Questionable decisions made while making questionable things.

CNC Router Table

29 December 2019

Here’s an overview of the CNC Router Table I’ve been building. The table is mostly operational, and I’ve used it to cut wood for a couple of different projects. But as of Dec 2019, there’s still a lot to finish, including manual and automatic tool change support, fine-tuning system integrity monitoring (like adding a sensor for sufficient air pressure), integrating a jog shuttle wheel, automatic tool length measurement, etc.

Base

I started with an AvidCNC PRO4896 4’ x 8’ router table, customized to accommodate a 9’ long work volume, and added my own control system (described later).

The extra 12” provides room for a rack-style tool corral for the automatic tool change function.

Spindle

Admittedly overkill for this router, the spindle motor is a beautiful, Italian-made, 4.5 kW, 24,000 rpm HSD ES330 Electrospindle. It uses an ISO 30 taper and provides for automatic tool changes using pneumatic pressure.

This is driven by a Delta VFD25AMS23ANSHA high-frequency inverter. Because of the maximum speed, this inverter model is limited to sale to US Citizens. If you’re trying to build a similar machine outside the US, you may run into issues acquiring the necessary inverter (it seems they can be used to drive uranium centrifuges).

Control System

Four Teknic CPM-SDSK-3411P-ELS servos provide motion, along with Teknic power supplies and power distribution hardware and cables.

LinuxCNC serves as the G-code interpreter, driving a Mesa Electronics 7i76e I/O card.

Pepperl + Fuchs inductive proximity limit switches from AvidCNC are wired directly into the Mesa I/O card.

UI

Currently using Axis from LinuxCNC, but I hope to move to Tormach’s Path Pilot UI. Unfortunately, they’re built atop an older version of LinuxCNC than I’m using, so integrating their UI will be challenging, and I’m deferring that for now. It’s a shame, because Path Pilot is vastly superior to Axis.

Jog Shuttle

This is proving challenging to integrate.

Tool Change

Automatic tool changing is not yet implemented, but it will be a rack-style tool holder.

Pneumatics

The tool change feature of the spindle requires a supply of compressed air, as does the bearing air purge (to help keep it clean of dust and other contaminants). A separate enclosure houses a few air filters, regulators, and solenoids to allow the controller to direct the flow of air throghout the system.