Large-scale DIY CNC

This large-scale CNC was designed to carve artist-scale deep reliefs in 3D, for less than $1000. This machine was built with a cutting area of 10×8 ft, and depth travel of 18″, and an accuracy of 1 mm. While similar machines can be found for around $4000, this CNC has a larger travel area at on quarter the cost. Design goals included the following:

1. Large-scale – The design uses a flying gantry with an independent table that allows for cutting of works of any depth, with easy change out of materials. It’s large enough that I can walk around inside the axes of the machine.

2. Portability – An unusual requirement for a large CNC machine, I wanted to avoid moving a heavy steel frame when moving the machine. This machine can be relocated by one person in about 1 hour. The main gantry contains all 3 drive axis mechanics.

3. Deep relief – A key design feature was to cut deep relief into foam for wax casting. The GiantCNC uses a 36″ lead screen to provide up to 18″ of Z-axis travel, with a unique fin-shaped mount for lateral stability. To keep down costs, cabinet slides are used for guide rails.

4. Low cost – The total cost of the machine is about $800, and is the lowest cost CNC machine for its size. Costs were reduced by using LVL lumber instead of steel, drawer slides for the Z-axis, lightweight chain, and common L-stock aluminum for X/Y-axis rails. Other costs were reduced with a special bearing box which allows the use of the same 1″ bearings throughout the machine.

First run was achieved on Aug 6th, 2012. A standard shop router was mounted to the Z-axis, and two circles were cut using a 1/2″ flat end mill. The speeds and feeds were way off, causing the darkend (burnt) wood, and several bits to break off during initial attempts.



Testing with a pencil allows for greater control, and demonstrates the precision of the machine despite its size. Here it draws a standard g-code pattern and text for ShapeOko.

ITHACA GENERATOR SIGN



The first real project was created on Sept 28th, 2012, for the Ithaca Generator makerspace, a new make and build space located in Ithaca, NY. This was a test in laminated plywood, hence the change in color at different depths. G-code errors still presented a challenge to completing the pattern.

GODDESS OF ATOMIC NUCLEI



Goddess of Atomic Nuclei. Hardwood relief sculpture in oak, Oct 18th, 2012. 36″ x 10″
Created from a pencil drawing original, and converted to paths using Adobe Illustrator.

VICTORIAN RELIEF



Victorian Relief. Nov 4th, 2012. 8″ x 6″. Oak hardwood.

True depth relief from a 3D rendered model. The original model was designed in 3D in Maya (software). A depth map was rendered to produce a continuous tone black-and-white image representing depth. From this, the g-code tool path was generated using custom software. This produced the green tool path shown in the image, which is the path the CNC tool must take to reproduce the original 3D model. Finally, the g-code was cut in one run into oak hardwood to a relief depth of 1/4″, with a horizontal accuracy of 1/32″ using a 1/8″ end mill.