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Converting a Roco Br44 to HO Fine (RP25/88)


Wyvern

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I thought I would post my progress so far on converting my Roco BR44 to HO-Fine standards which is similar to OO finescale using RP25/88 wheelsets and 14.8 back to back.   I have for quite a while now been very keen a German heavy freight locomotives and in particular the BR 44 2-10-0.  I have 2 of the Roco models but never been a fan of the deep flange NEM? wheels.  Although I have considered converting the loco to HO-Pur / Proto 87 standards I was concerned about how well it would stay on the rails despite its sprung front and rear drivers (sorry Ivan - so close yet so far... :no: ).  That and I was looking for a temporary distraction from 2mm finescale which I didn't what to be too involving.   That said I will likely look to modify a locomotive to HO Pur standards but this will be with Teichmann castings and chassis springing.   The wheels I started with are shown below, about 2.8mm wide and with flanges of about 1mm.   These were to be reduced to 2.2mm and 0.6mm respectively.   I reduced the flange width by about 0.1mm

 

roco%20wheels.jpg

 

My lathe setup as it currently stands.   A Taig lathe with added digital readouts on the carriage and cross slide.  They were invaluable for this work.

 

  IMG_20160913_191722.jpg

 

I first turned and bored a collet from aluminium tube stock to hold the wheels without damaging them. The collet needs to have its position in the lathe chuck marked to ensure its accurancy when re-inserted.  This shows the wheel in the collet ready for the flange to be reduced.   Once I had reduced the flanges, I used a mini file to shape the flanges and take off the hard edges.  

 

IMG_20160913_191822.jpg

 

I then used a collet to hold the wheels on their flanges for reducing the wheel width.   The wheel protruded from the collet allowing the width to be reduced.   I also polished the rims with fine sandpaper to improve the surface finish as they had worn off their nickel plating and are now running on a brass surface.   I have a set of new spares but i thought it best to practise with the well worn pair.  

 

In future I will produce a collet to hold the wheelset by one tyre at a time to ensure the tyre width is a consistent as possible to the tyre.

 

IMG_20160913_191935.jpg

 

This shows the wheel sets reassembled.   I added alot of spacers to take up the play designed into the chassis.

 

IMG_20160913_192738.jpg

 

IMG_20160913_192238.jpg

 

I certainly feel its a worthwhile improvement and the next stop will be turning the front pony and tender wheelsets.  Then I plan to make an HO fine track test piece possibly using peco code 75 and handbuilt turnouts.

 

IMG_20160913_192330.jpg

 

All the best

 

Guy

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Oh and beware that Roco use minutely different retaining bolt for the central motion (M1) as they do the outer wheelsets (M1.2).   It took a while before I realised this....

It might have made more sense to use M1.2 for the central driving axle, given that it has to bear two big ends and a return crank, but that's Roco for you. Even today, they're never quite sure what size of flange to use on their otherwise excellent stock. So that generation is definitely brass underneath - this will cover my old Br.41 and Br.23, both of which have 4xxxx catalogue numbers and 3mm driving axles. Interesting.....

 

The camera is quite cruel to the trailing axle's flanges by suggesting you could still get away with taking off a bit more from the rear faces.

 

Like the digital measurement setup a lot, but not sure how one would adapt it for use on a Unimat.

 

Teichmann castings and the other bits are in the post now; might arrive next week.

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Hi Horse,

 

You are quite correct that I could have taken more off the flanges, I was keen at the time to stick to the RP25/88 profile which has 0.6mm flange thickness.  You could reduce the wheelsets further to proto standards or to HOt which is as proto 87 with 0.5mm flanges.   The only thing is that as soon as you go down the Proto route, conversions can turn from straight wheel swaps to more complicated chassis conversions especially on long wheelbase 2-10-0s.   I also had the concern that the tolerances for wheel run out (wobble) would be significantly less when using the Proto standards and some runout had been identified on the lathe.   This is no worse than typical RTR I imagine but were enough to provide pause for thought.   

 

The Lathe DRO has been invaluable when dealing with the precision required when turning wheels.   I got the DRO from machine-dro.co.uk and used linear scales bolted to the carriage and cross slide :  http://www.machine-dro.co.uk/horizontal-linear-digital-scale-300mm-12-inch.html

 

A quick search shows how someone has done this with a Unimat : 

 

maxresdefault.jpg

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...as soon as you go down the Proto route, conversions can turn from straight wheel swaps to more complicated chassis conversions especially on long wheelbase 2-10-0s....

I've been playing with the idea of the DLM-converted "Reko52" 52.8055; nobody produces this modernised one-off, so a hybrid model would be an amusingly mad project.

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ooohh..... where might I find these etched chassis frames?

 

Wagenwerk.de - the brand is CN-Modelle, I think. The etch looks like it was designed as overlays, but there's nothing stopping you using them as templates to back them with something stronger, which is why I had the evil plan *manic echoing laughter*

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Hi Wyvern,

 

The continental modelling community (or minimum me...)  is waiting for your driving tests. Did you start already testing ?

Would be interesting to test the loco even you haven't changed the pony and tender wheel flanges.

 

Regards

Vecchio

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A really good website I managed to find a front bogie wheel in HO fine for a 44. Incidentally what is the ral number or paint colour for the red used on German steam chassis?

It looks like they deal in Weinert parts.http://www.weinert-modellbau.de/

Try direct, as I find this catalogue easier to read and even easier to spend silly money.

The Roco 44 has a great deal of side play in the drivers and tends to hunt on Peco track. Mine does, but  it is a very old version so not sure if they have tightened things up. I would suggest that you add some packing, especially if you do not intend to run it on small radius curves. It also seems to be lighter than other 2-10-0s and I have added a bit of weight which also tends to help reduce the hunting.

I like what you are doing but I am too far down the road to start altering wheels now, other than replacing the non drivers.

Bernard

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But they do publish a catalogue, including an on line version, where every thing can be seen at a glance.

Bernard

 

Yes, they do. And the price lists! :O  This then allows you to go to a dealer like Wagenwerk and find that it is possible to spend quite a lot of money really quite quickly....

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Hi Wyvern,

 

The continental modelling community (or minimum me...)  is waiting for your driving tests. Did you start already testing ?

Would be interesting to test the loco even you haven't changed the pony and tender wheel flanges.

 

Regards

Vecchio

Hi vecchio, I have pushed the loco backwards and forwards on some code 100 but this is as far as I have got at the moment. It appears to be OK however I dont have any finescale track to run it on yet. I plan to build a small layout to ho fine standards to test it on.

 

I have installed fibre washers on the front and rear drivers and cut biro tube on the central drivers to reduce sideplay as there is a lot built in to the chassis.

 

I may add weight if it seems necessary although I suspect the tighter tolerances will go some way to solving any hunting issues.

 

I normally model in 2mm fine scale so this is my first proper steps in HO.

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Thanks. Glue down the track under weights when you build your finescale test layout to be sure nothing is bent and everything is flat. I suppose with the small flanges the geometry is important. But in any case - a picture from the side of this loco looks quite real. Very nice.

 

Best regards

Vecchio

 

P.S.: 2mm fine scale is too expensive for me - I would carry all my money to the opticians to change my glasses every five days : :mosking:

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I would normally ensure the track is as smooth as practical as I would in 2mm scale. Bear in mind that the flanges are still 0.6 mm deep so there is still quite a bit of tolerance to track irregularities. Oh and the front and rear wheelsets are sprung which helps.

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