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24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Knuckles » Fri Jun 03, 2016 9:49 am

As the title suggests does anyone know where I could get these?

24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

I've been building the K2 with 14mm throw which explains why I had to file a wee bit of plastic off. Alan sold the 13mm ones but as a numpty I didn't buy them, will do from now on.
However, ideally I need 12" throw as that is what all the 21 / K2 Class drawings I have seem to indicate. I haven't found it in written form.

Would like to build the chassis with the correct wheels next time!

After checking Alan Gibson's catalogue he doesn't seem to do them in P4 or 00. :? Romford doesn't specify their 00 range.
Any ideas?
“He who dares not offend cannot be honest.” Thomas Paine

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Noel
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Noel » Fri Jun 03, 2016 10:23 am

Knuckles wrote:However, ideally I need 12" throw as that is what all the 21 / K2 Class drawings I have seem to indicate. I haven't found it in written form.


According to Wikipedia and Steamindex.com, the cylinders on a K2 were 18" x 24". As the crankpin throw equals one half of the cylinder stroke, 12" throw is apparently correct.
Regards
Noel

Knuckles
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Knuckles » Fri Jun 03, 2016 11:18 am

Didn't know that but will note it for the future. Thanks. At least the drawings in this case can be trusted it seems. :shock:

Any idea where they may be available?

As far as I know you have Markits/Romford - fine if you want 00, bad if you don't know what other prototypes had similar matching throws.
Alan Gibson - Great...except they don't always do what you want, even though the range is huge. No pleasing some is there!
Exactoscale - On the C&L Website they don't do the wheels I'm after, plus they only P4 (fine for me but not others) and they cost a lot.
Ultrascale - Also expensive and require you growing a beard if you don't already have one - they don't sell what I am looking for either.

I can get by but really would prefer doing things a bit more accurately.
I got no idea of other wheel companies currently.

:-|
“He who dares not offend cannot be honest.” Thomas Paine

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grovenor-2685
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby grovenor-2685 » Fri Jun 03, 2016 5:53 pm

As the crankpin throw equals one half of the cylinder stroke, 12" throw is apparently correct.

Note that that statement is not always true for inside cylinder locomotives. The rule applies to the throw of the crank axle but the throw of the crank pins for the coupling rods can be equal to the crank axle throw or not as the designer saw fit.

For outside cylinder locos the rule always applies. But even here I seem to remember reading of the odd case where the throw of the connecting sods and coupling rods was made different by having stepped crankpins that were not concentric.
Regards

Knuckles
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Knuckles » Fri Jun 03, 2016 6:59 pm

The drawings measure out at about 4mm, not found written proof but I trust the 12" conclusion.

I'm guessing no one knows where we could ideally get the correct throw wheels. Also wondering if Alan Gibson would be willing to make them.
“He who dares not offend cannot be honest.” Thomas Paine

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Mostly offering Loco kits & bits in 4mm.
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Alan Turner
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Alan Turner » Fri Jun 03, 2016 10:04 pm

Knuckles wrote:The drawings measure out at about 4mm, not found written proof but I trust the 12" conclusion.

I'm guessing no one knows where we could ideally get the correct throw wheels. Also wondering if Alan Gibson would be willing to make them.


He does a 6' - 20 spoke with a 13" throw. Can you really discern a difference of 0.3mm?

regards

Alan

Knuckles
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Knuckles » Fri Jun 03, 2016 10:50 pm

I can see a 0.3 difference very easily in all honesty. When I'm modelling a difference of less than that can bother me greatly and then it becomes a focal point I cannot ignore. That's not to say I'm a great modeller or anything but I do see the differences, 0.1 in the right place can look huge.

I'll be buying the 13" to try them out as I have been using 14" for the last two builds so will see.

I have in the past brought 3' bogie wheels from Alan Gibson and they measured to be 11mm's when they should be 12 so I know the measurements are not always scaled bang on.

The other reason I want a more accurate 12" throw wheel is because I can then reduce the height of the coupling rod splashers on the models as they are currently about 1mm too tall and to my eye at least the profile difference is noticable.

Will see how the 13" ones measure up and look etc. Looks like I got no choice yet. Just trying to improve things wherever I see an opening.
“He who dares not offend cannot be honest.” Thomas Paine

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Jol Wilkinson
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Jol Wilkinson » Sat Jun 04, 2016 6:58 am

Differences in dimensions are more noticeable when they can be judged against adjacent items. So a splasher that is 1mm too high may be obvious against the surrounding parts, but I expect .33mm may not be so obvious for crankpin throw. I have some locos that have marginally smaller than prototype wheels (we can always say the tyres are worn) but it isn't obvious to my eyes and no one else has yet commented on it.

Much of our modelling is about compromise and this is one point where it seems you have no option.

Knuckles
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Knuckles » Sat Jun 04, 2016 7:46 am

:|
Yeah, I think you are right and I will have to concede here. Will order the 13's and do some comparisons.

Without trying to derail the thread this wheel size issue has been driving me nuts on the J1 as you know. Alan sells 5' 8" wheels and 5' 6" so to represent 5'7 and a half I guess the former would be right....but then the latter is seen in most books and may be the nominal worn measurent as you and a few others taught me before. As a result I have been working on a chassis for both with the though of ditching one at the last minute when I finally make my mind up!
“He who dares not offend cannot be honest.” Thomas Paine

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dal-t
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby dal-t » Sat Jun 04, 2016 9:05 am

Sounds like you need to have a quiet word with that nice Mr Bedford, who in the past has announced that he has a cunning plan to make accurate wheels available for almost any class you care to mention - but meanwhile, welcome to the world the rest of us have to live in, where as Jol says we accept compromise, choose the nearest product available, and wait to see if anyone complains because there are 20 spokes instead of 19, or the crankpin is inline rather than between ...
David L-T

Knuckles
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Knuckles » Sat Jun 04, 2016 9:29 am

Aye. I'm not new to compromise, but the less we can get away with the better.
“He who dares not offend cannot be honest.” Thomas Paine

http://www.shapeways.com/shops/sparksho ... eationsscc
Mostly offering Loco kits & bits in 4mm.
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andrewnummelin
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3D printing for 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw?

Postby andrewnummelin » Sun Jun 05, 2016 7:33 am

I've seen on Shapeways web site that someone has produced a driving wheel in "steel" http://www.shapeways.com/product/GRVUZLGTX/57-inch-13-spoke-wheel-ho-thin-spoke?optionId=42096482 and I believe similar has been done in brass.

Has anyone any information on:
- can one achieve a ready to run quality with this technology?
- are these products strong enough to withstand finishing off in a lathe?
- can one achieve a finish good enough to fit a commercial P4 tyre to a 3D printed centre?
Regards,

Andrew Nummelin

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grovenor-2685
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby grovenor-2685 » Sun Jun 05, 2016 7:52 am

Pricing not bad, might be worth buying one to try?
Regards

Philip Hall
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Philip Hall » Sun Jun 05, 2016 8:33 am

David Lane of this parish has had Modelu produce a centre for a Manning Wardle wheel to fit an Exactoscale tyre, so it is possible to produce a centre in plastic/resin that is of the required standard. Perhaps David can confirm this? If the centre is metal then it ought to be strong enough to machine, so long as you have the lathe and the skills.

Philip

David Bigcheeseplant
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby David Bigcheeseplant » Sun Jun 05, 2016 11:24 am

Yes I got Modelu to print some Manning Wardle centres, the issue is getting tyres, I used Exactoscale tyres that C&L supplied then worked backwards making the centres fit the tyres. If are able to turn up your own tyres then there centres are not a problem as long as you can you 3D drawing software, I used Autodesk Inventor, which is what I use at work.

David

Winander
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Winander » Sun Jun 05, 2016 9:54 pm

David Bigcheeseplant wrote:Yes I got Modelu to print some Manning Wardle centres


David,

Do you recall what material they were printed in?

thanks
Richard

Knuckles
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Knuckles » Mon Jun 06, 2016 2:47 pm

Making custom wheels indeed is an option. As has been stated the tyres are the biggest issue besides printing material choice.
Ideally though if a mainstream vendor such as Alan Gibson would take up these then we could all easily use them. I guess it is a supply and demand issue more than anything else, I think Alan's range is very comprehensive as it is in all fairness so I may be that wee cricket chirping in the corner.
“He who dares not offend cannot be honest.” Thomas Paine

http://www.shapeways.com/shops/sparksho ... eationsscc
Mostly offering Loco kits & bits in 4mm.
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download/file.php?id=19320

Crepello
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Crepello » Tue Jun 07, 2016 1:41 pm

It is a bit disappointing to have to rely on tyres supplied as a favour rather than being listed as a catalogue item. Doesn't reassure, that they might not be forthcoming for a subsequent project.

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grovenor-2685
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby grovenor-2685 » Tue Jun 07, 2016 1:46 pm

If the worst comes to the worst you could always buy a set of wheels and remove the centres!
Once upon a time Studiolith did supply tyres for this sort of purpose.
I have examples of both the above running.
Regards

Philip Hall
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Philip Hall » Tue Jun 07, 2016 2:00 pm

i think it is fortunate than sometimes our suppliers are able to accommodate a request for parts rather than the complete item. To offer wheel tyres as a separate item as standard is not a realistic option, not least because the variations are almost endless; the margin on just a set of tyres is too small set against the hassle of packaging for sale. It also depends on the method of manufacture - whether the tyre is intended to be pushed on to the centre, or the centre designed to be moulded into the tyre.

Now there seems to be a viable alternative for wheel centres, 3D printing, of more interest would be the durability of the material used and its resistance to the common lubricants we use. How stable is it and is there any chance over time of shrinkage?

My philosophy these days is to get the crank throw as near as possible because when the engine is moving along the illusion of the road and gear moving is important. Whilst the engine is moving it is impossible to tell how many spokes there are or if they are in the right place, although I do try here as much as I can.

Philip

Crepello
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Crepello » Tue Jun 07, 2016 3:23 pm

Philip Hall wrote:Now there seems to be a viable alternative for wheel centres, 3D printing, of more interest would be the durability of the material used and its resistance to the common lubricants we use. How stable is it and is there any chance over time of shrinkage?

It's precisely from this that springs frustration, if tyre availability cannot be relied on. The answers to your concerns won't be determined without tyres to place the wheels into service.

Philip Hall
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Philip Hall » Tue Jun 07, 2016 7:56 pm

I don't think there will ever be a time where tyres will be available as a standard range from a manufacturer. Agreed, it undoubtedly frustrates the process, but the only viable alternative at the moment is to have tyres custom made for each application, which I suspect would actually cost many times more than we are used to paying for a complete set of wheels. Added to that is the fact that our principal 4mm scale wheelwrights are already incredibly busy with their current ranges, and that is where we came in with a favour being done.

I am interested in the materials used for 3D simply out of curiosity; I am fortunate to be able to get a wheel for most prototypes I need, or close enough. Whilst a lathe owner, my skills at present do not run to turning tyres even if I had a form tool. And if I did, my little lathe isn't really man enough for such a job.

Philip
Last edited by Philip Hall on Tue Jun 07, 2016 9:47 pm, edited 1 time in total.

Alan Turner
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby Alan Turner » Tue Jun 07, 2016 9:17 pm

Philip Hall wrote::shock: I don't think there will ever be a time where tyres will be available as a standard range from a manufacturer. Agreed, it undoubtedly frustrates the process, but the only viable alternative at the moment is to have tyres custom made for each application
Philip


The solution is to simply buy the wheel of the diameter required from AG, pop the centre out and replace with your 3D printed centre.

I would bet that the cost of some wheels is going to be a lot cheaper than commissioning bespoke wheel tyres.

regards

Alan

David Knight
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby David Knight » Tue Jun 07, 2016 11:33 pm

Alan Turner wrote:
Philip Hall wrote::shock: I don't think there will ever be a time where tyres will be available as a standard range from a manufacturer. Agreed, it undoubtedly frustrates the process, but the only viable alternative at the moment is to have tyres custom made for each application
Philip


The solution is to simply buy the wheel of the diameter required from AG, pop the centre out and replace with your 3D printed centre.

I would bet that the cost of some wheels is going to be a lot cheaper than commissioning bespoke wheel tyres.

regards

Alan

Very true. An example would be the highly anticipated Peckett from Hornby. AGW has the 12.6 mm bogie wheels from the Warship which are well within wear limits for size. Turn down the Hornby wheels, pop on the AGW tyres, done and dusted (well, maybe not that easy but near enough).

Cheers,

David

dal-t
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Re: 24mm's / 6' Wheels 20 Spoke with 12" Crankpin Throw

Postby dal-t » Wed Jun 08, 2016 7:39 am

Aren't AG tyres now 'locked' to the centres, or did I misunderstand that bit?
David L-T


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