RUMBA (R.eprap U.niversal M.ega B.oard with A.llegro driver) RUMBA is a feature rich all-in-one electronics solution for Reprap and other CNC devices. It features an onboard ATmega2560. Its six motor outputs are powered by Pololu pin compatible stepper drivers. ⎙ ZMIN X1 manual (Operation & User’s Manual, 43 pages): View X1 document online or download in PDF.

Basics¶

ZMIN X1i - there are 1 drivers found for the selected device, which you can download from our website for free. Select the driver needed and press download.

The Dual EndStop firmware update enables unprecedented precision more easily than ever before. Sinceday one I have never encouraged endstops be used, until now.

The Mostly Printed CNC and LowRider CNC are unique in the fact that two of the axes are powered ateach end of the axis. Using this fact and the new dual endstop firmware we can now more preciselyand accurately set the position of every single stepper on the machine independently. This shouldreliably give you repeat-ability on the order of your endstops resolution, even after powering off.

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Before this new firmware update all the machines in this category relied 100% on the users buildaccuracy, or manual measuring. This involves setting of each axis before engaging the steppers andlocking it in place. If the steppers are ever disengaged during use only the side of the axis withan endstop can accurately be accounted for. This makes fixturing, tool changes, and multi-day jobsextremely difficult to get repeatable results. A poor build or lack of axis alignment before eachjob will result in a non square skewed axis. A skewed axis will result in ovals and parallelogramsinstead of circles and 90° cornered rectangles. Changes in build accuracy due to use andenvironmental conditions need to be adjusted out or accounted for manually. Now just a minor offsetadjustment will correct this.

Plugging In The Steppers¶

Marlin’s extruders=0 or remapping of pins is used in the firmware to allow the use of all the control boards drivers. Theunused extruder driver/s are used for the extra stepper/s.

SKR Pro¶

If the firmware is set for EXTRUDERS=0 then E0 becomes X1 and E1 becomes Y2. (or LR would be E0=Y2E1=Z2)

RAMBo¶

Ramps¶

Mini-RAMBo¶

This board only has 4 drivers available and can easily be used with the LowRider CNC but can not full take advantage of the new firmware with the MPCNC.

Archim¶

Endstops¶

The min pins are used as normal for the first stepper and the max pins are used for the second stepper on that axis (X2, Y2, Z2), still as a min. For example, X1 pairs with Xmin, X2 pairs with Xmax.

DO NOT USE THE + (positive) Terminal. S & – (signal and Negative) Only

• Xmin=X1 limit switch
• Xmax=X2 limit switch
• Ymin=Y1 limit Switch
• Ymax=Y2 Limit switch
• Zmin=Touch probe. Signal pin to plate, negative to tool.

For the safest configuration the endstops should be wired in the Normally Closed position (NC), toprevent wire disconnects from damaging the machine during the homing sequence.

Mechanical endstops are connected to the signal and ground pins filtered or optical endstops use allthree pins, connect these with extreme caution. Using the wrongs pins will damage your controlboard.

Optical endstops are not recommended on a machine used for milling or routing. The debris caninhibit there function.

SKR Pro¶

Note

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Do not use the + (positive) pins or you will ruin your SKR Pro board.

RAMBo¶

Pay attention the pins are opposite each other, but clearly labeled on the board.

Ramps¶

Mini-RAMBo¶

This board only has 4 drivers available and can easily be used with the LowRider CNC (Y axis) butcan not full take advantage of the new firmware with the MPCNC.

Archim¶

Firmware¶

The dual endstop firmware is on the V1 Engineering Marlin Builder pagepage.

Remember small 1mm moves when initially powering it up, if driving your steppers the wrong way youcan rip your machine apart. If your steppers are moving the wrong direction, completely power offyour board before flipping the plug over.

Testing and Calibration¶

Download Driver Zmin

After all the endstops have been connected issuing a M119 command will let you see the currentstatus of each endstop. You should check that each endstop registers both an open and closed statusbefore proceeding. Open when not touching and closed when they are. You can test them individuallyby closing each one by hand and running an M119. Also verify the X1 corresponds to the X1 stepper.

Then verify a positive movement is away from the end stops.

The unfortunately designated M666 lets you test your offset to quickly calibrate your machine. Usingthe command M666 X0.72 would offset the X1 stepper 0.72mm away from it’s endstop, Y! can also beused. To verify your current settings during calibration just an M666 will show the current offsets.Once the correct offset are found you should input them into your firmware.

This is to simplify the actual placement of the endstops themselves, you only need to get them suchthat the X1 or Y1 endstop is at or slightly behind where it needs to be within a few Millimeters isbest.

1. You can verify how square your axis is by measuring the diagonals of the largest rectangle you can draw in your build area. The larger the more accurate…but also harder to measure. I only have 6″ calipers but I was more accurate with a tape measure at my 440mm available diagonal.
2. Measure the diagonals to the X1 and Y1 endstops blocks.
3. Offset the endstop that has the short dimension by the amount it is short or just a hair over. So if the X1 diagonal was 1mm short you would offset X1 by 1mm. M666 X1. Tip – If it is more than 2mm off move the stop block, each belt tooth is 2mm.
4. Draw a fresh one to verify. If that is correct you should edit your firmware to make this change permanent in configuration.h Or add it to all of your Gcode.
5. Enjoy!

Zmin X1i Driver

Care should be taken to use as little pen pressure as possible with the finest tip possible to getthe most accurate results and a pen mount with some give should be used, example penmount.

My trials and tribulations figuring this out….Feel free to make fun of me. Forumlink.

Use¶

First, most jobs will not benefit from using endstops. Getting the machine close and just running aquick one off carving or sign has no need to go through all the extra steps. People new to the CNCworld should not use this, this is a advanced technique. My support for this will be limited.

• You can now use the machine in two ways. Quick one off jobs as you always would setting the homeposition by hand and just running the job. Or by starting each job with a G28 (if using a touchplate) you can now reference or return to that position at any time. If you are not using a touchplate you can use G28 X Y

• You can use fixtures at a set reference points on the table to do repeat jobs or multiple sidedcuts utilizing CAM based work offsets or scripts.

• Tool changes can be done with multiple gcodes so you can do repeat jobs in order of bit usedinstead of per piece depending on if changing the part of the bit is the faster choice.

• Jobs can be restarted in case of power outage, tool breaks, long multi day jobs, apply paintbetween cuts, etc.

• If you don’t need the endstops you can just insert the command, G92 X0 Y0 Z0, in your gcode beforethe cut starts. This should allow for normal use without homing or work offsets, also no squaring.

For more info please see the Milling Basics page.

Driver Zmin X1

Work offsets¶

Make sure your job has a work offset if you use the endstops.

A typical part has the gcode built with the origin at the parts corner. If you where to cut out thatpart it would result in going negative past your endstops and misalign your machine.

Negative moves do not work on the X and Y axis with endstops.

Moving the origin in your CAM program is the easiest fix.

To get a more precise work offset it is best to add it in your CAD file. This can be done with abounding box, cut it as a separate path and used to position your material.