3D printers - messin' with resin

[AndyB]

As my birthday is next month (not saying which one) and the price of resin 3D printers has dropped a lot I took the plunge into resin and ordered something called an Elegoo Mars 2 Mono. Should arrive Saturday.

The build surface is a bit small but the resolution is pretty good so it will be interesting to see what it can do. The "mono" refers to the LCD that acts as a shutter for the UV light. Monochrome LCDs attenuate the UV less than color LCDs and that reduces the exposure time for each layer. It's supposed to be a few seconds so something as low profile as 00 track should not take too long to print - I hope!

 

[Martin Wynne]

Hi Andy,

Please keep us posted.

Someone else just starting with an Elegoo Mars is Paul Willis, see:

https://www.scalefour.org/forum/viewtopic.php?f=90&t=7399#p82623

cheers,

Martin.

 

[Daifly]

There are a few on Western Thunder too.
But here's printing that's impressive

 

[AndyB]

I don't think the resolution of the Mars is quite as good as that

 

[Rob Manchester]

As my birthday is next month (not saying which one) and the price of resin 3D printers has dropped a lot I took the plunge into resin and ordered something called an Elegoo Mars 2 Mono. Should arrive Saturday.

The build surface is a bit small but the resolution is pretty good so it will be interesting to see what it can do. The "mono" refers to the LCD that acts as a shutter for the UV light. Monochrome LCDs attenuate the UV less than color LCDs and that reduces the exposure time for each layer. It's supposed to be a few seconds so something as low profile as 00 track should not take too long to print - I hope!

Happy 75th Andy.....did you get somebody to pay for your 'present'?

Rob

 

[AndyB]

Happy 75th Andy.....did you get somebody to pay for your 'present'?

Rob

Joe Biden

 

[Martin Wynne]

Hi Andy,

You might be interested in this:

https://www.rmweb.co.uk/community/i...eaton-norrish/&do=findComment&comment=4350341

cheers,

Martin.

 

[AndyB]

Hi Andy,

You might be interested in this:

https://www.rmweb.co.uk/community/i...eaton-norrish/&do=findComment&comment=4350341

cheers,

Martin.

Hi Martin,

When I eventually get it up and running (which could take a while ) I'll be interested to see the amount of detail it can produce and the resilience of the final part. The "acid test" might be to see how close I can get FB rail secured by Pandrol clips, although that's probably pushing it a bit.

Cheers,
Andy

 

[richard_t]

I must admit I'm very tempted as well - I hadn't realised how much the prices for the printers had come down until recently.

This video on you tube might be interesting...

Hope you enjoy it, and please keep us informed.

 

[Martin Wynne]

Hi Andy,

I didn't have a birthday, but I did have some Amazon vouchers left from Christmas. I say "did have" because you can guess what happened.

Elegoo on its way, should be here tomorrow. Also some of the "ABS-like" resin, which is alleged to be less fragile than the standard resin. We shall see.

I've been thinking about resin printing for some time. I was very disappointed that I couldn't get better results from the BIBO filament printer for proper chairs, at least in 4mm scale. Even in 7mm they are fragile, and easily damaged when threading rail through them:

A hybrid approach seems more promising. Slide-on resin chairs which locate onto a filament-printed base. Doing both at once allows more precise dimensioning than using injection-moulded chairs, and the chairs can be tweaked for the best fit on the rail. Also far more special chairs can be printed than are available from the trade.

Narrow 6" wide Z chairs, side-by-side on a timber for example:

Sorry, I don't know who posted this, maybe Phil O? Another discovery in the archive.

There would be no way of doing that with filament printing in 4mm scale, and very tricky in 7mm.

The material cost of filament-printed chairs is almost nil, it will be interesting to see how the cost of resin chairs compares.

cheers,

Martin.

 

[Phil O]

Hi Martin,

Yes, that is one of mine. Glad those photos have been helpful, I have seen links to my posts on on rmweb and I have also linked to them on the Scaleforum site.

 

[Rob Manchester]

Hi Martin and Andy,
I will watch with interest how you get on with these printers. It was good of Richard to point us in the direction of the video as it answered some of the questions I had floating around in my mind.

A few more beginner(me!) questions :-
Does the software supplied give you an estimate of the amount of resin that will be used for the print ?
Does the print time change if you put 4 servo mounts on the design at once ? Maybe the answer is obvious and I haven't thought that one through
Is there a chance of distortion when curing the parts with a lamp ? There was a mention of window ledge/sunshine possibly causing issue but presumably a proper lamp setup would work fine.
When the mount was being cut off the cutters made a noise that suggested the material was quite 'hard' - unlike what happens if you cut a C&L chair off the sprue. Will the resin be flexible enough to grip the rail if used for chairs - time will tell on this one I guess?
If you just chairs this way is it likely there would be a suitable adhesive to bond them to ply sleepers?
My only use of 3D parts so far has been wagon buffers from Shapeways used to replace poorly shaped ones on kits and the quality of the parts and ease of use was fine.

As a final point - is there a possible intention for a library of chairs/baseplates/etc to be made available for use by Templot users. It doesn't make much sense for several people to be working away on a design for the same item.

Rob

 

[AndyB]

Hi Andy,

I didn't have a birthday, but I did have some Amazon vouchers left from Christmas. I say "did have" because you can guess what happened.

Elegoo on its way, should be here tomorrow. Also some of the "ABS-like" resin, which is alleged to be less fragile than the standard resin. We shall see.

I've been thinking about resin printing for some time. I was very disappointed that I couldn't get better results from the BIBO filament printer for proper chairs, at least in 4mm scale. Even in 7mm they are fragile, and easily damaged when threading rail through them:

A hybrid approach seems more promising. Slide-on resin chairs which locate onto a filament-printed base. Doing both at once allows more precise dimensioning than using injection-moulded chairs, and the chairs can be tweaked for the best fit on the rail. Also far more special chairs can be printed than are available from the trade.

Narrow 6" wide Z chairs, side-by-side on a timber for example:

Sorry, I don't know who posted this, maybe Phil O? Another discovery in the archive.

There would be no way of doing that with filament printing in 4mm scale, and very tricky in 7mm.

The material cost of filament-printed chairs is almost nil, it will be interesting to see how the cost of resin chairs compares.

cheers,

Martin.

Uh oh! What have I done now?

I sent for the same resin and it has arrived. The printer is now supposed to be here on Friday. As usual I have some heretical ideas about how to make all this work. Whatever happens I'm sure it will be quite entertaining.

Cheers,
Andy

 

[Rob Manchester]

Uh oh! What have I done now?

Cheers,
Andy

You have probably set back the launch date for Martin's boat

Rob

 

[Martin Wynne]

You have probably set back the launch date for Martin's boat

Hi Rob,

Not to mention the radio-controlled trains on plastic rails.

Answers from someone who as yet knows nothing:

Does the print time change if you put 4 servo mounts on the design at once ?

In theory the print time is determined only by the Z height of the component. We shall see. Unlike filament-printing where the volume of the component and nozzle size determines the print time.

Is there a chance of distortion when curing the parts with a lamp ? There was a mention of window ledge/sunshine possibly causing issue but presumably a proper lamp setup would work fine.

I've got 2 boxes coming, a red box and a yellow box. The red one does the printing, and the yellow one does the washing and curing afterwards. I didn't know that you could use a window cill instead (presumably only in daylight hours). It seems to me that there is a green one missing for a full set.

When the mount was being cut off the cutters made a noise that suggested the material was quite 'hard' - unlike what happens if you cut a C&L chair off the sprue. Will the resin be flexible enough to grip the rail if used for chairs - time will tell on this one I guess?

I believe the standard resin is quite brittle. But I've ordered some "ABS-like" resin which is claimed to be tougher and more flexible. That may mean it's not so good for fine detail. We shall see. Andy has just said that he has ordered the same stuff. It's a bit more expensive.

If you use chairs this way is it likely there would be a suitable adhesive to bond them to ply sleepers?

Some folks are supplying resin chairs now, so I assume there is an adhesive.

As a final point - is there a possible intention for a library of chairs/baseplates/etc to be made available for use by Templot users. It doesn't make much sense for several people to be working away on a design for the same item.

Yes indeed, that's what I'm hoping for. See at: https://85a.uk/templot/club/index.php?resources/categories/cad-and-3d-printing.9/ there is already a category for 3D files.

I'm also hoping to generate 3D files in Templot for direct export.

cheers,

Martin.

 

[AndyB]

Hi Martin and Andy,
I will watch with interest how you get on with these printers. It was good of Richard to point us in the direction of the video as it answered some of the questions I had floating around in my mind.

A few more beginner(me!) questions :-
Does the software supplied give you an estimate of the amount of resin that will be used for the print ?
Does the print time change if you put 4 servo mounts on the design at once ? Maybe the answer is obvious and I haven't thought that one through
Is there a chance of distortion when curing the parts with a lamp ? There was a mention of window ledge/sunshine possibly causing issue but presumably a proper lamp setup would work fine.
When the mount was being cut off the cutters made a noise that suggested the material was quite 'hard' - unlike what happens if you cut a C&L chair off the sprue. Will the resin be flexible enough to grip the rail if used for chairs - time will tell on this one I guess?
If you just chairs this way is it likely there would be a suitable adhesive to bond them to ply sleepers?
My only use of 3D parts so far has been wagon buffers from Shapeways used to replace poorly shaped ones on kits and the quality of the parts and ease of use was fine.

As a final point - is there a possible intention for a library of chairs/baseplates/etc to be made available for use by Templot users. It doesn't make much sense for several people to be working away on a design for the same item.

Rob

Hi Rob,

As we have come to expect Martin has provided a comprehensive response to your very valid questions. I doubt I can add anything.

I'm mainly interested in determining what is feasible/practical. Should be interesting as long as I don't do myself in with the pong from the resin

Cheers,
Andy

 

[Rob Manchester]

Thanks Martin, your answers are considered and to the point as usual. A scale 4mm scale Pandrol baseplate would I think indicate the technology is where we want it to be but I suspect that may be another generation or so in the future.

Andy, looking forward to see how you get on.

Rob

 

[Martin Wynne]

Hi Andy, Rob,

My feeling is that the new kits from Wayne Kinney are a game changer for building bullhead pointwork in 4mm scale:

https://www.rmweb.co.uk/community/i...pe-first-look/&do=findComment&comment=4348500
If as I hope he will, he makes the cast crossings and machined switch blades available separately, it's possible to imagine creating bespoke pointwork directly from Templot, by 3D printing a base designed to accept those components. Then building even quite complex pointwork reduces to cutting rails to length, sliding on the chairs, and plugging them into the printed base. It hardly needs gauges even.

A lot to think about.

cheers,

Martin.

 

[AndyB]

Hi Martin and Andy,
I will watch with interest how you get on with these printers. It was good of Richard to point us in the direction of the video as it answered some of the questions I had floating around in my mind.

A few more beginner(me!) questions :-
Does the software supplied give you an estimate of the amount of resin that will be used for the print ?
Does the print time change if you put 4 servo mounts on the design at once ? Maybe the answer is obvious and I haven't thought that one through
Is there a chance of distortion when curing the parts with a lamp ? There was a mention of window ledge/sunshine possibly causing issue but presumably a proper lamp setup would work fine.
When the mount was being cut off the cutters made a noise that suggested the material was quite 'hard' - unlike what happens if you cut a C&L chair off the sprue. Will the resin be flexible enough to grip the rail if used for chairs - time will tell on this one I guess?
If you just chairs this way is it likely there would be a suitable adhesive to bond them to ply sleepers?
My only use of 3D parts so far has been wagon buffers from Shapeways used to replace poorly shaped ones on kits and the quality of the parts and ease of use was fine.

As a final point - is there a possible intention for a library of chairs/baseplates/etc to be made available for use by Templot users. It doesn't make much sense for several people to be working away on a design for the same item.

Rob

Hi Rob,

Beware servos. They seem to have a sort of digital interface but it's really just analog. They are susceptible to drift and interference. Despite my great antiquity I do have some understanding of how these things actually work (or fail to work) but rather than try to explain that I've come to the conclusion that I might as well bash my head against a brick wall, a lot, and repeat.

Andy

 

[Charles Orr]

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

 

[Charles Orr]

I also have a complete Prusa SL1 system on order to add to my Prusa filament printer.

 

[richard_t]

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....

 

[Martin Wynne]

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:

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.

 

[Martin Wynne]

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.

 

[AndyB]

The printer arrived today, two days earlier than expected.

 

[AndyB]

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.

​

 

[AndyB]

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

 

[Martin Wynne]

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.

 

[AndyB]

Hi Martin,

The SG of this stuff is between 0.79 and 0.81 and it is not colored. $12 a US gallon. I'll give it a shot.

Cheers,
Andy

 

[Rob Manchester]

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

 

[John S]

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

 

[richard_t]

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.

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

 

[Martin Wynne]

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.

 

[richard_t]

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.

 

[Martin Wynne]

Hi Richard,

Files received. Now the fun begins...

Martin.

 

[richard_t]

From the old Templot Club, this is what the S1 chairs looked like from Shapeways (7mm):

https://85a.co.uk/forum/view_topic.php?id=2734&forum_id=6&jump_to=25126#p25126

 

[Martin Wynne]

All set up and ready to go:

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.

 

[AndyB]

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

 

[AndyB]

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.

 

[Martin Wynne]

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.