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In my limited amount of research I have noted two basic design concepts of smaller table top sized CNC routers:
1) Moving gantry
2) Moving table

What are the pros and cons of each?

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tim...
http://www.mcknightguitars.com

In general, the moving gantry doesn't require as much power as a moving table but it is also probably not as stiff. Also, beware of designs that have a moving table which is driven by 2 motors for each axis (if the 2 motors get at all out of step, this can cause some accuracy problems).

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http://www.PeakeGuitars.com

Moving gantry or moving table probably depends somewhat on the size of the machine. It's easier to move the table on a benchtop mill as opposed to a 48"x96" machine where it's easier to move the gantry. Inertia becomes an issue fairly fast as the size of the machine increases. Servo drives are normally programmable as to acceleration and deceleration ramps---large mass requires longer times for these events.
Nelson

Hello Tim,

I am not sure if these tests are true or not, but this guy seems to have done a lot of research to determine which type of gantry is better...

http://www.solsylva.com/cnc/mechanics.html

Might be good reading, or additional information to help you with your research. His points seem to make sense.

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-CyborgCNC
http://www.cncguitar.com
https://www.facebook.com/CncGuitar

Mine is a moving table. The table size is 24"x 30"

My reasoning for making a moving table Vs a gantry is because I can move the table toward me and have access to it easier. I am getting limited on space in my shop and am planning on putting this in a tight spot where access to the whole table might be an issue.

If you are going to use vacuum for a hold down, I could see where a moving gantry would be better. I use double sided tape, so it really doesnt matter

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Reguards,

Ken H

Nelson makes a good point about the inertia. Mine has a moving gantry simply because it's easier for me to deal with and takes up less space than a moving table would take up. My shop is too crowded for a tool that gets bigger when it's in use! The cnc is the only tool in my shop that won't be on a mobile base, so I need to contain it to the allocated space, even in terms of corridor space. My cnc is also long in width rather than depth as well, again to allow for better space allocation in the shop.

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

The ultimate for me would be a 2' x 4' fixed bridge across the 4' length with the table moving in the 2' direction.