Source for hollow round rails (pipe)

[Bruce Griffing]

I am interested in building a vertical cnc router. The reason for the vertical format is space. I simply don't have room for a horizontal unit. I was motivated to pursue this avenue by my panel saw. It works very well. It handles large panels and takes up very little space. I don't see why I could'nt build a cnc router in the same format. I want the machine for wood, as I already have CNC equipment for metal. This leads to my question. I am thinking of using round rails for the vertical members as the panel saw does. I think hollow tubing would be the best for stiffness to weight ratio. I want the machine to be precise to .005"-.01". Who sells this type of rail?

[ger21]

I think you're just talking about cold rolled steel tubing. I believe that DOM is the most precise.
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What do you plan on using for bearings?

Keep in mind that a router will put forces on the tubing in all directions, while a panel saw usually cuts along the length where the deflection is the least. With a router you may have significant deflection that wouldn't be noticed with a panel saw.

[Bruce Griffing]

I wasn't talking about DOM tubing or any other conventional tubing. I was talking about purpose built hollow round rails. My experience with DOM suggests that DOM tubing is not nearly precise enough for what I want. For the vertial bearings, I plan to use some teflon filled delrin material I have in hand - assuming I can find suitable way material. I plan to counterweight the gantry so the vertical axis motors don't work against gravity - accelerating the mass of the system is enough of a load.

[ger21]

What diameter are you looking for?

McMaster Carr has them, but they're very expensive. search for linear shafts.

[Bruce Griffing]

The MC shafts are exactly what I want. I am looking for 1.5" to 2" diameter. OTOH, at the MC price - I may consider another more conventional option. I will do a broader search using "linear shaft" as the search term.