An open source, parallel printing accessory that is fully compatible with LulzBotĀ® TAZ 3D printers

Nov 27, 2017

Project update 7 of 13

What Is Print Speed?

TLDR version: People focus way too much on print speed, printer output is what matters. Larger nozzles and taller layers make faster stronger parts while pushing the limits of printer speed makes sloppy parts and broken printers. You can now get a Twoolhead with larger nozzles for a boost in output and part strength, but it won’t be supported with the full set of print profiles.

There’s something that’s bothered me for a while that I’d like to bring up. Somewhere along the line the 3D printing community adopted print speed (in mm/s) as the universal standard of how fast a printer can make a thing. This figure is what’s advertised in printers specifications, used as a metric to compare printers and is inevitably one of the first things asked about with any new printer design. Print speed is important, but it’s just one of 3 equally important metrics that determine how fast any give object can be produced, and arguably the worst one to use at that. Since 3D printers print in, well, 3D, the amount of time it takes to print something depends equally on (1) how fast you’re moving, (2) how wide of a path you’re laying down and (3) how tall of a layer you’re laying down. While increasing nozzle size and layer height both make prints stronger, pushing the limits of print speed tends to introduce print defects making parts weaker while leading to increased wear on the printer.

This one of the main reasons that LulzBot printers default to 0.5 mm nozzles instead of the 0.4 mm like most other printers on the market. By using .5 instead of 0.4, minimum feature size is reduced by 0.1 mm (about the width of a human hair), but that usually doesn’t matter too much for things that are the right size to be useful to humans. You gain a lot in exchange. If you keep all other factors the same (layer height, movement speed, etc), you gain a 20% bump in printer output. If you take advantage of the larger nozzle to print taller layers, the effect is compounded and you get a 44% bump in printer output. This is all with the added advantages that taller layers and larger nozzle sizes produce much stronger parts, since the increased amount of plastic being laid down will be able to melt into the layer below it more consistently.

Pretty awesome benefits for a hairs worth of reduction in print fidelity. When those benefits are doubled by the Twoolhead, you’re going to see some pretty serious output :)

This is the reason I love printing with larger nozzle sizes when I can get away with it, the increases in part strength and decrease in print time is awesome, and the tall layers can actually look pretty great. In fact I’m already testing a version of the Twoolhead with 0.8 mm nozzles. While I’ll still need to print the more complex parts with the standard 0.5 mm Twoolhead (gears, extruder body), I’m able to get away with 0.8’s on several of the larger parts, which cuts print time of these parts by almost half compared to the 0.5 mm nozzles while producing stronger parts. Woot.

I’m happy to announce that I’ll be offering the Twoolhead in 0.8 mm as well as the default 0.5 mm. Existing orders will default to 0.5 mm, but you can contact us to change your nozzle size if you’re interested. The 0.8 mm nozzle size definitely isn’t for every print, but it seems like it’d be a huge benefit to some of the folks that have reached out during the campaign. If you’re not sure what nozzle size would be best for your application, reach out through the contact email on the campaign page and I’ll do my best to help you decide.

Thanks again for all the support!


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