There are many things to consider when deciding whether you should have a direct drive or a bowden style 3D printer.
There are pros and cons on both sides so regardless of which style extruder you choose you will have to deal with the good sides and the bad sides of both.
The main benefit of a direct drive extruder is the improved retraction ability which will reduce the stringiness of your prints. A direct drive extruder will also provide a more precise flow to the nozzle as well as improve your printer’s ability to print flexible filaments such as TPU.
1. Improved Retraction Accuracy.
Converting your printer to direct drive will increase the accuracy of your retraction settings which will reduce the imperfections that come along with poor retraction settings such as stringing and blobs/voids in your print walls.
Typically for a bowden style extruder the retraction will be around 5.0 – 6.0mm whereas a direct drive extruder will only require a 0.5 – 1.0mm retraction distance.
2. Reduce Stringing.
In general, a direct drive 3D printer will have less stringing on the print which is especially helpful when printing difficult prints such as chainmail or materials that are prone to stringing like PETG.
The reduced stringing will improve overall print quality by removing potentially destructive artifacts and will also reduce the amount of post-process cleaning required on the 3D prints.
3. Printing Flexible Filaments.
Direct drive printers are significantly better at printing flexible materials such as TPU 98A, TPU 85A and TPU 58D.
The most common flexible filament, TPU 98A, will print with little to no issues on a bowden style extruder. Softer flexible filaments, like TPU 85A, will need to be printed on a direct drive extruder.
4. More Precise Flow.
A direct drive extruder will offer more precision for the delivery of filament to the hot end, which will improve the precision of the flow.
If you are experiencing over or under extrusion on a direct drive 3D printer you probably are having an E-Step calibration issue and not a flow issue.
What Are The Cons Of A Direct Drive 3D Printer?
The main downside of a direct drive 3D printer is the additional weight that is added to the printer head. This additional weight can cause Z banding and will potentially cause you to print slower to avoid the reduction in print quality.
Some direct drive printers are designed with lightweight stepper motors and have optimized the print head to be as light as possible. For optimized direct drive printers the weight will be a minimum and probably will not affect the quality of the print.
For printer conversions, such as an Ender 3 direct drive conversion, the stepper motor is not specifically designed to be direct drive and will add significant weight to the head and might cause print quality issues.
2. Z Banding.
Z banding is a common issue on 3D printers with too much weight on the printer head. Z banding usually appears on a print as horizontal lines around the perimeter of the print and is caused by excess weight on the head resulting in the acceleration and deceleration of the print head to affect print quality.
Z Banding can typically be fixed by reducing print speeds.
3. Slower Print Speeds.
If your 3D printer is a conversion from a bowden style extruder to a direct drive extruder this may add additional weight to the print head which will cause Z banding and this Z banding will require the 3D printer to run more slowly to preserve print quality.
Is A Direct Drive Extruder Better Than A Bowden Extruder?
In general, a direct drive extruder performs better than a bowden extruder for flexible filaments as well as filaments that are prone to stringing and direct drive performs worse on machines that are prone to Z banding.
If the weight of the printer head is the same on both printers the direct drive printer will outperform a bowden style printer on in basically every metric.
Should I Convert From A Bowden Extruder To Direct Drive?
Converting to direct drive from bowden style is really a case by case choice, not all bowden style 3D printers will be well suited for direct drive and likewise not all direct drive printers will be well suited for bowden style.
The opposing point of the argument is that some direct drive printers would perform better as bowden style and some bowden style perform far better as direct drive.
There are ways to reduce the weight of your 3D printers head, like buying a pancake stepper motor, or replacing the drive system entirely for a lighter weight one.
Are There Alternatives To Direct Drive And Bowden Extruder?
There is a third option in the extrusion game which is basically the best of both worlds called a cable drive extruder.
A cable drive extruder is an extruder that keeps the extrusion motor mounted to the frame of the machine and the filament drive gears mounted to the head, therefore reducing the weight of the head. The system then uses a flexible drive cable to turn the gears using the motor that is attached to the frame.
The cable drive extruder is not extremely popular yet (I don’t know why). There are two manufacturers that make and distribute the cable drive extruders, the G5 Flex from flex3drive.com and the Nimble Flex from zesty.tech.
Direct drive is not for every 3D printer but it can be a great tool for your toolbox if you have multiple 3D printers or if you want to switch one 3D printer between direct drive and bowden style.
My current preference is I have a stock Ender 3 pro that is bowden style and I have an Ender 3V2 that I have converted to direct drive and have replaced the extruder motor with a lighter weight pancake stepper motor.