Hornby new Terrier

[Membership SecretaryKeymaster]

Hi all,

Has anyone converted one of these? I’ve just attempted (my first ever attempt at an EM conversion), using 2mm axles from the society with the existing wheels, but the drive gear is a loose fit, and measuring the existing axles, they’re 2mm at the end and nearly 2.2mm where the gear mounts. I’m therefore not sure what to do next!

And that’s before I get to trying to grind out the splashers to make room for the body to fit!

[Trade OfficerKeymaster]

Hi Nick

That is an awkward gap. It is too small to sleeve it unless you have access to a lathe! I assume Hornby did it for ease of assembly

I don’t know if  something like loctite 641 bearing retaining compound will fill that sort of gap. Probably not. Possibly 2 part epoxy? Making replacement if needed in the future, difficult

Either way you will need to make sure it is assembled square. How easy that is depends on the how much actual slop there is

John

[Membership SecretaryKeymaster]

Thanks John. I don’t have access to a lathe unfortunately! There’s enough slop that the gear visibly wobbles from side to side.

[Stuart FirthParticipant]

I don’t know how robust the gear is but could you bore it out to 1/8″? Then you could use a Branchlines 2mm – 1/8″ adapter bush, and secure it with Loctite.

[Membership SecretaryKeymaster]

Thanks Stuart, It’s a plastic gear (as they usually are these days), so I guess the only way to find out is to try, and it’ll either work or split!

[Stuart FirthParticipant]

I’ve had some success with drilling out plastic gears but also a high failure rate – the risk is that the drill can gouge too deeply and go off centre, so try to go up in very small stages, or, with apologies to the engineers reading this, do it by twiddling fine files, first from one side, then the other, and constantly checking against the bush you want to fit it onto.

[Garry owenParticipant]

You need a long taper reamer to open the hole out, it will not damage the plastic, And you can get a really good fit this way, Try tracy tools, they are cheap for this sort of stuff as the reamer will be carbon and not HSS, It will do plastic and metal and still last you years.

[John CutlerParticipant]

Before reaming out the bore of the gear-wheel…..

Have you abraded the replacement axle where the gear wheel sits? This replicates the knurled axle used by Hornby. Lay the axle on a cutting mat or similar. Take a coarse file and applying pressure, use the file edge to roll the axle up and down the mat. Try and limit the abrasion to the gear wheel position so take care.

If you twisted the gear-wheel off the Hornby axle instead of sliding it off, you may have damaged the gear bore. This might explain why you have a loose fit with the new axle. In this situation there is a chance that opening the gear bore out may not work satisfactorily. I suspect it may be better to buy a replacement gear wheel from Peter’s Spares.

Good Luck!

 

 

 

[Nigel BurbidgeParticipant]

Yes, I would second John’s suggestion.  I have converted a number of Hornby locos to EM using the methods suggested by Pete Hill in his conversion sheets (some on the society website and some on the Alan Gibson website).  He recommends replicating the knurling with a coarse file on the axle and it has worked on the conversions I have completed. I would also echo the comments on twisting the gear off the Hornby axle.

[Membership SecretaryKeymaster]

Thanks all. I did try to make sure I didn’t twist it as I took it off the Hornby axle. I’ll try using a file to replicate the knurling, though I suspect the gap will be too big for that to work. Looking again at the original axles, there’s a noticeable step at the ends, at the inner end of the knurled bit the wheels sit on, presumably to aid assembly in the factory.

[Author]

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