help on sprung csb chassis with cosmetic outside frames

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Le Corbusier
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help on sprung csb chassis with cosmetic outside frames

Postby Le Corbusier » Mon May 30, 2016 7:35 am

Any thoughts please.

I have an old k"s Kurtley 700 class outside frame goods loco which I am looking to rebuild/improve and run on a csb sprung LRM 2F chassis. My question is how to deal with the external frame horn blocks 'cosmetically'. The original kit simply elongates the cast representation of the blocks into a slot for the extended axles to run within - with no containing strap at the bottom and the blocks themselves compromised .... I assume hoping the external cranks will mask as much as possible the result. This does not seem a very good compromise solution to me. (picture attached)

Has anybody solved this problem cosmetically? or does anybody have any suggestions given the white metal outside frame starting point?

Thanks

Tim
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Flymo748
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Re: help on sprung csb chassis with cosmetic outside frames

Postby Flymo748 » Mon May 30, 2016 7:48 am

Le Corbusier wrote:I have an old k"s Kurtley 700 class outside frame goods loco which I am looking to rebuild/improve and run on a csb sprung LRM 2F chassis. My question is how to deal with the external frame horn blocks 'cosmetically'. The original kit simply elongates the cast representation of the blocks into a slot for the extended axles to run within - with no containing strap at the bottom and the blocks themselves compromised .... I assume hoping the external cranks will mask as much as possible the result. This does not seem a very good compromise solution to me. (picture attached)

Has anybody solved this problem cosmetically? or does anybody have any suggestions given the white metal outside frame starting point?


Hi Tim,

I haven't solved this problem myself, although I have a GWR 1076 Buffalo tank that needs building at some point in the future. So this is theoretical, but I have a question and a proposition.

The question is to ask how much detail do you want to achieve? You might be able to back up such a comment with a close-up of an individual bearing.

The proposition is that you build the (inside-framed, CSBed) chassis, and assess your cosmetic options from there.

Having seen a couple of my locos running at Railex this weekend (enormous thanks to Robin (Rolvenden) and Tim (Clutton) for the opportunity for them to stretch their legs) I remain astonished how *little* movement is needed in a chassis for it to run smoothly. The old "compensated so it can climb over a matchstick" really is just an extreme illustration of the technique, not a working need.

So you could build the outside axleboxes around the extended axles leaving perhaps 1.0mm up and down clearance on top and bottom. You may need to create a keeper plate or 14BA bolt arrangement if you envisage having to remove any cosmetic springs or tiebars under the axles, or you could make them semi-permanent if you're confident in the chassis running qualities before finishing it cosmetically.

As I started with, I haven't tried this myself, but based on recent experience it is an approach that I would start with.
HTH
Flymo
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Will L
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Re: help on sprung csb chassis with cosmetic outside frames

Postby Will L » Mon May 30, 2016 9:23 am

Lack of pertinent outside frame experience means I have nothing to add, beyond saying I that the following had me feverishly looking round for that like button again.

Flymo748 wrote:...I remain astonished how *little* movement is needed in a chassis for it to run smoothly. The old "compensated so it can climb over a matchstick" really is just an extreme illustration of the technique, not a working need.

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Le Corbusier
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Re: help on sprung csb chassis with cosmetic outside frames

Postby Le Corbusier » Mon May 30, 2016 9:30 am

Having seen a couple of my locos running at Railex this weekend (enormous thanks to Robin (Rolvenden) and Tim (Clutton) for the opportunity for them to stretch their legs) I remain astonished how *little* movement is needed in a chassis for it to run smoothly. ..... So you could build the outside axleboxes around the extended axles leaving perhaps 1.0mm up and down clearance on top and bottom.


Thanks Paul,

This is very helpful ... given that I am also still at the 'early' stage of track building and so my experience of actually running in P4 is very limited. I was intending to discuss this problem with you at the P4 stand yesterday but you were very busy and I thought drumming up new members should take priority.

From your thoughts I wonder if a first stab at a solution in this instance might be fit high-level horn blocks (or similar) within a cleared opening, The blocks opened out to allow the required degree of slop? It should be possible to set them such as to allow a degree of daylight above and below to increase realism and also to affix the bottom strap (much like on the slaters model attached). The question is ... would they need to be permanently fixed in place to work? Being able to drop the wheels out makes painting/maintenance etc much simpler.

Tim
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Re: help on sprung csb chassis with cosmetic outside frames

Postby Flymo748 » Mon May 30, 2016 11:07 am

Le Corbusier wrote:
Having seen a couple of my locos running at Railex this weekend (enormous thanks to Robin (Rolvenden) and Tim (Clutton) for the opportunity for them to stretch their legs) I remain astonished how *little* movement is needed in a chassis for it to run smoothly. ..... So you could build the outside axleboxes around the extended axles leaving perhaps 1.0mm up and down clearance on top and bottom.


From your thoughts I wonder if a first stab at a solution in this instance might be fit high-level horn blocks (or similar) within a cleared opening, The blocks opened out to allow the required degree of slop? It should be possible to set them such as to allow a degree of daylight above and below to increase realism and also to affix the bottom strap (much like on the slaters model attached). The question is ... would they need to be permanently fixed in place to work? Being able to drop the wheels out makes painting/maintenance etc much simpler.


I think that is a very plausible approach. The only real difficulty that I could foresee is setting the hornguides at the correct depth in the frames so the axleboxes project the correct distance through. It may be a non-issue - it's just that if the whitemetal outside frames are thick, you may have to file them down slightly, and also engage in some careful soldering. But given the quality of the High Level components, I'm sure that you will have no problems making them slide prototypically.

In terms of being permanently fixed, then I see no reason why the should be. My previous comment about a keeper plate arrangement was more for mounting the gubbins that can be seen under the axle rather than for technical reasons.

Cheers
Flymo
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Philip Hall
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Re: help on sprung csb chassis with cosmetic outside frames

Postby Philip Hall » Mon May 30, 2016 12:09 pm

I agree that a inner chassis, compensated, sprung or whatever is the best solution, with the outside frames merely cosmetic. As Paul says, the whitemetal frames might be a bit thick so might need to be thinned down. There should be plenty of room for a little clearance for an axle to move up and down.

An awful lot of years ago I fettled an OO K's Kirtley, just like yours, and still in existence, and I made up some straps under the axles in the outside frames from some U channel brass. They simply pushed on and off as required. Maybe a drop of cyano would help to retain them. Guy Williams pointed out in one of his articles how odd an engine looked without a regaining strap under the axle so I felt I ought to do something about it.

Philip

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Re: help on sprung csb chassis with cosmetic outside frames

Postby Le Corbusier » Mon May 30, 2016 5:45 pm

Thanks to you both.

I will let you know how I go on in due course.

Tim
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Ian Everett
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Re: help on sprung csb chassis with cosmetic outside frames

Postby Ian Everett » Mon May 30, 2016 6:39 pm

It might be relevant that the loco photographed climbing a matchstick in that early MRJ was an 08 DES with outside frames. Possibly the article about it might help?

Ian

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Re: help on sprung csb chassis with cosmetic outside frames

Postby billbedford » Tue May 31, 2016 7:30 am

Le Corbusier wrote:From your thoughts I wonder if a first stab at a solution in this instance might be fit high-level horn blocks (or similar) within a cleared opening,


Use Exactoscale hornblocks instead of any others. These are 4mm square and so closer to scale size. They will have to be thinned, as that original bearing was only 8" long. The main problem with outside frames is that the bearing was centred in the frame, so that there is only about 1mm of bearing inside the frame to mount the csb attachment. If you use handrail knobs on the bearings, plain pins for the fixed anchors you should be able to drop the wheelsets in. The only problems left solve would be suitable keepers and getting the motor.gearbox in and out of the frames.
Bill Bedford
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Le Corbusier
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Re: help on sprung csb chassis with cosmetic outside frames

Postby Le Corbusier » Tue May 31, 2016 7:46 am

Will L wrote:Lack of pertinent outside frame experience means I have nothing to add, beyond saying I that the following had me feverishly looking round for that like button again.

Flymo748 wrote:...I remain astonished how *little* movement is needed in a chassis for it to run smoothly. The old "compensated so it can climb over a matchstick" really is just an extreme illustration of the technique, not a working need.


Will,

We met at Scaleforum last year where you introduced me to the mysteries of CSBs. On the model you used to illustrate the theory I recall a particularly neat method for dropping out the break gear and springs to allow wheel removal for painting etc. Would it be too much trouble to ask you to enlighten me again as to how this was achieved ? Another look at the level "sprung" pick ups for the power would also be much appreciated.

Regards

Tim
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andrewnummelin
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Re: help on sprung csb chassis with cosmetic outside frames

Postby andrewnummelin » Tue May 31, 2016 10:10 am

I would echo the sentiments of others regarding care in chosing components - clearances are critical.

When I appealed for information regarding outside frames I received some very useful feedback that may also help you too, see
http://www.scalefour.org/forum/viewtopic.php?f=20&t=4817#p45006 (and later messages).

I'm currently scratch building an outside frame loco and have hit various clearance problems so you may find the following table interesting - the measurements were of Gibson wheels (with moulded crank as he didn't have plain ones of the diameter I needed), cranks and crank pins and HighLevel slimline bearing.

back to back (max) 17.75
twice tyre width 4.10
twice wheel boss 0.90
twice clearance 0.20
twice axlebox 4.40
twice clearance 0.20
twice crank 4.40
twice pin flange 0.05
twice coupling rod 2.67
twice pin nut 1.90

This gives an overall width of 36.57mm which is probably out of gauge! (Prototype dimensions I have come across vary from 33.58 to 35.67 ).

My sorry experiences in this area with CSBs and functional outside frames are:
- using Sharman wheels, add HighLevel slimline axleboxes with a little clearnace either side, Sharman cranks, correct thickness coupling rods, thinned down crankpin nuts: result was that the loco hits ground signals!
- with Gibson wheels, file off the front boss and a little of the spokes to ensure the CSB carrier does not foul the spokes: result was the CSB wire sometimes touching the wheel rim, probably acceptable only with a split chassis. (I might try this next time.)
I've now decided to go for thinning down the outside cranks with the hope that I'll gain enough to protect my ground signals (but I suspect the loco will still be technically out of gauge.) I'll report in my workbench page whether I not I succeed.

Thinking back to your situation with functional inside frames, and outside frames over the mid point of the bearings, I think I would try the following:
- buy or make a bearing that looks like the outside of the prototype, ensure that this is loose on the axle (it's not the functional bearing)
- cut a slot in the outside frame that just clears the bearing
- add angle pieces outside the frames like the prototype hornguides (also on the inside of the frames if needed to prevent any groove in the bearing snagging on the frames
- allow the outside "bearing" to move along the axle being constrained between the outside crank and the front of the wheel (the outside frame and hornguides only prevent the "bearing" rotating, they don't restrict movement along the axle, it is possible that a washer would be needed in front of the wheel depending on the dimensions of your actual components.)

Good luck!
Regards,

Andrew Nummelin

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Will L
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Re: help on sprung csb chassis with cosmetic outside frames

Postby Will L » Tue May 31, 2016 10:54 pm

Le Corbusier wrote:We met at Scaleforum last year where you introduced me to the mysteries of CSBs. On the model you used to illustrate the theory I recall a particularly neat method for dropping out the break gear and springs to allow wheel removal for painting etc. Would it be too much trouble to ask you to enlighten me again as to how this was achieved ? Another look at the level "sprung" pick ups for the power would also be much appreciated.


Tim

I will respond with the info you asked for, but it may take a few days before I can get to it.

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Re: help on sprung csb chassis with cosmetic outside frames

Postby Le Corbusier » Wed Jun 01, 2016 7:02 am

Will L wrote:
Tim

I will respond with the info you asked for, but it may take a few days before I can get to it.



Thanks Will ... much appreciated - and hopefully of interest to others.

Tim
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Re: help on sprung csb chassis with cosmetic outside frames

Postby Will L » Fri Jun 03, 2016 5:31 pm

Le Corbusier wrote:[.... On the model you used to illustrate the theory I recall a particularly neat method for dropping out the break gear and springs to allow wheel removal for painting etc. Would it be too much trouble to ask you to enlighten me again as to how this was achieved ? Another look at the level "sprung" pick ups for the power would also be much appreciated.


Finally I’ve found a few minutes to think about this.

Removable Brake Gear


For the explanation of the removable brake gear see the Buck Jumping on Mass - A Brake From Chassis Construction post on my Buckjumping on Mass thread.

Removable Pick Ups

As to your other questions about pick ups. I have covered the way I do things quite extensively before, so see this post Pickups for the J10 and Pick-ups for the J10 part 2 in which most of what you want is covered I think.

I have my doubt that your loco is ever going to have the room for pick ups above the wheel which I am so fond of and which are the primary focus of these two posts, but the final solution for the J10 which had the same problem is there.

Hope that isn't all to much.

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Re: help on sprung csb chassis with cosmetic outside frames

Postby Le Corbusier » Fri Jun 03, 2016 5:43 pm

Will L wrote:
Finally I’ve found a few minutes to think about this.

Removable Brake Gear


For the explanation of the removable brake gear see the Buck Jumping on Mass - A Brake From Chassis Construction post on my Buckjumping on Mass thread.

Removable Pick Ups

As to your other questions about pick ups. I have covered the way I do things quite extensively before, so see this post Pickups for the J10 and Pick-ups for the J10 part 2 in which most of what you want is covered I think.

I have my doubt that your loco is ever going to have the room for pick ups above the wheel which I am so fond of and which are the primary focus of these two posts, but the final solution for the J10 which had the same problem is there.

Hope that isn't all to much.


Thanks Will .... I will read up over the weekend with interest. I have a couple of loco builds on the go so all will be relevant.

Tim
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Re: help on sprung csb chassis with cosmetic outside frames

Postby Le Corbusier » Sat Jun 11, 2016 9:51 am

I have another quick question relating to AG crank pins etc.

I have a chassis which I am currently building and the coupling rods are a laminated split set for a perseverance kit. It would appear that the thickness of the laminated rods are deeper than the depth of the AG bush. This would appear to result in the lock nut trapping the rods? Is there something I can do to avoid this. I note that AG do deeper bushes meant for when valve gear is present .... perhaps the solution is to use these?

any thoughts or advice welcome

Thanks

Tim
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Re: help on sprung csb chassis with cosmetic outside frames

Postby dal-t » Sat Jun 11, 2016 11:11 am

I've used two bushes on top of each other (with the top one filed down a bit) in the past, but please don't tell anyone as I'm sure it's not 'best practice'!
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Re: help on sprung csb chassis with cosmetic outside frames

Postby billbedford » Sat Jun 11, 2016 12:21 pm

M1 washers?
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Will L
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Re: help on sprung csb chassis with cosmetic outside frames

Postby Will L » Sat Jun 11, 2016 8:42 pm

Le Corbusier wrote:I have a chassis which I am currently building and the coupling rods are a laminated split set for a perseverance kit. It would appear that the thickness of the laminated rods are deeper than the depth of the AG bush. This would appear to result in the lock nut trapping the rods? Is there something I can do to avoid this. I note that AG do deeper bushes meant for when valve gear is present .... perhaps the solution is to use these?


Yes

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Re: help on sprung csb chassis with cosmetic outside frames

Postby andrewnummelin » Sun Jun 12, 2016 7:35 am

Le Corbusier wrote:...thickness of the laminated rods are deeper than the depth of the AG bush...

Tim

Until you get the longer bushes, and shorten as needed, you could invert the nut as the thin section is the same diameter as the bush following AG's advice on working where clearances are limited like behind cross heads.
Regards,

Andrew Nummelin

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Re: help on sprung csb chassis with cosmetic outside frames

Postby Le Corbusier » Sun Jun 12, 2016 6:49 pm

Thanks for all the suggestions .... in the end I filed down the coupling rod bosses at the rear and with care managed to reduce the thickness to allow them to work.

Turning the nut upside down gave too much slop and filing down the deeper bush proved difficult to keep accurately true given the tools at my disposal.

Chassis is now running sweet so problem solved.

Tim
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Re: help on sprung csb chassis with cosmetic outside frames

Postby andrewnummelin » Tue Jun 14, 2016 7:15 pm

andrewnummelin wrote:....

This gives an overall width of 36.57mm which is probably out of gauge! (Prototype dimensions I have come across vary from 33.58 to 35.67 ).

.... I'll report in my workbench page whether I not I succeed.


I failed, thinning the Gibson cranks wasn't really an option.
http://www.scalefour.org/forum/viewtopic.php?f=100&t=4826&p=46268#p46268


Well done Tim, you picked a better approach!
Regards,

Andrew Nummelin

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Le Corbusier
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Re: help on sprung csb chassis with cosmetic outside frames

Postby Le Corbusier » Tue Jun 14, 2016 7:50 pm

andrewnummelin wrote:Well done Tim, you picked a better approach!


Andrew .... we'll have to see.

The outside frame Kirtley is the next on my list and is only at planning stage at the moment.

To date I have opened out one of the horn guides in the white metal such that one of the high level assemblies will fit and thinned it down locally from the rear. The plan at the moment is to open out the bearing so it is a loose fit and slip it on to the extended crank and then get the inside chassis running true. Once this is done I will use the chassis to locate the guide in the outside frame using the bearing to position it such that I can drop the wheels out by removing the bottom strap. I then plan to fettle up an extended 'U' section depth to the guides to bring them forward of the frames and fill in the gaps around the outside ... I will then need to put the rivets back in - I was going to experiment with rivet transfers but if this doesn't work will drill and fit small sections of wire "a la Rice".

It should work and cosmetically will hopefully look a lot more like the photo type .... but as I say we will have to see. The devil is likely to be in the detail coupled of course to the limits of my own skill set!

Fingers crossed.

Tim
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Re: help on sprung csb chassis with cosmetic outside frames

Postby Le Corbusier » Mon Sep 26, 2016 6:48 am

Le Corbusier wrote:
Having seen a couple of my locos running at Railex this weekend (enormous thanks to Robin (Rolvenden) and Tim (Clutton) for the opportunity for them to stretch their legs) I remain astonished how *little* movement is needed in a chassis for it to run smoothly. ..... So you could build the outside axleboxes around the extended axles leaving perhaps 1.0mm up and down clearance on top and bottom.


Thanks Paul,

This is very helpful ... given that I am also still at the 'early' stage of track building and so my experience of actually running in P4 is very limited. I was intending to discuss this problem with you at the P4 stand yesterday but you were very busy and I thought drumming up new members should take priority.

From your thoughts I wonder if a first stab at a solution in this instance might be fit high-level horn blocks (or similar) within a cleared opening, The blocks opened out to allow the required degree of slop? It should be possible to set them such as to allow a degree of daylight above and below to increase realism and also to affix the bottom strap (much like on the slaters model attached). The question is ... would they need to be permanently fixed in place to work? Being able to drop the wheels out makes painting/maintenance etc much simpler.

Tim


Still chipping away at the outside frame Kirtley after a summer away from modelling and re-enthused after scale forum. I am trying to figure a way of making the bottom straps below the axle boxes convincing yet removable. They will close across the bottom of the white metal frames. does anyone have a clever ruse? they will be purely cosmetic.
Tim Lee

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Re: help on sprung csb chassis with cosmetic outside frames

Postby billbedford » Tue Sep 27, 2016 9:43 am

Le Corbusier wrote:Still chipping away at the outside frame Kirtley after a summer away from modelling and re-enthused after scale forum. I am trying to figure a way of making the bottom straps below the axle boxes convincing yet removable. They will close across the bottom of the white metal frames. does anyone have a clever ruse? they will be purely cosmetic.


Solder a copper wire 'staple' onto the back of the keeper plates. The staples can then be put into two holes in the frames and bent over to hold the keeper in place.
Bill Bedford
Mousa Models
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