where to start?

[JAZZCNC]

One last question before I get designing....


As you can see by this image the sheets of 8 x 4 I'll be cutting get used almost right up to the edge of the wood. I will obviously need a frame which is larger so the router will be able to travel past the edge of the wood, I'm thinking 9 x 5 does this sound about right?

Not a straight forward yes or no. It will depend on a couple of measurements of the machine to how much extra length and width past the desired cutting area.

First I call the long axis X (length) and Y axis (width) is narrow, Z axis(Up,down) runs along the gantry or Y axis.

Regards Y axis(width) you will want it Just a bit wider than the width of the Z axis, basicly half the width of Z axis at each side plus a bit of stopping room.
The Z axis width will more than likely be determined by the bearings and screw used or the width of the router mounting plate. Wider is stronger because it positions the bearings on the Y axis further apart but wastes travel needing wider Y axis and machine. 200mm is a good width and will fit most routers and spindles plus allow for resonable Y axis bearing placement without wasting travel. 150mm is about the minimum I'd use for a good Zaxis.

Regards the X axis(length) well this depends on the position of the gantry cross beam on Xaxis bearing plates and how far off the front of the gantry the Z axis sticks plus the spindle or router used.
This will ultimatly give you the cutters position relative to where it falls in line with the X axis bearings, this will give you the needed extra for the X axis.

I try to position gantry cross beam back slightly from centre of the X axis bearings so that the cutter position basicly lines up with the front edge of the bearings.
This keeps everything contained within the X axis bearing plate length and nicely balanced weight distribution on the bearings.
No matter how you do it you have to have lose some wasted space at one end or the other.! . . Some sweep the gantry sides back and half the loss at each end.?
I just keep the loss at one end. . . you can always use this space for 4th axis head then it's not taking any table roomand can be left on.?

Doing it the way I do basicly means adding the length of the X axis bearing plates to the required cutting area.

Hope this makes sense.? If not just ask.