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Maybe these monomers could be mixed in right before printing, to allow gradual change of material properties in a single print?
To some extent, gradual change of material properties can be achieved with software (by gradually changing infill density, for example).

Otherwise, mixing filaments to combine them in real-time is already a reality in desktop 3D printing[1].

[1]https://www.mosaicmfg.com/products/palette-2

I'd even be happy with a single filament that gets UV cured by a light source on the print head.
Rather than more effective, I'd wish 3D printing were faster. My main grip with 3D printing stuff is the time it takes - and, depending on the printer, the noise it makes.
SLA printers are considerably faster and quieter, but the resins used are also much less safe than a spool of PLA (noxious fumes, gloves requried), and the post processing is more of a hurdle. I think FDM is already incredibly fast though, considering the achievable quality, precision, and ease of creating a single instance of something.
I think a novel resin that was safe for humans and safely disposable/biodegradable would be huge transformationally for home 3D printing. That might get the speed to a point where the average person would tolerate one.
The printers also need to get less fiddly for the average person. Things like setting the bed temperature, print head temp, fan speed, etc and watching the first couple layers to make sure they don't curl up on you. And those settings change with different brands of filament, and it is hard to tell which one to change and in which direction.
They sell printers which “solve” that problem by locking you in to one type of filament.

I would love to see automatic print failure detection (with a camera, even a micro camera at the nozzle).

Figuring out the correct settings for unknown plastic seems like it would be hard to solve, but perhaps there’s some base material properties that could be determined automatically which might help. I’ve noticed that the Prusa 3D printer software has a sizable database of filament brands in its material settings section. I’d be curious how foolproof those settings all are for each brand of filament. But of course a manufacturer could change formulation at any time...

I solve this problem by only buying one of two brands and keeping custom settings for them.

I started my career in CNC machining. People always thought that meant software did everything for me, but no I had to choose tool sizes, spindle RPM, feed rates, depth of cut, etc. The CNC is not a magic machine that makes parts for you, it’s a tool. So I guess I’m a bit biased for thinking that current 3D printers are super useful tools that require a certain amount of operator competency. You cannot put any random filament in and expect good results, and actually that might be a hard problem to solve on the back end. Much easier to pay attention to what brand you order and feed in good quality stuff.

But idk. You’re right that they’re fiddly AF and I’m just used to it. If they could solve those problems it would surely help adoption.

This feels like the filament should come with a barcode that tells the printer all the requirements
There’s some printer-specific factors that affect ideal temperature settings. Hot end geometry varies by printer and can affect ideal print temperature. Also they used to often have inaccurate temperature sensing, though that is fixable and perhaps things have improved there. I don’t know how much these factors would affect things, but if the variance across products is too great, filament manufacturers couldn’t solve the problem with pre defined settings.

Other factors that affect print quality are: filament diameter consistency (must be very precise), absolute filament diameter (must be known), nozzle wear (changes over time), environmental humidity and air temperature, and air flow. Michigan, Florida, and Arizona might require different settings. And then part geometry matters a lot. Someone up the comment thread mentioned curling. This can happen even with perfect temperature settings if part geometry is not ideal. Once I was totally unable to print a large rectangular part without curling until I replaced the 0.4mm nozzle with a 0.8mm nozzle. The thicker layers eliminated layer delamination that allowed the curling.

It really takes a bit of learning and experimentation to get things working sometimes. It’s not a perfect process by any means.

>I would love to see automatic print failure detection (with a camera, even a micro camera at the nozzle).

You probably already know about it, but Spaghetti Detective is pretty decent at detecting print failures - although as you say it'd be great to have this built in (and more reliable...)

Hey I didn’t know about that! Seems interesting. Thanks!
There are tons of human-safe SLA resins, the dental industry has been doing this for years. Maybe I misunderstood your point.
That currently usually means safe after curing, you still have to handle the resin printing process with gloves and (?) ventilation.
Theyre generally safe post cure and finishing. But in liquid state and while printing they're not (the curing reaction can give you serious burns if left uncleaned) and the fumes are noxious
Body safe resins exist, but they’re $200/liter. I don’t know anything about the chemistry but I remember they said they were “monomer free”.

https://www.3dresyns.com/

But yes, a cheap undeniably safe resin (there’s no MSDS on cheap resins) would be a boon! The sticky toxic mess my SLA printer leaves behind is a real issue.

newer stepper drivers have dramatically reduced noise. There have also been some pretty dramatic speed improvements made with newer motion control systems like CoreXY and Delta.

its still several orders of magnitude faster and cheaper than sending a schematic out to a traditional manufacturing prototyping shop, at least for parts that are appropriate for this particular method of manufacturing

Yeah, just shipping alone takes longer than 3d printing.
Desktop 3d printing gives ~everyone the ability to have their CAD models manufactured into parts, practically for free, and with same-day delivery (for most things).

IMO it is a stunning success if your biggest pain point is around the delivery time of the parts.

(Not necessarily disagreeing with you - it would be better if the parts were made faster - just lending my perspective).

I learned CAD last year for work and my prototype turnaround times went from weeks to days to same day. Truly game changing for me. I can iterate an idea 5 times faster at least, not to mention hundreds of times cheaper (in some cases $800 part down to ~$5 part)

Even faster would be better, but print speed often isn't the bottleneck, solving engineering problems often is.

That said, of course faster would be better.

What do you do for a living? I am purely a hobbyist, I have a bit of CAD experience and think I would be interested to do CAD professionally but have no idea where to start.
Hi, sorry just saw this today. I'm self taught and invent things that I sell myself, so I'm not really sure about what getting into CAD for a larger business looks like.
"do you want done it quick, good, or cheap? pick 2"
Pretends that there is some sort of achieved optimum and you can only move to other optimum (at the cost of current gain), while often a different approach can very much both improve speed, quality and price. It's just something nobody explored yet (in the proper way).
The noise depends on the printer I suppose. The Prusa MK3i is really quiet.

My main gripe is with the weakness along layer lines.

How fast are you looking for?

Most consumer FDM printers are using 0.4mm nozzles. I've found that 0.6mm is more suitable for general use, and that cuts print time by ~50% - it lays down 50% more material, which accounts for a 33% reduction, but the fact that it results in fewer discrete motions accounts for the rest.

When I'm printing something bigger than, say, 100mm^3, I switch out to a 1.0mm nozzle. Larger objects generally don't require such fine detail in all dimensions.

As for noise, my primary printer is a modified Creative3D Elf CoreXY, and it sits about 5' from my computer. It's quiet enough that it doesn't interrupt my flow. TMC2209 drivers and StealthChop go a long way.

3D printing is awesome, but I fail to come up with any legitimate reason to buy one for myself.

And I really don't like the plastics used by them, it sounds like a new source of waste that is bad for the environment.

I don't want to shame anyone for buying a 3D printer, but I wish we stop inventing new products that just creates a new source of pollution (failed prints).

It's true, speaking from the current state of the 3D printing world. However...

As the technology matures I personally believe it will be a net positive effect. We will save on shipping, new materials will be more environmentally friendly, new printing methods will allow better control over colors, resolution, texture and multi-material printing. Plastic is not necessarily the only material - composites, ceramics, metal will become more available. 3D printing can likely also increase the reuse of products by increasing reparability.

Perhaps it will not be in the current form of 3D-printing. I imagine specialty or high end printing will be from local printing shops, like high end printing products are today.

I agree that such benefits could exist, but what I've mostly observed is just nerds 'playing' with their toys. That's a netto negative.

Plastics is certainly not the only material, but most people do use them. They are the cheapest.

I would like to see actual numbers (easy for me to ask, I know) to become less sceptical.

It's awesome tech, but I feel that at no point is the environmental friendliness really, genuinely part of the equation.

A "toy" wasting biodegradable plastic (made from maize) seems fairly low impact, compared to many other hobbies.

Just driving 20km round trip for any other hobby you care to name uses a litre of petrol. That's 5-10 medium-large toys, or a hundred trinkets.

I thought the same, but the wife bought one for me for Christmas. After initially printing things I found on thingiverse, such as cell phone holders, I started learning to make my own models (mostly from OpenScad). And that opened up the true utility of 3D printers -- making things that don't exist (that I can't buy).

Recent example -- I got a Husky work table with a router plate insert (to make it a router table). I have an old Craftsman router. No one makes router table plates that have holes drilled for this model router. So I modeled and printed an adapter plate to screw onto the router, with threaded holes matching holes on the table's insert plate.

A previous example, I needed a plastic ring to hold magnets for a cadence sensor for my E-Bike kit. The kit came with a magnet ring for a mountain bike, but I have a road bike. Couldn't find anything suitable online for this particular bicycle. A couple hours of modeling, and 3 hours of printing later, I had the part that I needed.

As for plastic waste -- it isn't as much as you think. The slicing software (which converts a model file into gcode) lets you put in a fill percentage. Default is 15%, and upping it to 35% makes a fairly strong part. It uses a honeycomb fill pattern, which is strong yet uses minimal material. I'm still on my first two 1kg spools of material (and the slow speed of creating something means that you don't go through that much filament that fast).

Another project was making small clips that I used to mount a piece of plexiglass (from a big box store) over the TV, as protection from the grandkid that we are raising (it is surprising how delicate modern TVs are).

So in short, 3D printers are really good for making small parts that you need for various household projects or hobbies, and a $20 spool of filament lasts a long time. And they get really useful when you design your own "things" to print.

I agree. It really opens up a lot of things for people who like to tinker. Started just printing toys, but now am designing and printing useful parts needed during lockdown and School/work from home. I love it.
just made some clips to hang banners on my shutters. Also made some cool Halloween decorations. Friends have used me as a one off manufacturer for various things too. I am a big fan of 3d printing.
As someone who once printed things as a business and still has 4 printers on a shelf, I want to offer a counterpoint. The vast majority of people do not need a 3d printer for more than the occasional part/bit that they can't get easily at a store. And by "occasional" I mean "a few times a year". It's simply not worth the cost, learning curve, hassle, etc. for an inferior part at the end of the day in comparison to an injection molded piece off Amazon/eBay or paying someone else a nominal fee to print it for you. I'd be willing to bet that probably 90% of people who are initially enthusiastic about printing and buy a printer only use it once a month or less a year later. In other words, you're in the minority here.

It's also worth noting that none of the things you mentioned actually require a 3d printer. Your router mounting bracket could have been made the same way I made mine - a piece of acrylic (or wood), 2 minutes of sawing, and 5 minutes of drilling & tapping for a smoother surface and better strength than what you printed. Your bike bracket could have been made with some aluminum, a band saw, and some files (or just "good enough" formed with some epoxy putty or hot water moldable plastic). Etc.

What I'm trying to say is that 3d printing enthusiasts tend to be overly positive about the technology and fall into the "when you have a hammer, everything looks like a nail" trap. It's a great technology, but it's not for everyone (or even most people) and it's got a lot of limitations. I always urge people who are considering buying a printer to strongly consider their actual use cases and needs beyond the cool factor.

Very much agree that we enthusiasts can be overly positive about 3d printing, but I also underestimated the 'cool factor' until I got one.

It's just really fun to model a part and then use a slicer and print it in real plastic, at least for me. It has motivated me to learn about CAD, and has been an opportunity to solve some interesting mechanical problems.

Using the 3d printer is not usually practical for me, but it is a lot of fun, and I've learned a lot along the way.

Regarding the waste -- I find that I go through iterations of prototypes until I manage to make the piece I need. So there's definitely wasted material.

That may have to do more with my inexperience with industrial design -- having to iterate with physical objects vs in virtual space.

This. I've used mine to make:

* an adapter to let me my old vacuum cleaner attachments on my new vacuum

* a number of irreplaceable little plastic gewgaws whose breakage would have destroyed the utility of various products

* custom hooks for use with 3M Command strips

* mounting brackets that let me use some spare casters I had lying around with an Ikea Lack coffee table

I find that I use my printer often enough to fix or improve things around the house that it's certainly a net positive.

In the past year, I estimate I have had at most 1kg of failed prints. I've had another 2 or 3 kg of prints that were novelties or that failed to perform the desired function.

On the other hand, last week I printed a replacement keyboard case for my portable keyboard, which saved me buying another one (I use it constantly). A couple of months ago I designed and printed a new fan duct for my fridge. Had I not been able to do that, I would have had to buy a $300 part and thrown the old one out. The impact of manufacturing and shipping that one part likely outweighs the lifetime waste of my printer, and that's just one example.

Every time I print something and see the bits of extra plastic (nozzle cleaning, supports, the odd failure, etc), I feel a little guilty until I remember how much plastic would have been in the packaging alone had I ordered the part online or bought it in the store. Pretty much every time I order something small from Amazon or Ebay (the only really usable online retailers in western Canada), it almost always comes in a bubble-wrap-lined envelope that is essentially impossible to recycle.
I'm a bit surprised they're focused solely on 3d printing, when this polymer seems like it would also be quite useful for recycling plastic.

For many plastics, pelletizing them again to use in injection molding is anywhere from challenging to impossible. If this polymer is the cement, then recycled plastic could be the aggregate in a sort of plastic concrete. Granted, it probably wouldn't be useful for small diameter injectors, but we have a lot of larger plastic items too.