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Charter Oak Automation

CNC Controlled Machinery for Industrial and Serious Hobbyists

Charter Oak Automation
340 Quinnipiac Street
Building 19
Wallingford, CT 06492
(203) 562-0699

Home » Charter Oak Automation Products » High-Capacity Square Column CNC Bed Mill

High-Capacity Square Column CNC Bed Mill

Available in 3-Axis and 4-Axis Configurations

Key Features at a Glance:

Precision and Accuracy
Superior Power and Envelope Size
A Mill That Grows with Your Needs
Direct Competitor Comparison

Working Envelope 26" × 12½" × 22" (XYZ)
Table Dimensions 39½" × 9⅜"
Max (X,Y) Rapid 200 IPM (Inches Per Minute)
XYZ Positioning Closed-Loop AC Brushless Servo Motors
XYZ Linear Actuators P3-Grade Ball Screws
Encoder Resolution 6,400 PPR (Pulses Per Revolution)
Max Workpiece 500 lbs.
Spindle Motor 3 HP Variable-Frequency Drive
Spindle Speed 60 to 3,800 RPM
Spindle Taper R8 or NT30
Head Rotation -90° to +90°
Head Mount Diam. 12½”
Oiling System 17-Point
Power Req. 220-240V AC, 50/60Hz single phase
Computer System All-in-one PC on reticulated armature
Included Software Windows 8, Mach3 Preinstalled
Base Price $11,499.00

Optional Rotary Table

Size 8″ Surface, Tailstock Provided
Positioning Closed-Loop AC Brushless Servo Motor
Configuration Horizontal or Vertical

To Order or Request More Information:


Call: (203) 562-0699

Larger, Faster, More Powerful, and More Accurate Than the Competition

Our CNC bed mill has more than a decade of R&D and performance tuning behind it, and it shows! It has the largest working envelope in its class (with a whopping 26" × 12½" × 22" (XYZ) of servo-driven XYZ travel) plus an optional 8″ 4th axis rotary table with tailstock. The fully-ground and dovetailed ways run on high-precision ball screws, and the powerful 3 HP spindle motor with variable-frequency drive and six-speed gearbox ensures you always have the power you need at the speed you want (from 60 RPM to 3,800 RPM).

Precision and Accuracy Require Attention to Detail

To achieve the highest level of repeatable performance in a machine requires not only high-quality components, but also a thoughtful design. We’ve applied more than a decade of experience refining our systems to arrive at a precision CNC mill that will provide years of reliable service. Here are just some of the features that allow our CNC bed mill to deliver superior machining accuracy, precision, and performance to our customers:

  • Servo Control
    Closed-loop AC brushless servo motors have integrated encoders that guarantee positional accuracy during movement, ensuring that your work piece is really where the computer thinks it is. Stepper motors commonly used by our competitors lack this functionality, and positional accuracy can suffer as a result.
  • Precision Ball Screws
    The X, Y, and Z axes on our mills come standard with P3-grade ball screws for superior positional accuracy. Powder coated steel ball screw mounts significantly reduce the flexure associated with inferior aluminum or cast iron mounts, and separate support bearings for the X-axis ball screw provide additional rigidity during operation.
  • Fully Ground, Dovetailed Ways
    Every machine’s ways are completely ground for smooth operation, and each machine is custom-fitted to achieve optimal component mating.
  • One-Shot Oiler Lubrication System
    A single lever pull provides immediate lubrication to the ball screws, ways, dovetails, and gibs, helping to maintain their longevity and smooth performance for years to come.
  • Robust Electronics
    Our electronics feature segregation of high- and low-voltage circuits, separate cable routing for reduced inductive crosstalk, individually ferruled connectors for better surface contact, and integrated safety fuses to protect against line spikes.

Raw Power and Machining Volume: Superior Results for Less Expense

Charter Oak Automation’s CNC mill is the next generation of the popular IH CNC & Machinery Square Column Bed Mill, and we take its decade-long reputation for best-in-class machining abilities seriously. Our customers have two requirements that our competitors can’t measure up to:

  • A Larger Working Envelope
  • More Cutting Power

The unique features of our mill allow for greater machining capacity. Our customers can make larger cuts and use larger tooling without the excessive head shake and tool chatter that plagues other designs because our larger head mount offers superior torsional rigidity over our competitors.

Working Envelope

Our mill’s total travel dimensions are unparalleled for its footprint, with a larger table and a ball screw configuration that provides greater axis travel. All of this combines to allow larger work pieces to be machined, or more pieces to be produced during a single run. In a production setting, this equates directly to significant time and cost savings.

Our dimensional specifications speak for themselves:

Total Travel: 26" × 12½" × 22" (XYZ) Table Size: 39½" × 9⅜"
Spindle Nose to Table: 23" Spindle Center to Column: 12½"
Spindle Nose: 3.8" Maximum Work Piece: 500 lbs.

Cutting Power and Speed

But what good are impressive dimensions if the cutting power doesn’t measure up? Our CNC systems come standard with a 3 HP variable-frequency drive motor and six-speed gearbox. The machine will handle speeds from 60 RPM to 3,800 RPM with plenty of torque in each gear selection. The servo motors are designed to supply (X,Y) axis rapid speeds of up to 200 inches per minute, far in excess of competitors in our class.

Cooling System Compatibility

All of our CNC mills include a coolant hookup as a standard feature. Our customers have taken advantage of these capabilities for anything from drip coolant to full flood coolant at thousands of gallons per hour.

Side-Loading and Z-Loading Characteristics

Greater torque and faster spindle speeds naturally create more side-loading and Z-loading forces, and our mill is designed to withstand these so that its increased machining capabilities can be realized without undue tool chatter or mill head shake. Without the design enhancements implemented to counteract these forces, the increased milling power could not be used to its fullest potential.

A Mill That Grows with Your Needs

Machinists’ needs tend to grow over time, so we provide a wide range of options to help you keep your mill in line with your requirements as they expand.

Mach-1 Quick Change Tooling SystemMach-1 Quick Change Tooling System
The most popular quick change tooling system has been adapted by Mach-1 Systems Inc. specially for our mills. Swapping a tool takes only a few seconds, with just a small push on the quill lever — no wrenches or awkward reaching needed!

The patented Mach-1 system replaces the standard draw bar in our mills, and grips your tools with 600 lbs. of holding force. Tool length offsets are retained between collet changes, increasing your time efficiency and reducing human error. For industrial customers, the payback period from time savings alone can be as short as a few months at typical shop rates.

Fourth Axis Rotary Table with TailstockFourth Axis Rotary Table with Tailstock

The optional fourth axis rotary table allows you to machine more complex shapes and surfaces with ease, providing more versatility while reducing the need for workpiece refixturing. Our rotary table has an 8″ surface, and uses a 90:1 worm gear reduction system with adjustable backlash preset to zero. The tailstock is included, so you can hold your pieces horizontally on center (similarly to the setup on a lathe).

NT30 SpindleNT30 Spindle
Tooling for our standard R8 spindle has the advantages of being inexpensive and easily obtained, but some jobs require more spindle rigidity and resistance to side-loading forces. When you need bigger tooling or larger cutting passes to improve your machining efficiency, our NT30 spindle upgrade lets you get the job done faster.

Direct Competitor Comparison

Note that Tormach’s advertised price for a similar mill includes only a bare-bones CNC package. For the purposes of this comparison, we will attempt to construct a mill that is as similar as possible to our own using their à la carte pricing model.

(Tormach pricing as of June 4, 2013; Charter Oak Automation pricing is automatically updated in real time.)

Basic Machine Specifications

Charter Oak Automation CNC Mill — Complete CNC mill Tormach PCNC 1100 Personal CNC Mill (Series 3) — Bare-bones CNC mill; not directly comparable until options are added.
Axis Travel (Linear) 26" × 12½" × 22" (XYZ) 18" × 9½" × 16¼" (XYZ)
Axis Travel (Volumetric) 7,150.00 in.3 2,778.75 in.3
Table Size (Linear) 39½" × 9⅜" 34" × 9½"
Table Size (Areal) 370.3125 in.2 323 in.2
Spindle Nose to Table 23" 17"
Spindle Center to Column 12½" 11"
Spindle Nose Diameter 3.8" 3.375"
Spindle Taper R8 or NT30 R8
Maximum (X,Y) Axis Rapid 200 IPM 110 IPM
Maximum Workpiece 500 lbs. 500 lbs.
Spindle Motor Power 3 HP 1.5 HP
Minimum Spindle RPM 60 RPM 100 RPM
Maximum Spindle RPM 3,800 RPM 5,140 RPM
Ball Screw Grade P3 P4
Way Surfaces Ground and dovetailed Scraped and dovetailed; PTFE-filled Acetyl bonded surface.
Oiling Points 17 15
Axis Drives Closed-loop AC brushless servo motors Polyphase stepper motors
Encoder Positioning Servo-integrated No encoders
Encoder Resolution 6,400 PPR (Pulses Per Revolution) No encoders
Integrated Manual Quill Included Not offered
Head Rotation -90° to +90° Not offered
Power Requirements 220-240V AC, 50/60Hz single phase 220-240V AC, 60Hz single phase

Computer Controls

Machine Controller w/ Mach3 Included Not included
Keyboard Included Not included
Mouse Included Not included
LCD Monitor Included Not included
SVGA Video Cable Not Required (Integrated) Not included
USB Port Included on Keyboard Not included
USB Cable Included Not included
Computer Power Cord Included Not included
Controller Cable Included (8′ length) Not included (6′ length)
Additional Cost $0.00 — Everything already Included $1,021.51

4th Axis Rotary Table

8″ Rotary Table $1,350.00 — Optional Upgrade $1,447.11 — Optional Upgrade
8″ Rotary Table Tailstock Included with Table Not Included with Table — $157.30
Backlash Adjustable backlash (preset to zero) Adjustable backlash
Positioning Closed-loop AC brushless servo motor Polyphase stepper motor
Encoder Resolution 6,400 PPR (Pulses Per Revolution) No encoder



Comparison: Price vs. Performance

These setups are as equivalent as possible so far, given the options available in Tormach’s pricing model. However, the raw prices do not reflect the comparative value provided by our mill due to the vastly differing specifications in both machining envelope volume and available power. As such, a price comparison per unit of performance is the simplest and fairest comparison metric at our disposal. Both three-axis and four-axis setups are compared in this way below.

Price per Unit of Performance

Charter Oak Automation CNC Mill
Tormach PCNC 1100 with All Equivalent Options
3-Axis Setup
Basic Price $11,499.00 $9,501.51
Price Per Cubic Inch of Envelope $1.39 $3.42
Price Per Spindle Horsepower $3,833.00 $6,334.34
Price Per Max (X,Y) Rapid IPM $57.50 $86.38
4-Axis Setup
Basic Price $12,849.00 $11,105.92
Price Per Cubic Inch of Envelope $1.56 $4.00
Price Per Spindle Horsepower $4,283.00 $7,403.95
Price Per Max (X,Y) Rapid IPM $64.25 $100.96

Comparison Results

It is difficult to directly compare Tormach’s high-end offering to our own; the PCNC 1100 system’s base price is lower than our CNC bed mill’s, but its capabilities are also significantly reduced in comparison. Due to this persistent disparity, a price per unit of performance is the only fair comparison to perform on these two machines. After doing the math with Tormach’s à la carte pricing model, the final cost/benefit comparison to our product yields the following results:

  • A similarly outfitted PCNC 1100 mill costs slightly less than Charter Oak’s CNC bed mill (with Tormach’s four-axis configuration being less cost-competitive than their three-axis configuration, due to their more costly fourth-axis rotary table system), but offers substantially less power and versatility than our own CNC bed mill.
  • For this price differential, our CNC mill offers 2.57 times the working envelope, while Tormach’s cost per cubic inch is 246% of our own.
  • Our CNC mill has more power, and offers it at up to 42% less cost per horsepower than Tormach’s PCNC 1100.
  • Per inch of maximum (X,Y) rapid speed, Tormach’s PCNC 1100 costs up to 256% as much as our CNC bed mill, while having only 55% of our feed rate.

While Tormach’s PCNC 1100 is an impressive piece of engineering, Charter Oak Automation’s CNC bed mill blows it out of the water in both raw performance and value for your dollar.