Chassis for a J50

Julian Roberts
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Chassis for a J50

Postby Julian Roberts » Tue Jan 16, 2018 12:25 pm

I've been presented with this by a chum in the WS4G (thanks Ian!). It has the Ks label cast inside. Without doing a huge amount of research a chassis kit from Connoisseur Kits seemed to be a sensible option.

20180115_165718.jpg

20180115_165613.jpg


So here it is. It has no cut outs for hornblocks so for suspension I'm on my own. I have a plan that will work, to go the same route as my 782 class. It doesn't involve any tricky measuring or marking. However I thought it might be interesting to ask what the latest thinking is when embarking on P4-izing a basic rigid though accurate chassis, anyone? Not asking anyone to waste time on a massive description - answers on a digital postcard would be quite enough to start.

The project may be my next one after finishing the Crab which will take a few more weeks at my slow pace.

David Knight
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Re: Chassis for a J50

Postby David Knight » Tue Jan 16, 2018 2:38 pm

Julian,

Chris Gibbons has a CSB jig that allows you to locate cut outs on frames that don’t have them. A very useful piece of kit.

http://173.254.28.51/~highlev3/chris/Pages/jigpage.html

HTH

David

Julian Roberts
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Re: Chassis for a J50

Postby Julian Roberts » Tue Jan 16, 2018 4:46 pm

Yes David that is exactly what I will need, many thanks. I wonder if someone has written up the process in a blog style starting from a basic chassis like this.

Jeremy Good
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Re: Chassis for a J50

Postby Jeremy Good » Tue Jan 16, 2018 7:46 pm

Julian,

There is quite a good explanation of modifying an etched chassis for CSBs on the CLAG site - see http://www.clag.org.uk/pannier-csb.html.

Although it relates to a High Level 57XX chassis the basic principles are well set out. Alternatively Will Litchfield's notes on CSBs should be of assistance.

Jeremy

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Will L
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Re: Chassis for a J50

Postby Will L » Wed Jan 17, 2018 12:19 am

Jeremy Good wrote:Julian,

There is quite a good explanation of modifying an etched chassis for CSBs on the CLAG site - see http://www.clag.org.uk/pannier-csb.html.

Although it relates to a High Level 57XX chassis the basic principles are well set out. Alternatively Will Litchfield's notes on CSBs should be of assistance.


My post that covers the Highlevel Jig is here. While you can certainly use the jig just to get cut-outs in the frames right and compensate the results, why not go the whole hog and try CSB? I'm sure you are perfectly capable and quite presistent enough to succeed.

Edited to remove persistent late night finger trouble
Last edited by Will L on Wed Jan 17, 2018 6:13 pm, edited 2 times in total.

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David Thorpe
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Re: Chassis for a J50

Postby David Thorpe » Wed Jan 17, 2018 12:36 am

I'd go along with the CSB suggestion. I resurrected a Wills Mackintosh 0-6-0T that I'd part built several decades ago, bought some AG mainframes (hornguides happily already cut out), and used CSBs together with the High Level CSB hornblock system. It runs very nicely indeed.

DT

Julian Roberts
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Re: Chassis for a J50

Postby Julian Roberts » Wed Jan 17, 2018 12:12 pm

Many thanks everyone for these helpful replies. David a Mackintosh 0-6-0 must be a CR 782 class, no?

Will haha I am not sure what you mean by presentist! No matter - I have skimmed through that link. I see that you are starting from a similar holes only basic chassis so that is exactly my starting point too. What I have not seen, but maybe I have missed it, is on completion how to adjust the ride height by say 1mm or so. From experience this is the problem when marrying up components that are not a single kit. E.g. with my 782 I was marrying up a SEF body with Alan Gibson outline milled frames chassis and much of the fun was adjusting the frames to sit approximately right, then adjusting the ride height of the wheels within the chassis for that final correct buffer height. This last tweak is comparatively simple when using beams.

I would expect the Connoisseur frames to not be exactly correct for height given that they are part of a whole loco kit in etched brass (and I was surprised Jim was happy to sell me them without buying the whole thing).

Probably I have missed the relevant bit of your thread. If so could you just refer me to it? Sorry if this is rather a dumb question.

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David Thorpe
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Re: Chassis for a J50

Postby David Thorpe » Wed Jan 17, 2018 3:31 pm

Indeed it was a 782 class, Julian. Rather crude and I haven't done an awful lot to improve its appearance but it is recognisable as what it purports to be and it runs well and would probably pull all the freight stock that I have (must try that).

You're right to be concerned about the ride height when matching a CSB chassis with a different manufacturer's loco body. I have in the past had to resort to using a cutting disc to carve away some of the top surface of a chassis to get it to ride at the correct height when joined to the loco body. I'm sure that there must have been an easier way - Will?

DT
Last edited by David Thorpe on Wed Jan 17, 2018 4:22 pm, edited 1 time in total.

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Le Corbusier
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Re: Chassis for a J50

Postby Le Corbusier » Wed Jan 17, 2018 4:08 pm

I am looking at using some AG frames for my 1F tank ... marrying them to the craftsman body. I was assuming that by careful measurement the positioning of the handrail knobs for the CSB wires could be positioned to ensure that the ride height is there or there abouts. I was then planning to experiment with different wire thicknesses to fine tune?

.... So the answer to this question is quite pertinent :thumb
Tim Lee

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David Thorpe
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Re: Chassis for a J50

Postby David Thorpe » Wed Jan 17, 2018 4:36 pm

I'm not sure how you'll know whether the ride height is correct or not until you've actually tried it, by which time, if it isn't correct. the damage will have been done. I suspect thnat there must be a proper way of working this out and then placing the fulcrum points correctly, and it may involve maths..... The problem I had was largely my own fault - I assumed they would match up (my previous efforts involving AG frames all had) and they didn't. Presumably it involves putting a chassis side in place under the loco body and calculating where the axle centre should be. Once you know that, the rest should be easy (but it seldom is, is it?)

DT

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grovenor-2685
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Re: Chassis for a J50

Postby grovenor-2685 » Wed Jan 17, 2018 4:52 pm

If you do a trial assembly of the chassis, just tacked together with minimal spacers, before cutting the hornblock slots, you can put the the two outer wheelsets in pace, fit the body and check the ride height, so you know how much ro raise or lower when fitting the hornblocks.
The drawback is the need for a subsequent removal of one wheel from each axle, if that's a no-no then you could cut 1/8" slots first to allow the axles to fit in, using half bushes, and widen the slots later.
Regards

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Le Corbusier
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Re: Chassis for a J50

Postby Le Corbusier » Wed Jan 17, 2018 5:00 pm

Am I being thick here? I just assumed that we know the ride height required to the centre point of the buffer ... and we can measure the relationship of the centre of the buffer to the top of the frames. We know the diameter of the wheels. So can't we just scribe a line on the frames for the required centre line of the axles, and from this calculate where to put the CSB using the jig? After that presumably its all about selection of the wire to fine tune?
Tim Lee

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grovenor-2685
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Re: Chassis for a J50

Postby grovenor-2685 » Wed Jan 17, 2018 5:19 pm

The tricky bit is measuring from the buffer centres to the underside of the footplate or whatever part will sit on the top of the frames. So long as you can determine how to measure that then fine, measurement should work. Verification is re-assuring however.
Regards

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Will L
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Re: Chassis for a J50

Postby Will L » Wed Jan 17, 2018 5:49 pm

Julian Roberts wrote:Will haha I am not sure what you mean by presentist! .... What I have not seen, but maybe I have missed it, is on completion how to adjust the ride height by say 1mm or so. From experience this is the problem when marrying up components that are not a single kit. E.g. with my 782 I was marrying up a SEF body with Alan Gibson outline milled frames chassis and much of the fun was adjusting the frames to sit approximately right, then adjusting the ride height of the wheels within the chassis for that final correct buffer height. This last tweak is comparatively simple when using beams.

I would expect the Connoisseur frames to not be exactly correct for height given that they are part of a whole loco kit in etched brass (and I was surprised Jim was happy to sell me them without buying the whole thing).

Probably I have missed the relevant bit of your thread. If so could you just refer me to it? Sorry if this is rather a dumb question.


Sorry Julian the word was supposed to be persistence but my auto guessing machine decided otherwise. I'll correct the post.
It was, by the way, entirely complimentary, persistence being exactly the qaulity needed to work your way through the average kit and come out the other end with a satisfactory result. And no not a dumb question.

You didn't see anything on adjusting the ride height because it wasn't necessary once body weight and final wire size had been decided. The CSB method done right with the Highlevel jig will leave the wheels at exactly the same level as they would have been in the the original plain axle holes in the chassis. In my case, the loco body was designed to fit the chassis kit, the wheels were the right size and and in both cases they went together well so no adjustment was required.

I can see that it might not be true in your case with body and chassis from different sources. However I think it would be a mistake to to think about doing any significant adjustments within the chassis. You could use a slightly thicker or thinner wire but I wouldn't want to take that more than 0.1 mm either way (defections around .4 or .6 on the spread sheet) which frankly is barely visible. Anything more than that and the right way to go has to be to correct the sit of the body on the chassis as David has done in the past.

Trying to adjust the fulcrum heights, to correct how high the body sits above the track on the chassis, opens a whole can or worms, starting with how do you know how much adjustment is required at that very early stage in the build. I wouldn't go there.

Faced with your problem, I'd be matching the body and chassis side frames against a drawing to check the axle centre heights against the running plate before I assembled anything, to see how well my chassis and body were likely to go together, but its the joint between the two I'd be working on not the suspension.

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Will L
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Re: Chassis for a J50

Postby Will L » Wed Jan 17, 2018 6:09 pm

Le Corbusier wrote:Am I being thick here? I just assumed that we know the ride height required to the centre point of the buffer ... and we can measure the relationship of the centre of the buffer to the top of the frames. We know the diameter of the wheels. So can't we just scribe a line on the frames for the required centre line of the axles, and from this calculate where to put the CSB using the jig? After that presumably its all about selection of the wire to fine tune?


If you were doing things form scratch, yes. But if you have a body from one source and chassis from the another there is no guarantee that the two will fit together to give the right ride height. The material they body is made from will influence how thick the running plate is, and typically (but not necessarily) the chassis will sit against the underside of the footplate. So the top height of the chassis frames will be different depending on what sort of body the designer though would sit on top of it. Cast white metal and plastic footplates are quite thick, etch ones are thin. So a chassis designed for an etched body sitting under a cast body may well result in the body sitting a 2mm higher than it should while a chassis designed for a cast kit, sitting under an etch body could be 2mm too low. But this isn't a suspension problem. Build the chassis with the wheels where the were designed to be and do the gross adjustments between chassis and body. As you say wire changing is for fine adjustment only.

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Le Corbusier
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Re: Chassis for a J50

Postby Le Corbusier » Wed Jan 17, 2018 6:22 pm

Will L wrote:
Le Corbusier wrote:Am I being thick here? I just assumed that we know the ride height required to the centre point of the buffer ... and we can measure the relationship of the centre of the buffer to the top of the frames. We know the diameter of the wheels. So can't we just scribe a line on the frames for the required centre line of the axles, and from this calculate where to put the CSB using the jig? After that presumably its all about selection of the wire to fine tune?


If you were doing things form scratch, yes. But if you have a body from one source and chassis from the another there is no guarantee that the two will fit together to give the right ride height. The material they body is made from will influence how thick the running plate is, and typically (but not necessarily) the chassis will sit against the underside of the footplate. So the top height of the chassis frames will be different depending on what sort of body the designer though would sit on top of it. Cast white metal and plastic footplates are quite thick, etch ones are thin. So a chassis designed for an etched body sitting under a cast body may well result in the body sitting a 2mm higher than it should while a chassis designed for a cast kit, sitting under an etch body could be 2mm too low. But this isn't a suspension problem. Build the chassis with the wheels where the were designed to be and do the gross adjustments between chassis and body. As you say wire changing is for fine adjustment only.


My issue is that the frames I have came with the horn slots already cut .... so I don't have an axle height. Hence the idea of measuring from the underside of the footplate etch to the centre line of the buffer so theoretically I know where the buffer centre line is in relation to the top of the frames. This should let me plot the centre line of the axles and take it from there? I would hope I could get it within 0.2mm accuracy .. which would hopefully allow fine tuning with the csb wire?
Tim Lee

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Will L
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Re: Chassis for a J50

Postby Will L » Wed Jan 17, 2018 6:28 pm

Le Corbusier wrote:My issue is that the frames I have came with the horn slots already cut .... so I don't have an axle height.

Are but you do, (almost always) the cuts outs are 6mm by 6mm and the designed axle centre line is 3mm form the top.

Julian Roberts
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Re: Chassis for a J50

Postby Julian Roberts » Wed Jan 17, 2018 7:05 pm

I appreciate that Will and thanks for your explanation. Glad the question was not dumb. While digesting your reply and just as a quick response to Keith's suggestion, this is how I did it on the 782 starting pretty much with just holes in the chassis. I've also done this on the Crab that I'm writing up here. Having one wheel on its axle properly entails using the GW jig in a slightly different way to its intention when eventually putting the second wheel on but with no ill effect.

A big time waster was that the buffer height jig, at least mine, gives an incorrect buffer height, but I didn't know that. The height I had here was from following drawings as far as possible and it turned out to be pretty well correct. Measuring the distance from footplate to axle centre is problematic as they are on different levels. Then...is the drawing correct? All sorts of snares!
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Julian Roberts
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Re: Chassis for a J50

Postby Julian Roberts » Wed Jan 17, 2018 7:32 pm

David does your answer mean you model the CR?

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Flymo748
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Re: Chassis for a J50

Postby Flymo748 » Wed Jan 17, 2018 7:37 pm

Le Corbusier wrote:Am I being thick here? I just assumed that we know the ride height required to the centre point of the buffer ... and we can measure the relationship of the centre of the buffer to the top of the frames. We know the diameter of the wheels. So can't we just scribe a line on the frames for the required centre line of the axles, and from this calculate where to put the CSB using the jig? After that presumably its all about selection of the wire to fine tune?


Ah, you can spot an architect a mile off...

To be honest, this is exactly what I would have done. Alternatively, a scale diagram? Or even one in a different scale which you can obtain the ratio of heights from?

And starting from a frame with only holes for axles, you can easily mark the correct wheel centreline through the middle of the holes, and that would ensure that the built chassis is the correct height above the rails. You wouldn't want guard irons clouting crossings or anything like that. This is more difficult with frames with hornblock slots, and you have to find where within the possible range the axle centre really should be. I had to do that on my Y15 to establish the ride-height.

There is also one other possibility, but it is a bit of a cheat. The High Level "tags" to go on the bearings for CSBs have three holes etched in each of them. I think the distance between them is something like 0.75 to 1.0mm (I'm typing this on a Eurostar so can't exactly check my stock). You could start off with a medium grade wire and (say) the middle hole. Then, when the model is built and weighted, you can consider using the other holes, and different sizes of wire (with different amounts of "sag") to adjust up or down. I say this is a bit of a cheat, as it is moving the whole locomotive up and down ex-post, rather than establishing the height of the frames and thickness of the footplate ex-ante and building accordingly. But we all need to call on a bit of a bodge from time to time...

Cheers
Flymo
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Le Corbusier
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Re: Chassis for a J50

Postby Le Corbusier » Wed Jan 17, 2018 8:28 pm

Will L wrote:
Le Corbusier wrote:My issue is that the frames I have came with the horn slots already cut .... so I don't have an axle height.

Are but you do, (almost always) the cuts outs are 6mm by 6mm and the designed axle centre line is 3mm form the top.

:thumb :thumb
Tim Lee

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Le Corbusier
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Re: Chassis for a J50

Postby Le Corbusier » Wed Jan 17, 2018 8:29 pm

Flymo748 wrote:There is also one other possibility, but it is a bit of a cheat. The High Level "tags" to go on the bearings for CSBs have three holes etched in each of them. I think the distance between them is something like 0.75 to 1.0mm (I'm typing this on a Eurostar so can't exactly check my stock). You could start off with a medium grade wire and (say) the middle hole. Then, when the model is built and weighted, you can consider using the other holes, and different sizes of wire (with different amounts of "sag") to adjust up or down. I say this is a bit of a cheat, as it is moving the whole locomotive up and down ex-post, rather than establishing the height of the frames and thickness of the footplate ex-ante and building accordingly. But we all need to call on a bit of a bodge from time to time...

Cheers
Flymo

:thumb :thumb
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David Thorpe
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Re: Chassis for a J50

Postby David Thorpe » Wed Jan 17, 2018 9:21 pm

Julian Roberts wrote:David does your answer mean you model the CR?


Er......sort of. CR Northern Division in early BR days.

DT

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David Thorpe
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Re: Chassis for a J50

Postby David Thorpe » Wed Jan 17, 2018 9:59 pm

Flymo748 wrote:There is also one other possibility, but it is a bit of a cheat. The High Level "tags" to go on the bearings for CSBs have three holes etched in each of them. I think the distance between them is something like 0.75 to 1.0mm (I'm typing this on a Eurostar so can't exactly check my stock). You could start off with a medium grade wire and (say) the middle hole. Then, when the model is built and weighted, you can consider using the other holes, and different sizes of wire (with different amounts of "sag") to adjust up or down. I say this is a bit of a cheat, as it is moving the whole locomotive up and down ex-post, rather than establishing the height of the frames and thickness of the footplate ex-ante and building accordingly. But we all need to call on a bit of a bodge from time to time...


I'll do my best to remember that one (I always like a bodge). It wouldn't have worked in the past though as I used to use MJT hornblocks and Markits handrail knobs. I've since been using High Level CSB Products and they're usually fine though I do find that the hornblocks can stick in the hornguides even when they've been moving smoothly when tested.

DT

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MarkS
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Re: Chassis for a J50

Postby MarkS » Wed Jan 17, 2018 11:23 pm

I built my first CSB loco 15 years ago, before Chris Gibbon had produced his bearings and jigs, using Gibson bearings and handrail knobs.
Being my first CSB build, I made mistakes and learned plenty, and once the loco was on its feet, it was too low, so I just changed out the handrail knobs for longer ones - problem solved.

Then came along the the High Level jigs, with the bearings and tags etc., so now we can measure twice and cut once, and hopefully, not bodge (much)... however, being flexible in our approach does help.
Cheers,

Mark.
"In the end, when all is said and done, more will have been said than done..."


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