Messin' With Resin - 3D printed track

richard_t

Member
Location
nr Spalding
When I last researched this, 2 years ago, the recommended glue was super glue. This isn't ideal for me, as it doesn't "flash over" like mek does, and when I tried the super runny stuff with some chairs from Shapeways (not resin charts though), even though I used a micro applicator it still left glue marks on the sleepers.

Hopefully the "ABS like" resin might glue with mek and it's friends....
 
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Martin Wynne

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Hopefully the "ABS like" resin might glue with mek and it's friends....

Hi Richard,

My hope for the hybrid design is that it won't need glue. I'm thinking of a recess in the filament-printed timbers into which a chair with a thickened base would be a push fit. Or maybe a ridge and groove design to create a clip-fit. Something like this in cross-section for example, although in practice I would go for vertical rail:
clip_fit_chair.png


Apart from quick assembly and not needing messy glue, this would allow a faulty rail to be prised out of the base and replaced at any time.

Ideally one-click in Templot and you get a 3D file for the timbers and a 3D file for all the matching chairs to fit. Don't hold your breath. :)

For plywood timbers, someone using a laser cutter to prepare them would be able to make a cutout for the chair, if Templot exports a suitable file. And maybe ordinary pva adhesive would then be sufficient.

cheers,

Martin.
 
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Martin Wynne

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Amazon have done their stuff and the Elegoo has landed. Not deterred by a torrential hailstorm at the very moment the van pulled up outside.

All beautifully packed. Now all I have to do is work out what all the bits and bobs are for -- and not muddle up the ones for the washer with those for the printer. The one I do understand is a pair of genuine Xuron flush cutters, a surprising and welcome inclusion in the box of bits.

I have to find somewhere to install the printer where I can shut the door on it and open the window, to keep the pong under control. The machine includes an air filter and fan, which is intended to absorb the fumes. But I doubt it will be very effective, and it certainly won't be every time I take the lid off.

I think I shall clear a space for it in the computer graveyard. I may be gone some time. :)

But first a boiled egg.

cheers,

Martin.
 
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AndyB

Member
Amazon have done their stuff and the Elegoo has landed. Not deterred by a torrential hailstorm at the very moment the van pulled up outside.

All beautifully packed. Now all I have to do is work out what all the bits and bobs are for -- and not muddle up the ones for the washer with those for the printer. The one I do understand is a pair of genuine Xuron flush cutters, a surprising and welcome inclusion in the box of bits.

I have to find somewhere to install the printer where I can shut the door on it and open the window, to keep the pong under control. The machine includes an air filter and fan, which is intended to absorb the fumes. But I doubt it will be very effective, and it certainly won't be every time I take the lid off.

I think I shall clear a space for it in the computer graveyard. I may be gone some time. :)

But first a boiled egg.

cheers,

Martin.

Yes, beautifully packed. I was a bit alarmed when I saw one corner of the box was damaged but the printer looks unscathed.

You got the "Pro" version with the filter. After I read some comments that it's not much use I opted for the less expensive version. Not sure where I'm going to put it yet. It might be running al fresco for a bit.

BTW, I understand you can use denatured (meths) rather than isopropyl alcohol. Denatured is much cheaper and easier to get here. I'll give it a shot and see what happens when the time comes.

 
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AndyB

Member
Hi Andy,

I use servos to operate all my turnouts using MERG software.
I have had no problems at all.
I use a small pcb mounted on a 3D printed servo mount .
This PCB contains the servo driver and a relay to provide frog polarity switching.
The two end points for the servo and it's speed can be set very acurately and the relay changes over half way between the the set end points. Other versions of this use solid state switching instead of the relay

Charles

View attachment 500View attachment 498

Hi Charles,

That's a great way to use servos. You should not have any issues with interference when the driver is that close to the servo. It's the long wires between the driver and the servo that can cause problems.

Cheers,
Andy
 
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Martin Wynne

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The printer arrived today, two days earlier than expected.

Snap! :)

BTW, I understand you can use denatured (meths) rather than isopropyl alcohol. Denatured is much cheaper and easier to get here.

Hi Andy,

It's only cheaper than IPA here if you go for industrial grade meths, which is only 70% alcohol. Elegoo washing instructions say it needs to be at least 95% alcohol to work. I've got 5 litres 99% IPA coming from Amazon for £20, and laboratory grade meths is no cheaper.

https://www.amazon.co.uk/gp/product/B082XQ4W4R/

It should last well, the Elegoo instructions say it can be re-used up to 30 times. After that, the resin in solution can be precipitated out by exposing it to UV, and then after filtering it's good as new to re-use again. I shall believe it when I've tried it. :)

With UK meths you also get the added pong, and a purple residue after evaporation. But your mileage may vary, meths in your part of the world may be nothing like UK meths.

It might be worth trying paraffin/kerosene/whatever it's called there. I've found in the past that it makes an excellent degreaser, and it's a lot cheaper than anything else.

I went for the machine with an air filter because I don't get on well with solvent fumes. I prefer soldered track construction with cosmetic half-chairs mainly because I can't stand the smell of MEK/butanone for fixing functional chairs. In contrast the smell from PLA filament printing is actually quite pleasant -- PLA is made from sugar cane, and you can tell. Hot ABS is not nice though.

cheers,

Martin.
 
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I went for the machine with an air filter because I don't get on well with solvent fumes. I prefer soldered track construction with cosmetic half-chairs mainly because I can't stand the smell of MEK/butanone for fixing functional chairs.

cheers,

Martin.
Hi Martin,
I don't mind the fumes from MEK etc but it is prudent to keep the window open and a deskfan blowing the fumes towards it.

Put me down for some cosmetic half-chairs when you do the design work. I like ply and rivet...I may even have the punch/press I got back in the early 80's.

Rob
 
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John S

Member
Hi Charles,

That's a great way to use servos. You should not have any issues with interference when the driver is that close to the servo. It's the long wires between the driver and the servo that can cause problems.

Cheers,
Andy

Andy,
Is it worth using a screened twisted pair, with the screen earthed, between the driver and servo if it has to be a lond run?

John S from 33820 St Ciers sur Gironde
 
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richard_t

Member
Location
nr Spalding
I was going to be cheeky and ask if you wouldn't mind printing some chairs I'd designed a few years ago so that I could see how they came out, but the chairs are for 7mm scale and I'm back in 4mm land now. Also they are designed around C&L rail, and I'm planning on using DCC Concepts rail in the future. The biggest hurdle is that the STL files are huge (all round 100Mb each), and I don't have access to the software that generated the chairs anymore (Autodesk Inventor) so I can't shrink the files (either to 4mm, or in file size!). I have Autodesk Fusion 360, but I think it can only import Inventor files as one mesh, with it losing all the features.

a-switch.png


These are chairs and other fittings for an A switch...
 
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Martin Wynne

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These are chairs and other fittings for an A switch...

Hi Richard,

Wow, those look amazing!

I'm happy to have a go at printing them for you. But bear in mind that my experience of resin printing is currently nil. I doubt my efforts will match the results from someone with more 3D printing experience. Or at least, not yet.

I can re-scale the STL files to any scale, within reason.

You can send them to me via WeTransfer:

https://wetransfer.com
You can send up to 2GB for free. You don't need to sign up, you can just send files. My email address is:

martin - at - templot.com (you know what to do with that).

cheers,

Martin.
 
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richard_t

Member
Location
nr Spalding
I've sent three different sets of files - a-switch (chairs/etc for an A switch), keyed-s1 chairs, and PJ chairs.

The files compress quite well ... I remember I just upped the quality in the Inventor output process until I hit the file size limit for Shapeways.
 
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Martin Wynne

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Hi Richard,

Files received. Now the fun begins... :)

Martin.
 
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Martin Wynne

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All set up and ready to go:

3d_corner.jpg


Just waiting for the IPA, which should be here this evening.

This corner is where all the original work on Templot was done, as you can guess from the Delphi2 chart on the wall. I've left it up for old time's sake.

But for the last 10 years it has been a dumping ground for several derelict computers, monitors, old printers, and the rest. Plus a lot of other assorted junk. It's taken me several hours to restore it to this usable state. This room isn't used much, so I can set the printer going and shut the door on it to keep the fumes contained. Also I've discovered that the fan on the Elegoo Plus model is quite noisy and could get annoying, so being able to shut the door on it is a help. I'm not yet sure I've made the right choice in going for the one with an air filter.

It won't look like this for long. :)

cheers,

Martin.
 
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AndyB

Member
Andy,
Is it worth using a screened twisted pair, with the screen earthed, between the driver and servo if it has to be a lond run?

John S from 33820 St Ciers sur Gironde
Hi John,

Can't do any harm but it will depend on how aggressive the noise is in your environment. The only really "bomb proof" method I've found for long cables is to insert optoisolators.

Rather than derail this topic I'll start a new one later when I'm fully awake. Currently in bed drinking first mug of coffee 😀

Cheers,
Andy
 
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AndyB

Member
I've yet to crack open the bottle of resin but so far so good. I have a very basic model of FB track to print and I have a couple of questions:

Is it necessary to use supports under the sleepers or can they be plonked right onto the build plate?

Is it possible to speed up the print by forcing thicker layers for the sleepers?

The second question could be academic as the slicer says the print will only take eight minutes and that is regardless of how much track I can jam on to the build plate.

That being the case it might be realistic to produce an 00 turnout base in 30 minutes.
 
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Martin Wynne

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Is it necessary to use supports under the sleepers or can they be plonked right onto the build plate?

Hi Andy,

My understanding is that you need a reasonable area of slab as a starting point to ensure it sticks to the build plate. You then add supports from the base slab to small components as required. Putting small components directly on build plate, even if they have a suitable flat base such as a chair, means they won't stick to it and remain as submerged bits of cured resin, or stuck to the base of the tank instead.

What's a suitable minimum area of base slab, and how thick does it need to be? No idea, but maybe 30mm square and 2mm thick?

I suspect a 00 sleeper (32mm x 3.3mm) might not be a big enough area to stick by itself reliably. And if it does stick it might be difficult to remove without damage. The parts are quite soft until cured.

If you give the base slab undercut angled edges (I believe it's called a "skate"), it will be easier to remove using the (plastic) scraper supplied. You can't do that if it is the finished component.

He said, also having not yet opened the bottle of resin. But I do now have a supply of IPA, so no excuse not to get going. :)

I'm a bit puzzled what the supplied metal scraper is for, given that the instructions say not to use metal tools on the build plate? It will come in handy on the Bibo anyway, although I already have several others.

cheers,

Martin.
 
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