RC Locomotive 'Diesel-Electric'

[CertifiedMike]

Thanks @CertifiedMike if I was a bit more organised I would post a picture of the relevant section of the CAD drawing and individual parts drawings followed by a pile of raw materials, and explain myself a little better, then it might flow a bit better.

I admire the work of YouTubers who set the scene, explain their process and video it in full with each set and lighting planned, They take time to explain the tools they use and the processes, the work they put in is staggering. And to cap it all I notice that their their work space is always clean and organised and their machines, not a mark or pile of swarf to be seen!

I will try to do better. But I can’t promise a clean machine :0)

It wasn't your post. It is me who was slow on trying to assemble it all in my head.

Your threads are fantastic!

 

[Roog]

Question, oil is keeping the rust at bay for now, but what black paint should I use for the running gear and chassis?

Mostly mild steel

 

[CertifiedMike]

I think you need to be very careful about prep work. Getting a clean oil free surface is #1!

Finding a good self etching primer would be next.

Are you spraying with a gun or rattle can?

 

[Roog]

I think you need to be very careful about prep work. Getting a clean oil free surface is #1!

Finding a good self etching primer would be next.

Are you spraying with a gun or rattle can?

Good question @CertifiedMike, after posting i asked chatGPT a similar question, it came to the conclusion brush on zinc based primer and rattle can the colour. ‘Black’. I do have a compressor but I don’t have a decent paint spray gun so rattle can might suit better.

 

[WRM]

Rustoleum is probably the leader in the field of spray-can finishes/protection.

On Army Helicopters, for the most part, if it's external, it gets Cad Plate with CARC Epoxy Primer and Topcoat (internal/oil-wetted parts got black oxide). Before that it was Zinc Chromate primer, and that was still specified for operations like pressing bushings into gearboxes for dissimilar metals protection.

Look into powder-coating? Or if DIY, degrease/prep the best you can - then primer and topcoat.

 

[Roog]

Rustoleum is probably the leader in the field of spray-can finishes/protection.

On Army Helicopters, for the most part, if it's external, it gets Cad Plate with CARC Epoxy Primer and Topcoat (internal/oil-wetted parts got black oxide). Before that it was Zinc Chromate primer, and that was still specified for operations like pressing bushings into gearboxes for dissimilar metals protection.

Look into powder-coating? Or if DIY, degrease/prep the best you can - then primer and topcoat.

Thanks @WRM the voice of experience speaks, it’s going to be diy I’m afraid, and to some extent it needs to be a finish that I can repair. Spray finishes are clearly better for detail, but I am invariably going to take a brush to it at some point.

I take your point about prep, it’s all too easy to get excited and wack that coat of paint on for that feeling of instant gratification. I have acetone and isopropyl alcohol are either of these suitable?

 

[CertifiedMike]

I have had good luck with Rustoleum spray cans over the years too.

I believe both acetone and alcohol can be used for degreasing.

 

[Roog]

It’s May Day holiday today here in the UK so of course it’s raining! Which means I can go out to the shed for a few hours.

The Buffer beams fit to each end of the chassis and support the buffers. In my case it’s a flat bar of steel 2 1/2” x 6mm and the width of the chassis.

First cut the flat bar stock to length then face off in the mill.

This is were it fits, on the end, screwed into the block of aluminium.

Set up to drill each of the holes by coordinates.

Then counter sink the holes

Note the extra holes through which the buffers bolt through.

Then mark the hole positions in the block, drill and tap M6

Here’s one screwed to one end, I plan to reinforce this beam using a couple of ’buttress pieces’ on the inside. The body work should cover the screws, but I thought I’d counter sink them to be safe.

It’s starting to get heavy!

So despite being a ‘day off’ it feels like a day at work.

 

[Roog]

Ha! Just noticed that the buffer beam in the above image was screwed on up side down, below is the right way up and my buffer quickly bolted on

Right, I need a rest.

 

[Roog]

I've not been looking forward to this bit, ‘reinforcing the buffer beam’

I cut some rectangular pieces from 1 1/2” x 3/4” aluminium flat bar, faced off both ends of each piece so that they are the same length and square.

Btw the red blob on the work surface is paint not blood, although it often is!

Next I decided to chamfer one corner which I could have sawn, but milling involves less huff and puff.

Then each of the blocks are drilled and tapped and the respective bits that they attach to are drilled and countersunk to accept the screws.

Then screwed into position, it looks like a simple job but took a surprising amount of time.

And the other side of the buffer beam now looks a bit busy, hopefully it will look ok when I paint it black.
The gap in the middle is to allow me to fit a coupling to attach coaches/rail cars, not sure what form this takes, but I’ll find something that fits.

Chassis is upside down in this picture. The overall effect from the back is quite neat and now very rigid. Chassis is getting heavier by the week.

Next I have to make three more buffers.

 

[Doom!]

All of your hard work is quite evident in your finished parts. When they all come together it's going to be epic!

 

[Roog]

Back tracking the first time I made the buffer I forgot to photograph the stages. I made the first buffer from cut stock, which meant that I had a nice piece of metal firmly clamped in the chuck when I needed it. The problem with this is that it’s wasteful of metal leaving a fairly useless ‘puck’ of metal at the end. So for the rest of the buffers I wanted to establish a process by which I created less waste.

For the brass part this was quite easy because I was able to cut the stock to length machine one side then flip it to finish the other side.

Machining the cylinder side first, cutting the cylinder to 19mm diameter and the mounting flange 25mm.

Then drill out for the cylinder bore, finishing with the end mill to create a flat bottomed hole 12mm in diameter

Next flip the part holding the machined cylinder in the chuck making sure not to over tighten

Then start reducing the other side to create the spigot for the M8 male thread.

Once down to final diameter I can use a die in a die holder in the tail stock to get the thread on square

Turning to the buffer piston this involved spinning and centring just slightly less than 1ft of 2” diameter steel bar in my mini lathe. All in the interest of saving a few inches of bar.

Turning down the 2” to just under 1/2” remains a wasteful action which I still don’t feel great about.

Then into the band saw to cut off

Gripping the narrow diameter section I was able to carefully face off the large diameter, then flip it around to create the bore for the buffer return spring.

Below I’m starting off the M3 thread in the bottom of the spring recess to retain the central retaining rod.

Now all I need is a better method to reliably cut the male M3 threads on silver steel rods, if I ever do this again I might use mild steel instead.

I’ll not bore you with any more buffer building, anyone know what I can use the gold brass dust for? :0)

P.S not sure why I have duplicate images here at the end, I have tried to delete them.

 

[Roog]

All of your hard work is quite evident in your finished parts. When they all come together it's going to be epic!

Thanks @Doom! one thing I can be sure of is, it’s going to be heavy.

 

[WickedFog]

I’m not overly happy with the proposed belt route but then I’m only aiming for a top speed of 8 mph, 6 would be more appropriate (realistic)

View attachment 272237

Man, I got behind in my hiatus!

That lower left truck only having about 30% contact with the belt might be your point where the belt slips. Can you not run the bottom of the belt over the tensioner and add a second idler pulley to run the top of the belt under?

It blows my mind how fast you move through a build. This is looking WAY more impressive than I had imagined. Awesome job man.

 

[Roog]

Man, I got behind in my hiatus!

That lower left truck only having about 30% contact with the belt might be your point where the belt slips. Can you not run the bottom of the belt over the tensioner and add a second idler pulley to run the top of the belt under?

It blows my mind how fast you move through a build. This is looking WAY more impressive than I had imagined. Awesome job man.

Hi @WickedFog I've taken some time off recently and spent way too much of it in the workshop.

Agreed a two belt solution would be less prone to the belts jumping the pulleys, I drifted away from this because my earlier designs focused on an inboard chassis for the trucks but the reduced width meant that I had less room for the extra pulleys and the motor. But now the I have built an outboard solution I could go back to this, just means more belts and pulleys.

 

[Roog]

How about running dual belts?
I think it would be ok as is tho.

Hi @CertifiedMike as you mentioned and echoed by @WickedFog I have ordered the extra pulley’s to try this, also motors and VESCs on order, the fun bit is about to begin (could also be a nightmare)

 

[Roog]

Buffers are go, all four buffers have been made! I was hoping this would have been fun, but I’m just relieved that they are finished.

I even remembered to hand them.

On a different subject ‘prime movers’, I am thinking of dropping the engine lower in the chassis between the chassis ‘rails’ and fitting a single pot gas/petrol engine, possibly an RCGF 20cc or 26cc, these seem like good value for money, but I know little about how well they work? Their lower rev range would seem to fit my application and their power output of a couple of hp plus would leave some in hand.

Are there users of these on this forum? I did a quick global search but found very little, I believe they are also sold as ‘stinger’ engines.

 

[WRM]

Those are airplane engines and I'm not sure how you would adapt/engage the generator? You probably want something with a centrifugal clutch, like a marine (water-cooled) or 1/5 scale buggy (air-cooled). Genoah 26 (marine) might be a good choice depending on your power requirements (would need radiator and fan).
https://bonzisports.com/product/g260pum-marine-engine-with-carb-and-velocity-stack-zenoah/

There are LOTS of 1/5 Air-cooled buggy engines (search "Baja 5B engine").

 

[CertifiedMike]

Hi @CertifiedMike as you mentioned and echoed by @WickedFog I have ordered the extra pulley’s to try this, also motors and VESCs on order, the fun bit is about to begin (could also be a nightmare)

Adding motors makes everything more fun!!!

 

[Roog]

Those are airplane engines and I'm not sure how you would adapt/engage the generator? You probably want something with a centrifugal clutch, like a marine (water-cooled) or 1/5 scale buggy (air-cooled). Genoah 26 (marine) might be a good choice depending on your power requirements (would need radiator and fan).
https://bonzisports.com/product/g260pum-marine-engine-with-carb-and-velocity-stack-zenoah/

There are LOTS of 1/5 Air-cooled buggy engines (search "Baja 5B engine").

Thanks for the suggestions @WRM yes I like the look of the Genoah marine engines, I am in two thoughts as to whether water cooling with a roof mounted rad, big fan blowing up through it and a water pump and reservoir might be more challenging to fit and operate than an aero engine and a chunky 24V centrifical fan which might be cheaper and easier?

I will check out the ‘Baja 5B’ engine, cheers!