Friday, July 17, 2020

3D Printing - The Resin Printer

I've been struggling with my resin printer this week, trying to get it so it prints as well as it should.

In case you're interested (of course you are, you're reading this) I picked the Epax X1 instead of the more common, less expensive printers. I wanted the functionality that's built into this one and has to be tweaked into the others.

Pretty, ain't it? This one is solid metal construction except for that UV resistant orange plastic window. It's a heavy little beast.

The main reason I hadn't started on this when I bought it was that I didn't have the space set up for it. This involved A Process since I was replacing an existing plastic shelf set with a new shelf set for this. That meant emptying the old shelves, finding a place to put them, setting up the new shelves, making sure that one of the spaces was large enough to hold the printer, then putting stuff back on the shelves. Oh. I also had to mount the battery backup/UPS on the wall once I knew where things were going to be.

I finally bit the bullet and did all the reorganization. The new shelves weren't as tall as I had hoped and I'm very short on space so I - ahem - acquired the pieces to make it one level higher and all was well there. These are nice sturdy metal wire shelves and I put a piece of fiberboard (ok - it's a dollar store clipboard but same difference) under the printer for stability and also put it in a tinfoil pan in case of leaks. These printers don't move as much as the other kind since it the print bed goes up and down, slowly. There's no lateral movement. Cool.

There's a bit of a process in getting files ready for printing but I won't go into that. These printers don't allow me to throw on a print server so I have to keep shuffling the USB stick from the computer and back. Someone in the Epax Facebook group brought up the good point of how USB ports can wear out with use so I ordered a short extension cable so I don't have to fumble around for the port.

Oh yes. Gloves. Now is not a good time to be looking for nitrile gloves. Everyone wants them, no one has them. Harbor Freight's price has doubled due to supplier price increases, when you can get them. Nitrile gloves are required because the resin is pretty nasty stuff until it's cured. So when you're working with the printer you're wearing gloves. They have to be nitrile because the resin will very quickly eat latex gloves.

The way this kind of printer works is with UV light. There's a panel under the vat that shines light in the pattern for that layer to cure the resin. The printer moves the plate up so resin can flow back in, then down for the next layer. And so on and so on. This makes print times the same no matter how many objects you have on the print bed, unlike the other kind of printer. Nifty. Even if the print bed is much smaller.

Technically you can cure prints in sunlight. It's got all the right wavelengths. But that's a dicey process and difficult to control. So of course it's back to Amazon for the pieces for a cure station. You can buy fancy ones but I stuck with getting the lamp and a small solar powered turntable. A little work in a CAD program, some time on the other 3D printer, some tinfoil, and I had a curing station. Everything is covered in tinfoil - the foamcore I'm using for a base, the table on the turntable, and the interior of the curing station. I dug out a plastic container that fits inside for curing parts underwater. Trust me, it's just better to do that than cure them in open air. Something about oxygen saturation on the surface.

So. Ready to go. Right? No.

Resin printing involves post processing. In nitrile gloves. That means removing the excess resin off the print surface before curing it. It also means removing supports that you put on it so it would print. The resin print is pretty soft prior to curing which makes support removal easy - nip those suckers off and use a craft knife to scrape off the support point nubs. So prints get dunked into solution, supports removed, cleaned, then cured.

I'm using Simple Green to clean my prints rather than isopropyl alcohol. Turns out it works well, based on the anecdotes in the group and some videos on YouTube. I have two (dollar store) containers - one for the first soak then a second with clean solution for the scrub. That first one gets nasty FAST. Most people have an ultrasonic cleaner but for now I'm using a toothbrush. I'm debating about getting an ultrasonic cleaner.

Dunk, remove supports, scrub, rinse, scrub, rinse, into the curing pot. Then and only then do you have a finished print. Yay!

Except that you need to fiddle with the software settings in the program that converts the file to something the printer can understand. There's only two settings of note - layer thickness and how long to expose each layer to UV light. That's where calibration comes in. It's different for each brand of resin too so you don't get to just do calibration once.

I've been calibrating. And calibrating. And calibrating. The default settings that come with the printer configuration file are for 0.05mm layers. I wanted to push that sucker down to the limits of 0.02mm layers. Yes. The thickness of a human hair or slightly less. So I carefully read up on how to calibrate and got started.

These are all calibration prints. They're all failures. There's three kinds here.

Left - The AmeriLabs Town print. This has all kinds of different things to show how well your printer as a whole is working as well as if your layers are under or over exposed. Or just right.
Center-ish - The Resin-XP-Finder is something that prints quickly and has again a lot of little bits to show if your print is under or over exposed. Print, check, change setting, slice, print, check, etc.
Right - Another part of that Resin-XP-Finder is this seemingly flat piece that shows what happens with different exposure times. It's a boring piece to see but it helps you see how many seconds will give you the best starting point for calibrating.

I've also got piles of not-good prints that I thought would turn out better than they did. They're nice but they're not the detail that I bought the thing for. I would think I had it tuned. I would print. I would be disappointed. I would go back to calibration.

I'm back at the default of 0.05mm layers since at that level of detail there's no difference from 0.02mm unless you're looking at jewelry masters or dental pieces (yes, they have an adapter so it can print dental stuff). Some of the calibration pieces to the far left are at that level. And I was getting close!

I decided to print some small items since they don't use much resin and I could see how the detail turned out in the real world. I chose the familiars from Mia Kay and got them all prepped for printing. That's when it started. The print failed and I had stuff stuck to the film in the bottom of the resin vat. Did I not mention that the bottom of the resin vat has a film for the light to penetrate and 'hold' the layer while it cures? Well. That can backfire and pieces stay stuck to the film rather than the print bed.

Long story short (too late!) I ended up putting holes in my film. I'm cleaning off cured resin from the LCD screen and the printer comes with a replacement film. They're considered consumables and I ordered more so that I could have them on hand when I need to replace one. Tonight I emptied the vat and am getting the cured resin off the LCD. Tomorrow I'll put in a new film and see if I can print something to check out the detail.

Honestly I'm frustrated that it's taking me this long to get the exposure time right so I can print stuff. I see the prints everyone else is getting on their resin printers and I see mine. I'm not happy. The holes in the film are something I may or may not have been able to avoid until later. It's part of resin printers to have to replace those films and now I'll have done it so it won't be upsetting to me to do it again. Annoying, but not upsetting.

Would I recommend a resin printer? Sure. If you're looking for very fine detail and no layer lines then you need a resin printer. Would I recommend this resin printer? Sure. If you want something that comes calibrated out of the box and is a sturdy, supported printer and you can afford it buy this one. And lots of nitrile gloves.

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