The 00str00der is a belt-driven, gear-based, open-source extruder design intended for RepRap 3D Printers. It uses a precision linear-drive system to drive a hobbed bolt (or similar drive that grips filament/material), which in turn supplies filament to a nozzle used for 3D printing. The inspiration and research for this work was a natural progression based on existing open-source designs and is a result of collaboration between Lee Miller and Terawatt Industries (Colorado, USA). It is based on previous geared-extruder designs such as Wade's Geared Extruder, Adrian's Geared Extruder, and others; as well as Terawatt Industries' experience with RepRap drive systems.
- 1 Summary
- 2 Background
- 3 Mechanical Construction
- 3.1 Materials
- 3.2 3D CAD Files
- 3.3 Assembly instructions
- 3.4 How to make the hobbed bolt
- 3.5 Upgrade/Retrofit
- 3.6 Version History
- 3.7 Optional Parts
- 4 Extruder Calibration
- 5 Stepper Driver
The designers first shared concepts for the component in 2012, and agreed to collaborate on design and testing in January, 2013. Lee Miller designed the first 00str00der for the UConduit H-Bot 3D Printer with Bowden-style extrusion. Free Beachler of Terawatt Industries revised the design to work with a PrismX by supplying the Sheliak X-Carriage design. Both designs have converged (rev. C = 1.0) and a mounting plate has been added to attach this extruder to carriages like [http://www.thingiverse.com/thing:18657].
The 00str00der is perhaps the most versatile and reliable extruder available on the market today. It offers an ultra-long-life design with GT2 pulleys and belts, supports different size pulleys and belts for varying gear ratios, and supports direct-drive and Bowden configurations. The design has been revised several times and proven in the field by Terawatt Industries and Reprap users.
The 00str00der is designed to be affordable while offering greater precision, durability, and speed compared to extruder designs based on printed gears. It uses a small closed-loop GT2 belt to transfer power from a NEMA17 motor to a M8 hobbed bolt. GT2 pulleys are used on the NEMA motor and hobbed bolt to achieve an approximately 4:1 gear ratio. PLA and ABS filaments are driven by an M8 hobbed bolt, as is 'traditional' in the related designs mentioned here.
Terawatt Industries has tested and calibrated this component on a PrismX running at infill speeds up to 400mm/s. The 00str00der was first tested and proven on a PrismX 3D Printer in March, 2013 by Terawatt Industries. In April 2013 tests with the 00str00der on an h-bot in Bowden configuration were performed by Lee Miller. It performs exceptionally well in both configurations. On the PrismX it printed approx. 250+ hours total in March-April 2013.
I'll say qualitatively: it's difficult to drive a reprap (Prism, MendelMax, whatever) fast or hard enough to stress the 00str00der's drive system noticeably. During prints the nozzle experienced problems before we could drive our machine fast enough to stress the 00str00der or frame. During simple extrusion tests we hit speeds in excess of 1500mm/s; as noted before the nozzle shows problems performing at this speed.
The primary advantages to this design approach include:
- The belt-driven system is very smooth, therefore resistance in the drive system is decreased. The positive side-effects from this are several including: faster drive, more accurate drive, potential for smaller/cheaper/lighter motors such as NEMA14.
- The belt-driven system can be precisely calibrated. Instead of marking filament and attempting to measure travel inside of the robot's gantry (frame), we can measure the width of the hobbed bolt, and use a calculator for the rest.
- The belt-driven gear system is very durable. Printed gears shed PLA/ABS material within 100 hours of printing. The belts and pulleys are rated for 1000s of kilometers and more.
- Set-screws on the GT2 pulleys work more effectively than most set-screws on printed gears. Last longer too.
- The ratio of gears can be adjusted. One-to-one (direct-drive) can be achieved with a set of 36T GT2 pulleys.
Some disadvantages to this system include:
- The gears can't be printed, they must be sourced. This means we can't hack a new kind of herringbone gear and print/test it on an extruder. Purists will note, however, we can print decent GT2 pulleys in certain contexts...
- All the other disadvantages that come with using non-printed parts such as: finding suppliers, specifications, availability, lead-time, etc.
NOTE: Refer to the "Version History" section for information about the 00str00der's change history. These photos and BOM lists are not always current. However, the variations in the 1.x versions are slight and photos from older versions should still assist in assembly.
Version 1.0 BOM: http://kitbom.com/terawattindustries/00str00der-extruder-v10
Version 1.1 BOM: http://kitbom.com/terawattindustries/00str00der-extruder-v11
Version 1.2 BOM: http://kitbom.com/terawattindustries/00str00der-extruder-v12
Version 1.3 BOM: http://kitbom.com/terawattindustries/00str00der-extruder-v13
See Terawatt's 00str00der Github repo for slicing instructions.
|1||extruder idler block|
|1||adapter plate||optional - for mounting to www.thingiverse.com/thing:18657 - not needed for Sheliak X-Carriage|
- hardware BOM has changed in version 1.0; refer to "Version History" section.
- pulley sizes have changed in version 1.1; refer to "Version History" section.
- hardware BOM has changed in version 1.2; refer to "Version History" section.
- hardware BOM has changed in version 1.3; refer to "Version History" section.
3D CAD Files
IMPORTANT: STL files are not organized by version number - they are organized by GT2 pulley and belt sizes. Read the file at https://github.com/Terawatt-Industries/00str00der/dist/stl/README.md for more.
A few people have put an 00str00der kit together with only assembly guides based on earlier ancestors:
How to make the hobbed bolt
We've been using Terawatt Industries hobbed and knurled bolts with this component, which is a M8x60mm bolt hobbed at 30mm from the head. 65mm+ works slightly better with the current (Rev. B) extruder block design. We're considering a few options around revising this, including using a non-threaded M8 rod or other machined options; but currently the 'traditional' hobbed bolt works great.
If you don't want to purchase a hobbed bolt then Wade's_Geared_Extruder describes how to make your own.
Direct-drive configuration is where the 00str00der sits on a moving platform attached to the print-head (hot end), such as an X-carriage, as is popular on many Mendel-type designs.
There are two ways to upgrade or retro-fit an existing direct-drive machine to an 00str00der:
- Use the 00str00der Adapter Plate to attach to a compatible X-carriage. This is the fastest way. The plate is designed to work with hole spacing used on many popular open-source x-carriages found on the interwebs. (TODO: cite hole-spacing spec).
- Assemble the 00str00der with idler arm, hobbed bolt, pulley motor, hotend, and all.
- Attach the 00str00der onto the adapter plate using the 3-point mounting holes.
- Note the recessed holes (on bottom of plate) to accommodate two (2) M4x30mm socket cap screws; these are for the socket-cap screw heads. The screw heads must not protrude from the bottom of the plate so the plate can mount flush to the x-carriage.
- The third mounting point is one (1) M4x16mm low-head socket cap screw, underneath the motor. The nut is on the bottom of the plate here - reverse of the M4x30mm mounting screws. This screw can protrude from the bottom.
- Attach 00str00der+plate to a compatible x-carriage.
- Use the Sheliak X-Carriage to replace the entire x-carriage. The Sheliak X-Carriage is designed specifically for the 00str00der and is compatible with many Mendel-type machines that use 50mm linear rail spacing. Perhaps the best reason to replace the whole X-carriage is to take advantage of the press-fit bearing mounts on the Sheliak X-carriage. CAD files for the Sheliak X-carriage are in the PrismX 3D Printer Github repository.
- Assemble the x-carriage
- Assemble the 00str00der with idler arm, hobbed bolt, pulley motor, hotend, and all.
- Attach the 00str00der to the x-carriage
- Replace an existing x-carriage with the new one. Steps for this procedure depend on the type of 3D printer and are beyond the scope of this article.
Bowden configuration is where the 00str00der sits stationary, attached to a printer frame or externally, such as on many Delta 3D Printers and the UConduit H-Bot 3D printer.
The 00str00der has an (OpenSCAD) parametrized variant for a Bowden setup. In this variant the bore for the j-head is replaced with one that accommodates a press-to-fit connector. It also has mounting holes on the side for a right-angle attachment to a printer frame. Pictures of UConduit H-bot repraps show this setup in action.
For Bowden configurations upgrading or retrofitting an existing 3D printer with an 00str00der extruder should be straightforward. You will need to mount the 00str00der to the frame. The UConduit H-bot 3D printer has an example mount, but this is to attach to 3/4" tubing. Somebody still needs to design a mount for other types of frame materials...
NOTE: The photos above apply to version 0.9.
- Rev. A: for use with h-bot in Bowden configuration
- Rev. B: for use with Prism/MendelMax machine; 3-point attachment to Sheliak x-carriage
- Rev. C: converges rev.A + B; testing started: for use with M4x50mm bolts on idler
Based on 0.9 Rev. C. Considered stable. Vitamin BOM refined for nylock nuts and M4 screws for j-head groove-mount.
The complete version 1.0 BOM can be found on KitBom at http://kitbom.com/terawattindustries/00str00der-extruder-v10.
Considered stable. Same as version 1.0 but with 60T big pulley, 16T small pulley. 16T pulleys easier to source; 1:3.25 ratio reduces torque on tower; 60T pulley allows access to groove mount set-screws.
The complete version 1.1 BOM can be found on KitBom at http://kitbom.com/terawattindustries/00str00der-extruder-v11.
Considered stable. Same as version 1.1 but with slightly modified idler for M4. No more M3 hardware, just M4 and M8 in BOM.
The complete version 1.2 BOM can be found on KitBom at http://kitbom.com/terawattindustries/00str00der-extruder-v12.
Considered stable. Same as version 1.2 but with 1x M8 jam nut. The M8 jam nut is for use between big pulley and 608 bearing to reduce hobbed bolt wobble. It should be hand-tightened against the 608 bearing on the big pulley side during assembly. Then the big pulley is pressed snugly against the jam nut and locked into place with its set screw.
The complete version 1.3 BOM can be found on KitBom at http://kitbom.com/terawattindustries/00str00der-extruder-v13.
JK Adapter Plate
The adapter/mounting plate provides support for attaching the 00str00der to a Kuehling's compatible x-carriage, as described in "Upgrade/Retrofit". There are three (3) mounting holes for attaching the 00str00der to the plate. When using this setup, the extruder is rotated 90 degrees, perpendicular to the axis of motion. The plate can be machined or cast.
The 00dapter was added in 2014. The 00dapter provides compatibility for using an 00str00der with a Budaschnozzle. The 00dapter is based on the "Budapter" found on Thingiverse. It's intended to be used with the JK Adapter Plate. It is installed into the 00str00der grove-mount and fills the gap between the JK Adapter Plate and the Budschnozzle mount-plate.
Terawatt Industries has created the 00str00der Configurator which calculates the steps-per-mm for you. To use the 00str00der Configurator open a web browser to http://store.terawattindustries.com/00config.
The procedure to calibrate the 00str00der is as follows:
- Measure the O.D. of the knurled (hobbed) area of the M8 hobbed bolt, preferably with digital calipers. The exact OD will depend on things like manufacturer and batch.
- Calculate the gear ratio between small and larger gear.
- Find the step angle for the motor - most common NEMA17 motors are 200 steps per revolution.
- Find the microstepping value supported by your stepper drivers. This usually depends on brand of driver and type of control electronics.
- Use the following formula:
steps_per_mm = (gear_ratio / (hobbed_bolt_OD * Pi)) * ((360 / motor_step_size) * (1 / driver_microstepping))
- A hobbed bolt where the knurled bolt measures 7.52mm in outer-diameter (O.D.)
- The gear ratio for a 17-to-65-tooth gear system is ~3.8235. In other words, ~3.8235 revolutions of the smaller gear equal one revolution of the larger gear.
- NEMA17 motors are common with 1.8 step angle and RAMPS 1.4 with pololu drivers supports 1/16 microstepping.
steps_per_mm = (3.8235 / (7.52 * 3.1416)) * ((360 / 1.8) * (1 / 1/16)) = 517.8957 ~= 517.9
You can use community-tested electronics to drive this extruder.