3D Printing - whether to buy, what to buy and how to use it?

[Mike Trice]

This time of the year temperature can be important. Make sure machine is in an area over 20 degrees centrigrade. When this has not been possible I have used a heat gun to heat the inside of the machine and resin vat immediately before printing. Good luck.

 

[simond]

Thanks Mike,

it‘s in my daughter‘s bedroom, next door to the airing cupboard. It’s warm in there, even with the central heating off

 

[Boyblunder]

The protective layer on the new FEP caught me out with the previous printer, it was so fine I couldn't see it. If not done already you could also give the build plate a wipe with acetone as it is new. Several web gurus suggest it helps and I haven't had any non-adhesion failures since trying it.

 

[simond]

Thanks Robin, I already cleaned it with IPA, but I’ll try the acetone.

frustrating. I removed the protective films from the FEP and lcd screen, but I didn’t see this one.

ho hum.

 

[simond]

We’re not quite there yet, but attempt #2 is quite rewarding. We’re on the learning curve!



So the Sandgate Signal Co logo is legible, the resolution is impressive, the rear cover is about 6mm x 12. On the other hand there are things that are not as good. The upper surface, that nearest the build plate is generally lumpy on all the parts, even when the supports are removed. Need to understand what’s going on here.


and I obviously made the sides of the signal heads too thin, see-thru thin!

The lower surface has some striations, fine parallel lines, on the signal bases, these appear, though less obviously, on the toolboxes for the match truck. These also have the lumpy surface, perhaps I should have printed these parts hollow, but they‘d have been bathtubs, full of resin. Maybe a drain hole on the not-so-visible face.


Miles from perfect, but this shows promise.

 

[JimG]

On the other hand there are things that are not as good. The upper surface, that nearest the build plate is generally lumpy on all the parts, even when the supports are removed. Need to understand what’s going on here.

Simon,

I get that on any surface parallel or near parallel to the build plate and facing it. I assume that it is caused by the resin not draining off the surface and collecting around the supports, and that excess resin is partially set by stray UV. I either accept that happening if I can accept filing or sanding the problem surface after printing. Otherwise I tilt the part to avoid excess resin build up, or I re-position the part on its side.

Jim.

 

[mickoo]

Simon,

I get that on any surface parallel or near parallel to the build plate and facing it. I assume that it is caused by the resin not draining off the surface and collecting around the supports, and that excess resin is partially set by stray UV. I either accept that happening if I can accept filing or sanding the problem surface after printing. Otherwise I tilt the part to avoid excess resin build up, or I re-position the part on its side.

Jim.

What Jim said.

Accept that the surface closest to the build plate will not print well, this is your sacrificial face, I keep banging on about this, make this face the one with no detail that can be sanded smooth, if your object has no natural sacrificial face....redesign it so it does.

Most people want to print the whole object as one piece, it's natural after all, that's what 3D printers are good at, well they're not, wholly.

Don't be afraid to break down the object to give you good fixing faces that can be sanded back, make yourself mini kits so to speak.

The angling of your parts is way way too shallow, you're going for speed (understandable but naive) and it's giving you layers (steps), you can work it out mathematically the correct orientation to reduce the steps but generally speaking (each machine is different and resin temp as well as type of resin has an impact) you want to be in the 30-40° range.

As an experiment I tried an area with no supports, a large flat surface that traditionally requires supporting, it printed perfectly flat, smooth with no resin residue and no warping, I've not worked out is that's just pure luck or something more exciting. I have read reports of folks who support less but with slightly larger supports, there may be some mileage in that in certain circumstances.



Shallow angles is a fools folly, yes it prints faster but it ends up layered so it's only going in one place, the bin; thus you have to print again and guess what, no time was saved at all. When you hit the sweet spot the surface will merge all most perfectly smooth, however, be aware, it'll only ever be perfect for one maybe two surfaces, therefore make your best surface the one at the optimum angle and deal with the rest post processing.

Post processing, why? It's a 3D printer, prints are perfect, not so as noted above, try to get away from achieving perfection, it's a stress full road and guess what, when you do hit that sweet spot I'll bet a round of drinks the next time you print the exact same object it'll not be perfect.

Factor in post processing (any smoothing or support removal) during design and orientation, after all any lost wax or white metal casting we've used in the post needed post processing, why should 3D be any different.

Here's the Garratt bunker split down, red arrows point to sacrificial faces that can be sanded smooth and allow the part to have perfect orientation for printing. Most people would try to print something like this in one hit or maybe break it down in to two parts, in fairness the front coned section could be merged with the front access section with little detriment.



It's along road and folks can give you all the advice you need, more than you need, but I've found the only way to go forward is just keep grinding away and as Rob once famously said, get a bigger bin, you'll need it

perhaps I should have printed these parts hollow, but they‘d have been bathtubs, full of resin.

Yes it will, but is that a bad thing, detrimental to the print or worth concerning yourself over

Put another way, I almost exclusively print hollow structures (see drum image above with three hollow objects with a closed end) and in the same orientation, you've seen the results, even with just two dots I'm sure you can join them up

 

[simond]

Jim, Mick,

thanks for your patience, kind encouragement, and for sharing your experience.

I had come to the conclusion that Jim had confirmed about resin not draining, and I understand the layering issues, I hadn’t turned the wick up (down?) and it’s currently set at the default 50u, so there’s room for further adjustment there too. I’d started with shallow-ish angles on the parts, and I’m delighted to have actually printed something, even if the parts I’ve made are indeed going in the bin. Hopefully attempt #3 will result in something useable.

I’ll not dwell on the match truck, as previously noted, I know the cad is incorrect so there’s no point in splashing resin on it. When the CAD is right, hopefully sometime next spring, I’ll do it again.

I have a humongous list of things to print, so I guess it’s CAD time…

 

[michael080]

there was a hardened layer on the FEP, so it had been trying.

call it steep learning curve and everything will be good.

I had a similar situation and noticed that my reservoir was full of semi-hardened chips from layers that didn't stick on each other. It was really messy and I had to filter my resin to get rid of these chips. It might be a good idea to get one of these cheap washbasin sieves to clean up your resin. Just in case ...



Michael

 

[simond]

I bought a pack of fifty filters when I bought the machine… I’ve used two so far. I might be being a bit precious about it as there was no suggestion of miscellaneous extraneous bits in the second run.

might get a run of something else later today, maybe tomorrow. Gutters, rainwater goods, cowl vents, chimney pots…

vices, radiators, axleboxes, springs, buffer stocks,…

it would be good to have a couple of runs’ worth of CAD prepared as that would mean one less clean up.

 

[Arun Sharma]

Simon - If you ever need to rummage around in the contents of your resin tray, you will need a funnel with a very, very fine filter mesh if you plan to pour resin back into the bottle. I suggest something like this - 11cm dia with a removable filter plate - I reckon the holes are about 0.3-0.5mm so should stop any solid bits [such as broken supports] from reentering the system.
I suspect a major cause of upset to the FEP is when a support gets broken and the descending build plate pushes it into [or even though] the FEP where it then solidifies on the LED screen. Which is why the printer companies actally sell new LED screens and why videos of them being installed exist on YouTube.
Amazon sell this rather useful piece of kit:

 

[simond]

Thanks Arun,

I took a chance today and poured the unused resin back into the bottle unfiltered. I could see no issues with the print so maybe it was a good call, and maybe not…

the printing was rather fun. I’ve spent a bit of the day trying to draw up axleboxes and springs, not quite there, but making progress, meanwhile chimney pots, radiators, signal heads, and Daisy.

I also drew up a chimney breast for a signal box which I bought from Larry G when he downsized. The inspiration was The Broadway Signal Box

I'm rather pleased with the outcome, though on reflection, I estimated it a couple of feet too wide. I doubt I’ll reprint it.



time for a lick of paint

 

[michael080]

I reckon the holes are about 0.3-0.5mm so should stop any solid bits [such as broken supports] from reentering the system.

Interesting. The Formlabs resin would take a week to go through these holes. It took already ages through the sink sieve I proposed above.

Michael

 

[John Baker]

The prints look great Simon! When filtering rising back into bottles, I use paint filters like these.

 

[simond]

Thanks John, those are identical to, though cheaper than, those I purchased.

 

[Arun Sharma]

Interesting. The Formlabs resin would take a week to go through these holes. It took already ages through the sink sieve I proposed above.

Michael

That is interesting - I've only ever used Elegoo water washable print resin - It runs through that mesh quite easily. Perhaps the water washable resins are less dense than the IPA-soluble ones?

 

[Big Train James]

I'm going to guess that the Formlabs resin is the outlier? The Siraya Tech Fast goes through the paint filters without issue.

One other option for cleaning bits out of the bottom of the vat is the cleaning tool built into the Elegoo printers. Or at least it's built into the Mars 3. I'd be surprised if it's not available for the Saturn as well. In the "Tools" menu on the printer, there is a button to "Clean" the vat. It does something like a 15 second exposure of all pixels, resulting in a thin mat of cured resin that should include any extra bits. One caveat is that it will only absorb things that have settled to the bottom of the vat. Anything still in suspension may be missed.

Use care when peeling the thin slab of cured resin off the fep, to avoid damage. It's not as dangerous as it sounds, once an edge is started, the cured sheet peels off easily. And any incidental damage of the fep sheet occurs at the very edge of the printing area, a place which you will probably never use anyway. Allow excess resin to run off the cured sheet, then cure the sheet as you would any other print. Up to you whether to clean the sheet before curing, it's all waste no matter how you slice it.

Otherwise, I would recommend filtering the resin anytime it's placed back in the bottle. It's just a good practice.

 

[simond]

A further thought re the prints I did yesterday.

A white-ish deposit is visible in a few places, notably around the bottom of the signal heads. My guess is that when I washed the prints, they were not fully dry before curing, and this is the result of curing a thin layer of very dilute resin solution. To be fair, the instructions do warn not to do this.

I need to find some space to leave prints to drain over a drip tray. I guess if I were doing this in the factory, I’d blow the prints dry with an airline.

 

[simond]

Right, anything to do with what I'm doing with the printer will be on my workbench thread, whereas if it's specifically to do with the printer or the resin or filters or printing, I'll stick it in here. That way this thread can remain a resource for others walking this path, I hope.

Please do contnue to add your thoughts, experiences, purchases, disasters, etc,

 

[mickoo]

A further thought re the prints I did yesterday.

A white-ish deposit is visible in a few places, notably around the bottom of the signal heads. My guess is that when I washed the prints, they were not fully dry before curing, and this is the result of curing a thin layer of very dilute resin solution. To be fair, the instructions do warn not to do this.

I need to find some space to leave prints to drain over a drip tray. I guess if I were doing this in the factory, I’d blow the prints dry with an airline.

More as likely not fully washed, you're using Siraya Tech Fast Navy Grey (FNG) it has a habit of separating really fast, typically six hours so it needs stirring well before use, you'll find a thin layer of white on the FEP that needs to be scrapped up and mixed before use, the plastic scraper is good for that and you have to be a real animal to damage the FEP with that scraper.

You may find your resin wasn't fully mixed before use or you may find the resin has split down whilst it was sat in the machine, I've done late run prints over night that then sit on the build plate until I get up, easily over six, sometimes even eight hours, if the part is suspended and has a small cavity with resin sat in it then the white will migrate to the bottom of the puddle over time.

You can either wash in IPA in a small ultrasonic cleaner (rather than fill the cleaner with IPA pop the part in a small pot with IPA and float the pot in the US cleaner....failing that I've used zip lock bags with bits and IPA in....shades of fairground goldfish scenario....and floated in the water) or if you're lazy like me (raining outside and US cleaner is in man bunker), just use a small paint brush and make sure all the excess resin is out of the small cavities by washing/brushing with IPA.

If you use fresh IPA it should dry in seconds, maybe a few minutes max, I always brush mine and blow to aid drying, the brushing I find helps tease the soft skin resin into a smoother surface and partially reduce layering......but I didn't say that out loud.

The older the resin the longer it takes to dry, some folks let their used IPA sit so the resin sinks to the bottom, drain and reuse the liquid, I've never had good results doing that and parts feel tacky after washing in the 'cleansed' solution but other folks mileage might vary.