Gibson v Romford/ Markit wheel back to back settings

[Hayfield]

Whilst not quite track related I am building a loco chassis in EM gauge using Romford wheels initially, then reverting to Alan Gibson wheels, is my memory playing tricks or am I getting things mixed up. are they both 16.5mm back to back or are Gibson's 0.1mm wider please

Reason being is that I am building detachable brake gear and Gibson wheels are thinner

Thanks

 

[Martin Wynne]

@Hayfield

Hi John,

For standard EM:

RTR wheels: 16.4mm back-to-back MAX.

Romford/Markits wheels: 16.5mm back-to-back MAX.

Kit wheels (Alan Gibson, Ultrascale): 16.6mm back-to-back MAX.

For all of them: 16.3mm back-to-back MIN.

So for Alan Gibson wheels, 16.5mm or 16.6mm will work. However, for the best running, always get as close to the MAX as possible without exceeding it. So aim for 16.6mm.

cheers,

Martin.

 

[Hayfield]

Thank you, now I have just got to work out the positions of the etched brake blocks and cut microbore tube to size

 

[Rob Manchester]

Hi John,
Romford/Markits wheel back-to-backs are set by the distance between the shoulders on the axles although never having used them for EM I don't know what that dimension is set to when the axle is made. What do your axles measure over the shoulders ?

Rob

 

[Hayfield]

i have a cheap set of callipers, the axles read 16 mm

Like many I find Romford/Markit wheels easy to fit, but in the past I have struggled with Gibson's. I now have a G W Models wheel press, plus the loco I am building needs 4' 10" wheels. The other thing is, in my opinion Gibson's do look better

 

[Rob Manchester]

Hi John,
What back to back do the Romford wheels measure when mounted on the axle ? The raised boss on the back of the wheels will add to the length of the 16mm axle length. You really need to have a decent calliper or a back to back gauge set to your intended measurement.

The GW press will help with the Gibson wheels provided you take it steady. The main issue I have seen is when you remove wheels from the axle to paint the chassis or fit brake gear etc - they often don't go back on just right.

Rob

 

[Hayfield]

Romford seem to have 16.5 mm back to back.

This is partially my issue, I am using Romford wheels to build and test the chassis, when everything is tested, working and painted I will then fit the Gibson's

Its further complicated in the fact I wish to make the brake gear detachable, I am going to use a length of thin micro bore tube through the chassis and I need to know how long to make them, as they will go through the frames and soldered in place (where necessary the centre part will be cut out to fit the motor) I need to align the brake gear to fit Gibson wheels not Romford

with respect to my first post, I have checked the size of Gibson EM back to back gauges and they are 16.5 mm, I think certainly initially I will have to go with this

 

[Phil O]

Hi John,

I think that you will be hard pressed to work to a tolerance of 0.1mm unless working with a micrometer, as long as the brake shoes are clear of the flanges there should be enough meat on the tread to accommodate the shoe, the real thing is fairly slack.

 

[roythebus]

I've got several projects on the go where I used Gibson wheels. lovely to look at, but once I take them off to pain the chassis, the never go back on square! Seems like I'll revert to Romford/Markits with the square axles.

 

[Phil O]

I use Romfords/Markits wheels to get a running chassis, but once happy with it and it's been painted I fit the Gibson wheels.

 

[AndyB]

i have a cheap set of callipers, the axles read 16 mm

Try to find a set of vernier calipers like these. They should not be very expensive. No batteries. No uncertainty. All the resolution you need. I've had similar ones for about forty years. I have some electronic ones too but I trust these more and still use them all the time.

 

[roythebus]

Back in the day when whels were a very limited commodity, we used Hamblings wheels. They had knurled axles which fitted on a knurled boss in the middle of the plastic spokes with either brass or nickel silver tyres. You had to buy a special press to put those wheels. the problem then was getting a hobby vice that was square enough to make sure the wheels went on the axles square! Mine never did. Quartering was done by location holes for the crank pins and the wheels were clamped in place on 2 backplates. Two steel bars with coil springs round them were used to hold the clamp plates apart and helped relase the whole lot when it was taken out of the vice.

 

[roythebus]

Back in the day when whels were a very limited commodity, we used Hamblings wheels. They had knurled axles which fitted on a knurled boss in the middle of the plastic spokes with either brass or nickel silver tyres. You had to buy a special press to put those wheels. the problem then was getting a hobby vice that was square enough to make sure the wheels went on the axles square! Mine never did. Quartering was done by location holes for the crank pins and the wheels were clamped in place on 2 backplates. Two steel bars with coil springs round them were used to hold the clamp plates apart and helped release the whole lot when it was taken out of the vice.

 

[Rob Manchester]

Back in the day when whels were a very limited commodity, we used Hamblings wheels. They had knurled axles which fitted on a knurled boss in the middle of the plastic spokes with either brass or nickel silver tyres. You had to buy a special press to put those wheels. the problem then was getting a hobby vice that was square enough to make sure the wheels went on the axles square! Mine never did. Quartering was done by location holes for the crank pins and the wheels were clamped in place on 2 backplates. Two steel bars with coil springs round them were used to hold the clamp plates apart and helped relase the whole lot when it was taken out of the vice.

Roy,
I remember having some Hamblings wheels obtained second hand a few years ago. I never did use them.

The smart way to assemble push fit loco wheels such as Gibson, Ultrascale, Sharman or even Hamblings is to use a properly set-up lathe. Mount one wheel in the headstock using a chuck or collet and the other one in the tailstock in a similar way. You can check the crankpin alignment to assure correct quartering. The axle goes in a fixture on the cross/compound slide along with a back to back gauge, then just bring the 3 items together and bingo a pair of wheels mounted square and at the right back to back. It really needs a loco chassis with removeable hornguides so you can mount the wheels onto the axle away from the chassis. Most people I suspect would just use a GW Models wheel press.....

Rob

 

[roythebus]

I wonder how many peope have a lathe these days? I've still got my old Emco Unimat from the late 1960s. I don't see how I could mount a driving wheel in the tailstock. I doubt the 4-jaw chuck would get the wheel properly centred. Plus the tailstock on mine has always been slighty out of true. If I pit a rod in there, it tips upwards slightly towards the lathe chuck!

 

[Phil O]

I've always used the GW ( George Watts) wheel press and the EM gauge society B2B. I use Alan Gibson wheels.

I have a set of Romford/Markits wheels, which I use during the assembly process, once the chassis has had a couple of coats of paint and some general weathering, I then fit the AG wheels.

 

[Rob Manchester]

I wonder how many peope have a lathe these days? I've still got my old Emco Unimat from the late 1960s. I don't see how I could mount a driving wheel in the tailstock. I doubt the 4-jaw chuck would get the wheel properly centred. Plus the tailstock on mine has always been slighty out of true. If I pit a rod in there, it tips upwards slightly towards the lathe chuck!

Hi Roy,
Sounds like your tailstock needs checking and adjusting. The idea behing the lathe is simply to use it as a ( rather expensive ) version of the GW wheel press. The lathe in this instance isn't being used as a lathe to remove any metal. There are various ways to mount a wheel in the tailstock using collets, a chuck or custom made fixtures. The old Unimats were handy machines but depending on which model you have it may be rather more difficult to arrange it as a wheel press - and almost certainly more expensive than George Watt's device.

Rob