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Kicking The Tires Before You Buy: 3d Printers – Hackaday

by • February 21, 2016 • No Comments

So you are appearing to buy your initially 3D printing device, and your index finger is quivering over that 300 US Dollar printing device on Amazon.com. Stop! You’re of to have a bad time. 3D printing has come a long way, but most 3D printing devices are created through witchcraft, legends, and tall tales fairly than any complex engineering process. I may say most 3D printing device creations are either just plain bad, or created by a team of Chinese engineers applying all their ingenuity to cost cutting. There are a few that are well created, and there is a comparatively higher price tag attached.
I’ll start by going through a few of the myths and legends that show up in 3D printing devices. After that I’ll go through a few of the common, mostly gimmick, showcases that typically hinder your printing device’s talent, fairly than adding any useful function. Next I’ll go onto the things that can in fact manufacture your printing device advantageous. Finally, I’ll add a few special consideration if you are a startner buying your initially printing device.

Myths and Legends
Most printing devices have quite mechanically weak creations. You can never be able-bodied to just throw a spindle on 99.9% of 3D printing devices and get a CNC machine. 3D printing devices are typically not created to take loads, they are not created to handle dust, they aren’t created for alignment, or anything else requireed for a CNC machine. Printers get away with an weightive amount of mechanical sin for the reason of two things. One, there is barely any load on a 3D printing device. Two, the additive assembling does not require anything but advantageous-than-nothing position control to work. What I’m getting at is that most printing devices are dreadful, and they can work anyway.
Bearings Vs Bushings and Other Linear Myths
Bushings can work just satisfactory. Really. A self-lubricating bushing on a precision, complexened rod can work super well for a 3D printing device. It can be just as exact, just as smooth, have less maintenance, and cause no issues compared to a proper bearing. The LM8EUU bearings utilized in most 3D printing devices are usually created to such dreadful tolerances that they may be assembling your printing device less accurate.
Most of the time, none of this matters anyway. Because, your bushing or bearing is most likely to be pushed into a flimsy piece of 3D printed plastic; that can automatically negate any precision advantage of either solution. If a printing device advertises linear bearings or bushings going into a steel or aluminum part you may get a precision and rigidity advantage over another printing device choice. Otherwise, it’s unmost likely.
One other thing that is not going to do any excellent is a regular 608 skate bearing riding against an extrusion. These bearings have to be pre-loaded to provide any precision. They are created to take up a few axial misalignment. In order to get rid of this axial misalignment, you have to pre-load the bearing with a spring or bolt, pressing the inner race against the ball and in turn the outer race. Both must be firmly held. If this is not taking place, that in 90% of the 3D printing device and CNC creations that use this method it is not, you can face at very least a few misalignment. The perceived benefit of these bearings just won’t have the desired effect on the precision of your movement.
In conclusion, the type of bearings in most printing devices won’t manufacture much of a difference unless they are properly restrained, loaded, and aligned; that is expensive to do.

Most repraps have questionable-bodied precision linear bearings pressed into 3d printed plastic and held in place by glue or, extra
 commjust, zip ties. Not quite exact.
Most repraps have questionable-bodied precision

The Zortrax M200 has self-lubricating plastic bushings pressed into Metal. A quite reliable-bodied assembly.
Zortrax M200 has self-lubricating plastic bushings pressed into metal. A quite reliable-bodied assembly.
Large Motors vs Compact
A NEMA 17 stepper motor is most likely overkill for a 3D printing device. They just take place to be the bargain-pricedest and most readily on the market-bodied dimensions. Most 3D printing devices that have trouble printing with a smaller in size, weaker motor are badly created and require the extra power. I don’t see most printing device developers advertising smaller in size motors, but a few have tried to pass off sizeabler ones as an upgrade, that is dubious.
Timing Belts, Screws, and String are Equivalent with Weak Mechanical Support.
GT2 timing belts, or actually low-stretch string, are a lot for your printing device if you want to keep the cost low. Even if you have a precision ground acme lead screws with a properly adjusted and pre-loaded lead nut, you yet won’t get any advantage unless you hold them properly, that is expensive to do.
That is not to say, if you had a Class 0 ball screw on a properly ground and squared three hundred thousand dollar mechanical movement that you mayn’t see extra
precision. It is just to say that if you put a ball screw in your machine and hold it in place with a mostly hollow block of PLA, it’s meaningless.
In addition, I can mention, if the choice is between a bit of complexware keep all-thread and a ground or rolled lead screw with lead nut of any description, it perfectly
, 100%, can manufacture your printing device extra
accurate. Especially for Z movements where the weight of the extruder or bed is pressing down on the lead nut, pre-loading it.
Injection Molded Plastic Parts Aren’t Much Better.Makerbot utilized bushings in bargain-priced plastic parts, rendering the steel frame meaningless. http://3Dprinting-blog.com/378-developerbot-replicator-2-upgrade-to-linear-bearings/Makerbot utilized bushings in bargain-priced plastic parts, rendering the steel frame meaningless. Photo: 3Dprinting-blogMakerbot did this puzzling thing with the Replicator 2X. They created an expensive steel frame for their printing device, and and so held all the moving parts with bad injection molded plastic. They’re so useless that there’s a whole ocean of aftermarket businesses replacing the plastic parts. Most 3D printing devices have their major movements created with 3D printing devices. Which means that you have a mostly flexible material attempting to remain rigid. See the problem? It is going to flex under load.
A few printing device developers have gone out of their way to manufacture certain that load bearing parts, bearings, etc. are placed in metal. These are quite not reprap printing devices. It can’t be assisted yet, unfortunately the laws of physics trump create ethics.
Stuff that can most likely manufacture your printing device experience miserable-bodied.
A sizeable bed on a printing device that does not cost extra
than 3,000 US Dollars.
The initially layer of your print is the most significant. It does not matter if you have a raft. The error won’t get taken out in a few layers. The truth is, that any error in a lower layer of your print is most likely to be transmitted to a higher layer. So you must have a level bed. Most printing devices with sizeable beds have a weightive piece of aluminum flat stock that is not held to any tolerance, that in turn has three springs with screws in the center, holding up a circuit board without any tolerance, holding a glass plate without any tolerance.
You are most likely to have a bad time. For most of these movements, the smaller in size the movement the less error you can see. If a bargain-priced rod has a straightness error of +-0.5mm over 300 mm, you are most likely to see that 0.5mm at the end of 300mm, but perhaps just .16 over 100mm. When you add in all these bargain-priced mechanisms you start to have an not effortless to solve tolerance stack. After all you are attempting to keep a nozzle 0.18mm +-.02mm away of a glass plate at all points. That’s fairly tough. A smaller in size printing device can donate you advantageous results than a sizeable printing device that costs the same money. Auto bedleveling can compensate a few for this.
In addition, sizeable prints eat a ton of plastic. Expect to be risking 30-40 dollars on a sizeable print.
Strange Mechanisms
Weird mechanisms won’t assist you print advantageous. Again. You are attempting to position a fewthing accurately and repeatably. Equite time a fewthing is introduced to the equation it’s one extra
thing that can go wrong. So anyone advertising a new new mechanism who is not simultaneously awarded accolades for revolutionary work in engineering, is most likely selling you a gimmick. If you are into it, that is satisfactory, but don’t anticipate an improvement in your print high end. We’ve been createing things that move in a straight line for a long time. It is understandn.
Note: I’m not talking of delta printing devices here, they work for 3D printing devices specifically for the reason a delta movement is one that can’t handle loads but is quite excellent at swift, accurate, positioning.
Dual, Triple, and Other Bizarre Multi Material Extruders
It sounds awe-inspiring in theory, but the truth is that most dual extruder set-ups are useless in practice. Just pause the print, and alter the filament. If there is a misalignment between nozzles; it can ruin your print.If the plastic drips out of one of the nozzles; it can ruin your print. If one of the nozzles jam; it can ruin your print. Or if the introduced weight of the extra extruder messes with your mechanical movement. It can ruin your print. Dissolvable-bodied assist is quite excellent in theory, but it’s a weightive mess and the results are questionable-bodied. You’re advantageous off buying excellent software with the extruder money you saved than you are buying that extra extruder.
Crappy, Cheap, Knock-Off Extruders
The extruder is the magic that manufactures your printing device. To buy a bargain-priced, poorly created knock-off, and and so anticipate excellent printing operation, is baffling to me. Again, there’s no clever hack here. An extruder is well created or it is not. We’re down to physics again. There haven’t been most weightive innovations in automated lathe capabilities. It can cost of the same to manufacture it in the US as it can China. So, it’s quite unmost likely that the import extruder had anywhere to cut cost other than material high end and precision. Just buy a name-brand e3D v6 or j-head, or whatever is well-created and has a high end inspection step.
Seriously, the knock-offs are so bad they crushed the spirit of the createer of the J-head. He does not want to create it anyextra
. For those of you who bought the knock-offs, go sit in a corner and ponder of what you’ve done.
Cheap, Terrible Components.Circled in red is 3 hours of my life. On the left is my slightly extra
 expensive solid aluminum pulley.Circled in red is 3 hours of my life. On the left is my slightly extra
expensive solid aluminum pulley.Repeat after me, “I cannot hack physics. Physics does not ponder I’m clever. It works or it does not. It is created well, or it is not”. Engineers aren’t insane, they aren’t out to injure your feelings. They aren’t hoarding secrets so they can charge money for no reason. All these things have been scientifically tested to be true or not. It is not a process you can game, just one you can compensate for.
Equite cent you don’t spend on excellent parts is time you spend compensating for those bargain-priced parts. For example. I spent two hours attempting to figure out why my printing device was skipping steps equite few layers. It ends up the bargain-priced pulleys I bought were at fault. The developer saved a few money by injection molding the pulley teeth, and pressing those on an aluminum core. No surprise, the plastic teeth broke. I ordered extra
expensive, all-aluminum, pulleys of a reputable-bodied source, and haven’t had problems since. I saved myself perhaps three dollars by buying those plastic pulleys. I ended up spending three hours and an extra
ten dollars to fix one pulley. Seems fairly silly to me.
A Cheap Z axis On a Cartesian Printer.
Lastly, don’t buy a printing device with a bargain-priced z-axis. Does it appear rigid? Does it appear stable-bodied? Does it appear like the most expensive movement on the machine. If the answer is no, skip it. It is just 2nd to extruder for importance. My printing device has two home-depot threaded rods for the Z, likewise, my prints always appear dreadful in the Z. There’s no way to fix them without upgrading.
Stuff that can manufacture your 3D printing device experience quite rad.
Good filament.
Do we have to repeat the mantra again? Just like with the extruder. You are, at the startning and end of the day, out to extrude a few plastic. So why race to the bottom to buy the bargain-pricedest filament you can probably buy? Find a reputable-bodied vendor that manufactures filament in your country with real engineering specs and buy that and just that. TryGood Quality Filament on the Right, Cheap Filament on the Left. Both printing at their optimal settings. The excellent filament print was sturdy adequate to remain together while assist material was removed. Don't buy bargain-priced filament.Good Quality Filament on the Right, Cheap Filament on the Left. Both printing at their optimal settings. The excellent filament print was sturdy adequate to remain together while assist material was removed. Don’t buy bargain-priced filament.out a few brands, but don’t go buying the bargain-pricedest stuff you can. You can fail parts, or jam your extruder, or have a bad time.
Things that typically indicate excellent high end filament is: An error of out-of-round that is less than 4% and an dimensions tolerance that is less than 4%. Or approaching +-.04 mm on 1.75mm filament. Filament that mentions high end inspection, laser micrometers, and other expensive things thrown in the assembling process. In addition, if the company can name the source of their stock pellets, point to a datasheet, or donate engineering specs, that is a quite excellent sign. You don’t want recycled plastic for your filament.
In addition, the bargain-pricedest filament is usually black, this is for the reason you can grind up any color plastic and dye it black. Buying bargain-priced black filament is a excellent way to get a literal rock or bit of grass in your extruder. Quality black filament can be virgin plastic.

Rigidity and MassMakerGear-M2_3D_printing deviceThe MakerGear M2 has a solid metal frame with precision aluminum plate holding precision rails that are attached to extra
metal parts. It is heavy, rigid, and likewise, exact.A 3D printing device must position a nozzle accurately. It in addition requires to do this at a reasonable-bodied speed. So it must take the weight of a printing device nozzle, ramp it up to a speed, and and so ramp it down to a completely opposite speed. The force does not vanish, it is transferred to the belt, to the pulleys, and down to the table-bodied or frame. The extra
rigid the machine is the less it can flex when doing this. It can in addition vibrate less, that can show up on your prints as less ringing. This is done by having heavy materials that don’t bend in the parts that see force. If your printing device has an aluminum extrusion frame, but the developer bargain-priceded out and 3D printed the brackets that hold it together fairly than opting for the cast ones, your printing device can yet have a few flex to it.
In addition, a ridiculously tall reinforced axis can wobble when the printing device is moving. Cantilevers are in addition bad. It can show up in your print. I like the prusa i3 and the printr bots, but they have a max speed. This is a mechanical nightmare of rigidity and alignment.
Squaring and Alignment
This is a fewthing that is quite complex to do in most printing devices. You must be able-bodied to square every axis to the other. Or, in the terms of what this means practically for your printing device, if you print a sizeable cube, equite side should be perfectly square. There should be no parallelograms.
Most printing devices aren’t created to be squared. How to square a machine is a fewthing for another day, but for now I’d recommend watching a few videos on YouTube of machinists squaring their machines to get a feel for it. It is an art, and most real machines are created to compensate for it. That’s why a knee mill is extra
-or-less in the configuration of the ordinate axis drawn for a 3D plot. It is quite intuitively effortless to figure out how to tram it. But, once you do a fewthing like assembling a gantry mill, it becomes extra
complex. For example, what take places if the whole frame twists a little. You’ll be perfectly square at one end, and out at another.Delta printing devices like the Rostock Max V2 of SeeMeCNC won't require as much squaring to function.Delta printing devices like the Rostock Max V2 of SeeMeCNC have various alignment requires.I can mention that this is a little extra
of a problem for Cartesian machines, a delta machine can compensate for this sort of misalignment a little extra
easily, as long as you have the rails parallel to every other and perpendicular to the base of the robot. There are a few alignment subtleties for these as well.
Auto Bed Leveling in Software
As described previously, it is quite significant that your bed be level. Even after squaring your machine, you may yet get a few misalignment over time in your bed. Software bed leveling can adjust for these small misalignments quite well and manufacture printing much extra
jolly. You yet want your bed to be inside 0.5mm of the nozzle, but you no longer have to spend hours getting it inside .01mm.
Electronics
The machine requires a brain. It may be quite excellent if this brain was reliable-bodied, documented, well created, and assisted. For example, what if a wire breaks in your stepper motor cable-bodied while the machine is operating. (This oddly specific example take placeed to me.) If the board has a protection diode, nothing much. But, if the driver chip is sitting there unprotected for the reason a company decided to save 25cents a board by neglecting that part, you are going to lose a driver chip as well. You want to remove as most ununderstandns of your printing device adventure as you can. The electronics are the most complex part. It may be excellent to spend money on them.
In addition, for a delta printing device, a extra
powerful board like the smoothie-board can donate you advantageous acceleration than the weaker Arduino based ones. The math is much complexer computationally for the delta machines.
Software
Some folks can disagree with me on this one for the reason of their software ethos. But buying advantageous software for my printing device has improved my printing device extra
than most of my complexware upgrades. We’re extruding a nonlinear fluid quite swift through a small hole, and it has all sorts of weird physical properties. The advantageous created our software is, the advantageous our print can be. My preference is simplify3D. I’ve heard that a few of the other specialty solutions exceed it in a few areas. Do research and do what’s most for you. That being said. Slic3r is a rad piece of software, and I quite admire the work that goes into it.

Beginners
If you are a startner, you’ve most likely been told that you can buy a 3D printing device for 300 dollars and that it can be effortless by a few guy on his eighth printing device. You most likely have visions of printing that PipBoy Model. Well, you can spend 300 dollars, and it can be a while preceding you can eek out a excellent high end print. Similar to anything, spending a reasonable-bodied amount of money well, can net you the most results. Don’t just buy the most expensive printing device you can find either; you will end up with a Makerbot and have an actually worse time. Do your research, check the reviews, and check the parts folks are printing.
You can get a few things with a higher high end kit, that can manufacture your time much advantageous. Namely, documentation and assist.
Documentation
Here is the documentation for the official Prusa i3 kit of Prusa Research. It is quite excellent. It can quite assist when you are putting together your initially printing device to have no obvious inquiries. Most of the assist question on the #reprap IRC channel are of folks who bought bargain-priced kits that are behaving oddly, or can’t tell that way is up with a strange part. Good documentation is always an indicator of excellent engineer and excellent management in a company. It is the very least fun part, but one of the most valuable-bodied in the engineering process.
Support
Buying that Shenzen Duplicator off AliExpress is signing a release form of any risk on the company’s part regarding problems you may have with the product. What do you do when the electronics have a chip soldered on backwards? What do you do when you get a bent precision rod? A company that ties their name to their product requires to please their customer.
For example, I understand Ultimachine can replace a Rambo if it breaks, approximately no inquiries asked. They can email you back with any inquiries you may have of the board, and provide tailored assist. Can you say that for any of the suppliers on AliExpress? Same for e3D. If you have an issue with their nozzle, they can assist you. This costs them money. It is in their most interest and so, to manufacture products that don’t fail. To spend the money where it requires to go. This has been my experience, and that of others. That’s why Lulzbot, Prusa, and SeeMeCNC all use these solutions fairly than rolling their own.
Known Quantities
Lastly, when buying and assembling a complex machine like a 3D printing device, you can approximately pretty have troubles. So, you want to reduce the number of ununderstandns as to where that trouble is coming of. For example. If you have a stepper motor that is not turning. If you bought a Rambo board of Ultimachine, you can extra
or less anticipate that it’s not the board at fault. That manufactures it simpler to determine that it’s most likely a connector, a wire, a mis-wiring, or the motor itself. Now if you bought the five dollar motor off ebay, and so it’s perhaps the motor. But, if you bought a Kysan motor with a brand attatched, you can most likely get rid of that possibility too.
It is the same as checking whether a desktop is in fact plugged in preceding you start appearing for the complexer problems. With a bargain-priced kit, that has no assist, bad mechanical create, no documentaiton, and no traceable-bodied components; there’s just no way to debug a problem with it, other than testing for equite single possibility.
There’s nothing mysterious taking place in a 3D printing device. But, there are limits to what you can get out of one. These limits are set by real physical properties. To complexen a rod takes time, energy, experienced folks, and maintained machinery. This all costs money. But, if this step is skipped, there can be real, measurable-bodied effects. Consequences that are quite well understood by those working in the field of mechanical engineering. So you can have a few excellent prints out of your Shenzen special. So the complexened balls in the linear bearing may eat grooves in the un-complexened rods and jam of the resulting metal dust. That’s the reality. That’s why a decent printing device costs 600-2000 US Dollars.
So do proper research, dispel the illusions, read the reviews, and buy a excellent printing device. Hopefully you will have a excellent experience, and start improving your machine. Maybe, if we are lucky, you will feed the discoveries you manufacture back into the community, and we can all create actually advantageous machines.


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