Mamod SP2 stationary engine loco conversion

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Garethh
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Re: Mamod SP2 stationary engine loco conversion

Post by Garethh » Wed Jul 08, 2020 11:54 am

Tom85 wrote:
Tue Jul 07, 2020 3:12 pm
After removing the steam unit from the Mamod, and attaching it to the chassis, I hooked it up temporarily to the boiler using silicon tube... and it works! I am almost unreasonably happy about this.

It did throw up a couple of issues though. The chain seems quite loose when running, I'll try removing a link or two. Also, the engine only runs in one direction - this I was expecting, but for some reason I thought it would run the other way! This means the engine and flywheel are at the back of the chassis, not the front as expected. Could this be changed around by swapping the steam and exhaust pipes around? (nb. I really don't know much about this stuff).

Next steps will be to fit the boiler and firebox, and deciding whether to use the Mamod solid-fuel burner, or construct a meths one. The latter would probably perform better but would involve learning to silver-solder, so I haven't made my mind up yet. The bodywork also needs some thought; if anyone can advise what the best material to use for this is, and the best way of cutting sheet material (tin snips? hacksaw? jigsaw?) I'd be really grateful for the advice.

IMG_20200707_123429_2.jpg

I found with sheet brass I could score it with a scalpel and the carefully bend until it snaps on the join. Can’t remember what thickness I was using though!

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Re: Mamod SP2 stationary engine loco conversion

Post by steamyjim » Sat Aug 15, 2020 11:40 pm

Any progress on this project? Was rather enjoying it!
Check out my steam and engineering youtube channel at...

https://www.youtube.com/channel/UC8vX4P ... _PnvhldjjA

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Tom85
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Re: Mamod SP2 stationary engine loco conversion

Post by Tom85 » Fri Aug 28, 2020 9:51 am

Hi Jim,
Sadly not - unfortunately I haven't had anywhere near as much hobby time as I'd like of late. I have however been reading up on silver soldering, as my next job will be to scratchbuild a meths burner, having decided to make my own based on Peter Jones's design. So watch this space (not too closely though!)
Cheers,
Tom

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Re: Mamod SP2 stationary engine loco conversion

Post by Tom85 » Mon Oct 12, 2020 6:42 pm

Just silver soldered myself a burner!
IMG_20201012_172741.jpg

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Re: Mamod SP2 stationary engine loco conversion

Post by Old Man Aaron » Mon Oct 12, 2020 11:52 pm

Well done. Certainly better than the burners I've tried to solder up..

Once you get those wicks fine-tuned, that should make an excellent steam producer. If you've not already, it might be worth adding a filler pipe running out and away from the hole in the reservoir. As the burner heats up over a run, the meths will expand and vapourise further. An open hole in the reservoir so close to the lit wicks could result in a fireball! :bom:
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Re: Mamod SP2 stationary engine loco conversion

Post by Tom85 » Tue Oct 13, 2020 9:14 am

Cheers Aaron. I'm pretty happy with it for a first try. Since taking the photo I've been experimenting with getting the wicks right, I have trimmed them and now it doesn't flare as much. It seems to be more of an art than a science though. Good call on the filler tube, I'm planning to add one

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Re: Mamod SP2 stationary engine loco conversion

Post by Tom85 » Sun Apr 04, 2021 5:06 pm

Hi folks, just thought I'd give a quick update on this project. It is still happening. After my burner-contructing success, I hit a few snags and lost the will to live (well, the will to carry on with this project) for a while. Still, you only learn to dig ditches by digging ditches as they say, so I'm back on the horse now and should have some photos to show you soon.

After constructing the chassis, I didn't like the fact that the SP2 power unit would only run in one direction and decided to replace it with one from a Mamod traction engine, with a built in reversing valve. This involved cutting away part of the frame to fit the handle, so there's no going back. Big mistake! It turned out that soldering the steam pipes was insanely difficult - the stubs attached to the mamod unit kept dropping off as their solder melted whilst I heated the other end! I lost a couple of units that way - thankfully, they're available cheaply (got mine from Tony Green Steam Models who do Mamod spares).

The solution I came up with was to use a lot less heat (the units are only soft-soldered in the first place) and a sort of heat-shield around the steam unit end, made from a wet rag, itself shielded with tin foil. Meanwhile the existing pipes were also held in place using 3 cocktail sticks jammed into the port holes on the front of the unit, in case their solder was to melt. In this way I was finally able attach, by means of a sleeve, the 1/8 pipe which will connect the engine to the boiler.

With some of the skilled engineering on show here I feel a bit daft telling you about my rookie mistakes, but I'm certainly learning as I go. If I can build a basic loco, anyone can.

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Re: Mamod SP2 stationary engine loco conversion

Post by Tom85 » Thu Apr 08, 2021 7:53 pm

So finally we are up and running. I've attached a couple of photos for 'proof'! It ran well with the wheels off the ground, and on the track too, although only on the short section on my workbench. I'll set up a loop at the weekend to test properly. Next up is the firebox and bodywork - need to do some reading up on this first!

The home-made meths burner is working a treat, far better than the daft tablet things. My silver-soldering is very amateurish but hey, it works, and I'm really proud of it.

I've come up against a few pitfalls along the way, which I'm hoping some of those members less naive than myself towards engineering matters could answer?

One of the most frustrating things has been getting the Meccano components to fit correctly. The standard Meccano shaft is (I think) 4mm, but both the wheelsets (Essel) and Mamod crankshaft are 3/16. The article suggested 'running a 3/16 drill through them, or even better a 3/16 reamer). I bought a hand reamer to that end. However, neither with the drill or the reamer could I get an accurate hole - it always ended up off centre by the time it got through. Some practice (and wasted gears) got better results with the reamer, but still not perfect, meaning the gears and sprockets don't run as true as they should. Is there some secret to this that I should know?

The steam pipe is comically tall, due to a pipe union being fitted to the stub left on the top of the boiler. I'd like to tidy this up somehow but didn't want to remove the pipe from the boiler in case it couldn't be repaired. Does anyone know what this connection entails? If removed, could I fit a new one by means of a soldered insert of some kind?

Well, cheers for your help folks! I'll keep you updated when I have more to show.
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IMG_20210408_192057.jpg

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Old Man Aaron
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Re: Mamod SP2 stationary engine loco conversion

Post by Old Man Aaron » Fri Apr 09, 2021 1:26 am

Running issues aside, it's good to see more progress. Must agree, fuel tablets are a blight on an engine.
I think you'll need a lathe or mill to ream those gears accurately. If I lived in the UK, I'd offer to do it on my lathe. Surely there's a closer member on here willing to help you out? Don't suppose you have a drill press/pillar drill? You'd need the drill bit (not the reamer) but that would work, too.

As for the steampipe, these soft-soldered boilers are really easy to work on. If you can solder pipe unions, you'll be able to remove and re-solder the steampipe from the boiler. :)
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Re: Mamod SP2 stationary engine loco conversion

Post by Garethh » Fri Apr 09, 2021 5:54 am

Maybe something like these could help if you’re not confident soldering the boiler? https://maccmodels.co.uk/product-catego ... gs/elbows/

I’m not that local unfortunately but happy to help if you wanted to post the bits that need boring. Although I wonder how accurate the meccano bits are to start with...?

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Re: Mamod SP2 stationary engine loco conversion

Post by Tom85 » Fri Apr 09, 2021 3:16 pm

Many thanks, both of you.

I actually do have a drill press, but on inspection I don't think my table clamp (Clarke) is good enough for precision work. One of the jaws (the moving one) has some up-and-down movement in it, meaning when a part is clamped in it, one edge is lifted up slightly, which may be the problem. That said, the model works so the gears will do for now! I'm now viewing this model as a prentice-piece, to learn skills for making a (hopefully) better one next.

Garethh, I may well take you up on your offer for my next project if that's OK with you? Very kind of you to offer anyway. Cheers for the elbow connection as well, looks ideal.

Thanks, Tom

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Re: Mamod SP2 stationary engine loco conversion

Post by Old Man Aaron » Mon Apr 12, 2021 7:02 am

Tom85 wrote:
Fri Apr 09, 2021 3:16 pm
I don't think my table clamp (Clarke) is good enough for precision work. One of the jaws (the moving one) has some up-and-down movement in it, meaning when a part is clamped in it, one edge is lifted up slightly, which may be the problem.

Mine is that way, too. Having ruined several parts with it, I avoid using it when possible. I really ought to buy a decent older machine of these days..
Call me mad, but I'd simply hold the gear on the drill press' table, and hope it doesn't get caught by the drill bit - usually doesn't, in my case, anyway..
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