Converting a Dapol Class 22 to P4

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Captain Kernow
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Converting a Dapol Class 22 to P4

Postby Captain Kernow » Thu May 03, 2012 9:11 pm

There was quite a lot of debate on the Class 22 thread a while back about how one might convert it to EM or P4. I think that the EM gauge fraternity generally decided that the existing wheels could be pulled out slightly on their existing axles, and I hope that this has worked out for them.

This wasn't going to work in P4, and the original wheels could only have been used if they were turned down to P4 profiles. Some folk have suggested fitting P4 tyres to the existing Dapol wheels, and good luck to them, too.

The issue is that the Dapol Class 22 uses a split axle and associated pick up, as my photos will make clear. This means that the wheel tyres and axles have to be electrically connected. This wasn't a problem for Dapol, obviously, as they have mass produced a decent OO metal wheel for their model, which fits onto stub half-axles, that in turn fit into a central gear assembly.

Ultrascale considered doing a 'drop-in' wheel set for a while, but technical issues, which I understand were essentially associated with the fact that they didn't have an all-metal spoked wheel available, meant that they did not proceed with the project, although they do offer a bespoke wheel producing service for P4 modellers, albeit the price is very high and almost as much as the locomotive itself.

My method does use Ultrascale wheels, but an existing wheel from their range, namely a 3' 7" 10-spoked Southern tender wheel, which has one less spoke than the Class 22, but is the correct diameter. Each pair of wheels comes with a P4 axle.

Here is the Dapol motor bogie, with the keeper plate and one of the OO axles removed (I might add that despite being told how to remove the keeper plate by friends at DRAG, and the fact that it was 'easy', I didn't find it easy at all, and was in constant fear that I was going to break something with the amount of controlled force I was trying to apply at times). In the end, each keeper plate came away intact and without damage. The keeper plates are attached to the bogie side frames, as other photos will show.
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An OO wheelset, with a pair of Ultrascale P4 tender wheels
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22_003.JPG
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22_004.JPG
Dismantled OO wheelset
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22_005.JPG
The P4 axles need to be cut into two 10.5mm lengths. If you just cut them in half, there is the risk that the two pieces might meet inside the nylon worm housing and cause a short that you really don't want. The ends were cleaned up with a file in an electric drill (still haven't got the lathe set up, but this works just as well and is probably quicker...)
22_005.JPG (51.04 KiB) Viewed 7623 times


The next activity involves creating an electrical pathway from the wheel rim, over the nylon wheel centre, to the half axle. I chose to solder a piece of 0.3mm brass wire over the outside front of one of the spokes. The theory was that when the wheel is hidden behind the bogie side frames and painted & weathered, you simply won't notice it, and it saves messing around with the rear of the wheel and the back of the flange.

22_009.JPG
First, I cut groove in the outer end of each half axle and filed a groove big enough for the brass wire (in some cases, I over-did the filing a bit, but it doesn't matter, as the whole thing will be completely hidden afterwards)
22_009.JPG (54.52 KiB) Viewed 7623 times


22_010.JPG
Returning to the axle and worm, for each wheelset you are left with the central worm component and two half axles, each with a groove filed in the outer end
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What happens next was different for the first wheelset as compared with the other three, but the method adopted for the remaining 3 wheelsets was much easier and quicker, so..

22_011.JPG
Measure and mark a point 6mm from the outer end of each half axle and super-glue one half axle per wheel set into the worm assembly
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Do NOT glue the other half axle in! The worm assembly is actually hollow right the way through, so if you are not using the split axle method, you could use a complete 2mm diameter axle with the worm assembly mounted centrally, but this would require seperate pick ups and more modifications to the Dapol motor bogies than I felt was necessary.

Next is the really barbaric bit. It you love the excellent and well-engineered finish of an Ultrascale wheel set, look away now....

22_012.JPG
To secure the 0.3mm brass wire in the wheel rim, I first cut, then filed, a groove in the rim
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A length of 0.3mm brass wire is then put into the groove on the rim, and soldered to the wheel rim. The wire should be pre-trimmed so that the opposite end reaches just as far as the opposite side of the axle hole (ie. reaches from the outer race of the rim, along one spoke, and across the width of the 2mm axle.

I would then recommend temporarily mounting each wheel in the other half axle and removing the surplus solder carefully. I filed most of the unwanted material off with a needle file, then mounted the wheel in the electric drill and used two grades of fine wet & dry paper, then a glass fibre pen.

22_013.JPG
The first wheel of the pair is set aside and the second wheel can also have the brass wire soldered to the axle and cleaned up
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It's then a matter of assembling the components to make a viable P4 wheelset. These photos were taken of the first wheelset.

22_015.JPG
First on each axle is a 1mm wide brass slieve, cut from 2mm internal diameter brass tube
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22_016.JPG
Then the Dapol brass bearings are added to each half-axle
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22_017.JPG
Finally, the assembled P4 wheelset. There is a bit of slop in the assembly, but this helps the loco get round tight curves in my goods yard...
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22_018.JPG
Old and new
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What I did for the last three wheelsets, was to assemble the bearing, 1mm brass slieve and wheel to the axle already super-glued to the worm, solder the 0.3mm brass wire from that wheel rim to the steel axle, and then assemble the other side, bringing the whole lot carefully together using a GW Models wheel press and a back-to-back gauge.

22_019.JPG
The first wheelset in the motorbogie
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22_020.JPG
With the P4 wheelsets, there's not quite enough room inside the bogie frames, so some material was removed in the area of each wheel with a piercing saw and cleaned up
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22_021.JPG
This is the amount of plastic that needs to be removed from each corner of the bogie frame
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22_022.JPG
First wheelset sitting inside bogie frame, to check that there's enough room
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22_023.JPG
First bogie with both wheelsets fitted and keeper plate/side frames re-attached
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22_024.JPG
Second bogie with replacement wheelsets fitted, being test run, prior to it's keeper plate being re-fitted
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22_025.JPG
Completed conversion running on 'Callow Lane'. The side skirts and other bits now need to be fitted and the loco weathered
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22_026.JPG
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OK, so it's not the most 'high-tech' of conversions, it's a bit 'Heath Robinson'ish' in fact, but it works, and it worked first time, so I'm happy with it, and when the bogie side frames are on you can't count the spokes, nor can you really see the bit of brass wire on each wheel either...
Attachments
22_009.JPG
Checking the fit of the 0.3mm brass wire
22_009.JPG (54.52 KiB) Viewed 7623 times
Tim M
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David Knight
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Re: Converting a Dapol Class 22 to P4

Postby David Knight » Fri May 04, 2012 1:35 am

Tim,

Are the Dapol wheels of a substance suitable
for turning or are they plated zinc alloy?

Cheers,

David

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Captain Kernow
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Re: Converting a Dapol Class 22 to P4

Postby Captain Kernow » Fri May 04, 2012 7:52 am

davknigh wrote:Tim,

Are the Dapol wheels of a substance suitable
for turning or are they plated zinc alloy?

Cheers,

David

I doubt that it's suitable, David, although others have substituted a Gibson tread on the Dapol wheel centre.. - http://www.rmweb.co.uk/community/index. ... -class-22/
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Tim V
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Re: Converting a Dapol Class 22 to P4

Postby Tim V » Fri May 04, 2012 8:25 am

Blimey Tim, shows what you can achieve with perseverance and no lathe....
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iak
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Re: Converting a Dapol Class 22 to P4

Postby iak » Fri May 04, 2012 8:28 am

Very tasty sir 8-)
I shall have to read and cogitate on this - especially if the Dapol 21/29's follow the same drive format.
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David Knight
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Re: Converting a Dapol Class 22 to P4

Postby David Knight » Fri May 04, 2012 1:34 pm

Captain Kernow wrote:
davknigh wrote:Tim,

Are the Dapol wheels of a substance suitable
for turning or are they plated zinc alloy?

Cheers,

David

I doubt that it's suitable, David, although others have substituted a Gibson tread on the Dapol wheel centre.. - http://www.rmweb.co.uk/community/index. ... -class-22/


A very useful link Tim. I'm waiting for the 21/29 like Ian so no rush for the moment.

Cheers,

David

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Re: Converting a Dapol Class 22 to P4

Postby Knuckles » Fri May 04, 2012 5:07 pm

Ver interesting indeed. :) What you said about the keeper plate is kind of the same experience I had with the Heljan Hymek. Please answer a question though; what was the brass wire inside the wheel for? I've read it a few times but the penny is still in the money tree. :(
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Re: Converting a Dapol Class 22 to P4

Postby craig_whilding » Fri May 04, 2012 5:33 pm

Knuckles wrote:Ver interesting indeed. :) What you said about the keeper plate is kind of the same experience I had with the Heljan Hymek. Please answer a question though; what was the brass wire inside the wheel for? I've read it a few times but the penny is still in the money tree. :(


Makes the stub axles live which is how Dapol do the pickups (ie no wipers). In DCC i'd probably try to do a couple of spokes to get more cross section for the electric to go through though you do have multiple wheels as paths anyway.

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jjnewitt
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Re: Converting a Dapol Class 22 to P4

Postby jjnewitt » Fri May 04, 2012 9:22 pm

Nice work Captain. I like the way way you made the axles live, very neat.

Those close ups of the drivetrains are interesting. I hadn't seen the actual pickup arrangement before and it's good that they've used proper bearings on them. Hopefully the Westerns will be pretty much the same as these.

I've seen on forums a few attempts to convert the Dapol Class 22 to P4 and a lot of effort seems to be put into them simply to keep the split axle pickup arrangement. I can understand why people might like split axle pick ups but I wonder if it wouldn't save a lot of hassle simply to change the pickups to a more conventional system with wipers? I certainly wont be trying to preserve it in the Western. The idea of split axle sprung bogies makes my head hurt! :)

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Will L
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Re: Converting a Dapol Class 22 to P4

Postby Will L » Fri May 04, 2012 9:35 pm

jjnewitt wrote:.. The idea of split axle sprung bogies makes my head hurt! :)


I don't know, I've always thought that CSBs and split axles pick-ups might work together quite well.

Will

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Re: Converting a Dapol Class 22 to P4

Postby craig_whilding » Fri May 04, 2012 9:50 pm

jjnewitt wrote:I've seen on forums a few attempts to convert the Dapol Class 22 to P4 and a lot of effort seems to be put into them simply to keep the split axle pickup arrangement. I can understand why people might like split axle pick ups but I wonder if it wouldn't save a lot of hassle simply to change the pickups to a more conventional system with wipers? I certainly wont be trying to preserve it in the Western. The idea of split axle sprung bogies makes my head hurt! :)


It could be done if the sideframes were isolated maybe by soldering them to the main frame with double sided copperclad? Normal split chassis spacers would probably have issues with the bearing pads.

Mind I don't have issues with my sub £50 Dapol 22 as it was one without a motor and worms in so needs a new system anyway. One shame with the Dapol 22 is that the gear casing is quite large and square underneath spoiling the open nature of the prototype. I'd have hoped they could have come up with an inverted V of gears to avoid that.

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Re: Converting a Dapol Class 22 to P4

Postby jjnewitt » Mon May 07, 2012 6:10 pm

craig_whilding wrote:It could be done if the sideframes were isolated maybe by soldering them to the main frame with double sided copperclad? Normal split chassis spacers would probably have issues with the bearing pads.


I've had a think about it and have taken some paracetamol and it shouldn't be too difficult to do. Simply saw all the way down the middle! With appropriate non conductive material attached to the bogie spacers to provide the gap of course. You'd have to make sure that the bolster plate was insulated from the metal chassis block if it came into contact with it. You could attach the motor leads to the bolster plate as the current would pass through the secondary suspension and you wouldn't have any wiring to the bogie at all! Maybe I'll give it a go one day. Not sure how it would work on Ian's system though.

A sub £50 Dapol Class 22 sounds good Craig! Even without motor etc. I'll look forward to seeing how you go about motorising it.

Whilst thinking about split axle pickup on bogies I wonder if anyone who leans in that direction has "done a Dapol" on a Bachmann diesel? It shouldn't be too difficult as it has the brass bearings in the drivetrain to transmit the power through. The Bachmann drive gear could perhaps do with being a tiny bit wider to act as the sleeve but perhaps it would suffice? Just a thought.

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Re: Converting a Dapol Class 22 to P4

Postby Simon_S » Thu May 10, 2012 9:56 am

jjnewitt wrote:
craig_whilding wrote:Whilst thinking about split axle pickup on bogies I wonder if anyone who leans in that direction has "done a Dapol" on a Bachmann diesel? It shouldn't be too difficult as it has the brass bearings in the drivetrain to transmit the power through. The Bachmann drive gear could perhaps do with being a tiny bit wider to act as the sleeve but perhaps it would suffice? Just a thought.


That's pretty much what I did with my quick and dirty Bachmann 2EPB conversion: Bachmann 2EPB P4 Conversion

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Re: Converting a Dapol Class 22 to P4

Postby jjnewitt » Thu May 10, 2012 2:15 pm

Simon_S wrote:
jjnewitt wrote:Whilst thinking about split axle pickup on bogies I wonder if anyone who leans in that direction has "done a Dapol" on a Bachmann diesel? It shouldn't be too difficult as it has the brass bearings in the drivetrain to transmit the power through. The Bachmann drive gear could perhaps do with being a tiny bit wider to act as the sleeve but perhaps it would suffice? Just a thought.

That's pretty much what I did with my quick and dirty Bachmann 2EPB conversion: Bachmann 2EPB P4 Conversion


That's exactly what I had in mind! I hadn't seen your thread on the 2EPB. Nice work Simon. As I intimated in my previous post the only thing that worried me a little was if there was enough width on the drive gears for them to act as split axle sleeves but assuming you haven't had any issues with the driven axles(?) the answer must be yes.


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