Dapol 'OO' Mk2D I/C executive livery

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GWR_fan
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Dapol 'OO' Mk2D I/C executive livery

Postby GWR_fan » Tue Apr 19, 2016 5:21 am

I thought what could be simpler just swapping out the original plastic wheels for a set of Hornby 12.6 mm wheelsets. Alas, not to be. The original Dapol axle length is approximately 1.028". The Hornby axle length varies but is in the ballpark 1.010". That additional 0.020" length of the Dapol axle allows the needle points to sit correctly. Due the shorter axle length of the Hornby axle the needle points do not make contact and thus the contact area is the taper on the upper side of the axle as it rotates. This increase in friction is effectively putting the brakes on. A poor Bachmann class 37 was almost brought to a standstill, barely moving with just eight coaches.

My fix is a tophat bearing on one side only per axle of the bogie, allowing the needle points to make contact and reduce friction. The cars modified so far roll as well as I could wish. I need to source more bearings to complete the rake. I cannot recall the brandname used previously so will need to do a little research.

GWR_fan
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Re: Dapol 'OO' Mk2D I/C executive livery

Postby GWR_fan » Tue Apr 19, 2016 6:23 am

Are these what were called 2mm top hat bearings for 'OO' axles (2 mm hole to fit)?

http://www.ebay.co.uk/itm/Alan-Gibson-G ... 1527016304


Edit: I understand now the 4 mm refers to 4 mm scale and not 4 mm diameter.

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SRman
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Re: Dapol 'OO' Mk2D I/C executive livery

Postby SRman » Tue Apr 19, 2016 8:30 am

Are the axle diameters the same for the Hornby and Dapol wheel sets? If they are, would it be possible to ease the wheels off each axle and fit the Hornby ones on to the Dapol axles instead?

GWR_fan
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Re: Dapol 'OO' Mk2D I/C executive livery

Postby GWR_fan » Tue Apr 19, 2016 8:57 am

SRman wrote:Are the axle diameters the same for the Hornby and Dapol wheel sets? If they are, would it be possible to ease the wheels off each axle and fit the Hornby ones on to the Dapol axles instead?


Alas, no.

Hornby 0.080"

Dapol 0.094"

I sourced the referred to flanged/shouldered bearing from Liz ("kitlady"), so will await their arrival. The Hornby wheelset is not a good fit for the Dapol bogie (the bogie is wider and the wheel cutouts seem narrower causing the wheel flange to rub on the bogie bolster) . Oddly, it is different to the Airfix bogie (one would think that they would be the same tooling). I assume that Hornby resurrected the Airfix tooling when they released the Mk2D rather than the Dapol tooling.

GWR_fan
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Re: Dapol 'OO' Mk2D I/C executive livery

Postby GWR_fan » Wed May 04, 2016 4:59 am

The main issue seems to be that when fitting metal wheelsets that do not have the original Dapol axle length, that the wheel backs contact the inner face of the wheel cutouts in the bogie frame during running, effectively putting on the brakes. After fitting a shouldered brass bearing to one side of the bogie to take up some slack it became obvious that I would need to relieve the face of the wheel cutout so that the inner wheel face could not contact the bogie frame. I ensured that when fitting the shouldered bearings that they were on the same relative side on both bogies to avoid the coach sitting diagonally on the track.

Ideally, a better solution is a shouldered bearing each side, however this would entail an axle length around 24.5 mm. A pity that I recently sold off my supply of fine flanged Lima wheelsets as they would have been perfect.

After modification a ringfield Hornby bo-bo drive could easily haul a nine car rake. Previously, the same loco could not even move the set.

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Jim S-W
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Re: Dapol 'OO' Mk2D I/C executive livery

Postby Jim S-W » Fri May 06, 2016 10:20 am

Dapol used a standard 26mm axle. If hornbies are too short then most of the aftermarket wheels (eg Gibson) are a straight fit. Also bachmann wheels should fit too. 12.6mm are too big for a mk2 anyway. They used 3ft wheels (12mm)

HTH

Jim

GWR_fan
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Re: Dapol 'OO' Mk2D I/C executive livery

Postby GWR_fan » Fri May 06, 2016 11:30 am

Jim S-W wrote:........................................ 12.6mm are too big for a mk2 anyway. They used 3ft wheels (12mm)

HTH

Jim


Jim,
Lima redesigned their wheel profile a short while before going under and I had quite a few of their wheels, being a smaller diameter more like 12 mm than Hornby's 12.6 mm. Alas, I recently sold off my inventory of those wheels. For the sake of overall cost and my eyesight, the extra 0.3 mm on the radius of the wheel is something that I can comfortably ignore.


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