Dapol Class 73 conversion to P4

shipbadger
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Dapol Class 73 conversion to P4

Postby shipbadger » Fri Jan 15, 2016 5:42 pm

Hi all,

Has anybody completed the conversion of the new Dapol electro-diesel to P4 yet? I had a preliminary strip down of one of mine this afternoon and this is what I found:

The pipework and other detailing on the bogies is very fragile, keep something handy to put the bits you knock of into ready to re-attach later. I thought I was being ultra careful but still have half a dozen bits in the bag.

The cosmetic bogie frame is a real swine to remove. Anyone got any tips?

The pickups are inside the functional bogie and there are brass bearings in there as well.

The gear is moulded as part of a central muff in to which stub axles plug. So far nothing that can't be overcome with a modicum of effort.

Now the difficult part, the wheels are 3' 4" on the prototype so using a convenient set of Steam Era/Branchlines wheels looks a non-starter without upsetting the ride height.

All in all not as easy as the Metropolitan Rly electric I did the other week.

Any thoughts please?

Tony Comber

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Re: Dapol Class 73 conversion to P4

Postby grovenor-2685 » Fri Jan 15, 2016 5:50 pm

Maybe the 3'3" wheelsets that Alan Gibson does for the Hornby 31 centre axles, they would be within the wear allowance and come on 1.5mm stub axles?
You would need to ask him for a non-standard packet.
Regards
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taylorc
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Re: Dapol Class 73 conversion to P4

Postby taylorc » Wed Jan 20, 2016 7:16 pm

I am a bit stumped by this conversion as well.
The stub axles are a bit none standard. The axle is stepped. That part of the shaft which fits into the muff/gear and runs in the brass bearing is 2.07mm dia, whilst that part of the shaft which fits into the wheel is 1.80mm dia.
Has anyone converted it to P4 yet?

Its a very nice model, runs very smoothly especially at low speed, is well detailed and nothing has dropped off. I have the GBRf one which seems to be the correct colour especially when sat beside a Bachmann class 66 GBRf.

To get the bogie frame off I inserted a small flat bade screwdriver under the centre of the frame at the inner end and wiggled and turned it until the frame sprung out of its end clip. It takes a lot of force to release this clip. Once that's done unclip the two side clips [one either side], I used a scalpel with a long straight blade and these easily unclipped. The frame is then free to lift off.

I think I will contact Ultrascale to see if they plan a conversion set.

Colin

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jim s-w
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Re: Dapol Class 73 conversion to P4

Postby jim s-w » Wed Jan 20, 2016 7:57 pm

Of the bearing and bush is 2.07 mm then why can't you just use a standard 2mm axle? The fit of the axle to the wheel isn't relevant is it?

Bit confused as to where the problem is from the descriptions so far

Cheers

Jim

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Paul Willis
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Re: Dapol Class 73 conversion to P4

Postby Paul Willis » Thu Jan 21, 2016 7:23 am

jim s-w wrote:Of the bearing and bush is 2.07 mm then why can't you just use a standard 2mm axle? The fit of the axle to the wheel isn't relevant is it?

Bit confused as to where the problem is from the descriptions so far

Cheers

Jim

Hi Jim,

I think that I see what you mean. It may be a bit more clear if I took your original words and added " why can't you just use a standard 2mm axle? The fit of the axle to the wheel isn't relevant is it if you're replacing the wheel anyway?

As I understand it, the point that your making is that the middle of the axle that the gear sits on is a straight swap for a standard 2mm axle, and what hangs off that middle bit at either end doesn't actually matter. It then becomes a 2mm axle across the whole length of it. Which I agree with.

I'm sure that if I were Russ Elliott I could rattle up a quick illustration in Paint to show what I mean but at this hour of the morning just typing straight after one coffee is enough!

A different solution would be the Harrap route of turning down the wheels on the stub axles, but that requires all sorts of lathe possession that not many of us have.
HTH
Flymo

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shipbadger
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Re: Dapol Class 73 conversion to P4

Postby shipbadger » Thu Jan 21, 2016 8:37 am

The 'problem' is I think those of us looking for a P4 conversion were hoping that there would be something straightforward like the Branchlines stub axle/wheel sets for Bachmann DMUs. Apart from some rather odd axle dimensions there is also the fact that the wheel size of 3' 4" is unusual. Keith Norgrove pointed to a possible answer but at present Colin (aka Alan Gibson) is very busy and I would rather have a live chat than leave a message on his answerphone. If I find out more I'll post the info in this thread.

Tony Comber

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Re: Dapol Class 73 conversion to P4

Postby Paul Willis » Thu Jan 21, 2016 8:58 am

shipbadger wrote:The 'problem' is I think those of us looking for a P4 conversion were hoping that there would be something straightforward like the Branchlines stub axle/wheel sets for Bachmann DMUs. Apart from some rather odd axle dimensions there is also the fact that the wheel size of 3' 4" is unusual. Keith Norgrove pointed to a possible answer but at present Colin (aka Alan Gibson) is very busy and I would rather have a live chat than leave a message on his answerphone. If I find out more I'll post the info in this thread.

Tony Comber


Hi Tony,

Good points - I understand your thinking as well. There is a lot of merit if it becomes possible to swap over just the ends of the axles and not disturb the centre part of the axle with the gear wheel on it.

I hope that you don't think that we're sniping at your approach - it's merely kicking around a few ideas to see what may or may not work easiest. We all want to see some of these models running in P4, so it's finding the method that is most effective.

Cheers
Flymo
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Simon_S
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Re: Dapol Class 73 conversion to P4

Postby Simon_S » Thu Jan 21, 2016 11:38 am

I used Ultrascale Warship wheels (3' 3 1/2") for my Hornby 4-VEP. Unfortunately, Alan Gibson lists Warship wheels as 3' 2" so 2/3mm undersize.

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Re: Dapol Class 73 conversion to P4

Postby Knuckles » Thu Jan 21, 2016 12:16 pm

I noticed that the 3' wheels I brought from Alan Gibson were not 12mm diameter as they should be but a bit smaller.

Gotta be careful but it seems the only way of testing is buying. Silly.
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Jeremy Good
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Re: Dapol Class 73 conversion to P4

Postby Jeremy Good » Thu Jan 21, 2016 3:26 pm

In my recent experience, most of the diesel wheels available seem to come out undersized and having had this problem recently with a couple of other diesel conversions I have measured a number of them to try and find the closest fit. For my purposes the Ultrascale ones seem to be the most accurate.

If I remember correctly, the 14mm Branchlines wheels come out at about 13.6mm which scales 3ft 4in/3ft 5in so might work in this context. I can't remember the actual sizes of the other. It seems the only way to know is to measure them before you fit get them.

Also, be aware that not all of the locos have the correctly sized wheels in the first place - a number of Heljan's locos wheels are larger than reality hence the comments on Ultrascale's website - so it pays to actually measure the wheels before you start otherwise the ride height of the loco might also need adjusting.

Simples!

Jeremy

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Will L
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Re: Dapol Class 73 conversion to P4

Postby Will L » Thu Jan 21, 2016 5:31 pm

Jeremy Good wrote:In my recent experience, most of the diesel wheels available seem to come out undersized ....


...and have we agreed where exactly on the wheel you are supposed to be measuring?

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Re: Dapol Class 73 conversion to P4

Postby Jeremy Good » Thu Jan 21, 2016 8:09 pm

Will

Thanks and yes. That's why I asked a week or two back as I thought I'd got it wrong...

As a result of those investigations I have several low riding diesels that are waiting for some more accurately sized wheels to be fitted!

Jeremy

Philip Hall
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Re: Dapol Class 73 conversion to P4

Postby Philip Hall » Thu Jan 21, 2016 8:26 pm

When I converted a Heljan 33 a while back I deliberately purchased the Branchlines wheels as they were 14mm diameter. The Heljan ones were 15mm and the engine rode far too high.

Philip

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Re: Dapol Class 73 conversion to P4

Postby garethevans1986 » Mon Oct 10, 2016 1:57 pm

I'm certainly interested in this topic as I've recently purchased a Dapol 73.

Has anybody successfully fitted this loco with P4 wheels?
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shipbadger
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Re: Dapol Class 73 conversion to P4

Postby shipbadger » Mon Oct 10, 2016 9:19 pm

As the person who started this thread I suppose it is my duty to bring others up to date. My original intention after finding that Ultrascale did not intend doing a conversion pack was to ask Colin Seymour (Alan Gibson) if he could supply the wheels used on the middle axle of the class 31 bogie. Unfortunately as he has not been able to respond I assume he is too committed to other work at present.

Plan B or is it C by now has been to order some 'warship' wheels from Ultrascale. I'm now waiting for delivery which means the two locos have been moved from the workbench to the shelf for now :-(

Tony Comber

taylorc
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Re: Dapol Class 73 conversion to P4

Postby taylorc » Wed Oct 12, 2016 7:03 pm

I have converted a Dapol Class 73 to P4.
The main problem I found was that the wheel axles are non standard with an O/D of 2.07mm, see my original comments under post 3.
I used Ultrascale 3ft 31/2 inch Class 42 wheels which have a diameter of 13.25mm with there standard 2mm axles. Because the Dapol axle is 2.07mm, the gear that fits the axle will not grip the 2mm axle. To overcome this problem I used the edge of a coarse file to roughen the centre of the axle. This centred the gear on the axle and gripped it. To ensure that no slippage occurred I drilled a 1mm hole in the gear at 45 degrees and applied Zap CA thin. The 2mm axles seem to run in the 2.07mm bore bearings without problems.
The pickups need changing as we no longer have a split axle arrangement. I glued short lengths (15mm) of copperclad sleeper strip to the side of the bogie frame and soldered PB strip (1x 0.27mm) bearing on the back of the wheel flanges.
This gets the loco moving on P4 track however I found running was poor as any twist in the track (superelevation) or poor track laying caused derailment. I investigated this and found the bogie design very poor as it only allows the bogie to turn (yaw) with no ability roll or pitch. This is because on the top of the bogie frame there are 4 posts sticking up which touch the underside of the loco frame, like an inverted table with 4 legs, this prevents any movement apart from rotation. To overcome this I reduced the height of the two outer posts on each bogie to about half there height.
This has cured the derailments and the loco will now happily negotiate superelevated track.
I am a little disappointed at Dapols design as with a little bit of thought at there end these problems could have been designed out.

Colin T

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Re: Dapol Class 73 conversion to P4

Postby garethevans1986 » Thu Oct 13, 2016 1:41 pm

Colin,

Thank you for the reply. Was it this pack that you ordered? https://www.ultrascale.uk/eshop/product ... CAT014/285

Thanks
Gareth
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taylorc
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Re: Dapol Class 73 conversion to P4

Postby taylorc » Fri Oct 14, 2016 10:01 am

Gareth
No it was not. I used the individual Disc diesel wheels 3ft 3 1/2inch , 2mm axle n/s tyres suitable for a class 42/43 and not the conversion set you mentioned. However looking at the conversion set details they look the same as the individual axle sets, but I am not sure if the boss on the back of the wheels are the same thickness.

Regards
Colin T

garethevans1986
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Re: Dapol Class 73 conversion to P4

Postby garethevans1986 » Fri Oct 14, 2016 12:32 pm

Colin,

I've ordered 4 x 3ft 3.5" wheels like you've used and 1 x Warship Wheel pack from Ultrascale....now just have to wait.

Ill let you know how I get on.

Gareth
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garethevans1986
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Re: Dapol Class 73 conversion to P4

Postby garethevans1986 » Mon Oct 31, 2016 5:51 pm

Just to update you all, I purchased 4 x 3ft 3.5" AND the Bachman Western conversion pack and both sets of wheels fit in the loco.

The Western conversion pack need the "back" of the wheel taking down a few mm with a sanding disk on a drill or a file. IMHO the Western wheels, if taken down just enough for it to fit leave minimal horizontal movement compared to the 4 x 3ft 3.5" wheel pack.

More to follow.

Gareth
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garethevans1986
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Re: Dapol Class 73 conversion to P4

Postby garethevans1986 » Wed Nov 02, 2016 11:49 am

Just to update everybody,

It's possible to take the wheels out of the chassis to make it easier to work on them!

Using the guides attached you can see which bits come and off and which dont.
Class73-owners guide-A4.pdf
(4.65 MiB) Downloaded 117 times


Take the body off the chassis but following the guide.
Unsolder the wires from the motherboard, take the daughter board off.
I stripped the whole chassis unit as I plan to detail it at a later date.

The bogie frames take some force to get them off, use a flat screw driver to ping them off then the two side clips and they will come off.

Then take a flat head screw driver to the bogie retaining cap (part 13 from memory).

Remove the brass pickups (part 19), this is a bit of a tricky job because it's around two of the pegs inside the bogies.
I decided to remove ALL of the detailing bits from the bogies as some of the bits are very delicate.
Remove the 00 wheels, the wheels "split" from the gear - remember to put the brass bearings and gear to one side for each wheel as they're needed later on.

Take the ultrascale axles, use a file to flatten/roughen the middle of the axle so the gear can grip.
Put the gear onto the new axle, measure about 7.30mm from the end of the axle to the middle of the gear and get it to stay there somehow - I drilled a 1mm hole at 90 degrees in the cog and filled it with glue and left it to set.

If you are using the Bachmann Western conversion pack, file the back of the wheel stubs a few mm. If you're using the economy pack you won't need to do this as the backs of these wheels are "flat".

Ultrascale Bachmann Warship Conversion pack wheels -
IMAG0861.jpg

Note the black wheel stubs acting as shims on the back of the wheels.

Ultrascale economy pack wheels -
IMAG0862.jpg


Reconstruct the wheels and fit them.

Because the old wheels were split axles we now need to construct some new pickups for the bogies.

Take a piece of 10-15mm PCB strip.
Take a 30mm piece of phosphorus bronze wire, mark 12mm from one end, then 6mm, then the rest left will be 12mm.
Solder the 6mm section and electrical wire onto the PCB section.
Each end of the new pickup, curl back in a little.

IMAG0863.jpg

IMAG0864_BURST001.jpg


Take the bogie frames and file back the insides, this helps when refitting the frames onto the bogie later on.
IMAG0865.jpg

IMAG0866.jpg


Next glue the new pickups onto the bogie. You can tweak the ends of the pick up later on once the PCB is glued in place.
IMAG0867.jpg
IMAG0868.jpg


To test, put the bogie frame back onto the bogie, put the screw end (part 15) into the bogie, insert a flat end screw driver to act as the motor would do and turn it...the wheels should turn. You could use a multi meter to check for continuity from the wheel (or track) to the electrical wire on that side of the bogie.

This is as far as I've got at the moment I'm afraid as I need a DCC sound chip to fit and alot of detailing to do before the loco is finished to Barrowmore MRG standards.

I hope this helps somebody and If you have any questions, please feel free to get in touch.
Gareth
Attachments
OO gauge class 73_errata V1.1.pdf
(341.96 KiB) Downloaded 93 times
class 73 cab removal 1.0.pdf
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