Delta Rostock mini G2s

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Delta Rostock mini G2s Documentation
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Delta Rostock mini G2s

Release status: working

1Delta Rostock mini G2s.jpg
CAD Models
External Link

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This Rostock mini G2s is a companion piece of our new upgraded delta 3D printer -Rostock mini G2. G2s is designed to support dual extruder. With G2s you can print a single two-color object, or you can print two objects in one print job, each made from a different color. You can also print one single-color object, as with other single-extruder 3D printers. Or you can use one extruder for infill or support. The 2 extruder motor pushes filament through 2 head separately, so mixing colors printing is not applicable for the moment. This G2s is powered by our newly designed control system—GT2560 that supports 2 extruders and eliminates the complicated wiring of Mega2560+Ramps 1.4 and it is more space-saving. An auto-leveling auto-calibration device is also added on G2; which means you do not have to adjust it every time before you start printing, after the first assembly work, you can almost plug and play. In terms of printing filament, G2s not only support PLA and ABS, Nylon and wood filament is also available, which enables more possibilities to create 3D printing project. This G2s is also improved with LCD control panel; you can monitor the printing process in real time and with a SD card it can realize stand-alone printing, very convenient.

Main features:

  1. With dual extruder, support multiple way of printing.
  2. Support PLA, ABS, Nylon and Wood, giving more possibilities to create 3D printing project.
  3. New updated control system.
  4. Auto-leveling and auto-calibration.
  5. More flexible effectors and diagonal rods.
  6. More fluent printing process and higher precession.


Print Volume: 170 x 200mm

Chassis: laser -cut acrylic plate

The Layer Thickness: 0.1mm

Layer Resolution: 0.1mm

Filament Diameter: 1.75, 3mm

Nozzle Diameter: 0.3, 0.35, 0.4, 0.5mm

Print Speed: 60 to 120 mm/sec

Print Plate Size: 210 x 3mm

Print Plate (Build Platform): aluminum plate + heatbed

XYZ Bearings: carbon steel

Stepper Motors: 1.8° step angle with 1/16 micro-stepping

Max Heated Bed Temp: about 110 ℃

Max Extruder Temp: about 240 ℃

AC Input: 115V/1.5A 230V/0.75A


No. of Extruders: 2

Connectivity (Interface): USB, SD Card

Electronics: Geeetech GT2560

3D printing Software: Repetier Host

CAD Input data file format supported: STL, G code

Client Operating System: Windows, Linux, Mac

Machine Dimensions: 320 x 320 x 870mm

Machine weight:9kg

Shipping box dimensions:495*395*195mm

Shipping box weight:10kg


download the BOM here Media:Delta Rostock mini G2 Package List.pdf


Download the .STL file for the printed part here


Slic3r config

Printing test file

Building Instruction

For detailed building instruction, please visit here.

You can also download the PDF version here Media:Delta Rostock mini G2& G2s building instruction.pdf

Assembly Tips and Tricks

Community supported assembly tips (highly recommended!) are on the Delta Rostock mini G2s Build Manual page.


Update to the G2/G2s Pro firmware - even if you are on a 'plastic' G2/G2s. It has significant improvements, and works pretty much 'out of the box' to get you to the calibration and bed levelling stages.

See the official Geeetech wiki page for the G2 Pro:

Geeetech G2/G2s Pro Wiki Page

Manual Calibration Procedure

What the Calibration Parameters Change

  • Endstop trim affects the center point location (0, 0) of the nozzle, the total bed height, and the relative heights of the nozzle to the bed when the nozzle is at the tower.
    • When adjusting any other parameters, re-adjust your endstop trim such that the nozzle is at the same height when it is directly under each tower.
  • DELTA_DIAGONAL_ROD affects the Z height of the effector
    • A shorter DELTA_DIAGONAL_ROD pushes the nozzle towards the bed at the towers, and away from the bed at the adjustment screws, and a longer DELTA_DIAGONAL_ROD pulls the nozzle away from the bed at the towers, and towards the bed at the adjustment screws.
    • This should normally not be need to be modified for the G2/G2s.
  • DELTA_RADIUS controls overall flatness of the effector movement
  • DELTA_TOWER[1,2,3]_[X,Y] control flatness on a per axis basis.

Bed and Endstop Adjustment

The Geeetech G2/G2s typically will need endstop adjustment to achieve flatness.

This is complicated by the fact that there is a sprung adjustment screw at three points on the bed, and that the DELTA_RADIUS and DIAGONAL_ROD lengths can be out of spec by up to 2mm per tower.

To minimize the adjustment screw issues, either replace the spring with a fixed size spacer, or use a caliper to set all three adjustment screws such that the top of the bed is the same distance from the acrylic bed frame.

When calibrating the bed, I take my time, and calibrate in this order:

  1. First, select a calibration item - ie a domino, allen key, anything that is hard, a fixed known size, and will fit under the nozzle.
  2. For all the 'measure Z' steps, slowly move the nozzle down to the bed until you can just barely pass your calibration item under the nozzle with no interference.
    • Measuring Z this way is faster then the 'paper test', and you don't have to worry about burying your nozzle in the bed on X/Y moves.
  3. For each tower, adjust the tower's endstop trim so that the 'measured Z' is the same for each tower.
  4. Measure Z at the three adjustment screw locations.
    • If it is further from the bed than at the tower, you need to decrease your DELTA_RADIUS and/or DIAGNONAL_ROD for the other two towers.
    • If it is closer to the bed then at the tower, you need to increase your DELTA_RADIUS and/or DIAGONAL_ROD for the other two towers.
  5. Finally, measure Z at the origin. If the measure of Z is the same at the origin as it is on the edges - congratulations! Skip to the 'Z Home Setting' section below.

Effector Travel Flatness

The next step is to get the center and the edges to all have the same Z measure. You will not need to care what the measure is - just that it should be within +/- 0.1mm for all points.

Since the G2/G2s aluminum bed may be slightly warped, I recommend using a glass plate on the bed for this phase of calibration.

One thing of note while you are calibrating - the build variation of plastic carriages can cause ~1-2mm of variation in the distance of the diagonal rods from the smooth rods, which impact the per-tower delta radius, which influence the DELTA_TOWER settings.

To make this step easier use the following macros in Configure.h (approx line 130ish) - which will replace the existing DELTA_TOWER... macros.

#define DELTA_RADIUS_X (DELTA_RADIUS + 0.0)  // X tower correction
#define DELTA_RADIUS_Y (DELTA_RADIUS + 0.0) // Y tower correction
#define DELTA_RADIUS_Z (DELTA_RADIUS + 0.0)  // Z tower correction

#define DELTA_TOWER3_X 0.0 // back middle tower

The '0.0' is your per-tower correction factor, depending on how far your carriage is away from the expected distance from the smooth rods.

For example, my correction factors are '- 1.5', '- 3.0', and '+ 0.0', which means that my X axis carriage is 1.5mm farther inward toward the bed than expected, my Y axis carriage is 3mm too far in, and my Z carriage is correctly seated.

I don't yet have a simple and reliable technique to determine those factors, though - you'll have to do some trial and error.

Again, don't worry about the actual 'measured Z' value itself - you only need to care that they are the same for the bed center, the point next to the tower, and the point across from the tower.

During this phase, your Z measure of the origin should not change much - the changes to the DELTA_RADIUS_X/Y/Z should only change the tower and opposite-of-tower measured Z, simultaneously.

Now that your bed is flat, and your Delta is operating flat, we can move on to MANUAL_Z_HOME_POS.

Take the caliper-measured height of your calibration object and subtract your 'measured Z' position for the center of the bed. This value will be added to the current MANUAL_Z_HOME_POS.

For example, if you were using a 8mm hex key, your 'measured Z' was 10.73mm, and your MANUAL_Z_HOME_POS was 200, then:

// manual z pos = 200 + (8 - 10.73)

#define MANUAL_Z_HOME_POS 197.27

Finishing Up

And that should do it. If you add a glass plate, or have to remove and re-add your bed plate, your should only need to do the bed screw levelling and MANUAL_Z_HOME_POS procedure.

If you replace your carriage, you may need to do the DELTA_RADIUS_X/Y/Z procedure, and the MANUAL_Z_HOME_POS procedure.


Mechanical Modifications

Community supported build modifications (highly recommended!) are on the Delta Rostock mini G2s Development page.

Repetier Firmware Configuration

This is my (User:Ezrec's) first cut at a Repetier firmware config (0.91).

NOTE: If your Z Probe has any side to side or back to front wiggle, do not use autoprobing! Your head will tilt and slide all over the place, and you may damage your nozzle.

NOTE: This firmware config was built for a RAMPS 1.4 hardware, and has not been tested on the GT2560 controller. Use at your own risk.

Firmware config for Repetier 0.91: File:Delta Rostock mini G2s MOD Repetier 0.91 Configuration.h.

This configuration file has the full JSON config in it, so feel free to feed it back into Repetier's web-based configuration generator to build a firmware for a different version.


J-Head Leaks

If plastic oozes out between the PEEK cold region and the metal hot end, you may need to heat-tighten the J-Head.

First, a note of warning - until you have verified and calibrated the operation of your hot end/thermistor combination, DO NOT SET THE EXTRUDER ABOVE 200C.

Without the active cooling fan, the PEEK cylinder could begin to melt at approx 240C. If you are using the default hot end fan connection to PWM FAN, you can easily exceed the melting point of the PEEK cylinders if you set the hot-end temperature above 220C. To be safe, set the hot end to at or below 200C.

Since PEEK slightly expands when heated, if the J-Head was too cold when initially assembled, the PEEK threads will loosen once the PEEK reaches target temperature, and will allow plastic to ooze out between the threads.

The solution is as follows:

  • Heat the J-Head up to approx 200C (using your G-Code sender, RepetierHost is what Geeetech suggests), and let it "soak" at 200C for approx 5 minutes.
  • Using a vice-grip on the metal heater block of the J-Head (making sure not to clamp onto the nozzle!), loosen the heater block by a quarter turn
  • Wipe off any excess plastic from the heater block and PEEK cylinder with a dry paper towel.
    • Be careful not to wipe the nozzle - you can easily plug up a 0.3mm nozzle with paper fibers.
  • Tighten the heater block to a snug fit.

Do not over-tighten the J-Head! A snug fit is all that is needed - too much force will break the PEEK threads and destroy the head.

NOTE: For the G2s model, you may need to disassemble the spider's J-Head holder to be able to loosen and tighten the heater block.

G2s Misaligned Hot Ends

If you are getting prints on a G2s where the second J-Head's nozzle tip is hitting your print, then the one of your hot ends needs to be tightened.

This is especially visible on spiral-vase prints, and a spiral vase is a great object to use for this type of calibration. Make sure to have both J-Heads heated, so that you can see a blemish, instead of the interfering hot end causing a mechanical jam!

If your left J-Head nozzle is hitting the print while the right J-Head is extruding, tighten your left J-Head's hot end 1/8th of a turn.

If your right J-Head nozzle is hitting the print while the left J-Head is extruding, tighten your right J-Head's 1/8th of a turn.

If adjusting the hot-end is not able to eliminate the interference, add a 4mm washer (Bag #6) between the top retaining bracket and spider, where the 4mm bolt passes through. If the front J-Head is interfering, add a 4mm washer to the front, and if the rear J-Head is interfering, add a 4mm washer to the back.


For detailed set up instruction, you can see at here.