Britannia tender wheel castings

[britannia]

I am looking to renew two of the tender wheels on my Brit - problem with riding the tender and my weight! 

Anyone know the best supplier to obtain these 10 spoke 3.5inch tread castings?  I have usually gone to Blackgates straight away, but with the prices being so high these days, I thought I would seek any thoughts members of this board may have.

[uuu]

If it's just the treads that are worn, have you thought about fitting steel tyres? They'd be more durable than new cast iron wheels.

Wilf

[JonL]

If you mean the 3.5" britannia I have some tender wheel castings I would sell as a set if you are interested.

[JonL]

This is them on Reeves
www.ajreeves.com/10521.html

[britannia]

Jan 29, 2023 14:42:34 GMT uuu said:

If it's just the treads that are worn, have you thought about fitting steel tyres? They'd be more durable than new cast iron wheels.

Wilf

Yes I have thought about this and I am sure it is easy than you might think at first!  May go that way once I have some prices.  I have suitable wheel blanks.

[britannia]

Jan 29, 2023 15:00:19 GMT JonL said:

If you mean the 3.5" britannia I have some tender wheel castings I would sell as a set if you are interested.

Unfortunately no, these are for the 5 inch Brit.  many thanks for your offer

[britannia]

Jan 29, 2023 15:01:49 GMT JonL said:

This is them on Reeves
www.ajreeves.com/10521.html

Looks like they are the 31/2 in gauge wheels.  I should have made it clear on the thread that my Brit is a 5 inch version - the tread is 3.5 inch.  Not sure at a glance I can find the 5 inch casting from Reeves.

[ejparrott]

Tyre them. Dead easy and cheaper than new castings

[oldnorton]

Yes, definitely Richard, retyre them. The new steel will do a better job of coping with the additional wear from your weight.

You could do all the turning of the wheels on the axles between centres. Put lots of sticky tape around the axle boxes to keep the bearings clean and hold them still. You will soon find out if the wheels are fixed properly to the axles. Put a small step in the wheel and a matching one in the tyre, which is orientated to stop the tyre being pushed inwards.

The best way of securing them is with 0.003 - 0.004 inch interference fit on that 3.5 inch diameter. Heat the tyres to 250 degC and there will be a few thou clearance, but it all goes wrong if they are not presented exactly square (guess how I know). A bit tricky to rush to the press tool with the axles on there.

Alternatively, a nice loose fit and use loctite - the shoulder (step) will sit them dead square. I have read that the loctite might fail because of the rolling action of the tyre. Personally, I can't see it, especially if they are 1/4 inch thick. I would use loctite.

Norm

[RGR 60130]

Just picking up from Norm's good advice, there's a few pictures of when I did something similar for the driving wheels on Blue Peter here:- modeleng.proboards.com/thread/11467/new-peppercorn-blue-peter-gauge?page=2

Reg

[GWRdriver]

When I first began to use Loctite on assemblies which I felt had to run as nearly truly concentric as I could make them, it occurred to me that unless restrained or guided in some way the recommended curing space could allow misalignment or eccentricity to creep in. One larger scales this could be said to be negligible, but I there was the quite small assemblies where a .0035" curing space could allow a relatively large amount of runout.

What I began to do is turn mating diameters to a tight or resisting slip fit, which would mechanically align the parts, then on one mating face or the other (usually the male part) I would turn a channel .0035"± deep for the Loctite curing space. I would leave a ring of full diameter on each end of the channel which would assure perfect alignment and also give the Loctite a place to live.

In this case such a technique would give a metal to metal connection and eliminate the potential for the tyres to "walk" on the wheel centers.

[ianholder]

You do not need a "curing space" for a loctite assembly. Machine the parts to a slide fit with no shake, apply a film of loctite and assemble with a twisting motion and enough loctite will be taken in to create an immovable joint. If you refer to the loctite data sheets they give a maximum clearance dimension which allows the loctite to still retain enough strength to make a satisfactory joint, but the smaller the clearance the stronger the joint. The data sheets give methods for using loctite on force fits and also on shrink fits. The fact that they give this maximum clearance dimension has led people to think that you need this clearance for the loctite to work, and many published designers have stated that this is necessary when it is not. Loctite data sheets make interesting reading and it is a pity that so few do so, regards Ian

[britannia]

Thank for the responses from all of you (ianholder, oldnorm, Reg, ejparrot). I rang Blackgates and was advised the best route was to produce tyres as casting were now so expensive and they had been waiting for sometime for Brit castings from the foundry they use. I guess my reluctance is simply having not done this before! So now the big issue is where to start? I have some wheel blanks of suitable diameter and width, but will need to remove the core to a considerable diameter. Not sure if it will be possible to obtain a steel tube of suitable size which would be easier and less wasteful in terms of removing material.

All messages of advice gratefully received!

[GWRdriver]

I'll have to admit the last time I read a Loctite data sheet was about 40 years ago, so perhaps it's time for a remedial course, . . . but even so the technique I described has served me well and caused no harm.

[Cro]

Speak to Ed at MEL and get the blanks laser cut.

[oldnorton]

Yes, a great idea to get them laser cut to as near the size you want. So much easier than ploughing off metal in the lathe!

You only have to grip the cut tyres on their outside in a biggish 3 or 4 jaw, reversed jaws, and turn up the inside with the step to fit your wheels. It does not matter about the sides and top, you can machine those when they are bonded to the wheel. Thus the less metal you have to take off the better. Cutting on the wheels, between centres in the axles, guarantees that they all rotate true.

You really need an easy machining steel if you can get it, especially when you use large faced tools for profiling the flange. The work will chatter and sing. The problem with a lot of plate is that it is quite tough and stringy; it has been designed for welding. I would be interested to know if there is a grade of plate that cuts nicely in the lathe.

Leaded steel would be best but I think that only comes in bar section. An option would be to talk to m-machine 01325 381300 as they often have lots of big tube and will cut slices. Most of that tube might be a fancy alloy steel but some might be a good cutting grade. They will cut and machine specials for supply.

One you have got the tyres and fitted them, ask again about what we have all tried, done, and managed badly when we cut the treads!

Norm

[uuu]

I bought steel tube from my smokebox from m-machine, and it was good stuff. Looking at their catalogue (www.m-machine-metals.co.uk/downloads/metals%20catalogue.pdf) down on page 93, they have sizes that might be appropriate. Even really chunky stuff like 101.6mm OD and 25mm wall is only £5.28 per inch.

Wilf

[ettingtonliam]

Years ago I had several largish crankshaft blanks flame cut from what was then known as Grade 50 structural plate, intended for fabricating bridge beams and the like. Using a very low speed it cut well with a beautiful finish.

[britannia]

I see that Mac Models has steel tube which would exactly fit the job. 1/2 inch thickness and 4 inch OD at £5.26 per inch

[chrisb]

Here in NZ steel tyres seem quite common with a lot of people and suppliers using 4140 hollow bar to make them from. I will be going down this route with my 7 1/4” Wren once I get my new workshop built and fitted out.