What is the quality like of 3d printed lego pieces?
October 28, 2015 10:35 AM   Subscribe

How good are 3d printers under $2,000 these days at making things like Lego/Duplo? Do you have any experience either making pieces or using pieces someone else has made?

In another askme the asker mentioned a marble run system for Duplo. This sounds like it would be great for my daughter. I looked into buying it in Canada and the second link was for files to print your own which is appealing because I could make more of specific parts and customize colour as needed. But my worry is that the parts may not be any good.

Googling shows people who say that the resolution won't be good enough to be lego quality (but don't seem to have tried it) and people who have made their own and posted pictures but haven't made much comments on how they like the pieces. One person said that "The fit with real LEGO bricks is acceptable to my six-year-old son, but not satisfying to me. That’s entirely dependent on the printer though." which sounds fine because if the kids are happy with the pieces then my goal has been achieved, but a sample size of ONE is a bit small.

I am happy with using it for special/custom pieces only (like the marble run ones). But if it is worthwhile to use it to churn out regular pieces as well that would be good to know.

The printer would be shared with a group of 3-4 friends so between us and our spouses/kids we will make use of it for other things, I just want to know if it would be any good at making Lego/Duplo pieces. We'd be looking to get the printer some time in the next 2-6 months (no one is in any particular rush for it).
posted by any portmanteau in a storm to Technology (10 answers total)
I would think the bigger issue for making anything of considerable size is the time it would take to print all the pieces. You're going to spend weeks just printing pieces 24/7.
posted by If only I had a penguin... at 10:38 AM on October 28, 2015 [2 favorites]

One of the cool things about legos is that they are produced to astoundingly small size tolerances - just a couple of microns. They're manufactured so accurately that the manufacturer of the MRI systems I operate for a living uses legos embedded in gel to calibrate the gradient systems (you measure the size using the MRI scanner, then normalize that to the actual known size to get your calibration factor).

The tolerances you'll get with a home 3D printer will be nowhere near that. As to whether you can get it good enough that you're happy with it, I can't say. I think its primary use would be making weird custom pieces (and maybe custom weapons or accessories for minifigs?)
posted by telepanda at 10:48 AM on October 28, 2015 [26 favorites]

One issue I have had is that 3D printers print with a layering process-- that is, the printer creates an object by laying down a line of plastic on top of other lines of plastic, which may or may not be cross-barred or supported on the inside. So pulling or pushing pieces side to side will break them apart where the layers adhere. To get the pieces to click together and apart, you would be exerting more force than the pieces can take sometimes. I wouldn't print functional Legos with a printer, but maybe some to look at only.
posted by blnkfrnk at 10:54 AM on October 28, 2015 [5 favorites]

But if it is worthwhile to use it to churn out regular pieces as well that would be good to know.

Probably not. ABS filament costs something like $25/kg. It looks like on ebay you can get 12 pounds of Duplo blocks for less than $50. They'll fit together better, be stronger and cheaper, and won't take hours of printer time.
posted by aubilenon at 10:57 AM on October 28, 2015 [4 favorites]

The tolerances are tight on Lego because they replace/recut their molds often. But I think the main difference is going to be the materials - Lego plastic (ABS) is going to be much higher quality than anything extruded on a home machine. For example, the Lego plastic survived over 35 000 connections before failure in a DIY stress test and the pieces are relatively cheap.

There are lots of very fun stuff you can build - and I would suggest printed materials in support/conjunction with bricks could be used to create pretty neat things but as a replacement would be short lived.
posted by zenon at 10:59 AM on October 28, 2015

I should also note that I expect home 3d printers to approach/mimic the quality of many plastic toys (which need to be rugged) and someone might pop up here with just such a system - the pace of change/research has been intense. Even though Lego is a particularly high bar eventually that will be reasonably matched as well.
posted by zenon at 11:20 AM on October 28, 2015

For background: I have a ~$1500 printer, and use it to make a variety of minor fixes and enhancements around the house (eg: a special hidden shim that holds two pieces of furniture exactly parallel, a widget that holds a bifold door open at one particular angle, and so on). It's fucking great for weird around-the-house things.

I would not use it to print out run-of-the-mill Duplo parts (waste of expensive filament), but I would consider using it to print specialized pieces. I would expect those pieces will require some tweaking to get the fit right, and the type of tweaking will depend on the nature of the printer you're using (that is to say, you'll need to fiddle around with *your* printer specifically) but you should be able to refine your model files to mate reasonably well with Duplo. The connection between printed piece and Duplo will probably end up being either substantially weaker, or noticeably stronger (you're unlikely to get exactly the same level of attachment force).

If you're using the typical home 3D printer, the pieces will have a ridged feel to their vertical surfaces due to the layers, and will have a sort of odd crosshatch pattern on the horizontal surfaces, so the observer will tend to immediately realize they're not Duplo. If appearance matters, you would need to spend time sanding down your printed objects, substantially increasing the time investment -- so if appearance matters that much I would skip the whole thing.

The printed pieces could easily be quite strong; any competent 3D printer lets you tweak the "infill" settings, so you can have things come out almost hollow, or entirely solid. Your printed pieces, incidentally, will likely require thicker walls than real Duplo or they'll be too fragile for child use.

Having said all of that, if you believe your 3D modeling skills are up to the task, then a 3D printer can let you create customized bits & pieces with some aplomb. For example, a shim piece that turns a brick 30deg, or has an extra attachment point on the side, that sort of thing. I believe the Make magazine people are gearing up for a fairly huge "3d Printer Shoot-out" comparing a wide range of printers; you may want to hold off until that issue comes out.
posted by aramaic at 12:08 PM on October 28, 2015 [6 favorites]

To echo what others have said: you're not going to get he precision or durability out of your home printer. Additionally, printing pieces is relatively slow and the configuration of bricks, which are generally hollow means that you have "overhangs" which can be notoriously difficult to print and which require a well-calibrated machine and getting to well-calibrated can be a headache if you're not engineering-minded.

But, you can also do things like this, a lincoln log to lego connector, or this knex to lego connector.
posted by Barry B. Palindromer at 2:31 PM on October 28, 2015 [1 favorite]

I am a middle school teacher and my students make custom LEGO pieces for our LEGO robotics class. They work well overall but do not last and the layering process creates a lot of easily breakable stress points. That said the pieces they make are not available any other way. Sketchup 3d design tool has a warehouse full of ready made LEGO pieces that you can modify to your liking, I have found that I have to change a lot of studying though for a good fit ie: axles have to be reduced in size by 5%.
posted by dstopps at 2:38 PM on October 28, 2015 [4 favorites]

I would have to talk to my friends who have 3d printers(or work in shops/offices that do), but what i can say is that i've had several bad experiences with off brand bricks that were still injection molded like real bricks. The tolerances required to make things fit together well and not fall apart or seat properly on eachother are a lot smaller than you'd think. It was always pretty obvious when you were using an off brand brick as it would cause issues with the integrity of the whole structure.

Just from what i have seen of printing, i'm skeptical that most printers would be able to reliably print a brick that wouldn't need sanding/scraping/clean up to get cruft or inaccuracies out, or that they wouldn't produce a brick/piece that had weird weak points you wouldn't expect. This is something i'm going to send out some curious messages on though, and i'll report back. It seems like one of those combos of a particularly hard problem and a not fully mature tech, though. Sort of like rendering 3d animation at home was 15 years ago.
posted by emptythought at 3:02 AM on October 29, 2015

« Older Help me become good at relational databases   |   Vancouver shopping - where should I go? Newer »
This thread is closed to new comments.