Ivatt 2 tank in P4

[Jub45565]

Having had a slight change in personal circumstances, the last couple of weeks have seen a bit of modelling time. Though I am still working away as I have been for most of the last 18 months, it is currently only 3 days a week so could be worse.

 

Currently on the workbench is a Brassmasters Easi-chas A3, which has gone together very well, but has an intermittent tight spot I need to sort out before putting the motor back in (not that taking it out was in the instructions, but helps prove the chassis is free running!). However, the purpose of this thread is the next project for the workbench, a Mickey Mouse tank.

 

Got:

Bachmann body, Comet chassis, S4Soc/Bradwell Hornblocks, 0.8mm double sided PCB, Ultrascale pony wheels on order, EMGS split axles

Need:

Brassmasters pony trucks, HL gearbox, Gibson driving wheels

 

Plan:

The plan is to mount the hornblocks for the 2 driving axles that do not have the gearbox mounted on them on shims of PCB so as to insulate the hornblock from the frame. This will allow split axle pickup on these axles. Pony trucks to be decided, but thinking of having these 'American style' – ie have one pony being a pickup from one rail, through shorting the wheel to the axle, and having the other truck picking up from the other rail. This system – a bit of a pick-n-mix of the various systems around, but without having to overall insulate the chassis, and without having to worry about ensuring the driven axle splits are perfectly placed and wont be able to move and short out. This method would only result in 3 of 5 wheels on each rail pickup, but with no extra friction caused and nothing to tweak. Pickup wires could be added to the driven axle if it proved necessary, but I doubt it would. Pony trucks from Brassmasters, suitably modified as usefully noted by Dave Holt back in 2010:

 

http://www.rmweb.co.uk/community/index.php?/blog/140/entry-2952-delph-2-6-2-tank-trucks/

 

My Concerns:

Chassis' with which I have had success with to date have used Brassmasters/Comet hornblocks – the benefit being that the alignment is sorted in the design. Adding hornguides gives rise to the possibility of misalignment or twisting. While I agree that with care this is fine, it is another area where minor discrepancies can creep in and ruin the hopes of good running.

 

Wheel shorting. With Ultrascales (NS tyres) I am happy with the concept of soldering the spiders – but with the need for Gibson wheels on this project for driving wheels at least, soldering to steel isnt my idea of fun. Drilling just behind the tyre and trapping some wire may work, but could result in deforming the tyre. That or not actually having enough meat in the plastic wheel centre to do this.

 

There are a few projects I need to clear off the workbench before this makes it onto it, but I thought I would start the thread now for a couple of reasons. Partially, writing this clarified what I was planning on doing and will possibly keep it as my next project (I am good at flitting from one project to another). It also gives rise to the possibility of useful input from here to be incorporated into the plan before work commences.

[Tim V]

Sounds an interesting project.

 

I covered a more conventional split axle design for an Ivatt 2 tank on my workbench on the old RMweb.

[clecklewyke]

I have several split axle chassis and "American" pick-ups, all with spiders soldered to Gibson steel tyres, with no problems*. A hot iron, plenty of flux and instant cooling using a wet sponge and Bob's your uncle!

 

Ian

 

* Except for wheels on the white metal D49 touching the spashers and shorting. Should not be a problem with a plastic body!

[Dave Holt]

Pete,

 

There's an entry in the CLAG web site (www.clag.org.uk) which illustrates how I sprung the Ivatt/BR Standard pony trucks shown in the link you included, above.

 

Regards,

 

Dave.