SimonD’s workbench

[Richard Gawler]

The very tight clearances behind the crossheads mean I do not want the front axle to rock much, it'll need to move a bit, but only a bit...

I have ended up with barely +/- half a millimetre of movement on my MW class F (0-4-0) and it occurs to me, this will be fine for undulations in the rails and my own 0-MF points, but not the wheel drop at some crossings on friend's layouts.

For an 0-6-0, would it be possible to make the rear axle rigid, put a rocking axle at the front, and some gentle springs to hold the middle wheels onto the rails? The springs being sufficiently gentle to hold the wheels down but not to take the weight of the loco and lift one end off the track.

 

[simond]

Thanks Richard

I have used a hybrid suspension/compensation in the past and it is a sensible solution to some locos. My Dukedog has a rigid bogie support, soft leading axle stings and quite hard rear springs and works very well. My Castle is satisfactory, but not exemplary and it was built so long ago I can’t recall what, exactly, I did..,

 

[simond]

Dave,
I'm a further 100miles west of you and yet he still heard me say 'Plonker'
Simon(T)

Harsh. Harsh, but fair.

 

[Osgood]

I have ended up with barely +/- half a millimetre of movement on my MW class F (0-4-0) and it occurs to me, this will be fine for undulations in the rails and my own 0-MF points, but not the wheel drop at some crossings on friend's layouts.

For an 0-6-0, would it be possible to make the rear axle rigid, put a rocking axle at the front, and some gentle springs to hold the middle wheels onto the rails? The springs being sufficiently gentle to hold the wheels down but not to take the weight of the loco and lift one end off the track.

On the other hand - you will not be reliant upon wheel contact for your r/c powertrain, so you will have the full flange depth available for directional stability through other folks' pointwork

 

[Dog Star]

I can hear the S7 guys giggling to themselves and saying "told you so" from here

Sorry, was I THAT loud?

Dave,
I'm a further 100miles west of you and yet he still heard me say 'Plonker'

With increasing age comes increasing deafness...

Pardon? What was that joke?

regards, Graham

 

[Phil O]

The latest suspension development in 4mm is continuous springy beams (CSB). This comprises of fixed fulcrum points, these tend to be short handrail knobs, tags attached to the hornblocks and the suspension is guitar string, the size of which is dependent on the weight of the body.

The full information is in Will L workbench thread on the Scaleforum site. Sorry I can't link to it, at the moment. I don't know if it's a viable option in 7mm.

 

[daifly]

Probably the definitive source:

Continuous springy beams

Application and use of continuous springy beams to model railway locomotives

www.clag.org.uk

Dave (but I'll bet Simon is well-aware of this!)

 

[simond]

Thanks Dave, I do have that link as you surmise.

As I said, I’ve never tried it, perhaps experimenting on one of my own would be more appropriate…

Phil, probably not a guitar string, but a piece of thin piano wire. Surely possible in any scale bigger than 4mm, and somebody will have done it in 2mmFS…

cheers
Simon

 

[JimG]

Phil, probably not a guitar string, but a piece of thin piano wire. Surely possible in any scale bigger than 4mm, and somebody will have done it in 2mmFS

Simon,

The advantage of using guitar strings is that you get a wide range of gauges in half or one thou steps which allows fine adjustment to suit you loco or rolling stock. I use the D'Addario High Carbon Steel range which starts at 0.007" diameter :-

D'Addario Single Carbon Steel Strings

I've used them on S scale and 1:32 scale and I get the results which are calculated using Russ Elliot's formulae. I use 0.007" - 0.010" in S scale and up to 0.015" in 1:32 scale, although I'm still experimenting in 1:32. The other advantage is that, even though they come coiled, they spring out straight which can't be said for coiled piano wire.

Jim.

 

[King Crab]

Hot off the printer…

View attachment 197680

Yesterday’s print was a mixed bag, unfortunately, the standard GW cylinders failed, and the 1366 cylinders came out with their fixing holes blocked so I re-did the supports and ran another print overnight. At first sight, it looks hopeful.

The cylinder end covers and some valve thingies for the twin tank were ok on yesterday’s print.

The figures are part of my Modelu Patreon subscription, so I can take no credit there!

Simon, which Elegoo machine is that please?

Peter

 

[adrian]

The full information is in Will L workbench thread on the Scaleforum site. Sorry I can't link to it, at the moment. I don't know if it's a viable option in 7mm.

Yes it is a perfectly viable option in 7mm - all my loco builds in Scale7 have used CSB and in my opinion it's the easiest and best solution.

I used to help my Dad scratch build locos to order (Cherry Scale Models) so we have built everything from solid chassis, compensated to fully individually sprung axles - all depending on what the customer was prepared to pay for. Individually sprung chassis gave the best running qualities but it was a pain to set up in getting everything balanced correctly hence an expensive option. At the time (1980-1990) we were not aware of CSB if it "existed" at all at that time - certainly not in 7mm circles who were still building chassis with 1/16th brass plate and 3/16th hex brass frame spacers.

In a nutshell for 7mm the options are - caveated - just my opinion so feel free to ignore

• solid chassis - nope never an option appalling running characteristics although DCC with stay alive works around the problems.
• Simpson springs - a 2mmFS favoured option, works well for 0-4-0 chassis - a sloppy wheel bearing on one axle with a spring wire.
• Compensated chassis - a very controversial opinion but I'll stick my neck out on this rather than best of both "worlds" I consider compensation to be the worst of both worlds. Yes you have have some flexible movement of the wheels and compensation but for all the added complication you still have a solid direct mechanical link from the wheels to the chassis and the loco body. There is no shock absorber.
• Individual springing - this at least isolates the chassis and body from the wheels but it is a pain to setup and get balanced correctly. Coil springs are a waste of time in this scale, variations in individual spring strengths and coil locking means getting a good balance takes more time than it's worth, extremely difficult to change spring rates. Wire springing works better, much easier to change spring rates but still difficult. Applies to wagon and coach springing as well.
• CSB - best of all worlds. Spring rates easily changed, the chassis is fully sprung so it is isolated from the wheels, the fulcums in the right place automatically balance the wheel loading. For example on an 0-6-0 it is very simple to weight the loco so that the front and rear axles are more heavily loaded than the centre axle. Also if you make the CSB fulcrum points "holes" rather than "fulcrum points" then the CSB wire also locks the wheels into the chassis so you don't need to worry about any captive plates or bars at the bottom of the hornguides. Also if you look at full size prototypes the you will see they also effectively used CSB. Due to the larger size they could use coil springs but they still had compensating beams between axle boxes.

Anyway off my soapbox for now on this issue - give CSB a try by which I mean a proper effort then I would anticipate that you would never go back to compensation.

 

[simond]

Peter,

it’s a Saturn 8K. Very happy with it, does everything I hoped for, and performs as expected. If you buy one, don’t forget to take the protective films off the FEP before doing your first print. You can guess.

Adrian

thanks for your thoughts and the fruits of your experience. I’m very much inclined to follow your advice.

cheers
Simon

 

[WM183]

I have ended up with barely +/- half a millimetre of movement on my MW class F (0-4-0) and it occurs to me, this will be fine for undulations in the rails and my own 0-MF points, but not the wheel drop at some crossings on friend's layouts.

For an 0-6-0, would it be possible to make the rear axle rigid, put a rocking axle at the front, and some gentle springs to hold the middle wheels onto the rails? The springs being sufficiently gentle to hold the wheels down but not to take the weight of the loco and lift one end off the track.

This is the system I have adopted for 0-6-0s, and it works wondrously. The rocking front axle is easy to build and to hide, and the sprung center axle offers some shock absorption as well as being simplicity when using hornblocks and guides. I would wager that CSBs are "better" but I think it becomes a case of "the perfect is the enemy of the good". I will likely stay with this system for 8 coupled types as well, perhaps using a csb type guitar string spring for the center two axles, but springing every axle seems... overkill, I guess?

(Says the woman who compensates or springs every wagon, regardless of wheelbase)

Amanda

 

[simond]

Well. Chris has “liked” my post replying to Adrian, which I could take as permission to proceed

Slide bars are not going to be ready til next week but we could perhaps commit a bit of butchery on the frames.

I’ve got a 45xx of my own to do, so perhaps two birds with the same stone. Need to see what’s in the bits box!

 

[simond]

Right Ho.

Before attacking Chris’ loco, let’s have a look at my 45xx. Springside kit, my first 0 gauge loco build, 1997. Been DCC’ed, obviously pre 3DP from the plasticard speaker box. White metal pony trucks have suffered a bit, & brakes seem to have gone entirely AWOL but the reasons for a rebuild are a) the Portescap whine, and b) rigid chassis.

The years have otherwise not been too unkind… and I’m rather fond of the old girl.



So I have two Warren Shepherd pony trucks, ditto brakes, a set of Premier jointed rods, a set of Slaters brass horns & axle locks, and a Premier two sage helical 30:1 gearbox with Canon 1833



I’m also armed with the CLAG spreadsheet and Solidworks. Let battle commence!

 

[simond]

There’s a certain madness in taking apart a functional loco, but the whine annoyed me and the missing bits didn’t look good. Anyway, too late now.

I have been asked to provide details of the pickups I use, which are a derivation of those shown in a drawing kindly provided by the late David LO Smith, a most talented model engineer and thoroughly nice chap.

I use a coupling spring (these are Premier, but others no doubt are available) and some turned plastic rod (late MiL’s knitting needles) and some turned brass. Dimensions are not critical but I’ll do a drawing & put it on here for anyone who wants one. As you can see, you can extract them without disturbing the wheels. They fit into turned plastic bushes in the frames, and move with the axles if there’s any side play.



No way back now…



The chassis is going in something to dissolve epoxy (and paint) after I’ve measured it for a basic 3D model

 

[Yorkshire Dave]

The surprise comes when the cleaned parts metamorphose themselves into a chassis for a completely different loco.....

 

[Phil O]

Simon,

I'm now following this rebuild with some trepidation, having proposed it, but I'm hoping that all goes well, I have several builds on the go which have CSB suspension.

Locos that I have seen with it just seem to glide along.

 

[Pencarrow]

Well. Chris has “liked” my post replying to Adrian, which I could take as permission to proceed

Slide bars are not going to be ready til next week but we could perhaps commit a bit of butchery on the frames.

I’ve got a 45xx of my own to do, so perhaps two birds with the same stone. Need to see what’s in the bits box!

I'm liking on the basis that I obviously know nothing on the subject and that I'm happy that them what do know stuff will definitely come up with much better results than I did. Simon has free reign on solutions, no permissions required.

 

[simond]

the CAD is an invaluable tool.



I have sketched up the Springside frames - this is the inside of the right frame. There are a couple of issues to work through. The first is that there is a grey rectangle showing through the rear hornguide. The rectangle can be modified, but it's pretty important, it's the rear pony truck pivot.

The other issue is the pick-ups - they are the three larger holes. I think the two upper ones will need to be relocated to same height as the lower, central one, but of course I need to ensure there is room for the gearbox, so I will have to model that.

The three smaller holes are the brake hanger pivots, I think they'll be ok.

The four longer vertical dotted lines are the positions of the CSB fixings to the frames. The shorter is the current centre of gravity - a little too far backwards for convenience. I may try to add some weight in the smokebox to bring it forwards somewhat. That would certainly improve the weight distribution, and also the effective spring rate, particuarly for the rear axle.

I'll sleep on it.