Tuesday, November 01, 2016

009 loco couplings

Jeremy asks: 

I very much enjoyed your article in the October BRM regarding the freelanced OO9 engine. I was so taken by the project when you teased it earlier in your blog that I actually ordered a chassis myself. It's currently sitting on my desk, atop a bottle cap (for novelty's sake; it is amazingly tiny) while I decide what to do with it.
While your article is up to your usual standards, I wonder if you could elaborate on the couplings? What make are they, how are they mounted, recommended height, etc. I have some frets of Greenwich couplings laying around which I'll probably utilize, but I'm curious what your approach was.

No problem. The couplings were a bit of a bodge if I'm honest. In an ideal world, I'd have used Grenwich brass versions, but I couldn't find my fret of them. What I did lay my hands on was a set of Bemo plastic versions. A bit clunky, but better than nothing. 

The coupling shanks were shortened and then poked through square holes made in the buffer beams. Height was determined by running a wagon up to the beams and marking the hole. I have node idea what the "correct" height is, but they seem to work OK. 

The hole is quite tight but a dot of superglue keeps them in place.  

Jeremy responds: 

Thank you for your response. I think I'll have to do some experimenting with a temporary footplate. From looking at your construction photos, I thought the couplers might have been modified -- there's not much room between the chassis and the buffer beam.

If I can, I'm hoping to find someway to make the chassis swappable between whichever body is needed or fancied. I'd have to review your article again, but I believe you just boxed it in with styrene as opposed to being permanently fixed. Or if I misread that entirely, that's at least the approach I thought I'd try.

 I can't see why a swapable body should be a problem. Mines firmly gripped between bits of Plasticard, but again I'm not averse to extra tiny dots of superglue for this job as the joints can easily be broken if required.


Paul B. said...

Coupling height gauges are made by Greenwich (etched) and RT Models (resin). Of the two I prefer the RT Models version.

James H said...

Yes the RT resin one is what I use - and with a spot of blutak you can hold the coupling at the right height as it's glued in place if using Narrow Planet Bosna.

I don't fit loops to the locos, as it makes shunting easier!
You can see a whole range of locos on my blog (http://paxton-road.blogspot.com) - I generally use RT Models couplings (the Penrhyn and Harrogate ones) or the Narrow Planet Bosna that I designed. We were talking about doing another Narrow Planet one with a more British style.

Mark said...

It's also worth mentioning, as I don't think your article did, that the motor in this tiny chassis isn't rated for 12v; it's only rated for 6v if I remember correctly. So anyone intending to build a model around the chassis should probably fit a resistor to avoid burning out the motor. With a poor DC supply you could get away with just being careful with the dial but a modern PWM controller would supply the full 12v in bursts which could easily kill the motor.

Phil Parker said...

The resistor is mentioned in the instructions with the chassis but you are right, I should have put something in the article too as people probably don't read these.

Having said this, the loco seems happy enough on a basic DC supply but it won't last turned up high. Mind you, it looks like I'm going to be able to run the whole layout off a 3V battery as one of the other chassis that should be in use needs hardly any volts...

Maybe I should say it's a coreless motor. That seems to the bogeyman of the day making "modellers" throw thier hands up in horror at the moment.