A view of/on RTR conversions to EM/P4 part 2
Ok, so where were we? Ah, yes the victim had been reduced to pieces (or at least stripped of its means of movement( and was ready for reconstructive surgery. So now it is time to address the thorny subject of wheels.
As I mentioned before, you have basically three choices: Aland Gibson, Markits and Ultrascale. So lets compare what you can get for how much using a Bachmann 2251 Collett goods as our exemplar.
Ultrascale offer a conversion pack that includes all wheels (inc tender) and crankpins - in fact as they state - everything you will need. They also have notes offering advice on how to do the conversion.
What you get from Ultrascale. See: https://www.ultrascale.uk/eshop/products/view/CAT007/30
This will set you back £96.58 for wheels with Nickel Silver tyres or £70.57 for brass tyres (some Ultrascale packs offer steel tyres too which seem a couple of £ cheaper - the 3F tender engine for example). Ultrascale also state that the product is supplied as per the image. I take this to mean that the wheels arrive in the case of the the 2251 ready assembled - so quartered, correct back to back gauge, pins fitted and and with a (brass) gearwheels fitted in place. All you have to do is drop them in and add the coupling rods, reassemble, test admire followed by a bragging session at your local club of choice (although if you don't do the bragging at a model railway club you might get some odd looks or comments). So all in all quite a good deal. You can get the wheels unassembled with separate pins included and without a gear wheel for about £10 cheaper (in the 2251 example) - just make sure you select the correct diameter axle for the driving wheels. The biggest problem is that the range or ready assembled wheels is quite small - The range of Bachmann steam engines covered is just 5, but both the standard DIY wheel range and the diesel conversion range is much more comprehensive.
Which brings me to a useful digression … whatever your interest period if you are moving to EM or P4, buy a cheapo 2nd hand Bachmann or Hornby diesel, convert it (much quicker and simpler than a steam loco - I did one using an Ultrascale drop in set in under 30 mins) and you'll have something to test your track with (aka playing trains) while you build and convert your way to finescale nirvana.
Markits also offer complete conversion packs, the GWR 2251 is £72.15 (I emailed them to check) and for this you get all wheels (all with nickel silver tyres), 'super deluxe' crankpins and axle nut covers. The Markits wheels will need assembly (and the gear wheel(s) salvaging from the victim), but they are self quartering so that is a considerable amount of heartache and pain done away with. It is unclear whether these packs use their 'standard' profile or the finer flanged RP25 profile. If you know please let me know. It is also unclear from the website/catalogue whether P4 profile wheels can be supplied (I'm not hopeful) so these are probably an EM only option. Again, remember to state gauge (OO is their default) and axle diameter when ordering. Sometimes the Markits axle nut covers etch included in the conversion packs have balance weights too (for example the LNER V2) - a bonus that will save you fabricating them later.
Finally, there is Alan Gibson. AG also offer a conversion pack for the Bachmann 2251 Collet Goods at £20.00 with steel tyred wheels. However, this pack is for the driving wheels only. So when tender wheels, crankpins and coupling rod bushes are included that takes the price up to £37.70 (prices from the most recent catalogue (2018) on the Alan Gibson website).
So buy Ultrascale and get a drop in set, spend £24.43 less and you get everything you need for Markits but with some assembly required, spend £34.45 less than that and you get Alan Gibson with quite a lot of assembly required. But what Alan Gibson has in its favour (apart from being cheap) is that because its not an all in one deal you can spread the cost. Being a perennially poor thanks to a multitude of children much as I would love to buy Ultrascale drop in products (and if you ask me to do a conversion for you I'm afraid I'll insist you do) I usually end up using AG products.
So having laid out your choices in wheels, I'm going to ignore choice and concentrate on the ones that are cheapest and also probably need the most work. (It has struck me that these two things may be related).
The first thing to note is that Alan Gibson doesn't have an e-commerce portal (unlike Ultrascale), but then again Markits don't either (or do lots of others) relying instead on human determination and the innate stubbornness of the finescale modeller in trying to press money on businesses that often give an impression of not wanting to take it off us. For AG products there is a short cut - the EM Gauge Society stock his conversion packs and a limited range of other AG products - but unfortunately not the whole range. Happily they stock both EM and P4 versions, so another reason to be an EMGS member (even if you do P4).
So in preparing and assembling our AG wheels there are 4 different tasks:
- Fit crankpins
- Fit balance weights
- Assemble on the axle
- Quarter them
Fitting crankpins. This is the job I do first for a number of reason, mostly centred on its much easy to do them now than when the wheels are on the axle (or even on the loco). Some points to note:
- Some Alan Gibson wheels (the very earliest ones made for the range, like if my memory is correct, the J15) don't actually have any crankpin holes. Instead there is a blind drill mark at the location where you have to drill the hole. How big a hole? Ideally 0.75mm (see https://www.trfastenings.com/Products/knowledgebase/Tables-Standards-Terminology/Tapping-Sizes-and-Clearance-Holes ) as this will mean that the M1 machine screws AG supplies as crankpins will then cut their own thread in the plastic wheel centre. However, I have used 0.7mm drill bits quite successfully. The difficult bit is making sure that your hole is at right angles to the face of the wheel. Take your time, look at it from many angles as you slowly drill the hole.... If it isn't it might be enough to cause binding as it will, as it rotates, slightly increase and decease the distance between the wheels (or actually the pins) and we all know thanks to the great Iain Rice the importance of wheelbase and coupling rods matching.... don't we? I have in the past done this by hand, but now that I'm the slightly smug owner of a drill press and machine vice, hand shake is now a thing of the past.
Here we have a set of AG wheels destined for a Bachmann Stainer mogul (or it might be a Jubilee, but I think a Mogul). Left is as it comes out of the packet with no crankpin hole. Centre, with the crankpin hole drilled - and you can see its right on the edge of the indie of the boss. Right, countersunk ready for the crankpin to be fitted.
- Although I'll talk about coupling and connecting rods separately, it is also worth considering the combined thickness of the coupling and connecting rods, especially as with some that aim for a more prototypical profile (and why not?) through using multiple etched layers they can end up thicker than the bit of the AG crankpin that is left sticking out of the wheel. (It is also worth checking this even if you intend reusing the RTR rods - better safe than sorry.) If they are too short it can be solved by getting longer ones (yes I know - duh!!) (still M1 though) from any one of a multitude of sellers, many of whom inhabit ebay which at least makes buying them easy. However, longer ones can make using the GW quartering jig hard as they will be too long to fit in the receiver (answer only use long ones when you have to, shorten them as much as possible (but still giving you 2mm proud of the rods, screw them half in way, quarter the axle, and then screw pins fully home - but more on this later).
- The M1 machine screws have countersunk heads but the wheels do not have countersunk holes to receive them. So grab a 1.5mm or better a 2mm twist drill, centre it in the hole and give it a quick couple of twists (but no more) to provide a counter sink but not one so deep as to go through the wheel...I normally don't even put it in a pin vice, instead just holding it in my fingers.
- It is possible for the screws to unscrew themselves if the crankpin nut or eccentric crank is a bit tight on the thread. As this happens when the wheel is mounted on the loco, it is very difficult (but not impossible) to get it back in without undoing a lot of work. So when, happy with all other aspects of the budding relationship between wheel, rods and crankpin, you decide to fully screw the pin home, stop just before the head goes into the countersink. Using a pin introduce a bead of superglue between crankpin head and countersink and quickly screw home. This is especially important if you have overtightened the screw at any point and therefore stripped the soft plastic thread the screw cuts for itself.
- On some of the wheels the rear of the boss intrudes into the spot where the countersink will need to go. So grab a scalpel (or better yet a chisel ended scalpel blade and carve away the area so you have nice flat space to countersink.
Fit the balance weights. Take it from me (because I have forgotten to do this at this stage enough times), it is a lot easy to fit the balance weights now. The can use etched or pre cut plasticard ones from Markits or Ultrascale (or indeed anyone that makes such things) or you can make your own out of 5 thou plasticard and a set of dividers. Once the balance weights are fitted you can also, should the urge take you, paint/blacken tyre rims and paint balance weights - again its a lot easier now than once coupling rods are in place and you are staring at your new pride and joy wondering what isn't quite right (and its starting to annoy you....). If you are one of the sensible people doing an ornate pregroup livery that has wheels other than black, definitely paint them now, and you may as well line them too if needed.
For the Claude Hamilton I found that an egg cup was the perfect radius for finishing off the balance weights.
Just to show that I don't do what I say I should do. I forgot the balance weights on the Claude Hamilton until I had reassembled everything...
Assemble the wheels on the axle.
- First things first. Make sure the axle is the right length (because it won't be if you are EM'ing your loco - AG supplies P4 length axles that you have to reduce to length for EM). Finding out what the correct length is easy. Take a pair of wheels and your back to back gauge. Using hands (if you're like me you'll need two) hold the wheels on either side on the back to back gauge. Then (possibly using the third hand that you get issued with on joining the finescale fraternity) place a digital vernier /caliper/gauge across the two wheel bosses, note the distance, and then, because you are squeezing the wheels too hard to try to keep a grip on everything, catapult them into the air.
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The next bit may sound bad, but it really isn't. Reduce the axle to length. First use a black Sharpie (or similar) pen to paint a nice thick band around the axle roughly where you'll be cutting. Then with your vernier calipers put one end at the end that isn't black, and gently lay the other vernier prong aginst the other, spin the axle with your fingers and lo, a thin line shall appear around the axle. And there was much rejoicing. Which was rapidly stopped by the thought of how to cut the axle accurately. You have effectively two choices:
- Put axle in Dremmel (or similar) shove in a vice, set Dremmel in motion, attack with bastard file until either the axle is the right length or you say goodbye to your fingers. I DO NOT USE OR ADVOCATE THIS METHOD. I know exactly how hard it is cleaning blood of walls and the ceiling (admittedly this was after a minor table saw accident but my darling wife still doesn't let me forget about it and the club I was with at the time were a bit off with me too as it was their walls and ceiling).
- The safer way is to use a lathe with a parting off tool. Preferably someone elses - another reason to join a club, access to machine tools and gadgets you use too infrequently (or are too expensive) to justify having yourself.
- The next important job is to offer up one of your newly trimmed axles into the slots for the driven axle. Make sure you have an equal amount of axle sticking out of each side and part with your Sharpie (or similar) where the gear wheel needs to go.
Marking the position of the gear wheel on the axle.
- Then using the bastard file knurl the axle where you have marked. This means, on a resilient surface (not a hard one) like a cutting mat, using the short edge (mines about 4mm across), place it on the axle where you have marked roll the axle while pushing down hard with the file - don't allow the file to wander - and bingo a knurled axle that will probably grip your final drive gear wheel.
Knurling the axle for the gear wheel.
- Work out how many spacing washers for each axle. A tip - if you have outside cylinders etc go for no sideplay if there will be a wheel lurking behind the cylinders or slide bars - its just too infuriating to assemble everything and then find that on a curve the crankpin fouls the outside gubbings. For the other non gear wheel axles, probably not more than 1mm in total (unless you have a huge wheelbase and tiny curves to get it round). On the axle with the gear wheel, as much as you can without causing the gear wheel to lose contact with the intermediate gears - probably less the 0.5mm in total. So take the chassis, measure its width where the axle slots are, take this away from your back to back measurement and divide by 2 gives you the sideplay possible on each side. Then just add 1/8 inch brass washers of suitable thicknesses until you have the sideplay that you want.
- Take a 6mm (or there abouts drill bit) and using your fingers give it a quick twist where the axle fits into the rear of the wheel, just to take the sharp edge off and help the axle locate itself hopefully perpendicularly to the wheel when its is assembled.
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Now its time to assemble the wheels ready to quarter them. As I use a GW wheel press and quartering jig I'm assuming you will too...So:
- Take an axle, add the gear wheel by pressing it on carefully and without twisting it until it is in the correct position. Add any brass bearing that might have been included on the victim by the manufacturer, add the required spacing washers each side and grab a pair of wheels. And move to the quartering section.
- Repeat with the other axles.
Quartering.
Using a wheel press and quartering jig like the GW models one to fit AG wheels (or Ultrascale self assembly ones) should reduce your troubles here, but there is wheel wobble to think about. (I'm not going to worry about Markits ones as they are self quartering.) Simply put, even using the jig might not stop a wheel going on not quite square leading to a wobble. My view is that this is caused by the wheel boss sticking out beyond the wheel tyre, allowing it to twist on the mounting stud as the wheels are squeezed in the press. To stop this I have superglued 30thou of plasticard about 6mm above and below the mounting stud on each side of the wheel press.
My modified GW wheels press.
So you now should have the jig, with a wheel in each half, an axle with all the bits (bearings, spacing washers, gear wheel etc) and you are wondering how to get it all together. Well, it can be a bit of a juggle but three hands probably won't be needed - (but doing the chamfer of the inside of the axle socket mentioned above will help), and gently close the jig until the axle just starts to engage with the wheel. At this point stop, reach for your back to back gauge and insert it so that as you close the jig with finger pressure the B2B gauge will ensure that you set the correct gauge.
Squeezing everything together with the B2B gauge in place.
The jig is designed for axles that are the correct length, but this might not be the case, and it is easier to set the B2B now, rather than later. When you feel the jig press the axle home, release it and you have a wheel that is probably square and probably quartered. But until we get the coupling rods on, we can't be sure that each axle has exactly the same quartering...
Edited by drduncan
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