Postby chris_mccarthy » Mon Jul 18, 2011 12:52 am
Cracked it, chaps! Took me just 40 mins, topside, to convert it to P4 once I had worked out the method below. Thanks to Tim and Brian for the inspiration to have a go - and its not even my loco!
1. Remove the body by gently levering it along its sides and it will readily upclip from the whole chassis .
2. Dismantle brake gear and remove gear cover plate, both as described by Tim.
3. Remove wheels from their pinpoint axleboxes, using your thumbnail to gently prise apart the axleboxes. Having removed them pull, with twisting motion, each wheel in turn and the respective stub axle will come slowly out of the Delrin? moulded axle/gear sleeve. Put sleeves aside for reuse and discard 00 wheels.
4. (In my case) take 2 pinpoint ended axles of P4 Lomac 10.5mm diameter wheels. Using a piercing saw, cut the axles and discard say 3mm from near the centre of each axle, thus shortening it to provide an air gap insulation when these P4 wheel sets are later pushed into the Delrin. You end up with 4 stub axles with their P4 wheels undisturbed.
5. Short the P4 wheels from axle stub to rim to provide for the split axle pickup. I used the old trick of winding around a suitable rod (ie smaller diameter than the 2mm axle) a fine (0.35mm) phosphor bronze wire into a 3 coil spring, leaving a short tail. I used the piercing saw and the edge of a needle file to cut a small slot into the back of the wheel rim/flange deep enough to take most of the wire but not right through the flange depth. Slip the spring (wiggle it) on to a stub axle and solder the wire tail onto the back of the rim/flange. Use a very hot iron and (in my case) 138deg solder with liquid flux. Just a quick dab with the iron should suffice. I have done this before and have never (dangerous...) had any problem with melted or distorted plastic centres - but don't hold the iron there. File the solder and the part-protruding wire flat to the back of the flange. Enough of the wire remains in the slot to give good connectivity. Repeat for all wheels.
Don't try soldering the other end of the wire to the axle as the transmitted heat along the axle WILL distort the fit of the wheel on its centre and render it useless - I speak from experience. Use the spring method or something similar, as it gives a good and reliable current collection (unless you choose to smother the spring in grease or other gunge - so don't) without heat .
I have a feeling that someone (Branchlines?) does sell a solid, uninsulated, wheel which, if four were put onto two axles, would obviate the need for the shorting described - just cut the axles as described above. I don't know whether they make 10.5mm diameter. Anyway, I don't have any.
6. Again using a twisting action, first insert one stub axle into the end of the Delrin sleeve nearest to the moulded gearwheel. Persevere, as it gets tighter the further in you push it. If necessary, put the axle point down on a material like sheet lead (to protect the point) and VERY GENTLY tap the sleeve into place. Offer it up often to the loco chassis and it will become obvious, by eye, when to stop as the alignment of geartrain and position of the pinpoint to the axlebox is clear to see. Twist the second stub axle into the other end of the sleeve and check for BOTH gauge and for an easy fit (slight end float) in the axlebox bearings. You will find there is a small degree of wheel adjustment possible on the axle to ensure that both these happy states are readily achieved. If the wheel has moved under the twisting action (some of mine did and some didn't) use a touch of Loctite 603 better to secure the wheel on the axle.
7. Insert the wheels back into the chassis by springing the axleboxes apart slightly using your thumbnail. Check for end float and recheck gauge. The chassis can now be tested in that state since the wheels are retained by the pinpoint bearings in the axleboxes so won't fall out. In my case, the loco ran just as smoothly in its P4 state as it did in 00.
8. With a sharp scalpel, carve off the inside edges of the brake blocks as mentioned by Tim.
9. I realised that I had to get the gear housing out to access the screws retaining the Dapol hook and bar couplings. This could have been done earlier but I didn't think of it so at this stage had to remove the wheels again. Deep in the chassis the housing is retained by four clips which each need a good shove against the elasticity of their plastic lugs to release them. Use some force with a thin flat bladed jeweller's scredriver, just sufficient to bend them out of the way before they break - it felt a bit like touch and go. Pull out the housing vertically and then unscrew the couplings from the chassis baseplate. Replace the housing by pressing it down and the clips should recapture it if all is well.
10. Replace the gear housing cover, wiggle the brake gear back into place and its four legs into their sockets - a bit tricky and you may need to swing the sand pipes sideways, out of the way to make space.
11. Cliup the body back into place.
12. Put on track, turn on the power - and enjoy!
Incidently, for those of a DCC persuasion (like me) it is helpful to find that the loco is designed to take a direct plug in 8 pin DCC decoder via a removable blanking plate.
The whole conversion took me shy of 40mins actual working time. This description has taken rather longer.
Hope it helps spur further P4 conversions of a most excellent little engine.
Chris McCarthy
) Callow Lane.
)
