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3D Printing in 2mm Scale


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11 minutes ago, Nig H said:

Hi Kevin,

 

Do you know what the cost of materials is for these wagons? Is it proportional to the number printed off, or is it possible to achieve economies of scale via increase quantities?

 

Nigel Hunt

Based on a bit of a guesstimate - the weight of the resin used straight of the plate with supports taken into consideration plus adding a gram for liquid waste - they work out at 10 aussie cents a print (I use Anycubic black and get the 1ltr bottle from the Australian supplier - other resins will vary in cost based on what it is and where you get them from obviously).  The way I have mine set up, it takes just over 3 hours to print (0.05mm slice on a 30 degree angle with 7mm of support under) and I can get 5 on a print if I crowd them in.  I've been printing four wagons to a print to make it easier to get them off without damaging (although I rushed the 7plank prototype this morning and damaged the floor!)    Basically the economies are in the run time of the printer rather than the resin - the amount of resin depends on the model so doing 1 is 3 hours 20 plus 10c worth of resin - doing 4 is 3 hours 20 run time plus 40 cents worth of resin.  The power for the printer is negligible and I use metho to clean and 4 ltrs comes for the princely sum of $15.  All up, and going for the top end of the cost - allowing for power, metho and resin - I am reckoning it costs me around 25c a print - and that is probably high.  Other wagons - my LNWR D21 for example - are more expensive as they use more resin.  It is around the 35c mark.  This is not taking anything for my time - how do you value hobby time?

 

 

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IM pretty sure you can add the cost of resin into the slicer and it calculated the cost per print based upon the volume?

 

The valuable part is the stl file (and the generation of it). I would be very happy to print some of those off myself!

 

J.

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Just now, Valentin said:

Based on your everyone's experience, what would be considered to be good resins for printing models in 2mm:1ft scale? based on criteria like detail, resilience, priming and painting.

Hi Valentin,

 

I've tried a few different types of resin in my printer and have reverted to the resin which came with it - Anycubic Black.  This is on the Aussie principal that you don't put Ford spares in Holden cars.  I know others have had lots of success in using different resins in the same printer I have - I can't seem to find any at a price I'm willing to experiment with on the "better" ones.

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6 minutes ago, richbrummitt said:

I think it is most correct to put the solebars on a 3DP body. Why do people leave them off?
 

Other than that it appears to be excellent. 

Because they are on the etch and its easier to just build the etch?  That's just my experience so I don't draw them. 

 

I've built chassis to go under prints with sole bars and if the sole bar on the print isn't deep enough for the etch, it can be a right pita to sort out - and depending on the "designed for etch" you end up cutting bits and pieces around and having to glue bits of etch to the sole bar (v hangers - I'm looking at you) and that seems to be un-necessarily complicated.

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2 hours ago, Nig H said:

Hi Kevin,

 

Do you know what the cost of materials is for these wagons? Is it proportional to the number printed off, or is it possible to achieve economies of scale via increase quantities?

Probably not relevant to wagons, but when I sent the file for the pillars for the Dunallander canopies to the friend who printed them for me this was what he sent back, with the comment that he knew 2mm stuff was small, but this was rediculous! 

 

Screenshot_20201029-112343.png.1c43b08ff8bdd872ff6b54e27d6795b5.png

 

Jim 

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4 hours ago, Sithlord75 said:

The question is - do I amp up the detail (so make the bolt heads slightly bigger so they stand out, and do the same with the strapping) or do I leave it?  Suggestions on a postcard - on on here, whichever is easiest!

 

 

The real test would be to see if weathering washes and/or dry brushing will pick out the details.

 

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42 minutes ago, Sithlord75 said:

Because they are on the etch and its easier to just build the etch?  That's just my experience so I don't draw them. 

 

I've built chassis to go under prints with sole bars and if the sole bar on the print isn't deep enough for the etch, it can be a right pita to sort out - and depending on the "designed for etch" you end up cutting bits and pieces around and having to glue bits of etch to the sole bar (v hangers - I'm looking at you) and that seems to be un-necessarily complicated.

 

With the MR and others putting V hangers on the outside of the solebars I can see the counter argument. My comment is also not valid for the kind of vehicle that has a multitude of footsteps and other bits dangling off the them e.g. NPCS. Then it is worthwhile having a step inside up to the floor so that the body to chassis join is hidden from the side. I have not looked under one of your prints to see if that is something you already do this. Without I have often found it difficult to entirely eliminate any gapping between the two parts.  

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1 hour ago, richbrummitt said:

 

With the MR and others putting V hangers on the outside of the solebars I can see the counter argument. My comment is also not valid for the kind of vehicle that has a multitude of footsteps and other bits dangling off the them e.g. NPCS. Then it is worthwhile having a step inside up to the floor so that the body to chassis join is hidden from the side. I have not looked under one of your prints to see if that is something you already do this. Without I have often found it difficult to entirely eliminate any gapping between the two parts.  

 

I have not concluded whether printing the solebars with the wagon or not is the best way. But the best part of 3D-printing and its ability to produce things one at a time is that you can provide both options and allow people to choose which they prefer.

 

Chris

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I think a lot depends on whether the 3d print is designed to fit a specific etched underframe or not. Stephen Harris has produced some cast resin van bodies which have solebars as part of the casting, and there is a corresponding etched chassis carcass that plugs in underneath. It's a neat solution (as you would expect from Stephen), but it could be a real sod if you wanted to use an alternative underframe.

 

At the end of the day the gap problem is there whether you use an injection mouded plastic body or a 3d printed body, although a few of the plastic body kits in Shop 2 do include moulded solebars.

 

Andy

 

 

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Re: resin I like Anycubic resin too, mainly because it's cheap! Currently £85 for 5 litres from AliExpress, which is a veritable bargain! Siraya Tech Tenacious is great for mixing for things like bogies where you want a bit more flexibility.

 

I printed 3 JHA bodies earlier, and the estimated cost is 42p of resin per body. Definitely all the value is in the STL though!

 

50543699838_b06da8bd36_z.jpgUntitled by njee20, on Flickr

 

The LTF-25 bogies can take 2mm wheelsets as well, to keep this OT ;-)

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9 hours ago, richbrummitt said:

Without I have often found it difficult to entirely eliminate any gapping between the two parts.  

 

Exactly this!

 

I've always found it much harder to get a gapless join between a printed body and an etched chassis, compared to a plastic body. You inevitably have supports on the underside, which leave a less than perfectly flat surface when they're removed, and the chances are it won't be entirely 100% flat across the bottom to start with because printing forces don't tend to be perfectly balanced. I've never yet managed to sand the whole underside sufficiently flat across the whole surface to get a perfect fit. 

 

I've used an approach copied from "Stockprints" on Shapeways (who sell various pre-group mainly southern area wagons) of including the solebar and leaving a notch in the inside floor to accommodate the Association etched RCH W irons at the right spacing.

 

That does mean you end up needing to cobble together brake gear, levers, etc., from leftovers of other etches. I think I did float the idea of putting together an etched sheet of just brake gear for this kind of thing to @2mm Andy - but of course I never got around to it myself.

 

The other advantage of printing the solebar is making it easy to design in a sacrificial "skirt" to carry supports, which saves the risk of distortion around supports.

 

J

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1 hour ago, justin1985 said:

 

That does mean you end up needing to cobble together brake gear, levers, etc., from leftovers of other etches. I think I did float the idea of putting together an etched sheet of just brake gear for this kind of thing to @2mm Andy - but of course I never got around to it myself.

 

J

Something like this is on my etch design 'to-do' list, which is rather long at the moment. The 2mm shops did sell such a sheet years ago, and I do have one in my gloat box along with some of the old compensated wagon underframes. 

 

Andy

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1 hour ago, justin1985 said:

 

Exactly this!

 

I've always found it much harder to get a gapless join between a printed body and an etched chassis, compared to a plastic body. You inevitably have supports on the underside, which leave a less than perfectly flat surface when they're removed, and the chances are it won't be entirely 100% flat across the bottom to start with because printing forces don't tend to be perfectly balanced. I've never yet managed to sand the whole underside sufficiently flat across the whole surface to get a perfect fit. 

 

I've used an approach copied from "Stockprints" on Shapeways (who sell various pre-group mainly southern area wagons) of including the solebar and leaving a notch in the inside floor to accommodate the Association etched RCH W irons at the right spacing.

 

That does mean you end up needing to cobble together brake gear, levers, etc., from leftovers of other etches. I think I did float the idea of putting together an etched sheet of just brake gear for this kind of thing to @2mm Andy - but of course I never got around to it myself.

 

The other advantage of printing the solebar is making it easy to design in a sacrificial "skirt" to carry supports, which saves the risk of distortion around supports.

 

J

 

There is no doubt the solebars also make any 3D printed body more robust.

 

To be honest, the Association W-irons are a bit chunky for pre-group designs. I was very surprised at just how delicate LNWR ones were (particularly the early designs) in comparison, when I designed the LNWR wagon underframes.

 

Chris

 

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2105317433_5plnk1923bdnedt.jpg.1c917537af511c9262298b42cf9bf624.jpg515562880_5plnk1923bdnedtunder.jpg.a12b72128cb47094d67fff330b14a0f3.jpg

 

Two views of the 5 plank wagon - with bottom doors and a lip to hide the chassis.  I haven't done the catches for the side doors yet.  Did the 5 planker come with end doors? Or was that only 7 Plankers? (And Death Stars...)

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2 hours ago, Sithlord75 said:

2105317433_5plnk1923bdnedt.jpg.1c917537af511c9262298b42cf9bf624.jpg515562880_5plnk1923bdnedtunder.jpg.a12b72128cb47094d67fff330b14a0f3.jpg

 

Two views of the 5 plank wagon - with bottom doors and a lip to hide the chassis.  I haven't done the catches for the side doors yet.  Did the 5 planker come with end doors? Or was that only 7 Plankers? (And Death Stars...)

 

I don't think we can imagine all 'RCH 5-plank' wagons were of one design  (although Peco would probably like us to think so). For example, the 4mm Parkside kit has wooden end stantchions and ironwork on the inside.

 

https://www.ebay.co.uk/itm/133508923263

 

and the Cambrian kit for a china-clay version has end doors

 

https://www.ebay.co.uk/itm/323259066946

 

I can remember these running through Cheltenham behind a BR Western en-route between Cornwall and Staffordshire. 

 

Chris

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The saga of the RCH opens continues - this time the 1907 15' long 7 plank.  This wasn't very hard to do - I merely modified the 1923 16'6" one by adjusting the length of two of the sketches and tweaking the bolt head pattern on the angled bracing.  I timed the mod at just on 5 minutes.  I've done the variant with no bottom door too - so now 14 types of RCH wagon drawn up - pictures of some are on the Workbench thread.

 

1812065829_19077pbdned.jpg.39c443786c3221cca6cd653b0e98f058.jpg

 

As it is almost midnight Down Here and, to reassure @-missy-,  because I do need to sleep occasionally :D, the other 6 variants of the 7 planker will have to wait until tomorrow sometime!!

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2 hours ago, Sithlord75 said:

The saga of the RCH opens continues - this time the 1907 15' long 7 plank.  This wasn't very hard to do - I merely modified the 1923 16'6" one by adjusting the length of two of the sketches and tweaking the bolt head pattern on the angled bracing.  I timed the mod at just on 5 minutes.  I've done the variant with no bottom door too - so now 14 types of RCH wagon drawn up - pictures of some are on the Workbench thread.

 

1812065829_19077pbdned.jpg.39c443786c3221cca6cd653b0e98f058.jpg

 

As it is almost midnight Down Here and, to reassure @-missy-,  because I do need to sleep occasionally :D, the other 6 variants of the 7 planker will have to wait until tomorrow sometime!!

 

These are all looking great Kevin.  Might be worth checking your references as most 1907 RCH minerals at least started with even width planks rather than the deeper top planks of the 1923 version.

 

A question for those more knowledgeable than me: what length were most RCH 1907 mineral wagons?

 

Simon

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2 hours ago, 65179 said:

 

These are all looking great Kevin.  Might be worth checking your references as most 1907 RCH minerals at least started with even width planks rather than the deeper top planks of the 1923 version.

 

A question for those more knowledgeable than me: what length were most RCH 1907 mineral wagons?

 

Simon

 

I don’t know what length  was most common, but considering that the lengths were 14’6, 15’, 15’6 and even 16’ and heights varied between 2’10 and about 4’ there were so many possibilities that I doubt any particular size was a stand-out most common.  And you also need to consider location.  By 1912 several South Wales collieries were buying 12 ton, 16’ x 4’ tall wagons.  But at the same time small independent coal merchants were buying smaller wagons.  So near a colliery you might think larger wagons were the most common size, but in East Anglia or Cornwall a smaller size would appear to be more common.

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818609198_19077epbdned.jpg.268b7bd15aea718877215e41c0ae83d8.jpg

 

7 even planks for a height of 4' - 15' over headstocks.  Turns out it wasn't as I feared - I had managed to make all the details dependent on the plank position rather than floating so I just had to adjust the bolt heads on the angle once the heights were adjusted.

 

 

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I've been getting the hang of my new Proxxon MF70 mill and, as I'm starting to gain confidence with it, I've made a start designing a loco that will need a scratch built chassis.

 

824634168_LNERO2-1Body7-11-20.JPG.042e572a6eb3bd6421afc5983a57c407.JPG

 

I've not quite finished the CAD yet, but it is getting close.

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