Messin' With Resin - 3D printed track

[AndyB]

Hi Martin,

Based on a bit more digging I think you are correct. I'll probably give it a shot without supports for no other reason that it will simplify things if I can get away with it

The printer is "warming up" now and I'm thinking of giving it a go tonight. Stay tuned!

BTW, the rubber gasket for the lid won't stay put on mine. It's a bit too big. I might just apply a bit of RTV but I should probably ask for a new one.

My Ultra Violent light won't be here till Monday but it's supposed to be sunny here tomorrow which might be sufficient to cure something assuming it does not go in the bin first.

Cheers,
Andy

 

[Martin Wynne]

BTW, the rubber gasket for the lid won't stay put on mine. It's a bit too big. I might just apply a bit of RTV but I should probably ask for a new one.

Mine seemed to be the same. But after getting it on and firmly pressed down all round it has stayed on, and seems to have tightened up after a few hours. Or at least it hasn't come off after much handling of the lid.

I'm a bit puzzled why your lid needs a rubber seal if you don't have the air purifier option? The lid for the washer doesn't have the seal, but is otherwise identical and interchangeable. With IPA sloshing about inside, I would have thought it could do with a seal too.

cheers,

Martin.

 

[Martin Wynne]

The Elegoo build plate is 140mm x 80mm.

The longest standard timber is 19ft-6in, to reach across a double track crossover at 6ft way.

That's 78mm in 4mm/ft scale, so will just fit width-wise if you get the model precisely centred on the plate.

And 136.5mm in 7mm/ft scale, so will just fit length-wise if you get the model precisely centred on the plate.

Elegoo seem to be telling us something by giving the build plate an aspect ratio of 7:4 .

edit: forget that, the exposure screen is only 129mm long.

Martin.

 

[AndyB]

Yikes! It worked. I think the small amount of "flash" is a consequence of not elevating the first layer above the build plate. Uncured as yet. Will it survive insertion of the rail after curing? Stay tuned for further exciting episodes of "Track: Have it your way."

 

[Tom Allen]

regarding the "flashing", count how many initial layers are over exposed and draw this section smaller on the model.

 

[Tom Allen]

All set up and ready to go:

View attachment 524

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.

A good addition to your setup would be a shallow baking tray, and sit the printer in the tray making sure the tray is at least twice the size of the printer base. It's really easy to drip resin, and an absolute pain to deal with.

 

[Tom Allen]

Also spills of resin which will happen, trust me, however small need to be dealt with so plenty of heavy duty kitchen towel will be needed. I'm quite lucky and i seem to be pretty safe when it comes to "resin on the skin", but i have seen some really nasty reactions to resin. So nitrile gloves seem to be the safest way to go, but be brave and try a bit on your skin, you may be ok. I went through a whole box of gloves before i realised it does'nt bother me.

 

[Jim Guthrie]

Martin,

It's worth trying building directly on the plate even with smaller items like chairs. I've printed spoke centres for wagon wheels in S scale directly on the plate and they worked well. I reckon that the surface area of a split spoke centre of a wheel in contact with the build plate would be close to that of the base of a 4mm scale or S scale chair. This would also mean that the base of a chair was flat - printing a chair up on supports could mean having to treat the base of each chair printed to make sure they are flat - depends how the chairs are orientated. It might be worth a bit of experimenting, taking care to clean out your resin tank if something has dropped off.

I find that a roughened surface to the build plate helps to keep parts stuck to the plate. My first printer - a Phrozen Shuffle 2018 - was supplied with a build plate already roughened. My present printer - a Phrozen Sonic Mini 4X - was supplied with a smooth build plate but the accessories supplied included a small sheet of coarse sand paper if you wanted to roughen the plate's surface, which I did. What's really important is that the build plate is flat. There are occasional reports of plates being warped on new printers out of the box so if you have continual problems with parts not sticking, it's worth checking this.

The metal scraper to get parts off the plate needs to be really sharp these days to get things off the plate. The rafts on my 2018 printer were relatively thick which allowed a fairly sharp scraper to get under the lip created. But my current slicer produces much thinner rafts and therefore a much smaller gap under the lip and the metal scraper I have won't get into the gap. So I use a Stanley knife blade to get under the corner of a raft and lift it a little, then the metal scraper can get under that edge and remove the whole part. A sharp wood chisel would also do the job. The metal scraper can mark the plate sometimes but no worse than the sandpaper.

As you get experience, you will probably find that the key art to master in 3D printing is orientation of the part(s) and placement of supports.

Jim.

 

[Tom Allen]

Agreed on the build plate being roughened a bit. The print is always trying to stick to the FEP, it's just the natural order of things, so we have to coax the print to favour the build plate. My printer is an original Photon, and after a while i sanded the build plate which made a considerable difference, but it did have a downside, the print was a lot harder to remove.
Important rules, level the machine well, then level the build plate even better, the more time you spend getting the build plate correct the better the resuts. I've adopted the four corner approach, rather than one sheet of paper, far better.

 

[Matt M.]

Hi Tom,

Just because you don't have a reaction to resins now doesn't mean you won't develop one.
Sensitisation is an issue.

I know someone who built 1/43rd model cars for living. Never had a problem till he did.
Coughing up blood and such other joys. Ended up working in a book store.
Can't do modelling with any form of plastics and glues.

Keep your gloves on and the liquid resin off your skin. Avoid breathing the fumes.
When working with the finished product control the dust and don't inhale that either.

Regards, Matt M.

 

[Tom Allen]

Thanks Matt, it is always better to be safe.
As an old engineer my hands have taken a fair bit of rough treatment over the years, and once when a new type of coolant was tried out and ending up attacking everyones hands, i seemed to be quite immune to it.

 

[Charles Orr]

Hi Martin,
Some of the YouTube reviews for this printer say not to bother with the plastic tool but use the metal scraper to remove parts from the build plate.

Inspired by your enthusiasm I have a set of similar items arriving from Amazon shortly including a Mercury Plus Wash and Cure unit and the 2 Pro printer.

Charles

 

[Matt M.]

No problems Allen. I worked in the sign and display industry for a number of years,
before and after leaving school, and have seen some poor outcomes for long
term workers. The automotive industry, which I spent 10 years as a spare parts
interpreter, has had some fails as well.

Build up of toxicity seems to be an issue so I have always played safe.
Keeping all of it out of your lungs is a big one.

Matt M.

 

[Martin Wynne]

Keep your gloves on and the liquid resin off your skin. Avoid breathing the fumes.
When working with the finished product control the dust and don't inhale that either.

Hi Matt,

Thanks for the warning. I find wearing gloves very uncomfortable and make my hands sweat.

Is this stuff any good against the resin? I've always used it for engineering jobs, degreasing, etc., and never had any problems:

https://www.toolstation.com/rozalex-dri-guard-barrier-cream/p80597

Martin.

 

[Martin Wynne]

A good addition to your setup would be a shallow baking tray, and sit the printer in the tray making sure the tray is at least twice the size of the printer base. It's really easy to drip resin, and an absolute pain to deal with.

Thanks Tom.

Now installed in the biggest baking tray I could find. I couldn't get the tray to sit flat on the shelf, so I have used a bit of sponge rubber mat under each corner of the tray. Which has had the beneficial effect of damping the noise from the printer fan.

It meant re-levelling the printer by fiddling with the adjustable feet all over again, but I got there in the end. It's always a pleasure to use my grandfather's engineer's spirit level.

I may perhaps return the Bibo to where it was before, and gain more working space for the printer. Time will tell what's the most convenient arrangement.

cheers,

Martin.

 

[Martin Wynne]

Yikes! It worked

Hi Andy.

Well done, looks great.

How thick are those sleepers and webs?

Martin.

 

[Martin Wynne]

I find that a roughened surface to the build plate helps to keep parts stuck to the plate.

Hi Jim,

Thanks for the tips.

The Elegoo build plate is supplied ready sand-blasted. It's dead flat end-to-end, but fractionally convex side-to-side. Only by a couple of thou, so not likely to be a problem.

For my intended design, it doesn't matter if the base of a chair is not dead flat, the base clearance leaves space for some glue, although I'm hoping I can make them clip-fit:

On the other hand, the base plug needs to be a precise dimension without any flash, so will probably have to be done on supports.

I have a cheapo window scraper, which is just a Stanley-type blade in a plastic handle, but works fine on the Bibo.

The supplied Elegoo metal scraper is a good quality with a ground edge and polished blade. I'm surprised at the quality of the tools supplied with the Chinese machine. The Allen keys are ball-ended, and the genuine Xuron snips will come in very handy.

cheers,

Martin.

 

[Martin Wynne]

Inspired by your enthusiasm I have a set of similar items arriving from Amazon shortly including a Mercury Plus Wash and Cure unit and the 2 Pro printer.

Hi Charles,

Great! Between all of us we should be able to fathom this thing out.

cheers,

Martin.

 

[AndyB]

Hi Andy.

Well done, looks great.

How thick are those sleepers and webs?

Martin.

Hi Martin,

The sleepers are drawn 1.10 mm thick but measure 1.0 mm. Webs drawn 0.60 measure 0.56.

When I cured it in sunlight the sleepers bowed slightly. Up at the ends. IIRC the resin does shrink a bit when cured.

The chairs support the rail quite well and I have not managed to break any yet. The gauge is 0.1 mm narrow, but that might be my drawing. (It was originally a test panel for my filament printer.)

Don't do what I did. I left the resin in the vat/tank and covered it with cling-film. It developed a skin like custard overnight. I managed to get it off but punctured the FEP in the process. Fortunately I already ordered some FEP and it should be here tomorrow.

Cheers,
Andy

 

[Tom Allen]

resin can be left in the vat for days with no harm coming to it, as long as your cover is uv proof. If you're not sure cover the printer with the box it came in or a heavy duty garden quality bin bag, i've done both.
There are many subtle things to watch out for with resin printers, joining a model specific facebook group or forum will be a good start.