How important are zones on a nested table? We're currently in the process of purchasing our 1st CNC and have been looking at a lot of the mid-priced machines. I'm convinced that a 5x10 table would be best, but one of the ones I'm particularly interested in does not have any zones.
As of now, I see the machine doing 98% of 4x8 sheet processing. However, I know that when I start to figure things out we'll do a lot more with it, including a fair amount of solid machining. So, how important are the zones?
From contributor M:
Picture this: A fantastic 5 by 12 table you use one time for every 200 sheets of material put up. This is because you cut prefinished birch or maple and normally do not wish to handle 5 by 12 sheets of melamine, so usually cut 4 by 8s. Also all of your pre-laminated plastic is 4 by 8 because that is how V32 comes in.
That is where you will be and where I was a few years ago.
No zoning means you have to use scrap to cover the open table 199 times out of 200 or limit yourself to parts over about 1-1/2 square feet to keep the things from moving (or sacrifice spoilboard thickness etc. - many variables involved).
I am happier with my 4 by 8 with 2 zones I run now or the 4 by 8 with 4 zones I ran 10 years ago. The ideal situation is a 4 or 5 by 12, but it definitely needs zoning (IMHO) so that you can run the 99 percent of material you will use in real life without the headache of placing scrap over the open areas of the table almost all of the time. Sure, the occasional few sheets of Corian will limit you, but the everyday headache of half your bed being open almost all the time will likely limit and frustrate you even more.
Also, beware the 10HP vacuum pump in this situation. More is better with the 5 by 12.
As far as solid processing, pods are key. Even if they are double sided like mine, you can avoid a lot of headaches with the ability to switch to pods when needed. I think zones are very, very important.
While one zone is running, you set up the next zone to be ready to go. You don't have to worry about the gantry hitting you while you set up as long as all safety features are in place. Zones are pretty much useless when nesting sheets on a flatbed router.
The whole point of nest based manufacturing is to eliminate the need for zones for the most part. Most operations are done the same time as the panels are cut, eliminating the need for secondary operations if you engineer carefully. This system is better for small shops where you can wait a little longer for parts and have the machine do most of the work.
Covering the unused spoilboard surface is no big deal. If you have a grid table you don't even need to make a full size spoilboard, just gasket and seal what you aren't using.
Vacuum zones, yes with nested base. Placing scrap over exposed area is okay for an odd size part every now and then. A complete pain on almost every sheet. Dual operating zones not needed on nested base unless you have a 20' table and can place 2 sheets on table, and a machine that size is another question entirely.