P4 conversion work

Colin Parks

P4 conversion work

Postby Colin Parks » Fri Mar 21, 2014 8:49 am

This month I have actually made tentative steps to make a start on converting some of my 00 gauge stock to P4. This will be a great task due to the number of EMUs and wagons that I have. Added to the equation is the long wait for Ultrascale wheels, my 'wheel of choice' for all stock, where possible.

The first major experiment has been to see if it would be possible to convert Black Beeltle motor bogies to P4, using some Ultrascale wheels, kindly 'advanced ' to me by JFS. The use of these particular wheels has one great advantage over all the other makes that I know of as they have an extended boss on the inside of the wheel. This allows enough grip on the existing 00 axle, so no need to remove the axles and gear wheels. The 00 wheels were gently tapped out while holding the moulded plastic axle/motor mounting. After some measuring with vernier calipers, it became clear that 0.3mm of plastic would need to be removed from the boss on the rear of the Ultrascale wheels to achive the correct back to back dimension for P4.

This particular motor bogie was chosen for the experiment as I had nothing to lose if things went wrong or a component got damaged - it is for some reason a bad runner and always was. It can be seen that the wheels are on and to gauge, so success!

IMG_7354.JPG


The view from underneath. That piece of brass strip is to help with the messing of the gears, which are the root of this motor bogie's bad running.

IMG_7355 (1024x768).jpg


The unit place on some Exactoscale FastTrack, minus its pick-ups and top mounting component. Time taken for the operation was about an hour. The motor bogie has been converted back to 00 gauge for now. I am still in two mind about whether to compensate the trailing bogies of my EMUs. It would seem prudent to do so, but some say it isn't necessary - I tend to think compensation would at least eliminate one element of risk of derailment. The first EMU that in would intend to convert to P4 is a 4 SUB, but due to supply of wheels, that will be in about five month's time!


Colin
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John Fitton

Re: Starting out in P4

Postby John Fitton » Fri Mar 21, 2014 12:47 pm

Colin,

From personal experience I have found it essential to use correct length axles for P4 wheels, even if, as you say, there is a convenient boss which might allow shorter axles. Second, never remove P4 wheels from axles once assembled and to gauge: back to back gauge failures will be inevitable.

John Fitton

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Ian Everett
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Re: Starting out in P4

Postby Ian Everett » Fri Mar 21, 2014 1:44 pm

Colin Parks wrote:I am still in two mind about whether to compensate the trailing bogies of my EMUs. It would seem prudent to do so, but some say it isn't necessary - I tend to think compensation would at least eliminate one element of risk of derailment. The first EMU that in would intend to convert to P4 is a 4 SUB, but due to supply of wheels, that will be in about five month's time!


Colin


If you have a lot of rolling stock to convert I would strongly recommend not compensating or springing - at least in the short term. It will save much time and should work well, at least on half-decent track.

Many of us have numbers of rtr coaches which run perfectly well (albeit not as sinuously as they might with springing) with P4 wheel sets just dropped into the existing bogies. This is because the rtr bogies are precisely made, so that axles are perfectly parallel, and with their short wheel bases they are unlikely to derail.

Two points -

1) make sure the axles spin easily in their pinpoint bearings - you might need to use an appropriate tool (whose name escapes me for the moment) to adjust this.

2) make sure that at least one of the bogies can roll to accommodate twists in the track. I have found this is the most likely cause of serailments of such coaches.

Such conversions might not be quite as tolerant of poor track as coaches with more flexible suspensions but treat this as a positive - they will help you to discover bad track!

And if this is not a success, you have lost nothing - you can always fit suspensions if you feel you need to.

Good luck!

Ian

Colin Parks

Re: Starting out in P4

Postby Colin Parks » Fri Mar 21, 2014 8:56 pm

John Fitton wrote:Colin,

From personal experience I have found it essential to use correct length axles for P4 wheels, even if, as you say, there is a convenient boss which might allow shorter axles. Second, never remove P4 wheels from axles once assembled and to gauge: back to back gauge failures will be inevitable.

John Fitton


Thanks for the advice John.

I suppose I should not have removed the wheels once fitted- it was just to see if the idea would work at all. What would be intended with a permanent conversion would be to use some Loctite 603 to hold the wheels steady. The Black Beetle 00 gauge axles are not far off the length of P4 ones, although I must admit they are about 1mm short.

Are b. to b. gauge failures inevitable even with Loctite?

All the best,

Colin

Colin Parks

Re: Starting out in P4

Postby Colin Parks » Fri Mar 21, 2014 9:02 pm

Ian Everett wrote:
Colin Parks wrote:I am still in two mind about whether to compensate the trailing bogies of my EMUs. It would seem prudent to do so, but some say it isn't necessary - I tend to think compensation would at least eliminate one element of risk of derailment. The first EMU that in would intend to convert to P4 is a 4 SUB, but due to supply of wheels, that will be in about five month's time!


Colin


If you have a lot of rolling stock to convert I would strongly recommend not compensating or springing - at least in the short term. It will save much time and should work well, at least on half-decent track.

Many of us have numbers of rtr coaches which run perfectly well (albeit not as sinuously as they might with springing) with P4 wheel sets just dropped into the existing bogies. This is because the rtr bogies are precisely made, so that axles are perfectly parallel, and with their short wheel bases they are unlikely to derail.

Two points -

1) make sure the axles spin easily in their pinpoint bearings - you might need to use an appropriate tool (whose name escapes me for the moment) to adjust this.

2) make sure that at least one of the bogies can roll to accommodate twists in the track. I have found this is the most likely cause of serailments of such coaches.

Such conversions might not be quite as tolerant of poor track as coaches with more flexible suspensions but treat this as a positive - they will help you to discover bad track!

And if this is not a success, you have lost nothing - you can always fit suspensions if you feel you need to.

Good luck!

Ian


Thanks Ian.

I shall take heart in the fact that it is at least worth trying the stock with RTR bogies as you say. I think you might be referring to a 'truck-tuner' as the tools required in point 1. For point 2, I have been given the same advice by Mark Tatlow, so I shall definitely be adding the required strips to the bogie pivots to control 'twist'. It also looks like a lot more weight will be needed in my coaches to get up to the recommended 25g per axle loading.

All the best,

Colin

Terry Bendall
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Re: Starting out in P4

Postby Terry Bendall » Sat Mar 22, 2014 8:34 am

Colin Parks wrote:The first major experiment has been to see if it would be possible to convert Black Beeltle motor bogies to P4


It is possible to buy Black Beetle motor bogies already fitted with P4 wheels. For the 2 EPB units used on Elcot Road we used
EMU Bogie frame spaces are available from Clockwork ideas, 156 Greenfield Crescent, Horndean, Hampshire, PO8 . These give some movement in the bogie. On the 2EPB model it is usually necessary to adjust the bearings anyway since there is not sufficient space for P4 axles.

Terry Bendall

Colin Parks

Re: Starting out in P4

Postby Colin Parks » Sat Mar 22, 2014 9:37 am

Terry Bendall wrote:
Colin Parks wrote:The first major experiment has been to see if it would be possible to convert Black Beeltle motor bogies to P4


It is possible to buy Black Beetle motor bogies already fitted with P4 wheels. For the 2 EPB units used on Elcot Road we used
EMU Bogie frame spaces are available from Clockwork ideas, 156 Greenfield Crescent, Horndean, Hampshire, PO8 . These give some movement in the bogie. On the 2EPB model it is usually necessary to adjust the bearings anyway since there is not sufficient space for P4 axles.

Terry Bendall


Hi Terry,

Thanks for the address, I shall bear it in mind for when I get around to converting my Bachmann MLV to P4. I should think it would need the same work as your 2 EPB. Re. the Black Beetle motor bogies, there are five scratch-built EMUs in my fleet in need of conversion, so if it can be done without purchasing complete new units, there is a considerable saving to be made.

I can see that the cheapest of my EMUs to convert will be the 4 CIG, which has a Hornby class 73 motor bogie installed. The cost of conversion for that unit including one Ultrascale conversion pack and twelve axles' worth of 10mm disc wheels is only about £57.00. The Black Beetle-installed 4 SUB which I have recently completed (in 00 gauge) would cost with new BB and twelve axles = approx £90-100.00 to convert. So it is not that I am embarking on a bodging spree just for the sake of it. Cost is an issue!

All the best,

Colin

billbedford

Re: Starting out in P4

Postby billbedford » Sat Mar 22, 2014 10:22 am

Colin Parks wrote:I suppose I should not have removed the wheels once fitted- it was just to see if the idea would work at all. What would be intended with a permanent conversion would be to use some Loctite 603 to hold the wheels steady. The Black Beetle 00 gauge axles are not far off the length of P4 ones, although I must admit they are about 1mm short.

Are b. to b. gauge failures inevitable even with Loctite?


Loctite retainers do not stick to to plastic, or brass for that matter. They work by a chemical reaction with steel which makes them expand slightly. Whether this expansion is enough to fix wheels in place depends entirely on the way the plastic reacts to the increased pressure in it's bore.

Colin Parks

Re: Starting out in P4

Postby Colin Parks » Sat Mar 22, 2014 10:38 am

billbedford wrote:
Colin Parks wrote:I suppose I should not have removed the wheels once fitted- it was just to see if the idea would work at all. What would be intended with a permanent conversion would be to use some Loctite 603 to hold the wheels steady. The Black Beetle 00 gauge axles are not far off the length of P4 ones, although I must admit they are about 1mm short.

Are b. to b. gauge failures inevitable even with Loctite?


Loctite retainers do not stick to to plastic, or brass for that matter. They work by a chemical reaction with steel which makes them expand slightly. Whether this expansion is enough to fix wheels in place depends entirely on the way the plastic reacts to the increased pressure in it's bore.


Thanks for that Bill.

I am now quite confused as I had assumed that Loctite 603 was going to work. I have some Exactoscale wheels and axles which have to be assembled and fixed in much the same way as the Ultrascale wheels would be and have now have doubts as to how reliable those assemblies will prove to be.

Hmm. It's really looking to be too complicated!

Colin

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Will L
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Re: Starting out in P4

Postby Will L » Sat Mar 22, 2014 11:39 am

billbedford wrote:Loctite retainers do not stick to to plastic, or brass for that matter....
or steel if you want to be accurate
They work by a chemical reaction with steel which makes them expand slightly. Whether this expansion is enough to fix wheels in place depends entirely on the way the plastic reacts to the increased pressure in it's bore.

Bill is quite correct about its action. That said, the fact that it doesn't stick plastic or brass to steel doesn't stop it fixing worm wheels made of either to motor shafts effectively. Circumstance are everything.

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Re: Starting out in P4

Postby allanferguson » Sat Mar 22, 2014 11:44 am

Bill has made an interesting point about the action of Loctite retainers, which I hadn't previously realised. Now this has stirred a thought in my mind that someone, somewhere, wrote a piece on these useful chemicals and the way they work. Can anyone here recall it, or am I woolgathering again?

Allan F

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Russ Elliott
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Re: Starting out in P4

Postby Russ Elliott » Sat Mar 22, 2014 11:48 am

The loctites work in the absence of air and in the presence of metallic ions. As I understand it, the metal involved does not need to be steel, although perhaps there are more ferrous ions freely 'available' on a steel surface compared to say zinc and copper ones on brass. I've used loctite to fix brass to steel, and it seems to work sufficiently well.

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Guy Rixon
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Re: Starting out in P4

Postby Guy Rixon » Sat Mar 22, 2014 1:56 pm

Always good to RTFM. Henkel, makers of Loctite, have a technical brochure explaining where their retainers are appropriate.

http://www.henkelna.com/us/content_data/326508_9294_LT5021_Retaining_Brochure_FINAL.pdf

In the section on joint design, there's a table of relative strengths of bond for joining different materials. Taking steel as 1.0 (they reckon that mild and stainless steel have the same factor), "copper and alloys" have strength 0.4 and thermosetting plastics strength 0.3.

The bond strength also varies with the fit of the parts. It's best at about 0.025mm and drops to 50% of nominal at a clearance of ~0.25mm. Note that this graph is for slip fitting and may not apply to press fits.

Apparently the retainer doesn't like phosphoric acid - bond strength drops to 0.3 of optimal - so flux will eat the joints. Not that one would want flux on the wheels anyway.

The brochure gives a decision tree for choosing a particular kind of retainer. The old 603 product isn't listed in their chart. The medium-strength, oil-tolerant retainer looks like a candidate for wheels.

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Guy Rixon
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Re: Starting out in P4

Postby Guy Rixon » Sat Mar 22, 2014 2:04 pm

Further thoughts on retainer in wheels. The retainers are mainly designed for slip-fitted components, so should we be aiming to loosen the dry fit to give the retainer a chance? Maybe ream the wheels; would that preserve the concentricity?

If reaming is not good, would it make sense to groove, lightly, the plastic of the wheels so that the retainer can expend into the grooves?

Colin Parks

Re: Starting out in P4

Postby Colin Parks » Sat Mar 22, 2014 7:36 pm

Having had a think about this matter, it would now seem that the Exactoscale wheels and axles hold tight due to the fact that the axles are made of steel and that the Loctite 603 reacts with the steel to wedge the plastic moulded wheel centre tightly in place.

As for the Black Beetle axles, they appear to be plated (steel?) so the reaction is less likely to take place. I didn't mean to imply that I was going to 'stick' the plastic wheel centres to the axles when converting the motor bogie. Another question arises from this: six of the eight Ultrascale 14mm coach wheel sets were out of gauge on their axles (straight from a new packet). Re-gauging them requires the wheels to be moved on their axles. What is meant to keep them in place then?!

Confused Colin

John Fitton

Re: Starting out in P4

Postby John Fitton » Sat Mar 22, 2014 7:40 pm

To re-gauge coach wheels I use a very slight twisting motion and ease the wheels in or out of gauge as required. Rather odd that U/S wheels would be out of gauge though. I don't secure coach or wagon wheels to their axles. Friction is always sufficient.

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Will L
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Re: Starting out in P4

Postby Will L » Sat Mar 22, 2014 11:52 pm

Guy Rixon wrote:Further thoughts on retainer in wheels. The retainers are mainly designed for slip-fitted components, so should we be aiming to loosen the dry fit to give the retainer a chance? Maybe ream the wheels; would that preserve the concentricity?

If reaming is not good, would it make sense to groove, lightly, the plastic of the wheels so that the retainer can expend into the grooves?


I suspect that the strength of the bond between Gibson wheels and the axle is dependant on the surface skin on the moulded axle hole remaining intact, and is much reduced if the surface of the plastic is damaged. Which is why fitting the wheels multiple times is a recipe for slipped wheels.

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Re: Starting out in P4

Postby JFS » Sun Mar 23, 2014 10:04 am

Colin Parks wrote:Having had a think about this matter, it would now seem that the Exactoscale wheels and axles hold tight due to the fact that the axles are made of steel and that the Loctite 603 reacts with the steel to wedge the plastic moulded wheel centre tightly in place.

Confused Colin


Hello Colin,

Not sure if you are misspeaking yourself here - Exactoscale wheelsets are assembled with Loctite 603, but it is a metal to metal bond appropriately designed with clearance - and once it is done, 'tis done - you will destroy the wheelset before you will shift it!

I think the thread is running a bit of a risk of losing its sense of perspective here. Perhaps some of the posters in discussing the use of Loctite [603] have in mind loss of quartering with the driven axle of steam locos - which is not your situation - but is an issue for some of us.

To add. Firstly, you mention back to back failures, yet who here finds this to be a massive problem? You have said elsewhere that your policy with NH was to follow the pre-exhibition ritual of checking BBs and cleaning treads. I think if you follow the same policy in P4 you will have no issues. I will make another prediction that you will find that Ultrascale wheels do not move very much (bearing in mind again that we are not talking about steam loco drivers here).

As you know, I used the bodge of simply fitting Ultrascale wheels to the Hornby motor bogie axles - the oldest one shows no movement at all 12 months on. I am at a loss to explain why your Ultrascale wheels were "wrong out of the bag", though to complete the picture for others, I would point out that they had spent a couple of years lying about in someone else's drawer - possibly having bits of ploughing engine dropped on top of them...

Personally, I have never used Loctite on rolling stock wheelsets, and since converting to exclusively Ultrascale or Exactoscale, I have never had any need re-gauging (albeit not a massive fleet!). [I still have a bag of Gibson wheelset to give away to my worst enemy who will have the job of sorting the loose tyres, the wobbles and eccentricities]

Just to give you another re-assurance - there is a fair bit of tolerance in the P4 spec and you will find that wheelsets can be a fair way out before they give derailment trouble.

Many thanks to Guy for finally nailing the myth that Loctite "does not stick to plastic" - it is simply a weaker bond - but 30% of heluva lot is much better than 100% of b*gg*r all. BUT the joint should be properly engineered - not just spit and pray engineered!

Very Best Wishes,

Colin Parks

Re: Starting out in P4

Postby Colin Parks » Sun Mar 23, 2014 3:33 pm

Hi Howard.

Yes there was an element of misspeaking in my last comments. Exactoscale wheels have a steel bush in the moulded wheel centre. So, according to Loctitite's own spec.(see link in Guy's post), that gives a shear strength factor of 1.0, which would suggest that destruction of the wheel/axle assembly is the only means by which to parts the joint as you have said. As for the out-of gauge Ultrascle wheels, I really didn't see it as a problem, assuming that they could be twisted to gauge and given a dab of the dreaded Loctite 603 to ensure they held steady. The problem is more that I am now being told by others that this can't be done!

Moving on to the subject of using Loctite with thermo-set plastics and steel, the shear stregnth factor is 0.3. That would surely be still strong enough to hold a plastic wheel centre onto an axle of a motor bogie? I just cannot see how the tiny Mashima motor in a Black Beetle would produce enough torque to shear the joint.

Throughout the information given by Loctite (Guy's link) the word 'bond' is used. I am unsure how 'bond' differs from the word 'stick', but Henkel seem confident that their products do 'bond' to plastics and unless I have misunderstood their product information, the surfaces of those materials to be joined should not be too polished either (Linked Loctite Publication p11 Joint Design 'Factor 4'). The only difference between Loctite 603 and 648 (for our modelling purposes) would appear to be that Loctite 648 would be best used where the joint is in constant contact with a compound such as oil (joints in gear boxes etc.).

I shall take heart from the fact you have successfully converted a Hornby motor bogie in much the same way as I have been attempting with the Black Beetle. If it works for you, then I'm happy to follow your lead, and if my wheels do fall of, we can all have a laugh!

All the best,

Colin

JFS
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Re: Starting out in P4

Postby JFS » Sun Mar 23, 2014 5:46 pm

Hi Colin,

I think the reality is that once you have re-set your Ultrascale wheels to gauge, you will find they stay well and truly put. The combination of the extended centre bush and the tough plastic from which they are made makes for a pretty robust combination - so I personally don't think there is anything to be gained from the addition of Loctite retainer.

The real issue which stops Loctite working in our situation is not the fact that we are using plastic, but rather that the centre is already an interference fit on the axle - Loctite retainers require a clearance in order for the reaction to take place as others have described - hence, as Will suggests, the only way to enable the Loctite to work would be to ream out the wheel centre to a running fit in order to provide the necessary clearance. Then the question is - would the result be any stronger than the original interference fit?

I am seeking a bet that your Ultrascale wheels will not fall off - despite the abuse that you (and I) have meeted out to them!!

Very Best Wishes,

Colin Parks

Re: Starting out in P4

Postby Colin Parks » Sun Mar 23, 2014 7:03 pm

JFS wrote:Hi Colin,

I think the reality is that once you have re-set your Ultrascale wheels to gauge, you will find they stay well and truly put. The combination of the extended centre bush and the tough plastic from which they are made makes for a pretty robust combination - so I personally don't think there is anything to be gained from the addition of Loctite retainer.

The real issue which stops Loctite working in our situation is not the fact that we are using plastic, but rather that the centre is already an interference fit on the axle - Loctite retainers require a clearance in order for the reaction to take place as others have described - hence, as Will suggests, the only way to enable the Loctite to work would be to ream out the wheel centre to a running fit in order to provide the necessary clearance. Then the question is - would the result be any stronger than the original interference fit?

I am seeking a bet that your Ultrascale wheels will not fall off - despite the abuse that you (and I) have meeted out to them!!

Very Best Wishes,


Hi Howard,

Yes, the interference fit of the those Ultrascale wheels probably renders the use of Locttite redundant. Of course if I were to take the wheels on and off their axles a few times, the Loctite may work!

I would have to agree that the Ultrascale wheels have tough, moulded plastic centres and even after removal of 0.3mm on the rear of the boss, that still leaves over 4mm to grip the axle (or just under 4mm if using the original Black Beetle axles, (which are, to confuse matters slightly over-length for 00 gauge).

I think that Ultrascale wheels are excellent products and ideal for my re-wheeling projects, so let me not give the impression otherwise. I have checked and checked again and six other wheels you 'lent' me are out by between .005"-.008" (two U/scale sets being correct to gauge along with the two spoked wheelsets). Not a great problem to rectify and I'm sure a quick twist in the right direction will cure them.

Reaming out wheels sounds like a black art to me, so for now, if I move wheel on its axle (and we are talking Ultrascale not Exactoscale here), it'll get a dab of Loctite 603 as an insurance policy: an interference fit won't need the stuff, but a sliding fit will - so in it goes!

No takers on the bet then?!

Colin

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Re: Starting out in P4

Postby Terry Bendall » Sun Mar 23, 2014 7:55 pm

Colin Parks wrote:I shall bear it in mind for when I get around to converting my Bachmann MLV to P4.


There are two of these running on Elcot Road and we used the Clockwork Ideas bogie centres for them as well. I can see why you are converting the BB bogies to P4 if you already have them. I have used the Black Beetle 12mm coach wheels from Branchlines for all the unpowered axles so that they can be used for current collection. These might be cheaper than Ultrascale ones.

Terry Bendall

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Re: Starting out in P4

Postby JFS » Sun Mar 23, 2014 10:13 pm

Terry Bendall wrote:
Colin Parks wrote:I shall bear it in mind for when I get around to converting my Bachmann MLV to P4.


There are two of these running on Elcot Road and we used the Clockwork Ideas bogie centres for them as well.


Hi Terry,

Clockwork Ideas is a new name for me - I got as far as finding the chap on RMWeb, but his does not link to any website - do you know if there is such a thing please?

many thanks,

Howard.

shipbadger
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Re: Starting out in P4

Postby shipbadger » Mon Mar 24, 2014 7:19 am

Howard,

Item EMU01 from the stores I believe.

Tony Comber

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Re: Starting out in P4

Postby grovenor-2685 » Mon Mar 24, 2014 9:03 am

Yes, these were on display, and sale, on the stores stand at Scaleforum 2012, Branchlines do stub axle wheelsets for motor bogies which I used here and I understood to be designed for the Bachmann EMUs.
Keith
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