Clock Project Details:
-6061-T6 Aluminum Clock Base, machine fabricated with manual mill.
-C360 Brass Round Pen Holder, machine fabricated with manual lathe.
-1018 Cold Rolled Round Steel Pencil Holder fabricated with manual lathe
-9/16″ Brass Hex Nut (shop fabricated)
-1/8″ PMMA Clear Acrylic, laser cut and engraved with a hand-drawn clock face
-Off the shelf hardware for clock mechanism
Lessons Learned from Clock Fabrication:
1. Meeting such tight tolerances was incredibly difficult and tedious. This being the first project ever working with a manual lathe and mill, I realized the importance of pre-marking drilling locations and verifying each measurement and datum before each cut. Because of measurement errors, I had to scrap and restart the Aluminum clock base after drilling a hole out of tolerance.
2. Drilling blind holes to a specified depth is very difficult. Drill shallow first, then incrementally drill to tolerance.
3. Create critical features FIRST, if possible. By doing this, I ensured that mistakes didn’t cost me multiple hours of time I would have spend doing less-critical tasks only to have to restart when making an error on a critical feature
4. Do absolutely everything to verify your process, safety procedures, and measurements before beginning!
5. Most importantly, be kind to yourself when working with unfamiliar machines and processes. Comfortably comes with time, and experience comes with time. Let yourself make mistakes, and don’t get too frustrated with yourself when you do. Analyze where the mistake occurred, think about and make procedures to not make that mistake again, then continue onward!
Cost Estimation for production of One Clock:
Labor Cost (including production error)
Hours Spent
Manual Milling Tool, Clock Base Production – 5.0 hours
Brass Nut Production – 0.5 hours
Manual Lathe Tool, Brass Pencil Holder Production – 3.0 hours
Manual Lathe Tool, Steel Pen Holder Production – 2.5 hours
Laser Cutting Clock Face – 0.5 hours
Drawing, developing, and Laser Engraving Clock face – 4.0 hours
Additional Finishing Processes – 3.0 hours
Total Labor Cost
(Based on $26.25 mean hourly wage. source: US Bureau of Labor Statistics)
$26.25/hr * 18.5hr = Total Labor Cost = $485.63 per clock
(note: this cost would decrease over time given additional practice from me, the operator in this circumstance)
Raw Material Cost
Material Item
(all costs are calculated assuming low production volume & lowest ordering volumes)
– 2”x0.375” 6061-T6 Aluminum (8.12″ length required)
Source: Online Metals – Aluminum Bar
Cost: $12.93 / 1 ft
Cost per clock: ~$8.75 (assuming remaining stock is NOT disposed of / repurposed)
– 5/8″ C360 Brass Round Stock (2.2″ length required)
Source: Midwest Steel Supply – Brass Round
Cost: $36.26 / 1 ft
Cost per clock: ~$6.65 (2.2 inch)
– 5/8″ 1018 Cold Rolled Steel Round Stock (2.5″ length required)
Source: Online Metals – Steel Round
Cost: $5.09 / 1 ft
Cost per clock: ~$1.06 (2.5 inch)
– 9/16″ Brass Hex Stock (1″ length required)
Source: Online Metals – Brass Hex
Cost: $27.18 / 1 ft
Cost per clock: ~$2.27 (1 inch)
– 1/8″ Clear Acrylic (6″ * 6″)
Source: estreetplastics – Clear Acrylic Plexiglass Sheet
Cost (and cost per clock): $1.99 / 1 Sheet
-3/8″ Round Adhesive Felt Pads (4 required)
Source: The Home Depot – Adhesive Felt Pads
Cost: $5.27 / pack of 75
Cost per clock: ~$0.28 (4 felt pads)
-R91253A539 Black Alloy Steel Hex Drive Flat Head Screws
Source: Reli Tool – Hex Drive Flat Head Screws
Cost (and cost per clock): $0.15 / 1 screw
-Q-80 Quartz Clock Movement, 1/16″ Maximum Dial Thickness
Source: Klockit – Clock Mechanism with Arms
Cost (and cost per clock): $6.50 / 1 set
Total Raw Material Cost for Single Clock Production:
$27.65
Improving Production Efficiency, and theoretical production of 10,000 clocks
To improve production efficiency and cost on this clock, the #1 factor to remove is the human element. With my production cost for the first clock, around $486 at mean machinist income, the cost would rack up exponentially. To reduce these hours, the most efficient means of production would be through CNC milling and lathing processes. After the initial programming, the multi-hour operation of clock production could be reduced to under 1 hour per clock or less.
After manual raw-material cutting processes, the CNC mill would perform milling, facing, drilling, and chamfer operations on the aluminum base, as well as engraving the lettering underneath. The mill could perform all threading operations, turning operations, drilling, and debur with very little error. All of these operations would be performed within succession and quick-change tool heads installed on the machines, ran by certified operators. Finishing operations as well as final meteorology checks can then be done by manual labor. With a turret lathe already completing HEX nut creation operation, that process can remain as is.
A template for acrylic sheet was created for laser cutting, and this could be expanded upon for clock-face engraving. By creating a Photoshop template of the clock face, customization could be made extremely easy for custom requests.
Production Cost: 10,000 clocks
When creating in bulk, suppliers give bulk-order discounts on stock. The following prices are adjusted to account for these discounts. This is assuming a fully-automated production process, with 1 hour of finishing of labor per clock at minimum wage in Colorado. Excludes all shipping and handling.
– 2”x0.375” 6061-T6 Aluminum (6767 ft required)
Source: Online Metals – Aluminum Bar
Cost: $94.84 / 12 ft
Cost (quantity@ 564 units): $53,489.76
– 5/8″ C360 Brass Round Stock (1834 ft required)
Source: Midwest Steel Supply – Brass Round
Cost: $90.00 / 6 ft
Cost (quantity@ 306 units): $27,540.00
– 5/8″ 1018 Cold Rolled Steel Round Stock (2084 ft required)
Source: Online Metals – Steel Round
Cost: $27.70 / 8 ft
Cost (quantity@ 261 units): $7,229.70
– 9/16″ Brass Hex Stock (834 ft required)
Source: Online Metals – Brass Hex
Cost: $158.37 / 8 ft
Cost (quantity@ 105 units): $16,628.85
– 1/8″ Clear Acrylic (6″ * 6″)
Source: estreetplastics – Clear Acrylic Plexiglass Sheet
Cost (quantity @ 10,000 units): $19,900.00
-3/8″ Round Adhesive Felt Pads (4 required)
Source: The Home Depot – Adhesive Felt Pads
Cost: $5.27 / pack of 75
Cost per clock: ~$0.28 (4 felt pads)
Cost per 10,000 clocks: $2,800.00
-R91253A539 Black Alloy Steel Hex Drive Flat Head Screws
Source: Reli Tool – Hex Drive Flat Head Screws
Cost (and cost per clock): $0.15 / 1 screw
Cost per 10,000 clocks: $1,500.00
-Q-80 Quartz Clock Movement, 1/16″ Maximum Dial Thickness
Source: Klockit – Clock Mechanism with Arms
Cost: $6.50 / 1 set
Cost per 10,000 clocks: $65,000.00
Total Material Cost: $194,088.31
Total Labor Cost (Based on Colorado DLSS Minimum wage of $14.81): $148,100 (@1 hour per clock in labor)
TOTAL COST FOR 10,000 CLOCK MASS PRODUCTION: $342,188.31
This brings the price per clock in raw materials down to around $19.41 per clock, saving $8.24 per clock in materials when switching to mass production processing.