Atlantic's works: Portable layout update

[James Harrison]

Wow! What a stunningly good-looking machine.

[earlswood nob]

Good morning all

The valve gear for the old Nucast P2 kit was the same as that for the O2.

Now that South Eastern Finecast are re-issuing the Nucast range, the O2 should be availabe shortly. As they sell parts separately, the valve gear rods will then be available as a fret.

Of course there is the RTR O2 (Heljian?), but I've no idea if they sell spares.

Earlswood Nob

[Woodcock29]

I'm just wondering about the comment above? I have the original Ks P2 and the valve gear on that of course was not the same as the Nucast O2. Did Nucast replace the valve gear on the P2 with their own when they took over the Ks range?

I have measured both and the Ks valve gear is not exactly the same length as the Nucast O2 valve gear, eg the eccentric rod on the P2 is 1.5mm longer and the connecting rod at least 1mm longer on the Ks P2. Note I found that the Ks P2 valve gear didn't fit very well and I think I had to shorten the connecting rod - but that is well over 30 years ago now!
Andrew

[Atlantic 3279]

If anybody has the necessary true scale drawings, notes of dimensions, time, and ingenuity it would be interesting to know whether a single etch for a good-looking complete set of slidebars, con-rods, Walschaerts and motion brackets can be designed in such a way as to cater for O2, P1 and P2 applications without creating obvious errors in any of those cases. Apart from discrepancies in dimensions, alignments and angles, there is of course the slight snag that the P2s require a reversing lever that is slotted through the multi-layer expansion link, whereas the 02s and P1s had the reversing lever more conventionally placed aft of the expansion link...

Then there's the matter of studying all of the models (kit or RTR) to which users might want to fit such valve gear, in order to ensure that the motion bracket is capable of being fitted to the different chassis designs.

[Pebbles]

Many years ago Atlantic built a P1 using parts from ACE Models 02. Now ACE Models have test etched a P2- see Tony Wright's build- as earlswood nob would appear to live close to Redhill/Reigate may I suggest a visit to - if I remember correctly - Ringwood Road.

[Atlantic 3279]

A brief diversion from progress towards the Bugatti P2 noses, but nonetheless relevant to the Hornby P2 and very slightly connected with some current debate about the pros and cons of Hornby's "best" Chinese made Gresley Pacific mechanisms:

I'd been feeling smug (never wise) for a couple of years thanks to the belief that all three of my Hornby P2s ran well despite the troubles that other owners have reported with notchy motors. That smugness evaporated when I was operating Grantham's loco depot at the St.Neots (East Anglian) show a few weeks ago, and found that I could not easily get my factory original super-detail Cock o' then North model to stop just where I wanted it on the turntable deck. It would lurch half an inch beyond or stop half an inch short, but the control just wasn't fine enough to get it neatly on the turntable without a lot of shuffling back and forth. Not very realistic. Later investigation revealed that the motor in that particular model "cogged" significantly more than those in my other two P2s - I checked them all both in the chassis and released from the chassis, turning under power and turning the armatures by hand. No amount of further running-in on the bench appeared to do anything to smooth out the starting and stopping characteristics of the errant motor, so I presume it had either more highly magnetised or more closely fitting pole pieces than the other two.

I'd had an idea in mind for some time regarding an experimental motor upgrade for one or more of these locos anyway, so I was spurred on to try it out. I happened to have scooped a number of very attractively priced Can motors on eBay a couple of months ago, a type that appeared to be identical to those in Hornby's best LNER Pacifics, and on testing them found them all very smooth running. I reckoned that the girth of these would be no problem in the P2, but they were certainly too long to be a straight swap. Whilst I know that there is a shorter version of these 5 pole skew wound motors that is or was available from Hornby, which others have found to be an almost perfect drop-in fit, when I last bothered to check they were about £18 each whereas all of my spare motors together had cost less than that, so it was very tempting to find a way to fit the longer motor.

If you detach the wiring from the tags on the standard motor and pull the mass of spare wiring out of the way, the standard motor set-up looks something like this.

If you unscrew the two screws (fore and aft of the DCC socket) from the big block that sits on the front of the chassis, lift it and and unhook its rear lugs from their positions either side of the concealed motor worm, then unscrew the little yoke that holds down the rear of the motor, the motor will then lift out. In order to accommodate the longer motor I used a piercing saw to remove the part of the casting that holds the rear of the short motor, and then employed a half-round bastard file clear out the material that remained in the rear of the trough for the motor. OBVIOUSLY, I took care to keep filings out of the gears whilst doing this.
The worm gear, which turns out to have alarmingly little length of armature shaft inserted, was removed from the short motor. I have no puller, but just in case I needed the motor again, I avoided pulling or levering the worm directly against the motor casing and potentially wrecking the bearings and other internals. I achieved a "safe" worm removal by closing a pair of suitable pliers as far as they would close around the plain part of the worm gear and the armature shaft itself, nearest the motor. I then rested the pliers across the jaws of a vice with the motor hanging beneath, and using a piece of brass rod as a drift I tapped the armature shaft out of the gear.

The boss at the front of the standard Hornby Pacific motor (left in the picture below) isn't fat enough or long enough to suit. Using the boss on the short motor (right, below) as a pattern I built up the boss on the new motor to match. Four strips of 0.020" thick plasticard, 2mm wide, wrapped around the smaller boss and super-glued thoroughly in place brought the diameter up to the necessary "almost 10mm". A flat about 1mm deep compared to the original circular outline was then cut and filed on one side, giving the result seen centrally below.
On examining the worm gear and offering it up to the new armature shaft I was concerned that it might not have been drilled out to a sufficient size throughout its length. I wondered if it had been left too small, save for the part that sat on the short shaft of the original motor, as a deliberate means of preventing the gear from being pressed too far on to that original shaft. I didn't want to damage either the new motor or the worm gear through use of excessive fitting force, so I ran a suitable drill bit through the worm first. It still proved to be firm push fit on the new shaft, but I added some "goo" to retain it too.

The suitably prepared new motor goes in nicely as seen below. Without the rear support / retainer, thrust from the worm gear when the motor rotates in one direction pushes the motor rearwards out of its front mount if nothing more is done, so I had to decide how to secure the motor more fully. One possibility was to lash it in place with a horizontal loop of wire, twisted up tight, the front of the loop around the notch in the chassis block behind the DCC socket, the rear of the loop behind the motor. Tie-wrap might be used in a similar way, but in either case the extra material protruding from the smooth sides of the chassis could prove a nuisance when fitting and removing the body shell. If it becomes necessary to retain the motor in such a way I'll go for the wire loop option I think, but for the moment I've done something different. A curved sheet of 0.015"plasticard is glued with Evo-Stick impact adhesive to the underside of the motor Can, and similarly glued to the curved recess in the chassis. This nicely supports the rear of the motor, maintains the mesh, and appears to hold the motor very firmly.

The bigger motor, with the wiring reattached and tucked back into more or less its original position, goes in and out of the body shell without any bother. Start and stop control is now much smoother and the motor, as we know from use in the Pacifics, provides plenty of smooth power and speed.

Finally, for completeness and for comparison, here's a reminder of the simpler conversion option using the Hornby X9108 motor.

http://www.rmweb.co.uk/community/index. ... -flywheel/

https://www.youtube.com/watch?v=FSmFUx9YLU0

[manna]

G'day Gents

I haven't had a problem with my P2 (yet), but I have the same 'spare' motor as yourself, to get the armature tot he same thickness I drilled out a bit of plastic pipe, super gluing that in place then gluing the worm in place, same problem different solution

manna

[Mersey508138]

Hi Atlantic 3279

I like what you have done in remotoring the P2 chassis with the X4026 Hornby A3/4 motor.

I thought it was only the X9108 motor for the 8F that was a suitable replacement for the original motor so I would like to thankyou for providing alternative motor replacement information.

Any ideas how to remove the metal on the rear truck casting to allow suitable flanged wheels to be fitted without causing a short circuit. I would like to apologise if I have asked this before but I have been a bit out of sorts recently since losing my dad 7 weeks ago.

Thankyou again for the alternative motor suggestion.

[Nova]

Any ideas how to remove the metal on the rear truck casting to allow suitable flanged wheels to be fitted without causing a short circuit. I would like to apologise if I have asked this before but I have been a bit out of sorts recently since losing my dad 7 weeks ago.

first of all my most deepest sympathies regarding your dad, I went through the same thing back in 2013.

now to answer your question, I would suggest using a small sanding drum on a dremel-type tool and taking is slowly, also using a hand file for any precise work, checking every so often for clearance. I've done similar with the original super detail Pacific chassis taking away the "flange" around the axle hole and eventually gave it enough clearance to take 3rd radius curves with a flanged wheel. of course it's going to be much slower going in the case of the P2 as it's surrounded by metal on all sides

or if you have lots of money use a milling machine

[Atlantic 3279]

I really ought not to advise on alterations to the P2 rear truck as I haven't had a go at that particular job - yet, anyway.

[earlswood nob]

Good morning all

Woodcock's reply has got me thinking. I did build the old Kay's P2, but after a visit to the floor, the valve gear was replaced by the Nucast O2 version. It fitted so I assumed it was the same. I shall have to check, and look at my drawings to see if they match.

Pebbles is almost there with the address of ACE models. It was a private house in Ringley Park Road, about two miles from where I now live.

The great thing I like about this forum is that it gets one thinking.

Earlswood nob

[Pebbles]

Sorry about getting the road wrong earlswood nob but, its been some eight years since I was last at William's home.

[earlswood nob]

Good morning all

I have looked at the valve gear fret for the Kays/Nucast Earl Marischal and it differs from the Nucast fret for the O2. They differ in the lengths of the eccentric links and valve rods, with fractional differences in other rods.

The Isinglass drawings show that P2 valve gear rods are the same as those of the O2.

I have compared the frets with Isinglass drawings and the Kay's fret is closer scale to the original. However, the Kays P2 rods are wider than those of the original.

Earlswood nob

[Atlantic 3279]

The Isinglass drawings show that P2 valve gear rods are the same as those of the O2.
Earlswood nob

Interesting to hear all of your findings. In the specific bit I've quoted, did you definitely mean the P2, as opposed to the P1?

[Atlantic 3279]

The re-motored P2 certainly hasn't lost any top speed, light engine, with its Pacific motor. It would not have surprised me to find the fatter motor with longer armature to be slower revving. I'll try to do peak haulage tests compared to the two P2s with factory standard motors, if time permits.