Completing the 4mm NER 6 wheel coach

[Siberian Snooper]

Hi Mike,

 

I have to admit that I have a number of these chassis to build, to go under a variety of 6 wheel vehicles, I have never thought to ask what the minimum radii these things will operate down to, I was hoping that 30ins to 3ft would be a norm.

 

SS

[t-b-g]

My Brassmasters ones easily manage a 3' radius in EM and my solebars are a bit thicker than 30thou. With the play that exists in OO I would have thought that something less than 3' would be achievable without any difficulty.

 

Brassmasters have a display 6 wheeler made up and placed on some very tightly curved track on their show stand.

 

Replacing the solebars with 10 thou would give an extra 1mm total movement (0.5mm each side). It would only need to be so thin for a short length alongside each wheel set, as has been done already on the test.  

 

I wondered once or twice if the narrow W iron spacing is to allow some side movement between the solebars. If they were full normal width they would hardly be able to move at all.

 

I have used the Bill Bedford sprung axleboxes on a 4 wheeler but I chickened out on a 6 wheeler as I couldn't see any way of building any sideplay into them.

 

Tony

[Beatty 139]

Hi

I have been recently been discussing this matter of 6w coaches on the Gauge 1 yahoo group and two clear simple options have been discussed.

 

Option 1

To form a truck from the two axles with a pivot in the center and leave the other axle fixed, it works well but is noted as having some extra 'drag'

 

Option 2

A simplified system to allow all axles to move.

Again one pair of axles are pivoted like a lwb bogie but the other axle is also pivoted and links into the first as seen in the image. stock runs well and freely even on tight radius curves.

 

Hope the suggestions are of interest, note both systems use inner bearing with the W irons axle boxes being dummies.

 

Andy

[MikeTrice]

Flattened flange on fixed centre wheel set aka Chivers Fish Van .

I might have to adopt that if all else fails.

[MikeTrice]

My Brassmasters ones easily manage a 3' radius in EM and my solebars are a bit thicker than 30thou. With the play that exists in OO I would have thought that something less than 3' would be achievable without any difficulty.

 

Brassmasters have a display 6 wheeler made up and placed on some very tightly curved track on their show stand.

 

Replacing the solebars with 10 thou would give an extra 1mm total movement (0.5mm each side). It would only need to be so thin for a short length alongside each wheel set, as has been done already on the test.  

 

I wondered once or twice if the narrow W iron spacing is to allow some side movement between the solebars. If they were full normal width they would hardly be able to move at all.

 

I have used the Bill Bedford sprung axleboxes on a 4 wheeler but I chickened out on a 6 wheeler as I couldn't see any way of building any sideplay into them.

 

Tony

One problem is that the overall width of the coach is only 8'0" so it is quite narrow to start with. I could move the solebars out a bit more and probably get away with it. Yes, I did not argue with the narrow w-iron spacing as I realised space would be tight if moved out. Out of interest for your EM coaches what width do you have between solebars where it matters?

[MikeTrice]

Hi

I have been recently been discussing this matter of 6w coaches on the Gauge 1 yahoo group and two clear simple options have been discussed.

 

Option 1

To form a truck from the two axles with a pivot in the center and leave the other axle fixed, it works well but is noted as having some extra 'drag'

 

Option 2

A simplified system to allow all axles to move.

photo(176).JPG

Again one pair of axles are pivoted like a lwb bogie but the other axle is also pivoted and links into the first as seen in the image. stock runs well and freely even on tight radius curves.

 

Hope the suggestions are of interest, note both systems use inner bearing with the W irons axle boxes being dummies.

 

Andy

I think some form of inner bearing is probably going to give the most clearance, especially in OO.

[t-b-g]

One problem is that the overall width of the coach is only 8'0" so it is quite narrow to start with. I could move the solebars out a bit more and probably get away with it. Yes, I did not argue with the narrow w-iron spacing as I realised space would be tight if moved out. Out of interest for your EM coaches what width do you have between solebars where it matters?

 

Hello Mike,

 

The width between the solebars is 25.2mm give or take a thou or two. I used 40thou for the solebars giving an over the solebars dimension of 27.2mm. There would be scope for getting a bit extra inside by using thinner material.

 

I think it helps a great deal that in OO and EM there is a decent amount of play between the wheels and the rails anyway, which "buys" clearance round tighter curves. The amount of side movement in the brass W irons isn't huge but they go round the 3' curves as sweetly as anything. 

 

I hope that helps,

 

Tony

[t-b-g]

Just to add a little to the discussion, on Buckingham there are 6 wheelers that go round 2'6" curves in EM. They are built a little like the Gauge 1 example above, the only difference being the the inside bearings are also mounted on wire springs.

 

I cannot vouch for the scale accuracy of the spacings of the dummy outside axle guards but they look the part and go round curves that would defeat most 6 wheeled vehicles.

 

Tony 

[MikeTrice]

Thanks Tony, that helps a lot.

 

My mock up chassis has 26mm between the thinned solebar sections. Did you use the outside framed inner unit, or the supplied inside bearing version?

 

A quick mock up using Bill Bedford RCH sprung w-irons on the outer axles and an inner internal bearing floating axle also suggests it should work.

[buffalo]

...I have used the Bill Bedford sprung axleboxes on a 4 wheeler but I chickened out on a 6 wheeler as I couldn't see any way of building any sideplay into them.

 

Tony

 

Somewhere, I found a suggestion from Bill to mount the wheels on a piece of 2mm o/d, 1mm i/d tubing. This is cut flush with the outside of the wheels. The tube then slides on a 1mm pinpoint axle, either home-made or from Exactoscale. Very simple and works well on the couple of examples I've tried.

 

Nick

[t-b-g]

Thanks Tony, that helps a lot.

 

My mock up chassis has 26mm between the thinned solebar sections. Did you use the outside framed inner unit, or the supplied inside bearing version?

 

A quick mock up using Bill Bedford RCH sprung w-irons on the outer axles and an inner internal bearing floating axle also suggests it should work.

 

Hello Mike,

 

I used the outside bearings as I preferred the freer running of the pin points compared to the inside bearings.

 

I haven't tested it but I had some concerns over using sprung axleboxes at the outer ends of what becomes a very long wheelbase 4 wheeler with an extra floating axle in the centre.

 

On a tight curve, the wheel runs at an odd angle compared to the rail and I thought that there might be a tendancy for the springing to allow the wheel to ride up and over the rail. The shape of a wheel flange means that if that flange is pressed hard against an outside rail, the wheel tends to climb up and I found that what is, in effect, a wheel trying to run in a straight line into a curved rail caused derailment problems with long wheelbase sprung locos.

 

So I chose the Cleminson arrangement on the grounds that the wheels run along the line of the rail rather than attacking it at an angle.

 

But as I say, I didn't really give the sprung axleboxes a test on such a long wheelbase. It was more and instinctive feeling that it may lead to problems.

 

If you go ahead and prove that it works, I may have to give it a try someday as there are plenty more 6 wheelers to be built yet.

 

Tony

[MikeTrice]

Time to make a decision, I am going to go with the Brassmaster's Cleminson.

 

First task is to mark up the floor with the various centre lines. Having done that the mounting plate for the Cleminson has been positioned and traced around. Lines have been added crossing the floor demarking where the various trucks pivot/slide:

 

Mounting plate temporarily positioned:

 

A strip of 20thou styrene was cut a tad over 4mm in width. Pieces of Evergreen 4mm x 2mm styrene were then cut to fit between the areas where the trucks go, and laminated to the styrene strip:

 

The buffer beams were also cut from the 2mm x 4mm strip. They had a fancy profiled end so I started by using a knife needle file to file two slots:

 

The endges were rounded off and the central spur reduced:

 

We now have a pair of matching buffer beams:

 

Centres were marked for the buffers and the beams drilled through. One is slightly off centre, so has been dressed with a small round needle file prior to final opening out. At this point I am still undecided on the best buffers to fit:

 

The buffer beams are attached to the coach body:

 

And repeated for the other end:

 

The prepared solebars are trimmed to length and solvented in place:

 

The final (hopefully) assembly complete with wider apertures to give the Cleminson trucks maximum movement:

 

I will probably include a floating central axle using the 2mm tube and 1mm axle. Just waiting now to see if the solvent causes any distortion of the 20th solebars.

Edited March 11, 2014 by MikeTrice

[MikeOxon]

 

Fitted Romford Mansell wheels using the bearing provided by Brassmasters and ARGHHHH the w-irons splay alarmingly:

It's taken me a while to get round to photographing mine but i seem to have less splay than you.  As I mentioned in an earlier post (#57), I folded the transverse tabs first and then the W-irons.  I think this has forced the fold of the irons just a fraction further out, which seems to have helped.  Mine are standard Bachmann 00 coach wheels.  The problem I have is that 00 wheels are so close together that I have to bend the brake shoes in a long way, to come anywhere near the wheel treads!

 

 

Mike

Edited March 13, 2014 by MikeOxon

[jwealleans]

Fixed axle at one end and a concealed bogie for the other two?

 

Or two fixed and the centre one floating.

[JCL]

How about the two outer axles having a pivot point on a tab that is closer to the inside of the centre axle with some brass wire connecting all three to keep them lines up - this would allow all three axles to pivot, and I'm guessing that the pivoting wouldn't be so extreme.

[t-b-g]

The D & S GNR 6 wheelers have a fixed axle one end, a rocking W iron at the other and a floppy (on wire) centre axle.

 

The Buckingham Branch GCR 6 wheelers have a 4 wheel bogie arrangement at one end and a sprung axle at the other.

 

Slaters MR 6 wheeler kits have a Cleminson arrangement with inside bearings.

 

I have used all the above over the years and one or two mixes/variations in my quest to get a smooth running 6 wheeler.

 

I am all in favour of people investigating options and trying things out but for me, the Brassmasters arrangement has cracked the problem and I won't be using anything else from now on. If they should ever cease to be available, then I will scratchbuild a replica.

 

The rake of carriages I have built with them (OK - one finished and four still to finish but are runnable) knock all the others into a cocked hat in terms of smooth running and ability to deal with tight curves.

 

They are not perfect because of the splaying problem already mentioned but that is easily overcome and they are miles ahead of all the other methods I have tried.

 

Tony

[Buhar]

The May 2011 Railway Modeller has a piece by Neil Burgess describing a simple bar and wire inside bearing 6-wheeled chassis that seems to give plenty of room for sideplay.

[MikeTrice]

And now, a job I have been dreading, mainly because it is so fiddly. The alarm gear tell-tails.

 

Geoff appears to make his from styrene, however I wanted something stronger, so decided to use wire and brass. This does mean soldering however.

 

Two pieces of brass strip, carefully slotted with a jeweller's saw, with a 5p piece for comparison

 

Soldered to a length of 0.5mm brass wire. Overscale no doubt:

 

Checked against the end for length.

 

After lots of filing the end indicators have been reduced in size and rounded. Two hinge covers have been cut from styrene:

 

The unit located on the coach end and held in place with Blu Tak

 

The styrene covers solvented in place and left to cure. I did check these under a magnifier to ensure thay had secured properly.

 

Look Ma, no hands!

 

At a later time I will finish off the hinge covers with a needle file, just to tidy them up.

 

[MikeOxon]

The nice thing about scratch building is that you can add just as much (or little) detail as you want, and you don't have to do it all at once!  Thank you for showing exactly how you did this bit of detailing 

 

Mike

[MikeTrice]

Subsequence evidence suggests that the end handrail is not quite are semi-circular as I originally thought, so have produced a new drawings showing it flattened slightly. Here some 0.4mm NS wire is being coaxed into an approximation of the curve. I am not after a perfect match here as I wanted to be able to spring it into the locating holes.

 

Holes drilled and handrail knobs fitted (after threading onto the partially formed handrail) then the handrail fitted. All glueing by cyano applied with the small piece of wire:

 

In hindsight I would have preferred to use some short handrail knobs, but did not have any to hand. These are (I think) standard Gibson from over 20 years ago.

[MikeTrice]

I managed to pick up some Romford short handrail knobs so decided to redo the end handrails:

 

Much happier now:

 

The roof handles have now been added. A Bill Bedford handrail bending jig was used

 

[MikeTrice]

I am now starting to think about producing the axleboxes and springs, so I dug out earlier examples produced back in December. This was just after the time I started using Deluxe Plastic Magic.

 

Even though no warping was previously evident, after almost 3 months, they have warped alarmingly. So I guess the lesson from my perspective is AVOID PLASTIC MAGIC!

 

 

 

[MikeOxon]

...

Even though no warping was previously evident, after almost 3 months, they have warped alarmingly. ..

 

Interesting that it took so long!  I seem to remember you wrote that you laminated the layers in pairs.  Perhaps using threesomes would be better, as it might even up the stresses on each side of the central member.  That's pure speculation!

 

I think I'll stick to brass for running gear

[MikeTrice]

Interesting that it took so long!  I seem to remember you wrote that you laminated the layers in pairs.  Perhaps using threesomes would be better, as it might even up the stresses on each side of the central member.  That's pure speculation!

 

I think I'll stick to brass for running gear

The w-irons are three layer. To be honest using odd numbers of layers does not apply to styrene, the warping being caused by bonding the spring/axlebox to the side of the w-iron. I should add that so far the Di-Limonene has not caused any distortion.

[Colin parks]

Hi Mike,

 

What an excellent bit of coach building! I would have commented earlier had the topic not been tucked away in the Special Interests sub-forum. Re. solvents it looks as if D Limonene and Humbrol Liquid Poly are both safe solvents (in terms of distortion) for working with styrene sheet.

 

The photos of your work in post #95 are very impressive.

 

All the best,

 

Colin