What Is A Bowden Extruder | Tutorial – Direct Vs. Bowden – 3d Printing

Joe Mike Terranella

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Tutorial - Direct Vs. Bowden - 3d Printing


Hi, welcome to another tutorial. Whether you just started your journey into the world of 3d printing or you’re already building your fifth printer, you’ve most likely come across the terms direct drive and Bowden, while doing research on how teens and extruders I wanted to make a video explaining both what differences you’ll see between the two and the pros of cons of each first, so we’re on the same page. Let’s run down the basic components that make up your simple extruder setup. All right, Let’s start at the bottom where you have the hot end. The hot end is comprised of the nozzle, where the melted plastic is extruded, –nt onto the build platform and the print above the nozzle. You have a heater of some type. Usually in the form of a heater block, which is usually comprised of a heater cartridge and a thermistor above the block is a threaded tube with what’s called a heat. Break the heat break. Is this really skinny part above the block and below the rest of the threaded tube, This is officially where the hot end turns into the cold end following the threaded tube up, we usually find some form of heat absorption / Dissipation method. This can be as simple as a heat sink and a fan against a block or as intricate as a 360 degree fin and a fan design, You’ll see on a 3d products like the v6 or the Reprap hexagon. Both do the same thing Wick away the excess heat from the cold end now newbee moving past that is where we get into terms like direct and Bowden setups above the cold end of the extruder rests one of two things. Either You have a Nema Stepper motor with a hub gear or you have a PTFE Teflon tube, poking in the top with some form of pressure lock like on small water lines. We call the motor being directly on top of the cold end, a direct drive setup as the filament passes direct from the Haab gear down to the cold end. This is the default on most of 3d printers. You’ll see with the exception of Delta style printers. People get crafty with direct drives, even going as far as gearing them and making a custom hopped bolt. This is commonly referred to as a Wade’s extruder either way its still direct drive Direct drive is used as default because it’s reliable and easy to implement in most scenarios, But like most things, there are good aspects and not-so-good aspects of it. We’ll get into those in a bit, but I wanted to introduce the other guy first. This is what we call a. Bowden, set up a Bowden set up, takes the Nema Stepper off of the cold in and places it remotely on the printer Or in my case on the peg board since the motor with the hob gear isn’t directly over the cold end anymore. We need a reliable method to get the filament down to the hot end, while maintaining the accurate amount of pressure needed for extrusion. If the filament was just left out in the open, it would just bundle up, causing no pressure and no extrusion from the nozzle. This is where the PTFE tube comes in. This tube is size to allow 1.75 millimetre filament through without giving it the room to curl up and flex, thus maintaining back pressure from the extruder. It’s locked into place on both ends. That’s about all that makes up the infamous. Bowden setup. But at this point, you might be asking yourself, Joe. If my printer came with direct drive and direct direct drive works, Why would I plan to put a stupid tube on it and move my motor? Why is it worth the work? Simple answer is wait a single. Nema, 17 Stepper Motor weighs in around 8 to 10 ounces for reference. Here’s something else that weighs 8 to 10 ounces. Your standard salt or pepper shaker mill, the grinder that’s pretty hefty. That’s a good amount of weight just to hang out on a quick-moving axis. In some cases, it benefits you to get that weight off of the moving parts to demonstrate why we need it. Quick physics lesson about momentum is the product of the mass and velocity of an object in motion. If you have a large amount of momentum followed by a quick stop, you get what’s called, jerk. Get this going multiple times. A second and you have vibration vibration doesn’t bode well for 3d printing causes print artifacts like lines, skipped steps, etc. We try to compensate for this in the first firmware by playing with the acceleration and jerk values, it’s a complex calculation, but it usually boils down to slowing the print speed. But I want to print fast. It already takes 20 hours to print a life-sized skull in order to get better quality. I got to slow things down even more. No, thank you. It’s time to put science to work on the problem, so let’s take a look at our issue. We have lots of momentum. We have lots of swift stops. I have to decrease one of those to speed things up. I can’t really decrease the Swift stops. I need them to be Swift for quickness so that leaves momentum if momentum equals mass times velocity. How do I decrease momentum without decreasing velocity by decreasing the other variable mass so by by motor to demonstrate that more efficiently? I’m going to borrow my wife’s conditioner and use my shampoo. So let’s say that this conditioner is your Nema Stepper Motor and that the shampoo is your hot end assembly down the bottom, the NEMA motorways significantly more than your hot end assembly, so your hot end as far as your nozzle, your heater block and all the little bits and pieces. So let’s say that you got your standard direct set up one on top of the other, and you get these moving quickly with quick stops. This guy is really dragging me. So when I move quick and stop quick, I get jerked pretty far, and that’s part of the problem, and so I have to slow down in order to prevent myself from getting vibration going and getting all these jerks going, and that’s just not what I want to do. I want to be able to print faster, not have to go slower, so the option is take off the motor. We get that motor off the hot end, and now all you have. Is your basic hot in cold end? No motor on top so now. I can stay here and just move this thing around as fast as I’ve got charm. Yeah, without much jerk. So that is a reason why we go. Bowdoin getting that weight off The carriage allows you to really push those acceleration values and speed up the printer without making the printer dance as much. This is especially handy on a smaller printer like my little. Prusa this printer was rated for about 55 millimeters a second, But thanks to the Bowden. I can push that up to 90 easily. It flies now. Another application of the Bowden is with Delta machines. Deltas have a delicate disposition compared to a traditional Cartesian machine. The hot end setup is mounted to a platform called an effector which is just a simple mounting spot that the rods connect to. There’s not a lot of tolerance for weight on an effector. And you need to put a good deal of things on it already. So most deltas you see will utilize a Bowden setup placing the Extruder Stepper on the outside of the frame. I don’t personally have a delta printer, But if Folger Tech wanted to give me one of the kindness of their heart, so I could do tutorials on it. Hint hint. I would not at all turn it down. So Bowden is great, but far from perfect, it does have some drawbacks mainly. Its ability to handle flexible filaments, Try running ninjaflex through a Bowden setup and you’re going to have bad time for flexible filaments, A direct-drive setup with a well rounded, hopped gear. Is your best bet? Another hassle by the Bowden setup is retraction settings. Remember when I said that the PTFE Teflon tube doesn’t allow the filament to bundle up in between the motor and cold end, that’s true, but not 100 percent tolerance of a fit. There’s a little bit of gap between the filament and the inner walls of the tube. This makes those rigid retraction settings. You figured out on your direct drive setup, not so rigid anymore. You’ll need more distance and possibly some speed changes for retraction, so that’s the basic differences between a Bowden and a direct drive. I hope that this was informational informative. If you would like to see a tutorial on how to set up a Bowden, how to convert a direct drive printer from direct drive to Bowden? Leave me a message in the comments. Hit the thumbs up on this. If you like this video thumbs down if it was not really that different or informational informative. I think a talk, right, and if you like these tutorials, please feel free to subscribe as Ill. Be trying to get a tutorial out at least one a week going forward, so that’s all. I’ve got for you any questions. Leave them in the comments. Thanks for watching.

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