Exactoscale wagon chassis kits

hollybeau
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Exactoscale wagon chassis kits

Postby hollybeau » Mon May 25, 2020 6:47 pm

I have recently bought some of these chassis kits from Scalefour stores. I normally use the 9ft chassis kits originally produced by Craig Welsh for the society or the Bill Bedford spring units and so this is the first time I have encountered and used them. Just to be clear these are the ones with the parallel (1mm) axles, and not the pin points. Although a bit fiddly I have managed to make a running chassis but am having problems with the wheel sets dropping out of the axleguards when removing a wagon from the track. I have followed the instructions to the letter but can see no reference to this issue. The retaining tabs that fold up to keep the "sliders" in position by the axleguards have a further half etched line which is not referred to and is in any event on the inside and would be too low to act as a retainer. I should add that as yet the dummy axle boxes and springs are not yet in place and I am wondering if when they are it will "stiffen" the assembly and prevent the axleguards from springing outwards to let the wheels drop out. In such a well-thought-out and engineered product this seems an odd problem to be having - or else I am doing something wrong. I realise that some packing "washers" are available and I have a pack but haven't used them. It seems to me that adding them will only push the axleguards out further to a splayed position (as well as causing friction) rather than holding the wheels in place. To my eye the axles, and the corresponding bearings, are simply too short and while that may mean a smaller hole in the back of the (dummy) axle box it does have this unfortunate effect. Any advice or comments would be appreciated.
A second and related question is what overall weight do people use with these particular kits? I know that 50 grammes is the recommended or accepted norm but that I assume is for pin-pointed stock. To my mind that seems a little heavy for these rather delicate assemblies.
Finally, whilst writing I had quite a problem finding a copy of the instructions. (I can't recall where I got them from online). They are certainly not available anymore on the C and L web site. The position on whether these and other former Exactoscale products (other than track) will continue to be made is unclear to me but even if it does not continue I would have thought that there ought to be an independent library, say hosted by the Society itself, where instruction sheets can be made available for downloading. I'll leave that thought with the powers that be.

Bryan

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grovenor-2685
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Re: Exactoscale wagon chassis kits

Postby grovenor-2685 » Mon May 25, 2020 6:57 pm

hollybeau wrote:To my eye the axles, and the corresponding bearings, are simply too short and while that may mean a smaller hole in the back of the (dummy) axle box it does have this unfortunate effect. Any advice or comments would be appreciated.

I found this exact problem when I tried them some years ago, the short axles leave no margin of error. Journal centres should be 26mm apart, and pinpoints are designed to put the pinpoint at journal centre. These axles at 25mm do not even reach the journal centres! While using the bearings in the carriers puts the functional journal centres closer than scale I think the axles should be at least 26 mm and would be better at 27 mm or even 28 mm. After all its easy to shorten an axle, more difficult to lengthen them. I put this to Andrew Jukes a few years ago. His response was that they had a stock of thousands they could not afford to throw away so any change would be many years away.. A pity because it spoils the product for me.

The way out is to buy 1 mm steel rods, I have some bought from North West Short Line years ago, and I thought I had seen them on offer from Ultrascale but 1 mm is not currently listed.
Another option is to use two axles and join them in the wheel stub axle, then you can cut to your preferred length.
Regards
Keith
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jjnewitt
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Re: Exactoscale wagon chassis kits

Postby jjnewitt » Mon May 25, 2020 7:35 pm

grovenor-2685 wrote:I found this exact problem when I tried them some years ago, the short axles leave no margin of error. Journal centres should be 26mm apart, and pinpoints are designed to put the pinpoint at journal centre. These axles at 25mm do not even reach the journal centres!


I've never entirely understood why our axles have to have anything to do with prototype journal centres. The two are not related nor do they need to be. It's like someone, somewhere was scratching around for a dimension and thought it was a good idea. Personally I think we should have gone with imperial dimensions; 25.4mm length with 1/16" axles (for pinpoints, obviously less for parallel) and bearings. Some people might moan that the axle is underscale but it would have had a positive knock on effect on other things, such as our cosmetic axleboxes. There are plenty of types of axlebox that simply cannnot be modelled to scale due to our 2mm bearings and need to be done overscale. We're trying to fit scale 6" journals into boxes that are designed to fit 4" - 4 1/4" journals and it just doesn't work.

Whilst the Exactoscale axles could do with being a bit longer (or the bearings) I find them ok and don't have any problems with bearings dropping out. Mind you that is on my own underframes, and I seem to have a different way of retaining things than everyone else. I find the best approach is to space the bearings away from the carrier to leave about 0.25mm protruding past the axleguard then remove sideways movement of the axle by using washers leaving just a little room for things to sit where they want to and move with the springing. If you do that and can stop the spring carriersmoving past where they would sit with no weight on it then nothing should come free. If you're worried about the axleguards splaying outwards then solder spring/axlebox castings to them and, if possible, the underside of the solebar.

Justin

Edited for clarity

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PeteT
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Re: Exactoscale wagon chassis kits

Postby PeteT » Mon May 25, 2020 7:57 pm

The products which have been reintroduced had the datasheets and instructions available on the exactoscale website. This included all the track and chair data, and wheels - I'm not sure about underframes though.

However the website currently appears to be down.
https://exactoscale.com/

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grovenor-2685
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Re: Exactoscale wagon chassis kits

Postby grovenor-2685 » Mon May 25, 2020 8:59 pm

jjnewitt wrote:I've never entirely understood why our axles have to have anything to do with prototype journal centres. The two are not related nor do they need to be.

They should be related, it is what we are modelling after all. Just like you say below about the axlebox sizes.
You can get 1.5mm OD bearings for the 1mm axles and they will allow use of the small axleboxes.
It's like someone, somewhere was scratching around for a dimension and thought it was a good idea. Personally I think we should have gone with imperial dimensions; 25.4mm length with 1/16" axles (for pinpoints, obviously less for parallel) and bearings.

We don't have to go to imperial to get smaller sizes, 2mm is not the only metric size!
Some people might moan that the axle is underscale but it would have had a positive knock on effect on other things, such as our cosmetic axleboxes. There are plenty of types of axlebox that simply cannnot be modelled to scale due to our 2mm bearings and need to be done overscale. We're trying to fit scale 6" journals into boxes that are designed to fit 4" - 4 1/4" journals and it just doesn't work.

The original P4 axles were not 2mm, for the very reason that that is oversize for most rolling stock, the change to 2 mm came in with Alan Gibson and the demise of Studiolith. However the smaller axles did not extend to the pinpoint bearings which have always been 2 mm.

The Exactoscale parallel bearings were originally only available in the 1.5 mm OD size, which fitted the Exactoscale bearing carriers, I expect Bernard was thinking about small axleboxes. The 2mm OD bearings were requested to allow use of the parallel axles with other peoples bearing carriers, eg Bill's that were all made for the 2 mm pinpoints. The short axles though make it all difficult as you describe below, and like I said, its easy to shorten axles!
Whilst the Exactoscale axles could do with being a bit longer (or the bearings) I find them ok and don't have any problems with bearings dropping out. Mind you that is on my own underframes, and I seem to have a different way of retaining things than everyone else. I find the best approach is to space the bearings away from the carrier to leave about 0.25mm protruding past the axleguard then remove sideways movement of the axle by using washers leaving just a little room for things to sit where they want to and move with the springing. If you do that and can stop the spring carriers moving past where they would sit with no weight on it then nothing should come free. If you're worried about the axleguards splaying outwards then solder spring/axlebox castings to them and, if possible, the underside of the solebar.
Never found splaying out an issue with parallel bearings, that comes in with the pinpoints.
Regards
Keith
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jjnewitt
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Re: Exactoscale wagon chassis kits

Postby jjnewitt » Tue May 26, 2020 7:00 am

grovenor-2685 wrote:They should be related, it is what we are modelling after all.

Why? Sorry I don't understand why the length of our axles should be dictated by the scaled down measurement for prototype journal centres. That is journal centres, not prototype axle length which is, as I'm sure you know, longer.

How much we follow the prototype seems to be an entirely individual choice with some more keen than others. :) There are plenty of people out there using pin point axles and I haven't seen many of those on the prototype!

grovenor-2685 wrote:You can get 1.5mm OD bearings for the 1mm axles and they will allow use of the small axleboxes.

And then I can't sell them because people use 2mm bearings...

grovenor-2685 wrote:We don't have to go to imperial to get smaller sizes, 2mm is not the only metric size!

No we don't but we're still using 1/8" for steam loco axles so why not? 1.5mm would be fine, as would 1mm. Just not 2mm! Same goes for the bearings. It creates more problems than it solves but it seems to be what we're stuck with. Exactoscle had the right sort of idea with their wagon and carriage wheels. Perhaps things could have been done slightly differently. Shorter pinpoint axles to enable the use of smaller 1.5mm bearings and slightly longer parallel axles and bearings would have been good but they are workable with care. A bit like P4.

Justin

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johndarch
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Re: Exactoscale wagon chassis kits

Postby johndarch » Tue May 26, 2020 8:18 am

[quote="grovenor-2685"][quote="hollybeau"]I put this to Andrew Jukes a few years ago. His response was that they had a stock of thousands they could not afford to throw away so any change would be many years away.

That was the same response that I received when I asked him why they were still selling pinpoint bearings that were acknowledged to be faulty.

andrewnummelin
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Re: Exactoscale wagon chassis kits

Postby andrewnummelin » Tue May 26, 2020 10:17 am

By chance I've been working with similar problems. As an interlude from the lockdown challenge I decided to do something simple and build a Slater's MR van kit and fit it with Exactoscale suspension bits that I've had in stock for many years. I used the conversion bits (solebar and W irons as single etching) rather than a chassis kit but I'm sure the problems are similar.
Firstly, it would have been better to read all the instructions more than once rather than just following them in the order written. Not doing things in the right order meant that the Exactoscale alignment jigs could not be used. It is critical to get the W irons the correct distance apart so I had a bit of a fiddle...
Now to the real problems of retaining everything in place. The drawing below is from the Exactoscale instruction sheet 9.3 of Sept 1993.

Capture.JPG
Capture.JPG (89.91 KiB) Viewed 975 times

1. I found it difficult to trap the spring wire neatly - it is critical that it lies against the carrier. It does not just spring the wagon but it holds the carrier against the W iron. If the spring pops out of place (happens easily) the carrier may dislodge. (Also the carrier may need cleaning up to ensure it can fit flush against the W iron - if any of the bends have been reinforced with solder it could be that it is not fully flush.)
2. One could consider converting the slot to a hole; but this would defeat one of the design features of the system.
3. The cradle stops are the first thing intended to prevent the carrier falling out: they are so fine that they will not do their job if not bent perfectly or if the cradle is not fully flush against the W iron. (I found it easy to slightly distort the cradles when handling as the metal is so thin.)
4. The retaining strap is what is really designed to stop a wheel set falling out when the wagon is picked up. This will fail to do its job if the distance between the W irons at this point is too large as a result of any distortion.
P1020648.jpg
P1020648.jpg (297.42 KiB) Viewed 975 times

The bearing is only just held by the retaining strap "a" and the carrier "c" is not quite flush with the W iron: a washer between the wheel and bearing was nearly necessary.


======================
On the socially distanced challenge I've been try to work with a csb approach - first attempt was a failure https://www.scalefour.org/forum/viewtopic.php?f=100&t=6884#p75209 - more on the second attempt in due course.
Regards,

Andrew Nummelin

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grovenor-2685
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Re: Exactoscale wagon chassis kits

Postby grovenor-2685 » Tue May 26, 2020 10:25 am

The bearing is only just held by the retaining strap "a" and the carrier "c" is not quite flush with the W iron: a washer between the wheel and bearing was nearly necessary.

And that's where the longer axles and/or bearings would make a big difference. I would prefer longer axles as longer bearings will affect the axles freedom in tilt.
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Keith
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Guy Rixon
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Re: Exactoscale wagon chassis kits

Postby Guy Rixon » Tue May 26, 2020 2:24 pm

Andrew, what you have described is the Mk1 system. The gear sold by Exactoscale today is the Mk 2 system and the spring carriers are different.

Personally, I much preferred the Mk 1 system. It's easier for a barbarian like myself to put together and I've always found that the cradle stops did a good job of keeping the cradles in place. However, I always used to solder in the spring to the cradle. The fold-over clip is only enough to hold it while soldering, not in service.

IIRC, the springs in the Mk 1 system were designed for a 35g load on 2 axles, not 50g. I don't know the design weight for the Mk 2 system, but the springs there are a similar length and cross-section.

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grovenor-2685
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Re: Exactoscale wagon chassis kits

Postby grovenor-2685 » Tue May 26, 2020 3:06 pm

I'm with you Guy, those Mk2 spring holders are a nightmare to get right. Both systems were designed to bottom out and only spring downwards, so if you want it to ride on the springs you have to keep the weight down or beef up the spring wire size. I found this a fairly general trait with Exactoscale, when a Mk2 appeared it was more difficult to use than Mk1. But all ancient history now.
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Keith
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hollybeau
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Re: Exactoscale wagon chassis kits

Postby hollybeau » Sat Jun 06, 2020 4:05 pm

My thanks to all who replied - some interesting responses.
Having now completed more chassis kits I have found that part of the problem was that the W irons tend to splay outwards. Unlike the Bill Bedford and other variations it is not possible to put a fillet of solder at the fold-up join to strengthen this part of the assembly as it would prevent the carriers from moving to their "bottom stop". However, I have found that (in my case at least) there was a gap of around 1mm. between the front face of the Exactoscale units and the back face of the solebars. I have found that packing this with thin strips of plasticard helps give the W irons some strength/stability.
Overall though I agree with Keith - slightly longer axles with deeper bearings would have prevented this problem: there is plenty of "meat" in the axleboxes to withstand being carved out.
On a slightly different note I have also found that the bearings need easing slightly (with a fine broach) as out of the box the axles are too tight a fit and reduce any smooth running to zero. Pin points these are not!

Bryan

Paul Cram
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Re: Exactoscale wagon chassis kits

Postby Paul Cram » Mon Jun 08, 2020 10:57 am

hollybeau wrote:My thanks to all who replied - some interesting responses.
Having now completed more chassis kits I have found that part of the problem was that the W irons tend to splay outwards. Unlike the Bill Bedford and other variations it is not possible to put a fillet of solder at the fold-up join to strengthen this part of the assembly as it would prevent the carriers from moving to their "bottom stop". However, I have found that (in my case at least) there was a gap of around 1mm. between the front face of the Exactoscale units and the back face of the solebars. I have found that packing this with thin strips of plasticard helps give the W irons some strength/stability.
Overall though I agree with Keith - slightly longer axles with deeper bearings would have prevented this problem: there is plenty of "meat" in the axleboxes to withstand being carved out.
On a slightly different note I have also found that the bearings need easing slightly (with a fine broach) as out of the box the axles are too tight a fit and reduce any smooth running to zero. Pin points these are not!

Bryan

On the one I did I used the paralell axles and bearings

hollybeau
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Re: Exactoscale wagon chassis kits

Postby hollybeau » Mon Jun 08, 2020 4:18 pm

Mine are the 1mm parallel axles too. What I meant by my reference to pin-points was to say how less free-running these are compared to pin-points. Sorry Paul if I had not made that clear.

Bryan


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