Tools/boxford

Boxford 260 VMC CNC Milling Machine

This tool requires induction

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[edit]

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 here, and the post-processor is here

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

Steve's done a reference guide for speeds & feeds that have been tested on our machine.

Current status[edit]

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

Specifications[edit]

Operational Specifications[edit]

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[edit]

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[edit]

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[edit]

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

Boxford Caretakers[edit]

Inductions[edit]

The following people offer induction for the Boxford.

Name/Contact	Notes

Workshops[edit]

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

Introduction to CNC milling

Maintainers[edit]

Name/Contact	Notes

Recent Changes[edit]

Fit spindle current gauge and readjust the spindle controller for better response and stability Stever (talk) 17:55, 26 January 2022 (UTC)
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)