Z axis and Overall Table Size help

[NVTS]

Hello all,

I am in the process of building a 4X8 CNC router. I have the x and y axis figured out. What I want to know is the following:

1. What should the overall size be for x and y for the machine to cut a full 4 x 8 sheet.

2. What is the common length of travel for the z axis.

I know there are a lot of different sizes of travel, but bits are only a certain length. I am wanting to cut through ½ to 1 inch wood ply and plastic most of the times. Then I still might want to carve into a 4 to 6 inch wood piece with figure once in a while.

Thanks in advance.

Howard

[PaulRowntree]

Hi Howard;

It would seem that your question answers itself ! Are you asking how much larger the table is relative to the X-Y work dimensions? That depends on your design and constraints. My machine has large borders, so I lost ~4" each side. Some folks have clever gantry designs to minimize this (for example the BuildYourCNC machines allow the spindle to travel over the X rails to minimize wasted Y space).

Most folks keep the Z travel to less that 6" for stability, which fits well with your stated work sizes. Don't forget that you must be able to raise the spindle high enough to change the bit, and perhaps add a dust collection shoe.

[NVTS]

Paul,

Yes I agree. After asking the question I knew the answer was the loss of border size.

I am going to design the z axis for 8 inch travel.

Thanks for the reply.

Howard

[metalworkz]

Hello Howard,
Also keep in mind that the length of the carriage on the gantry slide(both X and Y work the same) for the Y axis will need to be compensated for in the overall length of the gantry(y axis) slides and ballscrew(actuator). Thus if you have a 6" carriage for your Z axis to travel across the Y axis you will need that much extra travel for your spindle to reach the extents you plan for the Y axis. I hope I described that correctly.