Consumer FDM printers
So I've had a "normal" 3D printer for a few years - an UP Plus 2. It works just fine - in fact better that all my friends' 3D printers which always need to need adjustment or repair. This one just print when I want it to and does a fine job. Like most domestic 3D printer it work by a method called Fusion Deposition Modelling (FDM). It quits out a line of melted ABS or PLA filament and it solidifies just quickly enough to form the shape you want.
Other types of 3D printer
However, this still didn't stop me wondering about the other sorts of printers out there. There are a few different interesting types. There's Selective Laser Sintering (SLS) which uses a laser to melt nylon (or even titanium) powder back into a solid lump. There are printers like the Objet series that inkjet print a resin that's then UV cured. Other models inkjet print a binder and maybe colour onto a powder base. There are a lot of different types but the majority of them are up about £10,000 if not £100,000. They may be great but they're the sort of thing you might buy if you're running a 3D printing business or your company manufactures and hence prototyping something very special and expensive.
For the hobbyist the next real alternative you might be aware of is SLA printing. I stands for Stereo Lithography although to be honest I have no idea why. The name you'll probably think of is Form Labs and their rather nice Form 2 printer. This uses a laser which is steered by a mirror to draw on a layer of UV curable liquid resin to solidify it. It's nice. It's a few thousand pounds/dollars. Worth it by all accounts, but that's a bit above the budget that I can justify - both to myself and definitely to my wife! Form Labs also plan to make the Fuse - probably the most affordable SLS printer at around £10,000 (plus maybe the same again for the cleaning station).
So there's one more option left for the hobbyist. Instead of a laser and some mirrors, how about just using a big fat UV LED shining through a monochrome LCD screen to cure your layer of resin? DLP printers were born! The LCD screen means the print area is a bit smaller than SLA. The resolution might be a bit less but is still great. The UV LED is a bit less bright than a laser so the resins need to be a bit more sensitive. The price? Some of them come in at around £500. Now that I can justify!
The two I narrowed it down to were the Wanhao Duplicator D7+ and the Anycubic Photon. When I saw the opportunity to snap up the Photon for £350 on eBay that was it. I'm in. There's a German seller that pops them out regularly for about £400 or so.
Now there are a few things that you need to know about DLP printers if you're used to just melting some ABS. These things also apply to SLA too.
- The resin is expensive. It cost about £40-£60 per litre. That's a fair bit more than filament for you FDM printer.
- The resin is smelly. Some people really can't stand it. You definitely won't want to be printing in the house.
- The resin is sticky. It's like honey. Or used engine oil. No matter how careful you are, some of it it will get on stuff.
- The uncured liquid resin needs to be washed off your print when you're done. In IPA which is also smelly.
- You need to give it a final blast of UV when you're done - either a UV lamp or even some sunshine.
As you can tell, it's all about the resin. I must admit I'd read up on this and was expecting it to be awful. However, I found that if you print in the garage and have a few paper towels to hand then it's not all that bad.
The Anycubic Photon
So. The printer arrived. It was good quality and well packed. All in all, better than I was expecting for the price. I'm impressed. I won't do an unboxing and I won't go into a detailed review. There are plenty of other people who have done that on YouTube. No point duplicating their excellent efforts. I'll just let you know what I found that fills in some of the gaps.
It comes with 250ml of translucent green resin. Great to get started but it won't last that long. I bought 3 x 1L of cheaper FunToDo resin. It had good reviews with the Photon. There's a spreadsheet of other people experience and settings which helped a lot. All the different resins worked just as well as I was led to believe.
I've only had one failed print so far which was caused by (I think) the Z height not being quite right and the model ended up flattened on the bottom of the VAT. No dramas really. The only issue I have is that it can be 2 hours before you can tell whether the print is working out. I since discovered that you can pause the print and it will be lifted out of the resin for a quick check. I'd recommend that you do this early when it's printing the raft and support if you want to check if it's stuck OK. It's shouldn't mark your print if you do it part way through as teh piece is lifted off teh bottom of the VAT for each layer, but I tended not to.
Every bit as good as you'll see in the review videos. If anything it's better in real life. No arguments here. Prepare to be amazed.
I'm not a figurine maker; I normally want to print a structural part that fits with something else. One thing I was concerned about is whether the dimensions come out as expected - especially when I saw figures like 3.5% shrinkage. What? That would be unusable! It turns out that the dimensional stability is excellent. Everything I printed came out the size I expected. Definitely as good as FDM prints if not better, I believe that figure is for volume not length, and seems high even for that.
Supports and orientation
Once again this is covered well by everyone else. The support looks similar to FDM support but is there for a different reason - to pull the partially finished print off the bottom of the VAT for each layer. Once you get this it makes sense.You're generally not supposed to print large flat pieces as these stick to the VAT. I found you could if you're sensible and think about it. Too much force can warp a still soft print midway. As can prising a raftless print of the build platform. I won't try to explain it in detail. You'll get it with some practice.
The piece shown printed fine in both orientations, once support had been added to the one on the left. The left one is how you're recommended to print things to avoid to much sticking from that large flat area.
The are many types of resin, including castable and flexible but I can only comment on the properties of those I used. I tried printing some gear bearings that have worked well for me on FDM printers. The finish was amazing, but the gears were fused together. Even after adjusting the gap a bit they were fused enough that as I tried to free them up the whole thing shattered. I don't think resin printing is ideal if printing parts close to each other. Strangely, as I put the broken outer ring under UV to fully cure, it welded itself back together.
The resin can also be a bit brittle. I printed a custom dash blank for my van and whilst inserting it I flexed it too much and it broke. Apparently it will continued to be "aged" by UV so I can imagine this only gets worse. I have seen painting recommended. The surface of the black resin is also a bit prone to showing up whits scratches.
There are quirks to resin printing. If you know what to expect then it can be really amazing.