Scalefour Forum

Professionals usually work from a surface plate with a vernier height gauge, which will probably cost more than you would like. However pre-vernier gauges should be available but a search engine didn't find them. I mention this because the set up is also useful when assembling models as checks can b...

The original models all have 30 or 40:1 High Level Roadrunner+ box with Mashima 1624 driving the centre axle. Seems you may have to find a substitute for the motor - see other thread.

DaveB

Stick it in the tender then.

DaveB

Sorry, meant to add that I fear that one day you will be mourning the lost 0.133 of cylinder centres! Crosshead clearance on leading crankpin is another area where a few of your sums would be worth doing before your start. They may well be offset slightly but something will be close.

DaveB

2 further variables, Pete: I've found some photos of the Comet axleboxes and there's a funny little rim on the outside which could be filed off. Also I've always considered the boss on the back of the wheel to be adjustable to control sideplay. I start with the frame spacing I want (I use 16.2 over)...

Annealing will make forming the boiler easier but it will damage more readily afterwards - the choice is yours. I've never rolled n/s so can't comment on relative difficulty. Certainly any cutouts are a disaster when trying to get a true shape and even handrail holes show signs of distortion which c...

No need to fret about rolling boilers, Pete. I learnt all I've ever needed to know about the subject while making a pastry cutter in school metalwork around 56 years ago. You must form the ends of the wrapper first using vice and piece of bar - even rollers don't do this bit. Despite using rollers f...

Lima chassis might have been a mechanical abomination but my memory of them from a very long time ago was that they would pick-up power and start more reliably than anything else available at the time. There was method in their madness somewhere.

DaveB

I should add to my basic information on a class 37 wheel profile the fundamental need for a radius at the flange tip, appropriate radius where flange meets tread and chamfer on outside edge of tyre, this latter being essential when passing trailing points. If the blade is lower than the stock rail, ...

There can't be anything wrong with your simplified wheel profile, Philip, as the profile called for in the P4 spec is just one of many in use on the railways and tramways. We had a thread a while ago which started with a report on a class 37 derailing and its wheel profile was essentially 2 straight...

I think this plan is ultimately doomed, Colin. You've 2 nice sidings there but you can't put anything in them without clearing out the goods yard first. The curve in there looks about 12" radius, too. Why not make it look like a through station and put the crossing at the other end - I think yo...

So there's folk out there using Romford wheels on P4 axles are there? Is it me as if they're RP25 wheels I can't see how they fit the track at 17.7 b-b. BRMSB will just but they won't go far. What sort of standard is this anyway? It's not going to do much for any outside cylinders, either.

DaveB

The late John Hayes described the assembly of the very similar Finney A3 way back in MRJs 66 and 67. He ground an old fine flat needle file down very thin for about an inch to fettle the slidebars - says he didn't have to take much off to achieve smooth operation.

DaveB

I'll be one of many here: I think your IWG is Imperial wire gauge and my Machinery Handbook of 1959 (a great find in a charity shop) says that the British SWG was formerly called IWG. In the next paragraph it says SWG is used to specify the wall thickness of tubing. Delving into Fowler's Mechanical ...

Neil, for complete coverage, are you aware of the secondary springs described by Chris P in MRJ 200 and fitted to some Bachmann coaches? You may be able to fit similar to the Ratio bogies which would save work.

DaveB

Ah, Neil, I was hoping you wouldn't place an order! There is just one 10ft bogie left but it will be the last of its type and any future bogies will be to a new style based on the 8ft 6in which will appear soon. No good if you want something typical or more stock. I'll take a coach to S4N and we can...

Very sorry, John, you're right. It was fresh in my mind last night but the repeat this morning failed miserably in its accuracy. You might want to check that teh cenre created by one of these drills matches your expectations of its appearance. They're not completely immune to breaking, either. I've ...

My late post last night seems to have disappeared. It referred to Drill Service (Horley) website who have more types of centre drill than you can imagine - look for HSS Curved type. I've always found their service very good and no min price. They also sell genuine number drills to give odd sizes. Ve...

I wasn't aware I was entering a discussion about types of springing, merely correcting some mis-information about my product. I'd kept out of it so far.

DaveB

If you just plunge in with a long drill the hole can be anywhere. You're right on both counts with the centre drill but what if your home made bodge wobbles? You could grind the shank off a drill and just hold the fluted bit in your chuck if you want to save the cost - or even wait until you break o...

I feel the piece on the CLAG site introduces some misconceptions with the Pendlenton bogie so would make the following comments: We've made a number of small changes to the Pendlenton bogie, mainly to improve assembly and I'm about to commit to new tooling for the 8ft 6in. Other stock has been run d...

I think a professional engineer would consider the measure and drill method - it depends if you're a fitter or machinist and both approaches are sound. A bit of equipment, vernier and drill table, certainly reduces the need for feel. It's down to personal preference, really. If it was mine, I might ...

As Philip says, you're likely to be better off with the Gibson pins, especially if the Romford type still require a tapped hole in the wheel which can end up anywhere - the hole, that is. JB's oversize holes are probably just one of those mysteries of the art of fitting. They would give confirmation...

David, There's certainly some sound stuff in the JB article but I don't think you're about to fit his axleboxes, which is where it all started. Assuming you have some axleboxes, somehow: 0.2 clearance in rods will be terrible - 0.1 is bad enough. You should be able to drill out to 1.5 and fit bushes...

A neglected line of reasoning in favour of all springing occurs when propelling sufficient vehicles for those next to the engine to be held by their buffers and hence prevented from following any dips in the rails. Only springs can maintain any pressure on the wheels to keep the thing from climbing ...