Bachmann Mk1's and 2's

[BigAndy]

Morning all,

 

                  I may be barking up the wrong tree here, but I've noticed a bit of a discrepancy between mk1's and mk2's roof heights.

 

Unfortunately, I am not computer savvy enough to provide any fots, but I wondered if anyone else has come across this issue, when combining Mk1's and 2's in a rake?

 

I am building a 6 coach raft at the moment, made up of mainly mk1's with a solitary mk2 thrown in the middle, as per a prototypical raft for Queen St.

 

Now something is wrong somewhere, and I cannot decide whether its the mk1 or mk2 thats wrong, but they definitely are at different heights! The roof levels are some 2 and a half millimetres different, with the mk2's being lower than the mk1's - a scale 6 inches........and it sticks out like a sore thumb.
Mk1's in a rake on their own look great and the same goes for the mk2's, but mix 'em together and it looks really strange.

 

I've mixed Bachmann mk2's together with airfix and Lima mk2's before in rakes, and they match really well, which would kind of lend a thought to the fact that it's the mk1 thats over scale.............

 

Has anyone else come across this, or knows the answers or has rectified it in some way?

 

cheers

 

Andy

[John Tomlinson]

I made exactly the same discovery when buying a solitary maroon Mk2 to go in a Mk1 rake. If IIRC perceived wisdom has it that the Mk1 sits a bit high, as do many locos, but the Mk2 if anything is a bit low.

 

My bodgers solution was based on the fact that the Mk1 (Bachmann) is by far my commonest coach, and seems to sit well with most RTR locos, and I so decided to take it as a datum for eveything else - most coaches of the kind we're discussing have a similar height being around 13ft. So my solitary Mk2 was packed up between bogie and body to bring it into line. I did buy one Hornby Gresley when they came out, and had a similar experience with that to the Mk2 - it hasn't troubled me further as the errors in the tumblehome and beading on the Gresleys meant I haven't ( and won't) buy any more, reverting to Kirk (now Coopercraft) kits as being less inaccurate. 

 

As you say in your post, it is the inconsistency that really jars, and whilst having everything to precise scale height is a great ideal, I felt my approach gave consistency without a huge amount of work. As a OO modeller, there's a 12% error in my trackwork that blows absolute accuracy right out of the water anyway!

 

John, with snaps on www.flickr.com/photos/51265696@N03

 

P.S. You mentioned Lima coaches, and I seem to recall that the wheels on these are a bit small, and well as having very deep flanges. From memory the radius is 1mm - scale 3 inches - undersize, so changing the wheels ought to lift the coaches by that amount. 

Edited April 6, 2014 by John Tomlinson

[naugytrax]

Exactly. The difference in height is ludicrous when the Bachmann MK 1's and MK 2's are coupled together. I'm sure that the MK 2's are too low. I raised mine somewhat on its bogies using washers (I only have one MK 2) but I couldn't match the roof heights without making the MK 2 look as if it was perching on stilts.

In the end I gave up and now I only run the Bachmann Mk 2 with my Mainline MK 1's, which match it because they are also too low.

 

[BigAndy]

Thanks for the replies Gents.

 

You're absolutely right about the Lima mk2's John, however, I'm building in EM so the whole Lima bogie has been discarded, being replaced with the rather excellent Replica B4's with Em wheelsets.

 

naugytrax, I still can't make my mind up whether it's the Mk1 or Mk2 that's out - maybe the Mk1 is slightly overscale and the Mk2 slightly under ( I'm not sure about the curvature of the roof profile on the Mk2, thinking it may be to 'flat' over the width of the coach, therefore giving a reduced height )

Having said that, when you offer both coaches together, the cantrail strips don't line up either...................something is way wrong though.

 

Anybody ever measured the protoype? or could shed any light on this? 

[John Tomlinson]

The 13ft height referred to in my post scales at 52mm, and I believe the buffer height, taken to the centre, should be 3ft 6in - 14mm above rail level. My own view, as I said is that one is a bit over, the other under, and its a matter of what if any compromises you're prepared to make or if you want absolute accuracy.

 

John.

Edited April 7, 2014 by John Tomlinson

[Flood]

When I first noticed this discrepancy in height between Bachmann Mk1 and Mk2 stock I checked Parkin's book on the Mark 1s and came to the conclusion that Bachmann Mk1s are the correct height (as also stated by a number of other modellers subsequently). I have therefore used 40 thou (1 mm) thick plasticard packers on the tops of the bogies on all my Bachmann Mk 2 stock to bring them up to the correct height. This also gives a more realistic gap between the rail and the underframe equipment.

Edited April 7, 2014 by Flood

[34theletterbetweenB&D]

...My bodgers solution was based on the fact that the Mk1 (Bachmann) is by far my commonest coach, and seems to sit well with most RTR locos, and I so decided to take it as a datum for eveything else - most coaches of the kind we're discussing have a similar height being around 13ft. So my solitary Mk2 was packed up between bogie and body to bring it into line. I did buy one Hornby Gresley when they came out, and had a similar experience with that to the Mk2 - it hasn't troubled me further as the errors in the tumblehome and beading on the Gresleys meant I haven't ( and won't) buy any more, reverting to Kirk (now Coopercraft) kits as being less inaccurate. 

 

As you say in your post, it is the inconsistency that really jars, and whilst having everything to precise scale height is a great ideal, I felt my approach gave consistency without a huge amount of work...

Seconded! When the Bach mk1 emerged, I was very pleased to find that the roof top was 50mm - so scaling 12'6" - above railhead, and a bob on match for my various Kirk kit and other LNER stock; all set up with the top of the roof at a scale 12'6" in accordance with the information in my 1976 copy of 'Historic Carriage Drawings in 4mm Scale' by Messrs Jenkinson and Campling.

 

Too deeply committed at that point to take on board any divergent opinion, and happily Harris' LNER coach book also holds to 12'6". So whatever is the true height of the top of the mk1's roof panels; pragmatically it's 12'6" or some close approximation thereto in my model world because that reproduces the prototype appearance of a uniform roof top line in a mixed formation of Gresley, Thompson and mk1 stock.

[BigAndy]

Thanks everyone, for your inputs.

[mark54]

The prototype Mk1 & Mk2 coach overall height was 12' 4.5" which is 49.5mm in 4mm scale. The original release of Bachmann Mk2 coaches was pretty close being a fraction under. The Bachmann Mk1 is too tall being a little over 50mm. The discrepancy is in the depth of the sides, so unfortunately you can't lower the bogie ride height. The Bachmann Mk2 should match the Hornby Mk1 though.

 

The 2nd release of Bachmann Mk2a coaches had a modified B4 bogie which incorrectly lowered the ride height. I suspect Bachmann modified the B4 to lower the ride height when fitted to Mk1's which originally rode even highter than the CW and BR1 fitted versions (nearer 50.5mm).

 

Gresley and Thompson coaches at 12' 6" would not match Mk1 coaches in overall height as can be seen with these sleeping cars:

 

https://www.flickr.com/photos/robertcwp/3411736681/sizes/o/

Edited April 7, 2014 by mark54

[Melly]

Hi BigAndy

 

yeah I noticed it to - mainly a BG within a Mk2 rake.  There is some more on this thread http://www.rmweb.co.uk/community/index.php?/topic/7502-Bachmann-mk2-coaches/.  I even noticed differing ride heights within Mk2s see this picture for the differing height of the bogie mounting!!

 

 

Unfortunately this issue not on my to do list in the immediate future but uniformity looking down a rake of combined Mk1s and 2s is something I aspire to.

 

Regards

 

Melly

 

[John Tomlinson]

Apologies to one and all for my somewhat cavalier reference to a 13ft height in my earlier posts, I'm glad to see that precision has since entered the discussion!

 

Its worth noting that the ventilators and periscopes stand above general roof level, and if I'm reading the Parkin drawing for gangwayed Mk1's correctly, give a height above rail level of 12ft 9 & 7/64 inches including these items, roughly 5 inches above the roof line. The Isinglass drawings I have for some LNER Pacifics give a maximum of 13ft 0& 15/16inches on these locos, over cab roof vent, dome and chimney, which presumably was the top of the loading gauge envelope, and gives another reference if we are to have a consistent if not entirely accurate height of our models.

 

The great Iain Rice once pointed out, IIRC in one of the Irwell wagon modelling books, that tyre wear, ageing springs, and indeed loadings such as coal and water in a tender, can give several inches of movement against "book" dimensions, which is also a thought here.

 

John.

['CHARD]

P.S. You mentioned Lima coaches, and I seem to recall that the wheels on these are a bit small, and well as having very deep flanges. From memory the radius is 1mm - scale 3 inches - undersize, so changing the wheels ought to lift the coaches by that amount. 

 

Strictly speaking, shouldn't a wheel change lift the ride height by twice the difference in the radius? 

 

EDITOR'S NOTE: we are no longer taking entries for today's DUMBEST contributor competition, owing to 'CHARD having won the trophy in deafening style!

Edited April 9, 2014 by 'CHARD

[sub39h]

Surely a wheel change will lift the ride height by twice the radius? 

 

the wheel only rests on the rails on one side at a time so it would only increase by the radius on the side touching the rail, not by the diameter of the wheel 

Edited April 9, 2014 by sub39h

['CHARD]

the wheel only rests on the rails on one side at a time so it would only increase by the radius on the side touching the rail, not by the diameter of the wheel 

 

Ah yes - of course - that's me not seeing the wood for the trees!

[Silver Sidelines]

Hello John
 
Small world - I must be in the slow learners group as it has taken me over three years to get to exactly the same position as you!

I made exactly the same discovery when buying a solitary maroon Mk2 to go in a Mk1 rake....
...

Like you did I have just received a single Mk2 to insert into a rake of Mk1s.  I have spent all evening searching the web for posts comparing Mk1 and Mk2 coaches.  It was only when I added 'Bachmann' to my searches that I was directed back to RMweb.  Should have read your Post before bidding.  1.5mm of packing later and it is nearly very good. Thank you John.


Bachmann BR Mk1 and Mk2 with c1.5mm packing

[John Tomlinson]

G

 

Hello John
 
Small world - I must be in the slow learners group as it has taken me over three years to get to exactly the same position as you!

Like you did I have just received a single Mk2 to insert into a rake of Mk1s.  I have spent all evening searching the web for posts comparing Mk1 and Mk2 coaches.  It was only when I added 'Bachmann' to my searches that I was directed back to RMweb.  Should have read your Post before bidding.  1.5mm of packing later and it is nearly very good. Thank you John.


Bachmann BR Mk1 and Mk2 with c1.5mm packing

 

Glad to be of assistance, Ray! I wondered what had provoked the picture on Flickr of these coaches.

 

I seem to remember that the models of these early Mk2's were quite poorly received, but like you I've found that one in a rake of Mk1's adds a fair bit of character to a consist, and dates the train to the mid '60's.

 

John.

[Flood]

Melly's photo in post#10 show one of the problems you now have with Bachmann Mk2 coaches.

 

The B4 bogies made before 2014 were as per his photo on the left, higher than those produced subsequently. This change in the bogie mounting means that all Bachmann Mk1 coaches now ride at the same height (on the old bogie those with B4s were too high). However, having lowered the overall height of the B4 Bachmann have now made their Mk2 stock ride even lower!

 

I try to swap the new bogies onto Bachmann Mk1 stock and the older bogies onto my Bachmann Mk2 stock but supply of the older bogie can now only be made if you buy a coach in the old style box.

 

Basically even more packing is now needed for the Bachmann Mk2 stock but with me able to perform my needed bogie swaps I don't know how much is now required.

 

Even though I have seen E.P.s of the air-con stock, and very nice they are too, I have not compared this stock to any others with regard to buffer and/or roof height.

Edited December 1, 2017 by Flood

[Silver Sidelines]

Thanks John

.......like you I've found that one in a rake of Mk1's adds a fair bit of character to a consist, and dates the train to the mid '60's..

1964 at the earliest - so perhaps not A4 hauled.

 

I am slightly puzzled as I seem to remember seeing a Deltic hauled Elizabethan passing Darlington with Mk2 coaches - but I thought that I had given up train spotting by 1964!

 

Regards

 

Ray