Class 31 P4 Conversion

[Down_Under]

After reading this post here by James on converting and detailing a Lima Class 31:

 

http://www.rmweb.co.uk/community/index.php?/topic/19369-brush-type-2-re-birth-judgement-day/?p=187845&fromsearch=1

 

I found the original article on James Blog:

 

http://eastmoor.blogspot.com.au/2010/11/project-31-finale.html

 

It inspired me to have a crack. So far I have mounted the bogies, and cut some plasticard for the motor mount. The next task was to convert the Hornby bogies to P4. Which is where the problems begin. The Ultrascale conversion pack is no longer available and neither is the Alan Gibson one (although I believe some are in the pipeline). Either way, I decided to attempt to convert using some readily available parts, So this is what I have done:

 

Firstly the axle on the Hornby Bogie are split axle, with a plastic centre incorporating a gear, with the metal ends running in non tapered bearings. I measured the length of these - 25.5mm. Pretty close to 26mm pinpoint wagon/carriage axles.

 

After disassembling the Hornby bogie, you find that the metal stub axles are 1.5mm diameter vs 2mm for the average wagon carriage axle. I decided to ream out the plastic centre, to 2mm(using a broach to open out the ends, and then a 2mm drill). There is plenty of meat on these - an o/d of 3mm. The plan was then to insert the wagon axle into the plastic centre and then place the correct set of drivers on then end.

 

 

 

As it turns out all the wheels are the correct diameter on the Hornby model a 14.3mm for the drivers and 12.5mm for the non powered centre axle. For proof of concept I used some Alan Gibson 14mm carriage wheels and 12mm 3 hole disc wheels, this is all I have kicking about the spares box. The below images show what I have ended up with. The 12mm disc is a little undersize (should be 3ft 1 1/2" or 12.5mm) so it doesn't quite touch the ground, this should be resolved with the correct size wheel.

 

 

 

Now, pick ups - the Hornby bogie uses the bearings as pick ups, obviously I can use these anymore, so a pick up strip will have to be made. But so far, it all seems to work. The blue side is it makes a much more ridged bogie.

 

The next step (apart from pick ups and ordering the correct size wheels - Ultrascale make some) is to decide whether or not to remove the Hornby non tapered bearings and replace these with some tapered bearings.

Edited November 12, 2014 by Down_Under

[Down_Under]

I have since careful prised off the copper conducting slip and bearings. The bearings are small 1.4mm I/d bearings pressed into place.



Normal pinpoint bearings (these ones are Romfords) are 1.92mm o/d.

I am going to careful ream them out and solder in the pinpoint bearing type.

 

 

The final problem will be the center axle - technically this should be un-powered - but i might for the time being have it powered  -  the drive to the rear axle go through it on the Hornby model. I could use some brass tube as a bearing, or ream out the plastic center slightly oversize so it rotates but does not provide power. Hmm.

Edited November 12, 2014 by Down_Under

[Down_Under]

This is very much work in progress...

 

So as it turns out trying to fit a pinpoint bearing increases the distance between the frames, to such an extent the wheels won't turn freely. Instead, I have slightly tapered the copper plates, firstly using. A 2mm drill to bore 0.5mm into the copper and then reaming this out. This seems to be the better option.

Even counter sinking the the pinpoint bearing, it is still too much (the copper conductor plate/bearing is pretty beefy, but not enought to fully countersink the bearing.

 

 

Slightly reamed copper plate (shiny metal where reamed)

Edited November 12, 2014 by Down_Under

[34theletterbetweenB&D]

The final problem will be the center axle - technically this should be un-powered - but i might for the time being have it powered  -  the drive to the rear axle go through it on the Hornby model. I could use some brass tube as a bearing, or ream out the plastic center slightly oversize so it rotates but does not provide power. Hmm.

All my OO class 30s have the centre gear reamed out slightly and greased inside so the centre wheelsets are not driven, and have operated satisfactorily in this form for what must now be near ten years.

[Down_Under]

All my OO class 30s have the centre gear reamed out slightly and greased inside so the centre wheelsets are not driven, and have operated satisfactorily in this form for what must now be near ten years.

Thanks for the tip!

 

I have completed one test bogie (haven't greased the middle axle yet) needs a little more reaming out.

 

 

I just need to work on spacing a little more. I have gently tapered the copper bearing/pick up strip with a tapered broach, but there is still some binding on one side of the bogie

 

 

I might convert all of these to waisted bearings, it seems the one I did seems to be the one with the bogie frame binding against it, thus I ma have countersunk it a little too far.

[Down_Under]

The main issue to the binding appears to be the lack of squareness to the Hornby moulding.

 

 

 

 

Fully converted to the left - note frame binding in top right

Partially converted on right - driven axles substituted with plain 14mm and 12mm wheel sets, un modified bearings.

[Down_Under]

I think I appear to have sorted out some of the binding - spacing of wheels on the axle and the correct spacing of the drive gear. Although the frames are a little wonky.

 

I've started to convert all the bearings to waisted type-but I guess I should have left as was - the pinpoint type should self centre in the original Hornby 1.5mm hole?

[Waveydavey]

Nice work there. I had come to the conclusion that the way forward with P4 conversion on these was to get a mate with a lathe to turn down the Hornby wheels to a P4 profile. Good to see someone taking a different approach.

 

Just thinking it through from my own limited experience of Hornby 31s, if you filed off the pin points (and arranged new pickups) would the bogie baseplate not hold the axles in mesh well enough and allow a bit of movement to cope with P4 track? Having the wheels running in pin point bearings might make everything a little too rigid. Talking to Ian 'Penbits' recently he said it looked like Hornby had looked at springing the bogies of the 31and 50 but had backed out at the last minute.

 

Cheers

 

David

[Down_Under]

Nice work there. I had come to the conclusion that the way forward with P4 conversion on these was to get a mate with a lathe to turn down the Hornby wheels to a P4 profile. Good to see someone taking a different approach.

Just thinking it through from my own limited experience of Hornby 31s, if you filed off the pin points (and arranged new pickups) would the bogie baseplate not hold the axles in mesh well enough and allow a bit of movement to cope with P4 track? Having the wheels running in pin point bearings might make everything a little too rigid. Talking to Ian 'Penbits' recently he said it looked like Hornby had looked at springing the bogies of the 31and 50 but had backed out at the last minute.

Cheers

David

The increased ridge-ness of the bogie is the first thing you notice. The middle axle still has some slop in it. I will convert one with pinpoint and one without to see what the difference is. I have noticed that there is still a fair bit of movement in the mesh if the gears, so if you could spring at the ends, like a wagon -it could work.

 

If I had a lathe, I think I would turn some 2mm rod down at the ends to 1.5mm like the Hornby wheelset and then push fit on new wheels.

[Down_Under]

So after a little faffing, I have come to the following conclusions:

 

Pinpoint bearings - cannot countersink enough, thus the axle forces the chassis apart, lots of binding and too ridged.

 

26mm/2mm diameter pinpoint axles - these seem to work fine, an acceptable level of movement. Sprung pickups may help here.

 

 

I managed to sort out the binding - I hadn't pushed the gear on far enough causing some offset and binding.

 

The next method I would like to try is to turn the ends down to 1.5mm on the lathe, or a length of 2mm steel rod.

 

Just need to build some pick ups, and finish mounting the motor.

[the penguin of doom]

Hi Down_Under.

 

A good start to an interesting project here.

 

Sadly, James has been banned from the site for around a year or so and so is unable to personally record his thanks here to you. It would not be "decent" of me to profer any opinion on this situation, however, James has asked me to publically record his thanks to you for your very kind comments with regards to his work and would like you, (and any other members considering similar conversions), to know that if you are having any difficulties with your project in the future he would be happy for you to contact him via his blog or indeed via a PM to me here.

 

Cheers.

 

Sean.

[Grovenor]

What I don't understand is why you did not just use the Alan Gibson Wheels (item 4800/7) in the first place, then the whole conversion just takes a few minutes. Of course its a bit late now you have reamed out the gears.

Regards

Keith

[Down_Under]

What I don't understand is why you did not just use the Alan Gibson Wheels (item 4800/7) in the first place, then the whole conversion just takes a few minutes. Of course its a bit late now you have reamed out the gears.

Regards

Keith

From what I understand, they are still currently unavailable - I also understand that Colin is trying to get some more made - although this is proving to take longer than he anticipated. Timeframe as I understand it is still open. I have am in need to to a parts order in to alan Gibson soon, so will recheck in to see if there is any more news on the items.

 

I also have a spare bogie, and thought why not have a bash t see if I could do it with everyday items. So, technically a success. you can use 26mm axles. Not sure how well it will run. (Need to build some test track and finish mounting the motor). But you can build it without any binding, and some minor movement (slop!) which should hopefully run ok. I am not sure on the longitivtiy of steel axles running in copper bearings, therefore I am going to have a go turning down the ends of a 2mm axle to see if this provides a neater solution to the problem.

 

The next problem is find the correct size wheels. Although Hornby have used near scale wheels, but I've tried various manufactures and some are slightly undersize, while others oversize. I think I will have to settle on slightly underside (14mm) drivers and scale (12.5mm) middle (carrying) axle, so that all wheels touch. And build some pick ups.

 

To answer David's question a little more, I thought about chopping off the ends, but upon taking apart the bogies, you find that the Hornby axles don't run on any bearings as such, the plastic gear/centre is undersize for the slot (should be visible in above photos). So the slop would be unacceptable. I think if I was to try and spring it, you would have to build some sub frames, and spring on the ends of the axles, like you would a wagon or carriage.

 

And finally, Sean, thanks for the update. You can let James know I'll be in contact, and look forward to his next blog post.

[Down_Under]

The prototype that in mind worked the High Dyke Branch - and it fits in nicely with my want to model the iron ore railways of the late 60s, early 70s. I found this set of photos by David on Flickr - you can also find them on this forum.

 

https://www.flickr.com/photos/davidwf2009/sets/72157626169910951/

 

The locomotive that I will be modelling is either:

 

31 #5671

 

https://www.flickr.com/photos/davidwf2009/5640302754/in/set-72157626420020389

 

or

31 #5673

 

https://www.flickr.com/photos/davidwf2009/5640302996/in/set-72157626420020389/

 

Or maybe both eventually. A little bit different is the tablet catcher recessed into the door.

Edited November 14, 2014 by Down_Under

[EHertsGER]

If everything goes according to plan we will be producing a sprung Class 31 chassis for P4 in the near future; the only obstacle is in not duplicating anything 'Penbits' is up to but the '31' seems some way off, so we have decided to do it ourselves. Delivery by the year end (ha! I didn't say which year, but meant 2016!)

 

It will be P4 only (go on, push me to do EM too) and designed around the Hornby 'modern' chassis, not the LIMA/Railroad version (though with a bit of ingenuity you could make it work for these too - maybe in the MK2 version...)

Edited June 29, 2016 by EHertsGER

[Waveydavey]

Although I'm a P4 modeller my only involvement with 4mm class 31s is in EM for Roundtrees Sidings so I'd be interested in seeing an EM version of your chassis.

[Horsetan]

If everything goes according to plan we will be producing a sprung Class 31 chassis for P4 in the near future; the only obstacle is in not duplicating anything 'Penbits' is up to but the '31' seems some way off, so we have decided to do it ourselves. Delivery by the year end (ha! I didn't say which year, but meant 2016!)

 

It will be P4 only....

 

Wonderful. Please put me on the list for one. It would be interesting to compare it with the TruScale Models effort of the late 1980s. Unfortunately I missed out on the Bill Bedford version, so there won't be any more of those.

[Down_Under]

If everything goes according to plan we will be producing a sprung Class 31 chassis for P4 in the near future; the only obstacle is in not duplicating anything 'Penbits' is up to but the '31' seems some way off, so we have decided to do it ourselves. Delivery by the year end (ha! I didn't say which year, but meant 2016!)

 

It will be P4 only (go on, push me to do EM too) and designed around the Hornby 'modern' chassis, not the LIMA/Railroad version (though with a bit of ingenuity you could make it work for these too - maybe in the MK2 version...)

Me too! I have put this project on hold - moving house means it's all boxed up. I have a Bedford chassis I was using as a basis - but alas little time. I'd be happy to have 2/3 of these.

[EHertsGER]

If everything goes according to plan we will be producing a sprung Class 31 chassis for P4 in the near future; the only obstacle is in not duplicating anything 'Penbits' is up to but the '31' seems some way off, so we have decided to do it ourselves. Delivery by the year end (ha! I didn't say which year, but meant 2016!)

It will be P4 only (go on, push me to do EM too) and designed around the Hornby 'modern' chassis, not the LIMA/Railroad version (though with a bit of ingenuity you could make it work for these too - maybe in the MK2 version...)

Ian 'Penbits' has pretty much given me the 'all clear' to get on with this; I felt I should see what he was up to before committing to work, simply to avoid duplication and do him the courtesy of first crack at the project. It seems other things are occupying his time and attention, so off we go...

[Waveydavey]

I'm fairly sure the architecture of the Hornby class 50 bogie is similar to that of the 31. If you could broaden the scope of the project to include the 50 you'd make me a very happy boy.

 

Cheers

 

David

[Horsetan]

I'm fairly sure the architecture of the Hornby class 50 bogie is similar to that of the 31. If you could broaden the scope of the project to include the 50 you'd make me a very happy boy.

 

I did drop hints to Ian about the Hornby 50, though he has his hands full with the Class 40/44/45/46 bogies and many other things!

[EHertsGER]

Now, steady on, chaps! Let's get the 31 bogies rolling first. With that done, we can move on to the '50s if Ian doesn't get there first...

[EHertsGER]

The current state of play is that we have all the 'stuff' we need to get on with this and a willing 'volunteer' for the prototyping/development work, but diaries are full until the end of September 2016. So, the proposed date of 'by the end of 2016' is still attainable as work will begin in a couple of weeks.

 

And yes, it will be P4 and EM and Class 31 (oh, alright, Class 30 as well..) only.

 

I'll keep you posted...

[Down_Under]

Awesome news!

[richierich]

Any further development news of the Class 31 EM / P4 Conversion kit?