OK, this is a really basic question … where do you get parts?
I am thinking about building a Hypercube variant. As a start, I want 12 500mm sticks of 3030 extrusion for the frame. (Yes, I might be over-engineering this a bit.)
From a vendor on Aliexpress (China), the cost is $79 (of which $50 is shipping). Not sure about the time to delivery.
I live in southern California, so there is local Misumi location (they came up when searching for 3030), such that 2-day shipping is about the same cost as driving there to do a pick-up. Shipping with UPS Ground (likely comparable in time to buying from China) totals to $76 (of which $11 is shipping).
Right. Aside from the fact that Misumi’s ordering process is a challenge in itself, this local supply (from a global corporation) looks to be at least competitive, or a bit better.
With Misumi you can specify very accurate lengths, pre-threaded ends, and durable inserts - at some cost - all of which I suspect the order from China will lack.
If you are building a printer from scratch, where do you get your parts?
@Joe_Walters Thanks. I already had a login. 
They do not seem to have 3030. Ordering the same lengths of 2020 (which is really not the same) works out to $89 (shipped UPS ground).
Misumi all the way. Their extrusions are straighter and cut to more precise length than any cheaper source I’ve found. 1mm increments on demand in a huge range of profiles? Yes please.
Their joint hardware is expensive though. You can find angle plates and T-slot nuts and such cheaper elsewhere.
Misumi is awesome extrusion. Their cut accuracy is so good compared to any others I’ve used. And just good cheap extrusion in general.
Misumi would get a lot more business from me if they had an automatic “Select Cheapest Option” button. I haven’t a clue about all the different types of metals and coatings, etc, and probably only need the cheapest, most common variant of whatever I’m shopping for. Give me a hint, Misumi! (I’ve been very happy with extrusion I’ve gotten from them, BTW).
I am based in Berlin Germany and I buy my stuff from eBay as German suppliers do a pretty good job in cutting extrusions to the right length. It also doesn’t cost much to ship, so it’s a logical decision.
Electrical parts from eBay must be tested and when they work out well I just stick with them. When it comes to printing I just design parts and print them. I have learned motorcycle mechanics in my first life (I am a process engineering tech now), so I have knowledge of mechanical stuff and should do a good job on laying out printers. By the way:
Has someone written a book about printer construction with formulas, things to and things don’t to do yet?
I have heard of 2020, 2040 and 4040. I have not heard of 3030. I do not order a bunch of extrusion though.
I have just finished ordering the parts to a new printer that I am building from scratch. I got my parts from a few different places. For extrusions, Misumi. For most of the other parts, I used Amazon(I really like prime). Some of the parts I needed were wayy too expensive on Amazon or simply weren’t there. I used ebay and gearbest for those. Gearbest was by far the cheapest.
@Griffin_Paquette Did you pay the extra fee for more accurate (±0.2mm) cuts?
@kongorilla Or at least some notion of the difference in cost between different variants. Of course, could just add each variant to the order, as a workaround. Bit tedious, but not hard.
@Daniel_Stauffer As it happens, my book on printer motion mechanism engineering is almost done Just working on illustrations now and then it’s off to the publisher.
Sign up for notification when it goes on sale: https://docs.google.com/forms/d/e/1FAIpQLScMr8Tg4pvVODTQiL2wzZXV6s6tMMl_q7QFEJYUB_1BHw1AxA/viewform?usp=sf_link
@Daniel_Stauffer When I asked the question, I assumed the answers would tend to be local. For me to order from your German suppliers would likely not be economic.
That said, your answer is going to be more useful to a builder nearer to Germany than southern California.
Also some periodic sum-up of the current state-of-the-art would be very useful. The number of bookmarks I have accumulated for 3D printing is a bit excessive.
@Preston_Bannister I can’t remember. But honestly if you’re talking a delta or even just a really solid Cartesian, spend the extra money. Square frames make a million percent difference
@Griffin_Paquette I agree (very strongly) that proper alignment is important, however it is quite possible to design for tolerance of some inaccuracy. That allowance can reduce BOM costs for later builders.
Makes the design a bit more challenging.
Agreed. Just remember a $10 saved one way may cost you in wasted filament from poor alignment in the future.
@Griffin_Paquette Several years ago I built a massive hinged door to cover an alcove in my garage, without any sort of precision tools. The rigid/heavy door opens and closes with fingertip pressure. My tools and fabrication might have been somewhat crude, but I paid careful attention to alignment, and it worked.
I built the desks in my study decades ago, again with limited tools, and relatively crude fabrication. When my neighbor who was a professional craftsman asked to look, I was a touch embarrassed. His comment: “None of your stuff has ever failed, has it?” This when I used somewhat light materials.
My tools and fabrication skills might be limited, but I have managed to get strong and precise results before.
Learning curve … you can only readily get corner cubes (one bracket and three screws to make a corner) for 2020 (and not 3030). Right.
Note I am not a fan of L-brackets (three brackets and six screws for a corner - nine pieces instead of four). The L-brackets lack mechanical advantage, so may not be rigid.
In the interest of over-engineering the first version, I expect to use strips of aluminum (not steel - for matched thermal expansion) as braces to turn the corners into rigid triangles. The fabrication of those braces can be fairly casual, as long as careful attention is paid to alignment during assembly.24 strips with 48 screws - that likely can be reduced.
Could use 3D printed plastic for the corners. Plastic is not nearly as rigid as metal … but might be good enough if taking simple compressive loads.
Nevermind. Iterations…
I used cast steel hidden corner brackets. They are super tough and worked way better than the plastic ones I tried.
I strongly advise against plastic corner brackets. They’re not rigid enough for anything but the smallest printers or triangular-braced frames where the joint strength isn’t important.
I use a combination of L-brackets and joint plates. The L-brackets enforce 90 degree angles between extrusions, and the plates keep all the extrusions flat in-plane so there’s no twist. It kinematically guarantees a precise square frame if the extrusions are straight and the proper length (which Misumi’s are).