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The loco referred to by Northroader is the first and only 2-2-2 that I have built. It can pull 6 wagons. It is unsprung and picks up on only 4 wheels. Most of my locomotive fleet is made up of 0-4-0 types and I have never found any problems with electrical pickup on them, so I decided that it was easier if the trailing wheels don't pick up. If they did pick up the force of pickups on them would stop them from turning as there is absolutely no weight on them at all. They are free to move up and down to compensate for irregularities in the track and are really just going along for the ride. It weighs 162g and more than half of the weight is over the driving axle.

 

I think to get your loco to run you'll have to do something similar as I imagine that it doesn't even weigh half of my No.11 and what weight you do have is spread over 3 axles.

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It weighs 162g and more than half of the weight is over the driving axle.

 

I think to get your loco to run you'll have to do something similar as I imagine that it doesn't even weigh half of my No.11 and what weight you do have is spread over 3 axles.

I've just checked and the Neilson weighs 3.5oz, or 99 grams in the 21st century. That's with most of the available boiler space filled with that 'liquid gravity' stuff, which I believe is steel. Clearly I have some way to go!
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Watching your video clip though, the problem is that the carrying wheels are taking too much of the weight. If you place your model symmetrically on a small piece of ply, then put this over a round pencil arranged transversely, and move backwards and forwards til it just rocks. This will show where your centre of mass is, hopefully close to the driving axle, just on one or the other side. You can then open up vertically the hole in the frames for the carrying axle on the opposite side, so that it floats without taking any weight. All you need to do then is arrange either light springing or dead weight to keep this wheelset in contact with the rails, and it’s best to allow some sideplay for track curvature on this axle. Probably pickups on the wheelset will apply too much friction and stop the wheels turning, as Ruston says.

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2-2-2 tanks make some of the prettiest little locos but the most pain-in-the-arse models to get to pull anything, Mr Burgundy on here built a nice Sharpie 2-2-2wt, I wonder how that manages?

I've seen a couple of 2-2-2's both of which had all wheel drive which solved the issue as long as you can work out the gearing for different size wheels. It makes my brain hurt ;)

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I've seen a couple of 2-2-2's both of which had all wheel drive which solved the issue as long as you can work out the gearing for different size wheels. It makes my brain hurt ;)

 

If leading and trailing wheels are the same diameter, the drive could be on these, with the "drivers" lightly sprung and free to rotate - an A1A?

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I've seen a couple of 2-2-2's both of which had all wheel drive which solved the issue as long as you can work out the gearing for different size wheels. It makes my brain hurt ;)

 

 

If leading and trailing wheels are the same diameter, the drive could be on these, with the "drivers" lightly sprung and free to rotate - an A1A?

 

The original plan was for it have the leading and trailing wheels driven and the larger wheels free, however the complication of sourcing and designing a gear train to do this put me off.

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Merry Christmas to all, hope everyone has had a happy and peaceful day. Mostly family stuff done today, but I did manage to get a shot of the most festive coloured train I have. 

 

An F class, exiting the tunnel with a train from Canterbury...

 

post-25124-0-88184500-1545767196_thumb.jpg

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An update on the F class - it works! The chassis runs under it's own steam, the tender rolls nicely, nothing derails over points. I'm quite happy with the top speed and low-speed control-ability too.

 

It does need further work though, on the following issues:

1) At the moment, it only picks up on the driving wheels - as you can see in the video, it is prone to stalling at low speed. 

2) It needs a bit more weight - I haven't added very much yet, there's plenty of space left in the boiler, I'm hoping to add a nice heavy cast crew as well. Then the traction issues you can see in the video should be solved.

3) The bogie needs rebuilding. I got a bit over-enthusiastic with fitting the bearings, so the axles are wonky, so the wheels don't all turn. Hopefully I can add pickups while I'm at it to help with problem 1.

 

However, these are mostly build issues, not design issues, so I'm hoping to release the prints for sale in the early new year.

 

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I've been thinking about the Neilson's weight problems (no I'm not going to make that joke...) and I think the existing weighting method leaves something to be desired. I'm using Deluxe Materials Liquid Gravity, which while very easy to use and very good for certain applications is not actually that dense. Doing some basic mass calculations, and assuming the stuff is steel and perfect spheres, you get a packing efficiency of 74%, in the best case (I knew that atomic structures lecture would come in handy at some point!). About a quarter of the space is therefore taken up by air and PVA glue - not heavy enough! I reckon the density of this mixture is about 5.9 g/cc. The density of Lead, for comparison, is roughly 11.3 g/cc, almost double. 

 

So my thoughts are, that if I don't have much more space to fit any ballast, I can replace the existing ballast with a more dense substance, provided I can get the original stuff out of course. I've ordered some lead strip used for fishing, which I should be able to pack in better. I think there is about 50g of ballast in the Neilson at the moment, with the loco and mechanism weighing about another 50g, so if I can replace the ballast with something about twice as dense, then that gets me to 150g(ish), a lot closer to Ruston's magical 162g figure and a big improvement on what I have now.

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I've been thinking about the Neilson's weight problems (no I'm not going to make that joke...) and I think the existing weighting method leaves something to be desired. I'm using Deluxe Materials Liquid Gravity, which while very easy to use and very good for certain applications is not actually that dense. Doing some basic mass calculations, and assuming the stuff is steel and perfect spheres, you get a packing efficiency of 74%, in the best case (I knew that atomic structures lecture would come in handy at some point!). About a quarter of the space is therefore taken up by air and PVA glue - not heavy enough! I reckon the density of this mixture is about 5.9 g/cc. The density of Lead, for comparison, is roughly 11.3 g/cc, almost double. 

 

So my thoughts are, that if I don't have much more space to fit any ballast, I can replace the existing ballast with a more dense substance, provided I can get the original stuff out of course. I've ordered some lead strip used for fishing, which I should be able to pack in better. I think there is about 50g of ballast in the Neilson at the moment, with the loco and mechanism weighing about another 50g, so if I can replace the ballast with something about twice as dense, then that gets me to 150g(ish), a lot closer to Ruston's magical 162g figure and a big improvement on what I have now.

I found the same problems with my 3D printer J3s in N Gauge, I just couldn't get enough Eileen's Emporium 'Liquid Lead' (not lead!) into the body. I end up using some (fairly thick) lead flashing folded up and squashed in a vice until it would fit. Despite not completely filling the boiler, it did provide much more weight than the 'liquid' product.

 

Be careful using PVA though, there are some horror stories around about the potential for the PVA to react with the metal and expand - with disastrous results for the models. I use super glue or epoxy and haven't come across any problems over the last four years since I first had a need to use this stuff.

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Be careful using PVA though, there are some horror stories around about the potential for the PVA to react with the metal and expand - with disastrous results for the models. I use super glue or epoxy and haven't come across any problems over the last four years since I first had a need to use this stuff.

 

I've heard that too - something in Lead reacting with something in PVA. That's another reason I'd used a non-lead based product in the first place. Good to hear I'm not completely barking up the wrong tree though!

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I've been thinking about the Neilson's weight problems (no I'm not going to make that joke...) and I think the existing weighting method leaves something to be desired. I'm using Deluxe Materials Liquid Gravity, which while very easy to use and very good for certain applications is not actually that dense. Doing some basic mass calculations, and assuming the stuff is steel and perfect spheres, you get a packing efficiency of 74%, in the best case (I knew that atomic structures lecture would come in handy at some point!). About a quarter of the space is therefore taken up by air and PVA glue - not heavy enough! I reckon the density of this mixture is about 5.9 g/cc. The density of Lead, for comparison, is roughly 11.3 g/cc, almost double. 

 

So my thoughts are, that if I don't have much more space to fit any ballast, I can replace the existing ballast with a more dense substance, provided I can get the original stuff out of course. I've ordered some lead strip used for fishing, which I should be able to pack in better. I think there is about 50g of ballast in the Neilson at the moment, with the loco and mechanism weighing about another 50g, so if I can replace the ballast with something about twice as dense, then that gets me to 150g(ish), a lot closer to Ruston's magical 162g figure and a big improvement on what I have now.

Are you sure that the stuff you have ordered is actually lead? I thought it was banned for use as fishing weights and so you may be getting something lighter than the real thing? Car balance weights used to be made from lead but these are another thing which is made from something other than lead these days and isn't as heavy as actual Pb.

 

Have you considered using depleted uranium? :jester:

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Are you sure that the stuff you have ordered is actually lead? I thought it was banned for use as fishing weights and so you may be getting something lighter than the real thing? Car balance weights used to be made from lead but these are another thing which is made from something other than lead these days and isn't as heavy as actual Pb.

 

Have you considered using depleted uranium? :jester:

 

Who knows if it's lead or not, but judging by the pictures it's much too flexible to be any other metal. And even if it's not it should be more dense than the liquid gravity stuff. I'm just hoping I don't get a visit from the boys in blue, wondering what I'm doing with toxic materials.

 

I asked the uni physics lab about depleted uranium, they said I'd need to keep it in a 1 inch thick lead-lined box, which rather defeats the point...

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Have you considered using depleted uranium? :jester:

Hi Ruston,

 

I had thought of that one as a cheeky reply but the side effects might be a tad more serious than the low adhesion that seems to be the current problem.

 

Might I suggest a safer alternative in Tungsten which has a density of 19600 kg/ m with the added bonus of an extra 800 kg/m more that Uranium.

 

The only metals that are more dense are Platinum 21400 kg/m, Osmium 22610 kg/m and Iridium 22650 kg/m. Gold at 19320 kg/mis actually the nearest and slightly less dense by 280 kg/m, Lead by comparison is 11340 kg/m which is some 8260 kg/mor only 52.5% as dense as Tungsten. Another bonus would be that I doubt that PVA will have any effect upon tungsten in the next couple of thousand years !

 

Find a welding shop that does TIG welding and cadge the burned out electrode tips from the torches the diameters are most commonly 10 SWG (3.2mm) but also 8 (4mm), 12 (2.4mm), 16 (1.6mm) and 19 SWG (1mm). If that is a non starter you could just buy some from eBay;

 

https://www.ebay.co.uk/itm/10Pcs-box-WL20-TIG-Welding-Lanthanum-Tungsten-Electrode-2-150mm-175mm-1-0-3-2mm/142911147486?hash=item21462b0dde:m:mNJwoB9Xnj-l-QCNCXXeY7g:rk:1:pf:0

 

Other than the price the next problem is cutting it for it is quite tough stuff, cutting disc in a grinder is about the only way.

 

Mind you fingers !

 

Gibbo.

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We're going back in time a bit today, back to where it all began...

 

While looking for a gimmick for my cakebox challenge entry, I thought I'd have a go at some 3D printing. That seemed to go ok, so next I thought I'd have a go at making a locomotive, but where to go for a prototype? I ended up designing a freelance engine based on a smaller version of Maunsell's diesel shunter prototypes, and getting it printed by Shapeways.

 

The Mk1 worked for a little while, but the gearset I'd chosen was tiny and didn't hold up well to anything less than a perfect mesh, so it had eaten itself after about 20 minutes of running. The loco then lay unused while I got on with other things, but the time has finally come (nearly a year later) to go back and do it properly. So I'm currently in the process of modifying the chassis to take a bigger Scale-link gear set of 50:1 ratio, slightly less than the old 60:1 set but with a nice big robust worm and drive gear. So hopefully, this Mk2 should finally run properly, without grinding noises and little flakes of plastic dropping out onto the track! I've also fitted a smaller flywheel to reduce the stress on the gears in the event of a sudden stop.

 

The pics show the old version, with the tiny gears, then the new one:

 

post-25124-0-72234900-1546171620_thumb.jpg

 

post-25124-0-55945600-1546171491_thumb.jpg

 

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Considering that the conrods are the wrong length and the quartering is not very good, the little diesel now runs reasonably well! There's still a small tight spot, but the flywheel covers that, and the new gears don't destroy themselves so it should be a regular part of my fleet from now on. Might not be part of my preferred era, but I can hardly leave out my first locomotive design can I?

 

Skip to the end of the video for a quick shunting puzzle - it turns out that mixing old Dublo and Wrenn stock with modern tension locks doesn't work all that well, so I should probably get round to upgrading the rest of my rolling stock at some point. The remote uncouplers worked pretty well though, considering they are so basic.

 

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A Happy New Year to all my digital friends on RMWeb!

 

A new year brings new projects... A slightly different approach is being trialled with a couple of new loco projects, some internet points are up for grabs for those who can identify the 2 locos from the screenshots below (beware: one of them is a bit of a trick question...).

 

As is usual for a student in January, I will be spending the next month revising and furiously typing reports as I have deadlines and exams throughout the month. This may slow my modelling down a bit, but I'll be sure to keep going and posting progress as it happens. I am also hoping to have the F class (and variants) and the Neilson 2-2-2t finished by the end of the month - ambitious, but hopefully achievable. I did threaten to do a livestream of some of the new models but that may have to wait until after exams. I couldn't do it over Christmas as the WiFi in my parent's house doesn't reach the workbench!

 

Many thanks to those that have encouraged me so far, it's the first year I've really done any regular posting on forums, which has got me back into modelling after a bit of a dry spell. So here's to a fun, train-themed 2019 for all  :locomotive:

 

post-25124-0-31175400-1546348305.jpg

 

post-25124-0-40869600-1546348314_thumb.jpg

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If I keep intoning 'Drummond... Drummond... Drummond...' in the background I'm sure well get an LSWR 4-4-0 in no time at all ;)

Happy New Year, Tom, and keep up the fabulous work whichever locos or rolling stock you decide to produce.

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I say I say I say, that bottom one looks a lot like an Electrotren/Jouef/Golden Valley Hobbies 0-6-0 chassis...

 

You may be on to something there...

 

If I keep intoning 'Drummond... Drummond... Drummond...' in the background I'm sure well get an LSWR 4-4-0 in no time at all ;)

 

Happy New Year, Tom, and keep up the fabulous work whichever locos or rolling stock you decide to produce.

 

When you say Drummond, is that T9, D15, C8, K10, L12 or one of the many others? I've got enough projects on for now, but maybe one for the future.

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You may be on to something there...

 

 

When you say Drummond, is that T9, D15, C8, K10, L12 or one of the many others? I've got enough projects on for now, but maybe one for the future.

 

If you're very good, you might get this:

 

post-29416-0-49951000-1546360589.jpg

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