3mm Beginner - J50 construction and chassis design

[BetweenTheTunnels]

@TT100 Diesels Oh my 'roundtuit' seems to change in size depending on workload!

 

I have however made a bit of progress on the J50 chassis. For those of you wondering, yes I am aware that its possible to purchase a chassis from 3SMR for the J50, but I wanted to have a go at designing one myself for two reasons a) to learn and prove I could do it, and b) so that when i want to build a loco for which a chassis isnt available, I know I have the skill.  I dont expect to get it right first time, but I am thinking ahead.

 

I have got the rough outline sorted, and I've got a few Mitsumi 12v motors from Cambridge Custom Transfers which are (12mm x 15mm) and the motor fits within the white metal body, so I'm looking at using one of them.  They have an 8000rpm, so through gearing I think it should be ok for the J50, especially with a brass flywheel on one end.  I need to work out what options there are for gearing.  I could use a High Level Kits gearbox, and may well do in the future, but again, I want to build the entire chassis, motor mount etc, so that I know I can design and deal with this.

 

So the thought is that the worm off the motor will mesh with an ideler gear which will mesh with the gear on the rear driving axle.  The axles at 1/8" inch on 3mm Society wheels, so I think the 2mm Association (of whom im also a member) gears will work as they are designed for 1/8" outside diameter axle muffs.  I just need to establish how I work out what 'toothed' gears I need to give a steady 30mph top speed, which for ECS and shunting work should be ideal.  Any advice would be welcomed.

 

 

It is the first time i've worked with the Sheet Metal features of Fusion360.  I'd tried to create this out of one piece of Nickle Silver that is half-etched on the inside fold lines and then folded into a U, but I am thinking as i want to spring the front two axles, that it will need to be two separate pieces with spacers to be solderer together in order to get the springing on the inside.

 

The block on the top represents the motor, which will have to be positioned a bit higher than i expected within the cab, but still remaining out of sight from the cab area.  I think the motor mount and gearbox sections will also need to be a separate piece folded together and possibly located using the axle of the rear driving wheels.

 

Richie

 

[BetweenTheTunnels]

Well where did March go to? Its just flying this year ... I need to find which button is the brake!

 

Family life has once again taken over, I have just about got the diorama boards finished in 3D planning, so I am not far off getting them cut now.  My current plan is that the CNC cutter can sort out the timbers for the paintwork at the same time.  It may have slightly grown to another board that includes the yard throat!

 

The J50 has been through the first stage of 'filler' process and had all the little gaps filled, following which it was given a light initial spray of grey undercoat and now looks very nice.  No further on with the chassis, but hopefully soon that will progress.  The High Level Kits gearbox and motor are here now, and I have got to have a trip to Lincoln soon, so the DCC (motor only at this stage) decoder and stay-alive will get picked at that point.

 

Wagon wise, I am continuing with the kits, the's now another box van and I am part way through an LNER 20-ton coal wagon (the first of five I have to build).  The body was a bit of a s*d to get together with all the angles, but I have got there. Then I lost the instructions, which didnt help as I couldn't work out where all the remaining angled bits went!  Now found another instruction set so can get back on with that.  Also start on construction of the first DG coupling for them this afternoon.

 

Finally I am about 40% of the way through completing the drawings for a Mk1 SO vehicle, so I am hoping that together with the J50 chassis will go off for etching together and fill a sheet. I have followed the Comet principle of construction, but still need to give through to rolling the brass/nickle silver for the roof .... and more importantly how the roof will attach to the coach.

 

Some pics of the J50 to follow this evening, once I the primer has dried.

 

Richie

[BetweenTheTunnels]

Morning all (he says shortly before heading to bed!)

I promises some pictures, so this is where the J50 stands after its first 'waft' with primer...

 

 

 

The primer showed up some of the issues with the white metal mouldings, so these have now been dealt with will filler - it now looks grey with pokadotted white spots!  The plan is to give it another covering of primer tomorrow, and hopefully it should look quite a bit better.  From a distance (ie normal viewing distance) it looks quite good I think.

 

 

In the background can be seen the growing wagon fleet, one of the rear two has had its roof added tonight as well.  So progress, slow progress, but progress all the same.  I really want to push on with the J50 chassis however.

 

 

Richie

Edited March 30 by BetweenTheTunnels