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Bachmann Ivatt 4MT in EM for South Pelaw


RichardClayton

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During South Pelaw’s outing to Expo EM North a few weekends ago I noticed that on several occasions we had a large number (well 3) K1s lined up in the Stella Gill approach roads. In the interests of variety, and because I like their rather stark lines, I thought it would be good to add an Ivatt 4MT to our pool of available locos.

 

I have not seen any evidence of 4MTs at South Pelaw, but it is entirely plausible for one of the engines shedded at Darlo, Gateshead, or Teeside would have at least worked in to Stella Gill. So I bought a very cheap secondhand Bachmann model with a broken return crank from Hatton's, an Alan Gibson EM conversion set, and off we go.

 

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Further inspection following the not entirely straightforward separation of body and chassis revealed a broken pickup, but nothing that can’t easily be fixed.

 

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First job was to sort out the wheels, crankpins, and balance weights. The first set of balance weights I made from black plastikard were based on the Bachmann wheels, but then I looked carefully at some prototype photos, and the central balance weights not only have a different arc length, but also a smaller inside radius. I think the Brassmasters etch may also be incorrect here ...

 

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Next problem was the coupling rods — the holes for the crankpins in the Bachmann rods are rather large. Normal practice would be to solder Alan Gibson crankpin bushes into these holes (see the downloads on the AG website), but in this case the bushes were a very sloppy fit and I was not confident about locating them centrally. To my delight I found that Dave Franks of Lanarkshire models does an etched set, and these arrived today. The centres are spot on for the Bachmann chassis, and although not finished yet, they are going to be a big improvement over the Bachmann offering. 

 

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My initial investigations suggest that clearances behind the cross head will be OK. We will see...

 

Richard

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Here’s a bit of an update, with the new rods — including oil corks! — just placed on the crankpins for now. No dramas with riveting the forked joints as the instructions are very clear and helpful. Both are tight, with no fore and aft slop, but move freely. The oil corks started life as a full length of 0.33 mm hard brass wire, soldered in and snipped off, and are a nice touch.

 

Fortunately I have remembered to do a left hand and right hand set of rods ...

 

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Edited by RichardClayton
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I usually dread fitting wheels to axles, as it can be a painful process. I must be doing something right though, because the last few locos have run very nicely pretty much first go.

 

I tap the crankpin holes in Alan Gibson wheels, and then insert the crankpin screws carefully. There is a high-tech bit where I work out exactly how long the axles need to be using a vernier, pencil, and card (see below). I then cut and file the axles to length.

 

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I have found that inserting the first axle part way using a pillar drill keeps it nice and straight.

 

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Quartering is then achieved with a GW models quartering jig and the wheels pressed to a back to back gauge. This is when you find out if you can add up correctly, and if the axles are the correct length ...

 

With the Ivatt, all was OK, apart from the dreaded clearance behind the cross head. I ended up filing down the bosses on the back of the coupling rods, as well as the securing nut, to give a reasonable degree (about 0.5 mm) of clearance. There is almost no side play on the front axle, so this should be OK.

 

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Apart from the wonky lubricator (sigh), this photo shows that the brake shoes are nicely aligned with EM wheels. It also shows just how far the wheels are from the frames. I did think about adding plasticard frame overlays, but I’m not convinced that it these will even be visible at normal viewing distances.

 

Most importantly, the EM chassis runs very smoothly on DC, and the new wheels and rods look the part.

 

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Next job will be to replace the wiring and electrical gubbins with a dcc chip, then it will be time for details and paint.

Edited by RichardClayton
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Some substantial progress to report in the last few weeks. Here goes ...

 

This model is supposedly DCC ready, but the chosen chip (ZN68 from DCC concepts was a tight squeeze, so I removed the built in socket and soldered the 8 pin connector onto the pickup strips directly. A bit of a pin, and two of the pickups needed to be replaced with phosphor bronze strip as they broke off.

 

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Alls well that ends well, and a working chassis ensued, in fact it runs very nicely indeed.

 

Next job was sandpipes. Inexplicably missing from the Bachmann model. Inspiration struck while my mind was wandering one Sunday morning in our local church, and a couple of assemblies were swiftly put together.

 

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The picture above shows these assemblies, along with a fall plate, tender coupling bar, and brake rodding. The sandpipe assemblies were designed to fit the retainer plate.

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They were coloured using a black sharpie (as are the wheel rims and other sundry bits of pipe work). This is a vast improvement over nasty chemicals, ant takes paint very well.

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So now we are ready for a good test run around South Pelaw, to be followed by renumbering, coal, crew, and some weathering.

 

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Edited by RichardClayton
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A new identity. I’m not 100% confident that the large BR emblem on the tender is correct. I’ve not been able to find any photos of the loco before 1960 that show the tender detail. I think it looks quite fetching though ...

 

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