The Gantry

The real enemy for the CNC router gantry is mass. It makes things sag. It makes people go with bigger and bigger motors which creates more mass. It puts more strain on the system that makes things move and reduces accuracy.

http://gaboats.com/boats/snowshoe16.html
A 15'6" boat that weighs 32 lbs.

Careful engineering can build in strength without adding mass. For this first build, I am not going this far, but here is a perfect example. Platt Monfort was designing ultra light boats that are tremendously strong for their weight. The boat pictured on the left weighs 32 lbs and has a capacity of 500 lbs. There are examples where you can even get lighter.  Except for a little Kevlar roving and the Dacron fabric, this is made with stuff that you could pick up at Home Depot. The Kevlar roving can be had for $25 for a 300 ft. spool. We are not looking at a major investment. Michael Storer had a little Rushton designed Wee Lassie canoe that he got down to the ridiculous neighborhood of 12 lbs. Even a big 3 hp router weighs less than 20 lbs. Why on earth would you need to build a support that weighs hundreds of pounds? These monsters routers are made to use free hand unless you are using some huge shaper or panel raising bits. Why do you need inches thick aluminum extrusions or big steel beams to hold it up? Many of the big gantries I see on 4' x 8' routers could lift an engine out of a car. Come on. Be serious. We are holding up a 10-20 lb router or smaller. I am planning on using a RotoZip on mine. It weighs in at under 4 lbs. It is pretty simple to get a gantry that can support it without sagging over a 4 ft. span in under 30 lbs without breaking a sweat. With a lot of thinking, you could get much lower.