Etched loco chassis

[nick_bastable]

ever the optimist I embarked on the  M7 chassis today opting to build as a 4-2-2  laminating the frame's  was interesting but   eventually resolved by  "soldering" on top of the cooker ring (dont let Mrs B know  )  hopefully my results will be better than my previous efforts     reducing the pcb strip to 6mm was even better only having 7mm to hand 

 

wish me luck

 

Nick

[Chris Higgs]

ever the optimist I embarked on the  M7 chassis today opting to build as a 4-2-2  laminating the frame's  was interesting but   eventually resolved by  "soldering" on top of the cooker ring (dont let Mrs B know  )  hopefully my results will be better than my previous efforts     reducing the pcb strip to 6mm was even better only having 7mm to hand 

 

wish me luck

 

Nick

 

I have heard of this method of soldering being used before. I think Exactoscale even recommended it as it should lead to stress-free frames. I was not convinced myself. Solder paste in combination with a RSU or heavy soldering iron is what you need.

 

I once used a blow-torch (a big one) to solder a shower head back on. I had to wait several minutes for the solder to re-solidify!

 

What you really need is one of these:

 

 

 

Chris

Edited January 13, 2017 by Chris Higgs

[nick_bastable]

I was surprised how well it works some Aluminium to protect the electric ring and away you go, I think the idea is it heats the whole frame evenly 

 

mini blow torches are for creme brulee or silver soldering

 

Nick

[Donw]

If using a torch you need to move the flame about to give even heating and watch for the solder appearing at the edges. A big soft flame would probably work better than a small hot one.

Don

[Tim V]

I used a hot air gun today to melt solder on a very large tag - but not on a model railway.

[Izzy]

I have finally (!) got around to finishing my first etched 08 chassis. ( I did post some shots a while back on the VAG). A Blue Farish body from BR lines sits on top. Here it's buffered up to a green Farish one with machined wheels and 2mm SA etched cranks and rods. It sits a bit lower than the Farish, at the correct height to match most rolling stock. A replacement chassis for the green is now being started on the workbench.

 

 

The 2mm SA can motor originally fitted has been replaced with one of the china/ebay sourced 7mm coreless cans, and runs beautifully. It sits/is glued onto a plasticard cradle which also forms an outer box around it on which the CT decoder is plonked. I have had to stuff the Farish body with lead where possible to get the overall weight up to that of the standard Farish model - 47gms - as the etched chassis, even with the brass/pcb footplate and etched outside frames is 6gms lighter. Quite okay at less weight, just less traction, but might suit those wishing to fit sound, as the small Zimo 649 would fit on top of the motor and a cube would I am sure fit into the front bit behind the rad. The chassis takes up much less space in the body than the original, as the comparison shows.

 

 

The difference in looks between it and the Farish doesn't appear so pronounced in the shots due to having the same size cranks and rods, but is quite a bit in real life.

 

Thank you for the all the effort involved in producing the etches Chris.

 

Izzy

 

 

p.s. if anybody would like to see the bare chassis construction shots from the VAG I can re-post them here if it would help anyone with construction.

[nick_bastable]

 

 

 

p.s. if anybody would like to see the bare chassis construction shots from the VAG I can re-post them here if it would help anyone with construction.

yes please did you do the fully geared version or con-rod version ?

 

Nick

[Orange Cat]

 

The difference in looks between it and the Farish doesn't appear so pronounced in the shots due to having the same size cranks and rods, but is quite a bit in real life.

 

 

 

I was thinking just the opposite, and what a marked difference it makes. One of the noticeable features of the full size loco is the spoked wheels and the new chassis shows these in a way the original does not.

[Izzy]

 I did the rear axle geared version Nick, because the chassis is 'modified' - I think that's the right word - to slotted axles so the wheels drop out of the chassis. They are retained by a nickel-silver strip, the screws also holding the chassis to the footplate. The reason is simple. I have never found the skill/ability that others seem to have to cleanly push interference fit wheels onto axles in a chassis with any degree of success. I rarely if ever get things right first/second/third time - I envy those who can and do - and this design arrangement allows the 'rescue' of less than perfect construction. It's done quite crudely, my usual style, by just filing downwards after soldering the bearings into the frames, so they are really just half-bearings now. Along with Simpson springs it gives a simple sprung chassis, which allows the wheels to be removed for chassis fettling. Doubly useful for a chassis where the wheels have outside cranks that are soldered onto the ends of the axles!

 

The challenge with this chassis is the need to keep the outside frames separate from both each other and the footplate/bufferbeams as the axles could carry current to them. So they were soldered to strips of point sleeper strip - this was before the sheets of PCB became available which I will use with the chassis for the green one, and cryno'd to the brass sheet footplate(10thou brass shim cut to size with a scalpel), and 'jogged' to fit behind the front steps. Plasticard sheet fits between to insulate the chassis from said footplate as well. I hope the shots make it mostly self-explanetary.

 

 

 

 

 

 

 

 

 

 

 

This shows the buffer height difference a bit better.

 

 

 

Izzy

 

 

 

 

[nick_bastable]

I assume the wheels plus bearings slot out similar to Farish / Dapol 

 

Nick

[DavidLong]

Thanks very much for that information about the 08 chassis, Bob. A couple of questions:

What is the thickness of the nickel strip that you used?

I didn't quite understand the sentence " It's done quite crudely, my usual style, by just filing downwards after soldering the bearings into the frames, so they are really just half-bearings now". Could you elaborate a little more as it sounds to be a critical part of the process.

 

David

[Izzy]

I assume the wheels plus bearings slot out similar to Farish / Dapol 

 

Nick

 

 

Thanks very much for that information about the 08 chassis, Bob. A couple of questions:

What is the thickness of the nickel strip that you used?

I didn't quite understand the sentence " It's done quite crudely, my usual style, by just filing downwards after soldering the bearings into the frames, so they are really just half-bearings now". Could you elaborate a little more as it sounds to be a critical part of the process.

 

David

 

Hi Nick, David.

 

I'll try and answer the questions as best I can, and hope it will make things clearer. First off though there is no need to slot the frames if you don't want to, it's just my basic build method which I thought I aught to mention as the N/S keeper strip is quite obvious in the chassis shots.

 

Firstly, it isn't like the recent Farish locos with separate hornblock type bearings that slide into the frame. I did think about making some, but this seemed an easier/simpler method I could use to advantage.

 

Basically the normal PB axle bearings were soldered into the frames, as you would with 'standard' construction, and then using mostly a rat tailed needle file the holes were opened up downwards until a slot was formed to the bottom of the frame. This will of course quite probably horrify many modellers, and is why I called it crude, which it is. But if done slowly and carefully a decent result can be obtained. Past about 0.5mm depth if the slot widens a bit - more than a good running fit - then it doesn't really matter because it's very doubtful the wheels in use on track will drop further than this in the frames.

 

This leaves a slot with a U shaped bearing at the top of it. If you think logically about it, a locos axles just mainly rest/run on the top of a bearing with the rest preventing it from moving back/forth/down, so with bearing surfaces also at the front/back it can only move down. The keeper strip determines how far. Virtually none for the rear driven axle, 0.5 - 0.8mm for the others.

 

Here's a shot with the keeper strip removed. I can't/don't want to drop out the wheels because this would mean having to unsolder the outside brake rigging, which is hinged to move out of the way, but only when absolutely neccesary. But I hope this may make things a bit clearer including the spring wire pickups on the front two axles - none on the rear - no space.

 

 

regards,

 

Izzy/Bob

 

 

Oh the keeper strip, sorry. Just a bit of scrap etch from a 2mm SA coach kit, so 10thou I would think.

Edited January 16, 2017 by Izzy

[nick_bastable]

thanks for that the last picture cleared up my misconception

 

I may try this idea on future chassis as it would resolve several issues I have with the "enclosed" system

 

thanks

 

Nick

[Chris Higgs]

thanks for that the last picture cleared up my misconception

 

I may try this idea on future chassis as it would resolve several issues I have with the "enclosed" system

 

thanks

 

Nick

 

Mick SImpson also likes to build his locos with a keeper plate. I don't recall exactly how he does it though.

 

Basically all you have to do is make sure the wheels don't fall out when the loco is the right way up but off the track. The weight of the body is all that is needed to keep the wheels at the top of the bearings when it's on the track.

 

I know in 4mm I have seen locos where removable wires run across the bottom of the hornblocks/bearings and achieve the same result.

 

I had given some thought to etching frames on my chassis with slots in that could use the hornblocks we now sell for the Farish locos.

 

Chris

Edited January 16, 2017 by Chris Higgs

[nick_bastable]

interesting I found the Jinty conversion easier to manage with the wheels off dropping the whole wheels rod unit in place (shame it runs like a dog on the track while fine on a rolling road    )

 

fixing the wheels / muffs etc in a ridged frame  housing has always caused me issues and no end of grief with bent coupling pins, plus I have got one working and then after stripping to paint the chassis been unable to replicate the running,  I may have to rethink the M7

 

thanks

 

Nick

[Chris Higgs]

interesting I found the Jinty conversion easier to manage with the wheels off dropping the whole wheels rod unit in place (shame it runs like a dog on the track while fine on a rolling road    )

 

fixing the wheels / muffs etc in a ridged frame  housing has always caused me issues and no end of grief with bent coupling pins, plus I have got one working and then after stripping to paint the chassis been unable to replicate the running,  I may have to rethink the M7

 

thanks

 

Nick

 

There is a school of thought that says you do not need to strip the chassis. You can paint the chassis before you put the wheels in, I have done this, and then glued the brakes rather than soldering. Or spray it as recommended by Iain Rice, with the wheels in and the mechanism running.

 

Chris

[DavidLong]

I was surprised how well it works some Aluminium to protect the electric ring and away you go, I think the idea is it heats the whole frame evenly 

 

mini blow torches are for creme brulee or silver soldering

 

Nick

 

It would a lot easier with an RSU like this:

 

https://traders.scalefour.org/LondonRoadModels/various/soldering-materials-and-tools/

 

Unfortunately it is about £80 more than when I bought mine but I wouldn't be without it.

 

David

[DavidLong]

Hi Nick, David.

 

I'll try and answer the questions as best I can, and hope it will make things clearer. First off though there is no need to slot the frames if you don't want to, it's just my basic build method which I thought I aught to mention as the N/S keeper strip is quite obvious in the chassis shots.

 

Firstly, it isn't like the recent Farish locos with separate hornblock type bearings that slide into the frame. I did think about making some, but this seemed an easier/simpler method I could use to advantage.

 

Basically the normal PB axle bearings were soldered into the frames, as you would with 'standard' construction, and then using mostly a rat tailed needle file the holes were opened up downwards until a slot was formed to the bottom of the frame. This will of course quite probably horrify many modellers, and is why I called it crude, which it is. But if done slowly and carefully a decent result can be obtained. Past about 0.5mm depth if the slot widens a bit - more than a good running fit - then it doesn't really matter because it's very doubtful the wheels in use on track will drop further than this in the frames.

 

This leaves a slot with a U shaped bearing at the top of it. If you think logically about it, a locos axles just mainly rest/run on the top of a bearing with the rest preventing it from moving back/forth/down, so with bearing surfaces also at the front/back it can only move down. The keeper strip determines how far. Virtually none for the rear driven axle, 0.5 - 0.8mm for the others.

 

Here's a shot with the keeper strip removed. I can't/don't want to drop out the wheels because this would mean having to unsolder the outside brake rigging, which is hinged to move out of the way, but only when absolutely neccesary. But I hope this may make things a bit clearer including the spring wire pickups on the front two axles - none on the rear - no space.

 

08 web 12.jpg

 

regards,

 

Izzy/Bob

 

 

Oh the keeper strip, sorry. Just a bit of scrap etch from a 2mm SA coach kit, so 10thou I would think.

 

Many thanks for that explanation, Bob. Is there enough movement in the axles to make it worthwhile to joint the rods? I'm getting a real downer on rigid coupled chassis, these days especially those with short wheelbases but we don't seem to do compensation in 2mm scale; apart from Mr Watt who builds impossibly small Caledonian locos which probably wouldn't run without it! We don't seem to have access to any commercial stay-alives that are small enough for locos like the 08 for which they would be ideal. Nigel Cliffe has described how to build one but I have insufficient understanding of how to do it.

 

David

[Donw]

Many thanks for that explanation, Bob. Is there enough movement in the axles to make it worthwhile to joint the rods? I'm getting a real downer on rigid coupled chassis, these days especially those with short wheelbases but we don't seem to do compensation in 2mm scale; apart from Mr Watt who builds impossibly small Caledonian locos which probably wouldn't run without it! We don't seem to have access to any commercial stay-alives that are small enough for locos like the 08 for which they would be ideal. Nigel Cliffe has described how to build one but I have insufficient understanding of how to do it.

 

David

 

Jointed rods are always worth while if you have the skill , as well as allowing more up and down movement they also facilitate getting round tight curves. Trouble is they are much easier to make rigid.

Don 

[Izzy]

Many thanks for that explanation, Bob. Is there enough movement in the axles to make it worthwhile to joint the rods? I'm getting a real downer on rigid coupled chassis, these days especially those with short wheelbases but we don't seem to do compensation in 2mm scale; apart from Mr Watt who builds impossibly small Caledonian locos which probably wouldn't run without it! We don't seem to have access to any commercial stay-alives that are small enough for locos like the 08 for which they would be ideal. Nigel Cliffe has described how to build one but I have insufficient understanding of how to do it.

 

David

 

Hi David,

 

I haven't built a 'rigid' chassis in many decades, all have some form of springing/compensation/movement however crude and simple it might be, not so much to aid track holding, but as much for decent pick-up. I believe Jim Watt and others do so for basically the same reasons. I have of course seen the wonderful cubes of magic electronics Nigel makes first hand. The difference one has made to his tiny 02 had to be seen to be believed. However, like you, it's all rather beyond me. I just look on in awe.

 

As regards jointed rods, while I used to use them as default years ago (I designed the universal etched jointed rods for Alan Gibson) I have come to realise that in the main they aren't needed, and there can be situations where they are. how shall I say, unhelpful, if the pivot joints are not precise. Exact rod crankpin centres which don't alter are more important than the degree to which the rods fit on the crankpins - they can be quite a sloppy fit as many RTR models will attest, so fixed rods with a modicum of loose fitting on the crankpins are usually more than sufficient to allow enough axle movement to achieve what is needed. It's each to his own of course, this is just what has seemed to work best for me over time.

 

regards,

 

Bob

[CF MRC]

I have never fitted jointed rods to a 2mm loco. As Bob has mentioned there should be enough movement in the pins and axle holes to give sufficient road holding; especially after 100 miles or so of running. Our small shunting engines often have inconspicuous pickup skates running on the track. These give 100% pickup and the track gets cleaner and cleaner as the show progresses. The only down side is that they can be vulnerable to handling.

 

Painting a chassis is a bit of a liability. I always chemically black the chassis and wheels before final assembly. On Lord President I am musing on whether to have the wheels demountable. On balance, I probably won't. If a heavy overhaul is required then it's no big deal to melt the muff with a soldering iron, extract the wheels and do whatever rebushing is required. This engine pushes around our 600 mm minimum radius on CF without the need for jointed rods, but will require moderate slack between the crankpin washers and rods at the rear. The front pins don't have a retaining washer.

 

I would certainly solder or screw on brake gear: it won't last five minutes in the hurly burly of an exhibition layout if simply glued on - the gluing areas would be awfully small.

 

The only compensated chassis I made (Kirtley 0-4-4) wore out and was replaced with a rigid version that works better. I don't think a sprung / compensated chassis would stand the miles that our engines cover on CF. However, weight distribution and wheel / track contact requires a good deal of lateral thinking on suspension arrangements with engines such as well tanks and singles.

 

Tim

[Chris Higgs]

I would certainly solder or screw on brake gear: it won't last five minutes in the hurly burly of an exhibition layout if simply glued on - the gluing areas would be awfully small.

 

 

 

Depends on the glue. I bought some industrial strength cyanoacrylate at a show. It claimed it would be stronger as a  joint than the material it was joining. I was very skeptical. One of the belts on my bandsaw broke, and as spares were unobtainable, I was forced to glue it back together with a butt joint. Five years later it is still going.

 

Chris

Edited January 17, 2017 by Chris Higgs

[nick_bastable]

It would a lot easier with an RSU like this:

 

https://traders.scalefour.org/LondonRoadModels/various/soldering-materials-and-tools/

 

Unfortunately it is about £80 more than when I bought mine but I wouldn't be without it.

 

David

nice  but I would probably melt the etch, the  cooker worked for me so that was a result

 

Nick

[Chris Higgs]

nice  but I would probably melt the etch, the  cooker worked for me so that was a result

 

Nick

 

Naah, it will be fine. I build all my stuff with an RSU. It can vapourise brass wire used in wagon brake gear, but not a nice solid frame.

 

Chris

Edited January 17, 2017 by Chris Higgs

[nick_bastable]

Naah, it will be fine. I build all my stuff with an RSU. It can vapourise brass wire used in wagon brake gear, but not a nice solid frame.

 

Chris

Chris

 

I think you seriously under estimate what a three thumbed klutz I'm  

 

at the moment budget is limited anyway and the next major investment will be upgrading the laser cutter lens/diode 

 

Nick