Tools/boxford

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Boxford 260 VMC CNC Milling Machine

This tool requires induction
Inductionrequired.svg
Owing to it's dangerous nature, delicate nature, or expense, this tool requires that you be inducted on it's proper handling before use.

Introduction

The Boxford 260 VMC Milling machine
The working area of the Boxford 260 VMC Milling machine

The Boxford 260 VMC is an educational model CNC mill that is in the process of being upgraded with a modern controller and electronics. The CNC milling machine has a maximum travel of 250mm x 130mm and a vertical travel of 180mm, the spindle is speed controlled from 100-3000rpm. It's suitable for use with Aluminium, Brass, Mild steel (with caution), stainless steel (very, very slowly) and most Plastics. The Boxford mill requires induction before you can use it as it is a complex and challenging to use tool.

The Boxford is kept downstairs on the west wall between the drill press and the linisher. The lab does not keep a regular stock of milling cutters, although you might find some around the place from time to time. If you have a specific job in mind then it's recommended that you bring your own tooling, we do this because a clumsy operator can easily break hundreds of pounds worth of tools in a few minutes and it wouldn't be fair to other members for the lab to have to pay for that. At the moment we're recommending a maximum speed of 800mm/sec for travel moves (although speeds up to 1200mm/min are available) and 300mm/sec for cutting moves, although the exact speed you want to use will depend on many factors (see the induction). The Boxford is protected from damage by Prudence, the safety goat. The Fusion-360 definition file for the boxford is File:Boxford Smoothie.machine, and the post-processor is File:Boxford Smoothie.cps

A quick reference guide for trained users can be found here.

Current status

Date Status Comment
30th July 2021 Operating Normally Spindle bearings have been replaced, normal operation can resume

Specifications

Operational Specifications

Working Area

X 250mm

Y 130mm

Z 180mm

Maximum load on table 25Kg
Spindle Speeds 100-3000rpm (500-2500rpm recommended)
Spindle power Originally 500W, now limited to more like 250W
Maximum travel speed 800mm/min recommended, 1200mm/min allowed
Maximum recommended cutting speed 300mm/min
Maximum tool size 16mm in ER25 collet, a larger carbide insert face mill is available
Maximum recommended drill size 6mm (8mm possible if feed is slow enough, holes over 6mm should be milled where practical)
Cooling system Minimum Quantity Lubrication via oil mister
Electrical requirement 10A 240V single-phase
Air requirements 8CFM @ 5 Bar

Technical and maintenance specifications

Spindle Bearings 45 x 75 x 16 mm bearings (2 required), Originally 6009-2Z-C3 Deep groove

Replaced with 7009B-P4 Angular contact bearings

Spindle Motor Lenke 180V DC permanent magnet motor
Spindle Driver Parker Controls 508/00/20/00 12A 180V motor driver
Limit Switches SIP10-C2 NPN NO AECO V3 Shielded inductive sensors
Stepper PSU 60V DC 1500W switch mode power supply
Air system PSU RS components 24V 2A DIN rail PSU
Logic PSU RS components 12V 2A DIN rail PSU
Stepper drivers DM860H 7.2A fan-cooled stepper drivers, set for 4.3A continuous, 5.2A peak, no idle current reduction
Stepper Motors NEMA34 8-wire steppers that are about 80mm deep, The X and Y Axis motors are unknown, the Z-axis motor is RS part number 180-5291

Planned Upgrades

  • Make new front panel - Will require linuxCNC upgrade first
  • Reinstate touch probe
  • Replace controller with MESA 7i76E
  • Install LinuxCNC option
  • New spindle motor and driver - To possibly increase max spindle speed

Known Issues

  • Door interlock switch disconnected (might not want to reconnect)
  • Head needs tramming

Boxford Caretakers

Inductions

The following people offer induction for the Boxford.

Name/Contact Notes
Steve-R

Workshops

The following workshops are available which use the boxford CNC milling machine

Maintainers

Name/Contact Notes
Steve-R

Recent Changes

  • Tighten play on spindle bearings slightly. Seems to be settling down and wearing in OK, Easy-change chuck still performing poorly Stever (talk) 22:28, 20 September 2021 (BST)
  • Increase rapid G0 speed limit to 1200mm/sec on X and Y, increase travel limit on Y to 130mm Stever (talk) 18:08, 12 September 2021 (BST)
  • Added Script to allow Rapid G0, even on Fusion360 Personal accounts. For more ask Steve. Ruperte (talk) 17:34, 12 September 2021 (BST)
  • Fit non-return valve on MQL system, priming should no longer be needed and valve should not be adjusted Stever (talk) 17:04, 11 September 2021 (BST)
  • Readjust Y and Z axis gibs for best balance between backlash and slop, screws on order to adjust X-axis Stever (talk) 22:48, 6 September 2021 (BST)
  • Replace spindle bearings, re-manufacture pre-load shim and retaining washer, set up and run in, replace spindle cooling fan. Stever (talk) 10:35, 30 July 2021 (BST)
  • Clean and lubricate spindle, bearings continue to give concern. Clean and relube the EZ change chuck, replace damaged release pin Stever (talk) 16:50, 12 July 2021 (BST)
  • Implement proper spindle shut-down on E-stop, increase maximum allowed travel speeds to 1000mm/min Stever (talk) 15:48, 5 July 2021 (BST)
  • 2A slow-blow fuses do not work in the controller circuit, decision made to rate the circuit at 4A regular speed fuses Stever (talk) 08:15, 22 May 2021 (BST)
  • Phase-2 rewire finished Stever (talk) 18:13, 5 May 2021 (BST)
  • Replace fusing system with better breaking capacity fuses Stever (talk) 16:04, 30 April 2021 (BST)
  • Final fit of limit switches, connect stepper enable lines to +12V, add proper EMI suppression on air solenoids Stever (talk) 18:43, 29 April 2021 (BST)
  • Replace failed spindle motor controller Stever (talk) 22:52, 21 April 2021 (BST)
  • Install limit switches and configure Stever (talk) 21:41, 19 April 2021 (BST)
  • Replace Z-axis stepper motor, reinstate mist cooler and covers Stever (talk) 22:06, 7 April 2021 (BST)
  • Replace PSU with 60V 1500W unit, re-install enclosure lights, tidy wiring considerably, re-install protection fuses, connect spindle driver to E-stop system Stever (talk) 18:03, 25 March 2021 (UTC)
  • Readjust gibs that had loosened Stever (talk) 18:00, 19 March 2021 (UTC)
  • Fitted new drivers, wiring is a mess that needs redoing. Stever (talk) 22:01, 27 February 2021 (UTC)
  • Adjust gibs on all axis, neaten up wiring and improve star-grounding, re-connect spindle cooling fan. Stever (talk) 22:30, 21 February 2021 (UTC)
  • Phase-1 rewire completed, boxford returned to service. Stever (talk) 02:12, 25 August 2019 (UTC)
  • Rewire continues but we lost a driver and the bridge rectifier to an unexpected ground-return loop. Stever (talk) 02:58, 19 August 2019 (UTC)
  • The stepper driver has been repaired, boxford is functional again. Stever (talk) 10:55, 27 September 2018 (UTC)
  • The x-axis stepper driver has failed under test, is being investigated to determine if it can be repaired or replaced Stever (talk) 20:11, 23 September 2018 (UTC)

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