Well done Paul with your track experiments, it is something much needed.
I too have been experimenting, but only for personal use. I decided just to try plain sleepers with alternating ties under the rail, and use spikes to fix the rails in place.
There was a major difference though in that I used a relatively cheap and cheerful printer only, rather than one which comes as part of a package. This has the advantage that I can use (cheap) resins from numerous sources, and adjust their exposure time and other values to suit my needs. This is because the manufacturer essentially sells only the printer, and relies on other manufacturers to supply the resins.
Regarding supports, I use Meshmixer or ChiTuBox to generate the supports, then export the supported model as an stl. This is loaded into the printer and printed straight off. These two programmes are free, and I would have thought that you could do the same.
However, I just printed these sleepers flat onto the printer bed so there is no cleaning up, and they come with a flat underside. Dead simple, but of course as you rightly point out, this way takes a lot more time, made worse as my printer has a smaller print area than yours.
Lastly, might it be more commercially worthwhile to print and sell individual sleepers?
Dave.

The limiting factor is getting more on the build platform across the X & Y axis. ?Roughly speaking the print time doesn’t increase massively if you add more stuff in a layer as the system has to scan the entire layer anyway. Adding layers i.e. increasing Z adds to the time even if just one spiky bit is taller than the rest.

Back to back doesn’t work. Because for the resin flow reasons mentioned previously the print has to lean away from vertical. This would mean that the facing back print would end up with the support connection points all over the viewing side. This is something I have avoided so far because you don’t then have to put much effort into clean up
.

Printing vertical and increasing the number of sleepers in a strip is probably a dead end. My trial failed because I got mean with the supports but the longer strip with its inclination cut capacity faster than the strip length increased.? There is also an issue that isn’t just down to the printing. The 8 sleeper strips are noticeably harder to thread onto the rail.

I am having an e-mail discussion with the Formlabs people about being able to edit the bases. As far as I know at the moment the software just generates them and you have no control. You can overlap the bases to pack the parts in more densely, but I need to understand the ramifications. You can also print without the bases, but this method tends to increase the support connections to the part but could be scope for experiment.

In a bizarre way due to the need to live a life not dominated by the damned printer the ideal would be to pack it full and it take 23 hours to print. Then at 11 am when it finished I could empty the prints into the cleaning process, clean and reload the printer and set it off for another run at Midday, knock off for lunch, fish the printed bits out of the cleaner and stick them in the UV cure. Printer minding done for the day!

“I'm also assuming that this potentially opens the way to printing to order to a specified sleeper size and spacing” in a word NO! ?If this goes anywhere it will be one style of base and ME rail either Code 70 or Code 83.?

The main reason for saying this is the niggly thing of this being my livelihood. At the moment I am doodling with this experimenting with what the printer can do. To go into production, it has to make a profit and pay back some of the development costs. That alone risks making this not viable with just one style. Lots of different styles just dilutes any chance of making a living.?? I do, of course, do commissioned work so on that basis I could develop your flavour of track – roughly a week’s work at ?45 an hour and you can have the track you want.

Karlgarlin Rail – again NO!?? I can’t supply it economically. I have talked to Richard about having it as a stock item but me being VAT registered, him not and there being no dealer margin would mean I would have to sell it at 20% more than anyone else. I am not interested in selling just sleeper bases for a rail I can’t supply.?? Again, its this making a living niggle that gets in the way. I can get ME rail trade that gives me a little extra margin to absorb a bit of the high cost of printing and still make a few quid.

This making a living is a bit of a nuisance. The internet is full of very iffy 3D printed models for stupidly low prices. If you like this stuff buy it when you see it because those prices have made no allowance for the producer making a living, they’ve conveniently not thought about repaying the cost of, maintenance or replacement of the machine. Doing it at home they most likely haven’t even considered the electricity it uses. When they realise any of those things or realise they’re working for bugger all return they’ll disappear

My experiments will continue.

?

?

?

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Hi John,

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This is a really interesting development Paul. I'm assuming the main limiting factor is time not printed volume, although more volume = more resin cost. I wonder if you could get a larger quantity and use less support by printing them vertically back to back with just a few joiners at the bottom to stop them flapping about. I'm also assuming that this potentially opens the way to printing to order to a specified sleeper size and spacing - and for turnout bases too. All we need now is castings for crossings and planed blades in Karlgarin and ME profiles.

John

Robin

Thanks for spreading the sculptamold word.

I should perhaps declare an inside track on the net curtain source. Annie works in the fundraising section of St Leonard’s Hospice here in York. They have a number of shops around the area. Thanks to Annie my nets were ‘insider trading’ from the back door for a few quid dropped in the collection tin. You may need to find the shop that does the receiving/sorting in your area to acquire some from this source as it tends to get filtered to the rag waste and not get to pure retail outlets.

I got put on to Sculptamold by a mate with a bad back. Having had a layout he now couldn’t move he built a H0n3 layout on an ironing board that he could carry in one hand. He was next to me at a weekend long show with a bit of hill made in sculptamold to extol it’s virtues. He spent the weekend telling people how strong it was whilst bashing it on a table top. It took him until Sunday afternoon to break it!

?

Paul

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Brian asking about printing directly on the build platform gives me the opportunity to talk about printers.

Suggesting I print on the build platform suggests he is thinking of an FDM printer. FDM stands for Fused Depositin Modelling and is more easily described as "the sort of printer that melts a filament and squirts it out of a nozzle. They typically look like this.

These do print directly on to the, typically, heated bed and squirt PLA plastic in layers to build up the model. Its the bed and the extruder on the gantry that do all the gyrating around. Whilst these can produce useful stuff its not usually fine enough for model purposes with the layering quite visible.? [ I started with one of these but since I have had my new printer I haven't touched it]

There is a technology that i have had stuff printed by commercially - this is what CW rail use - that I will mention as it explains a progression. In this sort of machine you start a set of prints with a tank filled with resin. The controlling software places items to be printed at various locations in this tank shaped space. It can stack them, add items inside other items and there isn't a visible support mechanism for stacked items. The reason for this is that you start with a tank full of resin and the lasers then operate to cure the resin. The process is costly because it turns the tank of resin in "stuff" or "scrap" there is no reuse of that resin. The uncured stuff has the consistency of, well, that tablet of soap you left in a puddle on the sink. Its not solid and its not really liquid. After the process it washes off with a pressure wash leaving your model.

The motivation with this sort of printer is to pack as much stuff in a print run as you can and minimise the scrap. This partly explains why when you order a model from the likes of Shapeways one time it comes out printed the way up you wanted and the layers don't really show but the next time its done a different way up and looks horrible. At a certain level they don't care about your model, their profitability relies on them packin stuff in.

My new printer is a resin printer but it works in a different way

This is a Formlabs Form 2. All the laser stuff is in the base of this machine and the build platform is on the Z axis which moves up and down.

On top of the base is what they call a tank but its more of a tray really. It has a photoreacitve that the laser works up through. On the right you can see a black arm that stirs the resin and just off the end of it you can see a slope under a black mass. The black mass is the resin cartridge. In the top of the shot you can see some prints hanging from the build platform

This is looking up at the print with the build platform elevated to its finished position.

When you set the machine up the tanks come a virgin clean tanks and you can put any one of 28 differen resin cartridges in the machine. They are all chipped and the contol software moniters them. When you put a virgin tank on for the first time and then add the resin cartridge it then pairs that sort of resin to that tank. You can change the cartridge for another of the same material but it won't let you mix them.
When you start a print this happens

1. The machine checks the tank and cartridge to check they are paired or pairs them if they are new
2. lets resin in to a fill level
3. starts to heat the resin to 31'
4. stirs it occasionally whilst it heat.
5. Lowers the build platfrom into the resin
6. Cures the first layer
7. raises the platform
8. stirs the resin
9. lowers the platform
10. cures the next layer.
11. repeats until done, topping up the resin in the tray

As you can see your stuff prints upside down dangling like a stalactite and surplus resin drains off. When you set up your prints you have to consider this draining. Flat horizontal surface tend to pool resin which cures by association leaving a bobbly surface. The set up software tries to prevent this. As an example in the Townsend Hook loco body kit the reason the tank fillers are a seperate item is so that there is a hole for the tanks to drain of resin and these sleepers, which are hollow backed rather than solid have holes in them under where the rail goes.

I think thats enough of 3D printing for tonight

Paul

On Tue, Dec 3, 2019 at 04:15 PM, Brian wrote:

Paul,

How come you can’t just print the sleepers on the table base without all the other support structure?

.

Simply - its not that sort of printer. Detail in a seperate message

Paul

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Hi Paul

Sorry, yes I did, and though I’d been told, I forgot you’d had to change plans 8-(

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Just to elaborate a bit more before you all go planning layouts using this flexible track this is some way off being a product.

It prints on a base similar to that shown above and all the support material is cost in both print time and material cost and how many you can print at a time is governed by the size of the printers build platform. The above was my first experiment and you could only fit five of them on the build platform. There is no way that would be viable as a product but it left a lot of open space that couldnt be used.

Having proved my daft idea actually worked the print was turned on its side. This had a number of benefits.

• 14 of them now fitted on the build platform.
• There is a lot less support material both in the base and in the skeleton.
• Tuning the skeleton removed even more material whilst leaving it supported.
• Now, in to fluid dynamics rather than models, it also improved the flow of uncurred resin runnin of the print.

It is these prints that the sample track is made from.
Still on the printer, whilst there are now 14 prints of 6 sleepers filling the 145mm x 145mm build platform there is a lot of the 175mm Z axis not being used.
Thus the next plan was vertical

This didn't work entirely. I increased it to 8 sleepers and would go more if it worked but I cut back too much of the supports on one side and the end of the sleepers tended to droop. The program put too much support in other places and added interconnecting stringers that weren't there in the smaller prints. This still might be the way to go if I can sort the support and increase the number of sleepers to utilise the available height. A couple of other things come into play in the printer set up.

• Print Time
• Cycle Time

Print TIme: the printer takes quite a time to print these but arguably you could print twice as many of the half height ones in the same time it took to do the full height ones so on print time alone there isn't a lot in it. Then cycle time become significant.
Cycle Time: Basically, the time it takes to print a set, get them off the machine and reset it. Prints happen quite happily with the printer working unsupervised but when it completes a print its a manual job to take the prints off, clean the build platform and start the next print.? Ideally you want a build time of say 10 hours or alternatively 18+ hours.? With the former you can do two runs a day, with the latter one print a day.

It's very easy to find your day is ruled by the damn thing. At one stage when I was trying to catch up with the Townsend Hook kits I was getting up at stupid O'clock to reset the machine for the next print to get three runs a day out of it. That is the way to madness.

Another consideration is the material. There are 28 different resins available with different characteristics. At the moment I am playing with the standard grey as its the cheaper resin for experimenting with but it is quite brittle and its easy to knock the spike off when threading the rail. Doing it for myself one missing spike doesn't matter but thats not a saleable way forward. Luckily the printer supplier is very supportive and will print samples in different resins as a trial before i commit to one. I suspect this will end up on what they call their durable resin which trades a little in resolution for being a lot more resistant to shocks. What I dont know at the moment is if you can add a pigment because in its raw state its translucent blue.?

Whilst the machine is very flexible in that it can easily swap from one material to another but setting it up for a material for the first time commits you to around a ?450 outlay so you need to be sure..

Its all interesting stuff to experiment with but it is very absorbing and you can lose track of doing the stuff you should be doing to earn a living as its more interesting.

I'll let you know how the experiments go but don't hold your breath waiting for the next installment

Paul

On Tue, Dec 3, 2019 at 01:30 PM, Simon Jones wrote:

You’re most welcome to test if it’s idiot-proof by bringing a sample for the O14 idiot at Derby next week ;-)

Simon, I assume you mean for the group curry?? Sorry won't be there as I am working here in York that day until late. Some clown decided to have an election

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So I got a whizzy high end 3D printer
I wanted to build some 0-14 track

........... I wonder if.....


Here we have a yard length of 0-14 flex track with ME code 70 weathered rail.



Here it is a bit closer.

Well it works and its flexible. Before you ask I haven't tried to find out what its minimum radius is. Its not modelled on any particular railways track, I didnt even measure a sleeper I just made something up. The joining idea between each sleeper was copied from the San Juan 0n3 flex track I have. Somehow the single hinge/join down the middle seems more appealing than the alternate either side you usually see. It's shallow enough that its covered by the ballast.

Having proved the basic idea I may develop the CAD around some specific sleepers. I quite fancy the South African pressed steel type used on the WHR but whilst basically a channel section the squashed end is challenging my CAD skills

Will this become a product. I dont know. It would probably need a resin change on my printer as this is printed in bog standard grey resin which is quite brittle and it would probably be quite expensive. It would depend where the line between convenience and cost was reckoned to be. If it were sold it may well be in the form of sleeper strip and rail because I don't have the temperament for threading sleepers on to rail. One yard was enough.

Paul Martin
EDM Models