profiling EM wheels to P4

DougN
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Re: profiling EM wheels to P4

Postby DougN » Mon Dec 10, 2012 3:54 am

Sorry Tim I have this vision of an intravenus file.. :o and can almost hear at the emergency room.... Now explain to me what you were doing to have the file inbeded under the skin on your right forearm.??
Doug
Still not doing enough modelling

martin goodall
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Re: profiling EM wheels to P4

Postby martin goodall » Mon Dec 10, 2012 10:23 am

jasp wrote:Is there anyone out there willing and able to re-profile 4 bogie wheels?
I have some 2'-6" Sharman wheels purchased many years ago. They appear to be 00/EM, presumably supplied in error and not checked by me at the time.
I have been unable to find a small enough wheel to replace these.
Jim


Mike Sharman himself advised that his Type 'B' wheels (EM/00-finescale profile) would run on P4 track, and that was 30 years ago. Why not just set these wheels to the P4 B-B gauge and see what happens? I strongly suspect that you are worrying about something that isn't actually a problem.

billbedford

Re: profiling EM wheels to P4

Postby billbedford » Mon Dec 10, 2012 11:11 am

All Sharman wheels (including the 'P4' ones) were 2.3 mm wide instead of a scale 1.8 mm.

martin goodall
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Re: profiling EM wheels to P4

Postby martin goodall » Mon Dec 10, 2012 12:22 pm

billbedford wrote:All Sharman wheels (including the 'P4' ones) were 2.3 mm wide instead of a scale 1.8 mm.


Clearly the width of Mike Sharman's wheels has not been a problem for people working in P4, or we would have heard about it - they were very widely used at one stage, and it is only their non-availability in more recent years that has led to people seeking out alternatives.

The 'standard' EM wheel is 2.5mm wide over the tyre, and these are OK in most appications in P4, although on an outside-cylinder engine, it might be better to use wheels that are no more than 2mm wide, unless you ease out the cylinders slightly to get the necessary clearance.

Clive Impey
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Re: profiling EM wheels to P4

Postby Clive Impey » Mon Dec 10, 2012 12:33 pm

There is an article in Scalefour News number 5 (its in the archive) by Ray Hammond on reprofiling Sharman 00/EM wheels to P4. What Ray did was to remove 0.5mm from the back of the wheel; doing anything to the flange being optioinal.
I think that Roye England produced finer drivers for early Pendon locos by rubbing the wheel backs on abrasive paper - you might like to try this it would be much safer than a minidrill and file.

Clive lincs

Alan Turner
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Re: profiling EM wheels to P4

Postby Alan Turner » Mon Dec 10, 2012 12:45 pm

The original Sharman instructions advised that 12 thou was removed from the back by rubbing on fine emery paper.

Alan

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grovenor-2685
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Re: profiling EM wheels to P4

Postby grovenor-2685 » Mon Dec 10, 2012 12:52 pm

The 'standard' EM wheel is 2.5mm wide over the tyre, and these are OK in most applications in P4,

Except that, for me, it defeats the primary objective of modelling in P4.
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Keith
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Tim V
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Re: profiling EM wheels to P4

Postby Tim V » Mon Dec 10, 2012 4:53 pm

DougN wrote:Sorry Tim I have this vision of an intravenus file.. :o and can almost hear at the emergency room.... Now explain to me what you were doing to have the file inbeded under the skin on your right forearm.??

It didn't happen to me!

All machine tools should be treated with caution. Properly used machine tools are fine. Do not consider using needle files (without a handle) anywhere near rotating machinery.
Tim V
(Not all railways in Somerset went to Dorset)

Philip Hall
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Re: profiling EM wheels to P4

Postby Philip Hall » Mon Dec 10, 2012 7:35 pm

Mike Sharman used the same tyre width for EM/00 as for P4, so what you got was a wheel that was a trifle slim for the EM standard, and a trifle fat for P4. I am currently trying to re-profile some Hornby wheels for one of their 'Thomas' engines (for EM), and this will involve setting the wheels further out on the axles and reducing the radius at the root of the flange a bit, because these wheels are a touch coarser than Hornby often use these days. To do this I am using a piece of tool steel which I ground up a while back for P4, just the root of the flange and the coning, not a proper form tool which my Unimat SL would not manage. I was interested to compare the root of a flange on a Sharman P4 wheel to that on an EM one and found they were very nearly the same, so I can use my tool to do these EM wheels because it's not that critical so long as the flange is a touch shallower and a better shape.

So Mike's suggestion of rubbing the back of the wheel down a bit should work fine in P4.

Philip
Last edited by Philip Hall on Sat Dec 15, 2012 4:37 pm, edited 1 time in total.

DougN
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Re: profiling EM wheels to P4

Postby DougN » Tue Dec 11, 2012 2:03 am

Tim I wasn't suggesting that you had been in that situation! Personally I am very wary of all powered tools and even manual ones after a couple of 12" to the ft modelling efforts..... don't worry too much they only needed stitches :cry: ! it is one of the things I have not had an issue since I did a safety course (had to for work) and all my guys at work know I am the first one to make sure that every one is safe. If you want a nanny around have a look at Worksafe Victoria's website then in the construction industry section.... i know in paper form we have manual handling issues moving the files (Joking there, it is only 3 arch leaver folders full) Over regulation is one of the problems I deal with!

Any how back to the wheels. I liked the sharman wheels on my N9 which I built 10 years ago but at about that time they became unavailable... so every thing since then is Alan Gibson P4's.
Doug
Still not doing enough modelling

billbedford

Re: profiling EM wheels to P4

Postby billbedford » Tue Dec 11, 2012 9:57 am

martin goodall wrote:
billbedford wrote:All Sharman wheels (including the 'P4' ones) were 2.3 mm wide instead of a scale 1.8 mm.


Clearly the width of Mike Sharman's wheels has not been a problem for people working in P4, or we would have heard about it - they were very widely used at one stage, and it is only their non-availability in more recent years that has led to people seeking out alternatives.

You obviously have never been to CLAG…….

martin goodall
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Re: profiling EM wheels to P4

Postby martin goodall » Tue Dec 11, 2012 10:24 am

My impression is that CLAG contains some very skilled precision engineers. Their view of such matters may perhaps be coloured by their general approach to model-making, with much greater emphasis on dimensional accuracy (particularly in the engineering) than the average model-maker.

The question is whether the inaccuracy (as a precision engineeer would see it) in the flange profile of the Sharman 'Type B' wheel will actually cause problems on P4 track in practice (irrespective of any theoretical objections). Anecdotal evidence suggests not and, as I mentioned, Mike Sharman himself always reckoned that these wheels would run OK on P4 track.

The point of the original query was what to do with a set of four Sharman 2' 6" bogie wheels. Rather than messing about trying to reprofile them, I would seriously suggest that they be used as supplied, set to the minimum P4 back-to-back (i.e. about 17.7mm), and I am willing to bet they will be fine.

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Hardwicke
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Re: profiling EM wheels to P4

Postby Hardwicke » Tue Dec 11, 2012 3:56 pm

Without a wheel form tool, is it possible to turn down 00 and EM wheels by reducing their width and taking some of the flange off? I'm thinking predominantly wagons and coaches.
I tried to make a wheel form tool but it didn't work.
Ordsall Road (BR(E)), Forge Mill Sidings (BR(M)), Kirkcliffe Coking Plant (BR(E)), Swanage (BR (S)) and Heaby (LMS/MR). Acquired Thorneywood (GNR). Still trying to "Keep the Balance".

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Tim V
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Re: profiling EM wheels to P4

Postby Tim V » Tue Dec 11, 2012 5:18 pm

The problem isn't the form tool but how you hold the wheel. The forces at the cutting edge are great. You'd have to remove the rim from the centre, then mount the rim (somehow) for turning.

Better off trying Martin's idea than attempt to reprofile the wheels.
Tim V
(Not all railways in Somerset went to Dorset)

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John Bateson
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Re: profiling EM wheels to P4

Postby John Bateson » Tue Dec 11, 2012 7:04 pm

The problem isn't the form tool but how you hold the wheel. The forces at the cutting edge are great. You'd have to remove the rim from the centre, then mount the rim (somehow) for turning.

Better off trying Martin's idea than attempt to reprofile the wheels.


Tim,
The method of holding the wheel rims is described in the latest MRJ - its on the list of things to try when I am desperate.
John
Slaving away still on GCR stuff ...

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Tim V
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Re: profiling EM wheels to P4

Postby Tim V » Tue Dec 11, 2012 7:11 pm

I don't think either of the tools in there would hold a rim such that it could be re-profiled with a form tool.
Tim V
(Not all railways in Somerset went to Dorset)

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45609
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Re: profiling EM wheels to P4

Postby 45609 » Tue Dec 11, 2012 7:25 pm

Tim V wrote:I don't think either of the tools in there would hold a rim such that it could be re-profiled with a form tool.


Agreed, but something like this may work with a form tool. The rim is registered to the alumnium mandrel by the internal diameter lip of the steel tyre. It might not suit all wheels types, and certainly not disc wheels, but it is an approach worth trying.

Morgan

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martin goodall
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Re: profiling EM wheels to P4

Postby martin goodall » Wed Dec 12, 2012 10:05 am

Tim V wrote:Better off trying Martin's idea than attempt to reprofile the wheels.


Coming from someone as experienced at 'proper' engineering with a lathe as Tim is, I find this a very refreshing commonsense response to what is in reality a non-problem.

I see, however, that others are still busily trying to find engineering solutions where none is required. It seems to me that this rather reflects an all too common 'hair shirt mentality' in the hobby, particularly noticeable among those who aspire to a 'finescale' approach to model-making, which seems to be far more concerned with processes than results. Never mind that there is a simple solution, or (as in this case) no engineering problem at all, we must strive for the good of our souls to do it the hard way.

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LesGros
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Re: profiling EM wheels to P4

Postby LesGros » Wed Dec 12, 2012 11:26 am

Six months ago Tim wrote:
Don't let Martin Goodall see this thread...

Tim,
Having read the above rant about "hair shirts", it looks like your suggestion was a wise one :)
LesG

The man who never made a mistake
never made anything useful

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Captain Kernow
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Re: profiling EM wheels to P4

Postby Captain Kernow » Wed Dec 12, 2012 4:30 pm

martin goodall wrote:I see, however, that others are still busily trying to find engineering solutions where none is required. It seems to me that this rather reflects an all too common 'hair shirt mentality' in the hobby, particularly noticeable among those who aspire to a 'finescale' approach to model-making, which seems to be far more concerned with processes than results. Never mind that there is a simple solution, or (as in this case) no engineering problem at all, we must strive for the good of our souls to do it the hard way.


I think we will have to allow each to have their own preferences, Martin, whether that be over or under-engineered (or with just the right amount of engineering...). For my part, however, I'm with you on this one! :D
Tim M
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Tim V
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Re: profiling EM wheels to P4

Postby Tim V » Wed Dec 12, 2012 6:45 pm

I haven't said I agree with Martin.

What I have said in these circumstances, with a bunch of EM/OO wheels sitting around, with the potential to be re-profiled is to take Martin's advice and try them. The work involved in re-profiling a bunch of wheels may not be worth the benefit derived.

I have already said that re-profiling these wheels is not going to be easy. Working out some way of holding them is difficult. Some suggestions have come forward - which may be worth pursuit. But Martin has proposed a work-around that is at least worth a go - before re-profiling if necessary.

If aesthetically the wheels fail the test - which any EM profile wheel will, then clearly re-profiling is the only way to go.
Tim V
(Not all railways in Somerset went to Dorset)

billbedford

Re: profiling EM wheels to P4

Postby billbedford » Thu Dec 13, 2012 9:32 am

martin goodall wrote:My impression is that CLAG contains some very skilled precision engineers. Their view of such matters may perhaps be coloured by their general approach to model-making, with much greater emphasis on dimensional accuracy (particularly in the engineering) than the average model-maker.

None of us are engineers, though one our number is an ex watch matchmaker. But we all understand what 'scale' means.

Clive Impey
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Re: profiling EM wheels to P4

Postby Clive Impey » Thu Dec 13, 2012 11:57 am

In my post of Dec 10 I stated that Ray hammond took 0.5mm off the back of Sharman wheels. This should have been 5thou of course. My appologies to those of you who now have rather thin flanges.

Also in Scalefour News 5 is a letter from Mike Sharman on the origins of the wheel profile he used.

CliveLincs

Alan Turner
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Re: profiling EM wheels to P4

Postby Alan Turner » Sat Dec 15, 2012 2:52 pm

Fohrmann sell wheel holding devices similar to above. see: http://www.fohrmann.com/ specialist tools for railway modellers.

regards

Alan

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Hardwicke
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Re: profiling EM wheels to P4

Postby Hardwicke » Sat Dec 15, 2012 4:05 pm

Yes, I have one of those "wheel holding fixtures". So I take 5thou off the wheel thickness at the back? Right?
Ordsall Road (BR(E)), Forge Mill Sidings (BR(M)), Kirkcliffe Coking Plant (BR(E)), Swanage (BR (S)) and Heaby (LMS/MR). Acquired Thorneywood (GNR). Still trying to "Keep the Balance".


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