EM-ing a Bachmann Ivatt 2MT

[Mad McCann]

I'm about to convert a Bachmann Ivatt 2MT chassis to EM (above decks, it's going to become a BR Standard.

I'd be interested to hear of anyone else who's regauged one of these in the interests of hearing how others went about the task.

 

Cheers.

 

Dave.

[Quarryscapes]

Likewise. Do you mean the Tank or the mogul though? I'm after the mogul myself. 

[mike morley]

I'm doing my Mogul as I type this!

 

Biggest problem so far has been with the keeper-plate/pick-ups mount/brake-gear thingy that screws to the underside of the chassis block.

For my first attempt I slit it down the middle and widened it with a strip of plasticard but the result fouled the spacing washers used on the axles.  When I tried to cut clearance areas in it the recycled dustbin liners from which it appears to be moulded shattered.  At ExpoEM I had a useful chat with Worsdell Forever of this parish about his and my second attempt uses a new bit, pretty much as supplied.

The Bachmann chassis allows for miles of sideplay in it's 00 mode, so lots of spacing washers are required.  Once EM'd the big gap twixt wheels and chassis is a bit obvious so I also made some cosmetic frames from black 20thou plastic and spaced them out with 40thou blocks.  The only tricky bit making them was getting the diagonal slots that the cab support brackets fit into right.  I also cut the dummy springs off the original broken keeper plate and glued them outboard of the springs on the new keeper plate, again to reduce the gaps behind the wheels.

 

At the moment I'm fitting Dave Franks coupling rods to the Markits wheels.  The rods are intended for use with either Ultrascale or Gibson wheels so I'm using Gibson bushes to make it all fit properly.  They need just a kiss with a reamer to get them to fit happily on Markits crankpins and I've just had my fourth of the afternoon go Ping!  Trouble is, I'm not sure I've now got enough left to finish the job!

One blessing is that early indications are that the slidebars, crossheads etc look as though they will accommodate EM wheelsets without modification.  Obviously I wont be able to confirm that until I get the rods fitted and the crankpins cut down, but I'm very optimistic.

 

One head-scratcher I have got at the moment is the front pony truck.  I'm using the Comet one, which can be built in GWR or LMS/BR guises.  Logic says the massive majority should have the LMS/BR version, yet photographic evidence suggests the massive majority were actually fitted with the GWR type.  Can anyone shed any light on the subject?

 

Mine will eventually have one of Dave Franks superb CSB chassis under the tender.  The tender will also have pick-ups, connected to the loco via the plug and fly-lead intended for DCC.  One word or warning about the plug.  It is extremely difficult to un-plug it.  I've had to resort to brute force and ignorance with a pair of pliers and gritted teeth every time I've done it and its only a matter of time before it breaks.

 

I'll update as work progresses.

[Mad McCann]

Thanks Mike. Mine's a mogul too. I took a look at a friends yesterday and it didn't look too major a task. Like yourself I'm using Markits wheels on 3mm axles with LMS Rods. I also have the CSB chassis for the tender so it looks like we're following a similar route.

 

Cheers.

 

Dave.

[mike morley]

After discussing the subject with the club's LMS expert yesterday evening and having a look at one of his books it becomes apparent that surprisingly few Ivatt 2MT's were fitted with the LMS/BR pony truck.  Personally, I think that's a good thing is it was a rather bitty, untidy looking thing.  Another thing he was able to clarify is the arrangement of the front guard irons that majority of locos had..  I'd assumed they disappeared up into the gloom under the footplate where they attached to the front pony truck, Swindon style.  In fact, they were rather more pre-Grouping in nature and went up even further to attach to the frames behind the buffer beam.  In other words, if using the Comet pony truck, don't use either set of guard irons but fabricate your own.

 

More good news - the brake gear can accommodate EM wheels without alteration.  I assume the conversion-friendly clearances of both the brakes and the crossheads owe their existence to the massive amounts of side-play Bachmann expected them to cope with.

 

One mistake I belatedly realise I made was in cutting the cosmetic chassis sides I made to match the straight lower edge of the Bachmann chassis, rather than approximating the shape of the prototype.  The error is not obtrusive - which is just as well, as it's too late to do anything about it now - but because I know its there it will annoy me.

[mike morley]

A few steps forwards, several step back.

As predicted, The loco/tender fly-lead plug broke the very next time I tried to unplug it.  I decided to simplify things by wiring the pick-ups direct to the motor and realised very quickly that the route the wiring has to take is extremely cramped and tortuous.  Having finally managed to thread them through I then realised that there is not one iota of space in which to hide/contain the slack the wires need to have if the keeper plate is to be removed.

With the benefit of eagle-eyed hindsight I would advise retaining the original arrangement of leads, plugs and sockets but taking a file to the barb that retains the plug so it can be disconnected without needing to resort to brute force and ignorance with its consequent risk of damage.  Okay, after prolonged running the plug might drop off if the barb is removed, but that is nowhere near as big a problem as those caused by having to re-wire the loco.

 

Oh yeah . .

I've spent most of the afternoon picking up and putting down the part-dismantled chassis while I've worked on it.  A few minutes ago I missed the edge of the table when I put it down for the umpteenth time and its fall to the floor shattered the motor cradle (The time taken to make this posting is part of my don't-hurl-the-bloody-thing-at-the-wall therapy)  This obviously wouldn't have happened if the original plug and socket hadn't shattered, prompting the need for the re-wire.

 

I'm off to the mountains of Mid-Wales (One of the later outposts of the Mickey Mice) in a couple of days, so there won't be any further progress for a couple of weeks.

[Mark Forrest]

I can't offer any advice as steam isn't normally my thing, but as I have 4MT mogul to convert I've opted for a Brassmasters pony truck. Not done anything with it but it looks beautifully detailed and hellishly complicated in equal measures.

 

Interested in the tender chassis as I'm considering the same, but need to work out which is the correct one for under a BR tender. Have a Gibson wheelset for mine.

[Jamie]

Mark you might want 1/8" diameter axles for the 4MT - if the LMS version is anything like the BR 76xxx anyway.

 

This doesn't apply to the 2MT - both mine were spot-on for 3mm axles

[Worsdell forever]

Mine was quite a straight forward conversion (I'd rather spend my time building stuff than converting, but these jobs need doing!). A Gibson conversion pack (don't forget the coupling rod washers!) and brass tube as spacers. I seem to remember that I filed a bit off the back of the brake shoes and then bent out the pick ups, but then this needs doing straight out of the box anyway. The tender has just had the Bachmann wheels pulled out but it does need something better.

 

  

[mike morley]

There was enormous quantities of slop in the Bachmann chassis I got and the eighth-inch Markits axles I used have vast amounts of waggle in them.  This, I would suggest, is how Bachmann get their locos to go round hairpin bends.

[davefrk]

I've been watching this thread with interest as I'm looking for some mojo to get me own Ivatt 2 finished. The loco chassis conversion to EM has been done and the old Maygib wheelsets look good, the 1/8th axles fitted the Bachmann slots perfectly (same with my Ivatt 4mt), I'm amazed at the slop with 3mm axles in these chassis. The coupling rods were made long ago for an abortive Jidenco kit but were a good fit for the Ivatt. Lanarkshire Models do the correct ones now. The chassis block width has been packed out by 4mm with black plasticard but I've mislaid the footplate brackets to fix them back on. The tender chassis has already been mentioned by Mad McCann so I've put up a photo to prove I've actually built one.... Although not painted yet it's been well tested as Dave and Jamie will testify.

 

 

All the best,

Dave Franks

[Jamie]

I didn't find the wee ones particularly sloppy with 3mm axles Dave - but whilst mine aren't too bad, yours is certainly a better runner.  Maybe that's partly why.

[Quarryscapes]

This thread has given me the confidence I need to tackle mine! I had to take the body off to straighten out the cab (some how it had come off on one side only) and fiddling around getting the sand pipes to come out without ripping off themselves or the pickups put me right off getting on with the EM conversion!

 

The 3mm vs 1/8" axle is a bit worrying though - mine runs sweet as anything, the second best runner I have on DC 00 at least with it's factory fit 3mms, so think I'd be better off sticking to that?

Any advice on swapping out the drive gear?

 

And the most basic of all - what spec wheels? I'm planning on UIltrascales if I can, can't abide with the clunkiness of Romfords or the general faff that comes with Gibsons! 

[mike morley]

A question for those who have already converted one of these.

 

What did you use to bush the big-ends of the connecting rods in order to make them fit finescale crankpins?   Nothing I've considered even comes close.

[davefrk]

A question for those who have already converted one of these.

 

What did you use to bush the big-ends of the connecting rods in order to make them fit finescale crankpins?   Nothing I've considered even comes close.

 

Hi Mike, sorry but I turned some bushes up in the lathe to be a push fit in the big ends. I realise not everyone has access to a machine but a couple of bits of tube inside each other and the big end reamed out for a good fit would do. That's what I used to do.

 

Dave Franks.

[mike morley]

I am pleased to report that a bit of delicate use of a razor saw and files turns the hollow, large diameter crankpins from the original Bachmann centre drivers into what looks like becoming acceptable big-end bushes.  They aren't yet fitted but the early indications are good.

 

Not so good is the Comet pony truck.

This is not a fault of the Comet product.  One problem is that the mounting point on the loco chassis is intended for a narrow truck with a wide pivot, which is the exact opposite of the Comet version on both counts.  The other, greater problem is that the pivot point on the chassis is far lower than the Comet replacement was designed for and I've already bent the thing so much its started to look odd without yet getting it to the stage where it will sit or track properly.

If Mark Forrest is still following this thread I'd be interested to hear if he thinks the Brassmasters version would be any better in this respect.

If not I will probably be reverting to a cleaned-up, thinned-down version of the Bachmann original.

[Mark Forrest]

If Mark Forrest is still following this thread I'd be interested to hear if he thinks the Brassmasters version would be any better in this respect.

If not I will probably be reverting to a cleaned-up, thinned-down version of the Bachmann original.

Yes, I'm still here; I've still not been brave enough to start folding and soldering the pony truck though 

However, as far as I can tell it looks like it going to be a direct fit, at least it does on my BR Mogul, so I hope the same is true of the LMS one.

 

 

Details on the Brassmasters pony here; some more photos here which seem to suggest it is designed to use the original Bachmann mounting point, their chassis kit from which it is taken having being designed to make use of the Bachmann chassis block.

[mike morley]

I haven't made much progress lately due to other commitments, but I am pleased to report that decent-quality, snug-fitting coupling rods (provided in this case by Lanarkshire Models) do a lot to inhibit the waggle in the drivers.  They might not stamp it out completely, but the vast amount of slop in the axles make you expect the loco to stagger like a drunk on crutches and it is a relief to find it is far, far better than that.

 

Another thing the coupling rods do is give what I guess are supposed to be the balance weights on the weightshaft the gentlest of kisses at top-dead centre.  The kiss is so gentle it took me a while to realise that the symptom - the merest hint of a stutter when running slowly - was not caused by the aforementioned slack in the axles.

The weightshafts are stubs that plug into the chassis block and mine had a bit of a droop that was probably the cause of the problem, rather than the Markits wheels I'm using having slightly over-scale crank-throws.  Whatever the cause, it was far easier to cure than it was to diagnose.