We've added several of OpenBuilds' CNC machine bundles to our store. If you are new to CNC routers you might be overwhelmed by the options and uncertain of all the features. We hope that this post can help you decide what bundle might be best suited for your needs.
We want to start out by saying that the OpenBuilds system of parts is very modular in nature and easy to configure in many different ways. This can lead to a lot of variety in designs that more or less accomplish the same overall goals. Many of the OpenBuilds CNC designs offered were originally created and shared by members of the OpenBuilds' community, and reflect the original designers personal design preferences. These slightly different approaches often end up creating designs that all share a lot of the same overall potential.
All of the OpenBuilds CNC systems we currently
carry have several key similarities
- All of the designs use OpenBuilds C-Beam extrusions for their linear rails. This is the currently the largest and stiffest V-slot rail offered by Openbuilds. Stiffness is important in a CNC application to support the weight of the machine parts and reduce flexing that occurs as the cutting bit is pushed into the material. All other things being equal, a stiffer machine is a more accurate machine and has the potential to cut material faster.
- All of the designs are based on using NEMA 23 sized motors. NEMA 23 refers to the size of the motor's mounting flange, in this case 2.3 x 2.3 inches (58.4 x 58.4 mm). This means that all of the OpenBuilds CNC bundles we carry can all use the same size motors and therefore have the same power potential
- All of the OpenBuilds CNC bundles we carry are available with the same control electronics and power supply, or they can use any suitable electronics/power supply you choose. Since they can all use the same electronics, they can also all use the same software for control and design. Once again this means they have the same potential.
So what really are the main differences in
the different machines?
1. Machine Size
The most obvious difference is in the size of the machines. This can be broken down into 3 areas.
- The machine's "footprint" or the area the machine will take up on a desk/table/workbench. For some people especially those with small shops and limited space this may be the deciding factor in their selection.
- The machine's "travel area" or the maximum distance the moving parts of the machine can travel. This is most user's primary factor in selecting a machine as it generally determines the maximum size of an object/area that the CNC router can machine.
- The machine's "Workable Material Height" or the thickness of the material that can be cut on the machine. This can vary slightly depending on the length of the cutting bit, the thickness of the machine's spoil board, etc. This is easy to modify on some designs, and much harder to modify on others.
Here is a quick comparison chart of the current OpenBuilds CNC bundles listed generally from smallest to largest.
Workable Material Height
(Based on a 1/2" spoiler board)
Price* of base kit (mechanical parts only)
*as of 11/17/2021
|MiniMill||22" x 16"
(560mm x 406mm)
X Axis 4.5" (120mm),
Y Axis 7" (180mm),
Z Axis 3" (~80mm)
|C-Beam Machine||21.5" x 20"(546mm x 500mm)||
X Axis 13.5" (350mm),
Y Axis 11" (280mm),
Z Axis 3.5" (~85mm)
|Sphinx 55||20" x 20"(500mm x 500mm)||
X Axis 13" (333mm),
Y Axis 12.5" (325mm),
Z Axis 3.2" (~85mm)
|2.25” ( ~57mm )||$1169.99|
|Sphinx 1050||40" x 20"
(1000mm x 500mm)
X Axis 32.5" (883.5mm),
Y Axis 12.5" (325mm),
Z Axis 3.5" (~85mm)
|WorkBee 1050||40" x 20"
(1000mm x 500mm)
X Axis 12.5"(325mm),
Y Axis 30" (760mm),
Z Axis 4.5" (~122mm)
|LEAD 1010||40" x 40"
(1000mm x 1000mm)
X Axis 29" (730mm),
Y Axis 32" (810mm),
Z Axis 4" (~100mm)
Upgradeable to 8" (`203mm) with the "High Z mod"
|WorkBee 1010||40" x 40"
(1000mm x 1000mm)
X Axis 32" (824mm),
Y Axis 30.5" (780mm),
Z Axis 4.5" (~122mm)
|WorkBee 1510||60" x 40"
(1500mm x 1000mm)
X Axis 32" (824mm)
Y Axis 50" (1280mm)
Z Axis 3" (~76mm)
|LEAD CNC 1515||60" x 60"
(1500mm x 1500mm)
X Axis 46" (1170mm),
Y Axis 49" (1250mm),
Z Axis 3.5" (~90mm)
2. Bed / Gantry design
Some CNC routers use a moving bed design which physically moves the part you are cutting/milling along one or both axis. This can help reduce the footprint of the machine and simplify construction but it also has some limitations. It can limit the maximum size of the work piece you plan on cutting as it can only move the part so far before potentially hitting part of the machine's frame. It also is not suited for doing very large work as the motor has to provide all the force to move the weight of the material in addition to the force needed to push the work piece into the cutting tool. Both current OpenBuilds designs featuring this style of movement also use a single motor driving each axis. This design is best suited for precision cutting of smaller items where the potential of deflection (flex) in larger beams and the increased inertia of moving a heavy gantry can be a concern.
Other CNCs designs feature a completely fixed bed with the spindle/router mounted on gantrys that moves back and forth along the X and Y axis. While this adds more weight to the motion system, when dealing with large format machines the weight of moving the gantry can be much less than what would be required to move a large heavy bed+workpiece. The OpenBuilds' designs using this approach all have an extra motor on the Y-axis to compensate for the added weight of the gantry assemblies. This design approach is much easier to scale larger by simply extending the length of the rail and corresponding belts/lead screws and wiring. These designs also feature a flat open design on one axis which allows materials longer than your machines footprint to fit on the bed and can allow you to cut parts longer than your machine's travel area by moving the work piece and doing multiple separate passes.
Individual design differences
Aside from overall size and motion style, the other main differences are generally based on the original designers preferences and beliefs on what creates a better machine. There are a lot of different view points out there on the best approach for doing certain jobs. We've compiled a few notes on the individual designs below.
Moving Bed/Table Designs
The MiniMill -The main advantages in this design is the very small form factor, stiffness, and lower cost. The machine includes manual jog knobs on the X/Y axis for manually moving the axis to position a work piece manually, or for taking light manual cutting passes. It is intended generally for people looking to precisely cut small parts and is composed entirely of common OpenBuilds parts.
The C-Beam Machine - This is generally a scaled up version of the MiniMill intended for users who wish to cut out machine plates and other parts no larger than about 12" wide. It uses a moving bed on the Y-axis, while mounting the X axis on a gantry. It is also composed entirely of common OpenBuilds parts.
Fixed Bed Designs
The Sphinx - This design uses custom cut aluminum plates to reduce the complexity and amount of parts needed. This design uses mostly mini v-wheels riding along the inside of channel of the C-beam to protect them from debris and also uses some full size v-wheels for additional support on the outer channels of the extrusions. The Sphinx design uses a belt driven Z-axis to relocate the Z-axis motor to the back of the extrusion. This allows the user to potentially gain increased torque and higher resolution on the Z axis by changing the ratio between the drive pulleys. Relocating the motor also reduces the vertical clearance needed above the machine by about 4" (~100mm) which can be beneficial to users working under cabinets/shelving, or wanting to build an enclosure around their CNC to reduce dust/noise. (The Sphinx-based designs are currently being phased out by OpenBuilds, but the parts list on OpenBuild.com can still be sourced for those interested in building these machines)
The Workbee - Like the Sphinx, the Workbee design also features custom cut plates, but uses higher number of entirely full-size v-wheels to support the moving parts of the machine. The V-wheels are also supported by plates on both sides of the linear rails on the X and Y axis, making for a very sturdy assembly. The Workbee's gantry plate design includes bolt patterns for using either a belt-driven or screw-driven design for both the X and Y axis, making switching to a belt drive to expand either axis over 1000mm very easy without requiring new custom cut gantry plates. (The Workbee-based designs are slowly being phased out by OpenBuilds, but the kits can still be ordered for those interested in building these machines)
The LEAD 1515 CNC - is the newest OpenBuilds Design. It builds upon the great success of the LEAD 1010, but has 2 key design changes. The LEAD 1515's design features a new tensioning system for the X and Y-axis LEAD screws to virtually eliminate "screw whip" that can occur when using 8mm LEAD screws on drives over 1000mm long. The LEAD 1515's X-Axis has also been stiffened through the incorporation of dual C-Beam Linear Rails to achieve even better accuracy and help it to support heavier spindles/routers. These changes allowed the design to be expanded 50% in width/length and the LEAD 1515 CNC's larger cutting area make it possible to create large projects with 4’ x 4’ sheets of material!
These are just some of the differences in each design. Each approach has it's own strengths and weaknesses but generally all the designs have similar capabilities overall. The great part about all the OpenBuilds machines is that their modular nature and large community of builders makes it easy to customize the designs further to best suit your needs!