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Release status: working

00str00der firstever 1.JPG
The RepRap Wiki 00str00der page.
CAD Models
External Link

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.



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 an H-Bot-style 3D Printer (TBA) with Bowden-style extrusion. Free Beachler of Terawatt Industries revised the design to work with a Prism (TW's PrismX RepRap) by supplying the Sheliak X-Carriage design. Both designs are being converged (rev. C) and a mounting plate has been added to attach this extruder to carriages like [http://www.thingiverse.com/thing:18657].


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.

Mechanical Construction


Printed Parts

Quantity Description Comments Diagram
1 extruder block
00str00der block
1 extruder idler block
00str00der idler block
1 adapter plate optional - for mounting to www.thingiverse.com/thing:18657 - not needed for Sheliak X-Carriage
00str00der idler block

Non-Printed Parts

Quantity Description Type Comments
Drive System
1 65T Plastic GT2 Pulley, 8mm bore, 2mm pitch, 6mm width Drive System 8mm bore for hobbed bolt; metal pulleys are OK; note: if this pulley does not have a set screw you will need an M8 nylock nut for the hobbed bolt
1 17T Plastic GT2 Pulley, 5mm bore, 2mm pitch, 6mm width Drive System 5mm bore for NEMA motor; metal pulleys also work; must have set screw
1 GT2 Belt, 88T, 186mm length, 2mm pitch, 6mm width Drive System +/- 1 tooth works OK
3 608 bearings, skateboard bearings Bearings
1 M8×60mm hobbed bolt (65mm works perhaps better) hobbed bolt M8×60 barely makes it through the pulley, 65mm is perhaps better
1 M8 Fender Washer Fastener Nyloc works better, but a pair of nuts will also work
4-5 M8 washers Fastener to space the large pulley clear of the extruder base
1 M8 nylock nut Fastener optional - not pictured - I recommend using the set-screw on the M8 GT2 pulley to tighten things
1 608 bearing, skateboard bearing Bearings the 608RS are resealable, so if they get clogged with plastic the bearing cage can be exposed, cleaned, and re-assembled.
1 M8×20 Threaded rod
1 M3×30 socket-head cap screw Fastener mount idler arm to extruder block
2 M3×50 or M3×45 socket-head cap screws Fastener for idler tension
3 M3 nuts Fastener one (1) for block mount
5 M3 Fender washers Fastener one (1) for mounting to block - std washer is OK
2 ~4mm ID springs Spring Sized to fit over an M3/M4 bolt, unsprung length of 10-12mm, each spring providing 25-35N load. For a given filament drive force, you'll need about twice the spring force - i.e., if you want 100N of filament drive, your springs need to push with about 50N each.
NOTE: Some users have their extruders working without springs, but springs are recommended. It can be tough to find good springs - often Home Depot will have an assortment and something that works can be found in there. Also check with the recommended vendors.
'Hotend Mount
2 M3x25mm Fastener M2.5 works OK but is pricier, while M3 is a little tight so extra de-burring required
NOTE: The only current tested hotend mount is the j-head style mount reflected in the SCAD/STL files for the extruder block.
Stepper Motor Mount
00str00der - 14.jpg
2 M3×12 bolts Fastener Low profile bolt heads might work better here
2 M3 Fender washers Fastener std. washers will work
2 M3 lock washers Fastener optional - resists vibration
Stepper Motor
1 NEMA 17 bipolar stepper motors Stepper 0.49 Nm (69 ozf*in) works well. We've been using the Stepper Motors from Terawatt Industries and it appears to be much more force than necessary. Should be capable of creating a holding torque of at least 0.4Nm (56.6 ozf*in), at the very least.
Extruder Mount
2 M4×20 socket cap screw Fastener The Sheliak X-Carriage has a three-point mounting system for this extruder.
1 M4×20 button head cap screw Fastener Required. We're discussing a revision so a regular screw can be used.
3 M4 nuts Fastener x-carriage mount - nylock nuts are better, then skip the lock washers
3 M4 washers Fastener x-carriage mount
3 M4 lock washers Fastener optional if using nylock nuts

Assembly instructions

We need to write specific assembly instructions. For now the best we have are some assembly guies based on earlier ancestors:

How to make the hobbed bolt

We've been using Terawatt Industries hobbed bolts for testing on 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 modifying 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.


  • 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; potential revision on hobbed bolt and/or mount

3D CAD Files

The design files for the latest version can be found on Github at https://github.com/Terawatt-Industries/00str00der and https://github.com/iquizzle/00str00der.

Extruder Calibration

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))

For example:

  • 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

Stepper Driver

You can use community-tested electronics to drive this extruder. Experimental electronics like 4Pi should work OK also.