CNC Router Design: Custom Gantry Plates vs Standard Plates Plus Extrusion

Browsing through the designs here and elsewhere (OX, shapeoko, CNC router parts, etc.) there seems to be a basic commonality to all of them: the use of custom gantry plates. The plates have various holes for mounting wheels, motors, linear guide, and usually a pattern of holes for mounting the tapped holes of extrusion for the cross beam.

I've been toying with a couple of design ideas that use just 'standard' gantry plates instead. One or two C-Beam gantry plates attached to 20x40 extrusion. Then any cross beams can rest on the extrusion attached with as many attachment plates/brackets as I want on the sides or the bottom so it is secure.

The disadvantage is that there are more pieces. But you end up with a 'plate' that is 20mm thick. You can tighten the screws into steel T-nuts rather than easily stripped and tricky to tap aluminum end holes. And overall it seems easier to make a wider gantry for more wheels and stability if needed.

What do you think? Are there any hidden gotchas here? When is it better to use custom plates and when is it better to use the cheaper 'standard' plates?

-D

 

One example is how I built the gantry for my CNC glass grinder. I attached a single piece of extrusion to two different standard C-Beam gantry plates which gave it a very wide base of support and 8 wheels. You can see the crosswise piece of aluminum in this shot:

http://openbuilds.com/attachments/photo-feb-16-6-57-25-pm-jpg.14198/

Another example is shown on the parts store where they have a sample build for the double wide gantry plate:

http://cdn1.bigcommerce.com/server2...ide_Plate__20877.1458424233.1280.1280.jpg?c=2

Here they show the z-axis C-beam held onto a double wide gantry plate by black corner brackets instead of having custom y-axis or z-axis gantry plates.

I've been thinking, why not do a router entirely this way? Instead of using OX plates, some other plates, or designing my own. Has anyone built a cnc router just out of standard parts from the parts store without custom gantry plates?

-D