Screwdriver Project Details:
– Created two screwdrivers, one from a standardized Philips head blank to use in injection molding, the other a O1 Tool Steel Round cast in Aluminum
-The aluminum was ran in CNC mill to cut to cut to the needed handle diameter to be manually knurled. This machine program was created and provided by the CSU EMECH.
– The tip was heated and drop forged to shape, then ground to tolerance. The final shape was then heat treated to 460 degrees Fahrenheit and tempered to desired hardness by “chasing the band” to straw yellow.
Lessons Learned from Screwdriver Fabrication:
– Knurling is an INCREDIBLY difficult and tedious process to set up. Do NOT be afraid to take time in setup, as it pays off BIG once beginning
-The tempering process happens incredibly quickly, and how a metal is cooled greatly impacts it’s final result. When tempering, cool in water. When heat treating, cool in oil.
-Grinding the tip of O1 Tool steel to precise tolerances using an automatic grinder can be incredibly tricky! Over grinding is easy, and I had caught myself doing just that. Chase for flatness first, then tip thickness, followed by width. The more you grind, the skinnier the tip, as you may see in the above photo
-The tip CAN be sanded to smoothness, but be prepared to spend much longer on it then intended
FOR INJECTION MOLDING:
-Be patient with the injection molder, and allow time for the plastic to heat and combine!
-When adding new plastic, it’s best to ensure ALL old plastic is purged. There were often times when previous users did not do this, creating strange mixtures and weaknesses in the plastic
-Recycled Plastic to Non-Recycled plastic ratio: Good at around 20% Recycled to 80% Non-Recycled. Totally recycled is possible, but prepare for the handle to be much weaker and more brittle
Cost Estimation for production of One Case O1 Tool Steel Screwdriver:
Labor Cost (including production error)
Hours Spent
Knurling and Facing – 2 hours
Drop Forging and Grinding – 2 hours
Heat Treatment and Anealment – .5 hours
Total Labor Cost
(Based on $26.25 mean hourly wage. source: US Bureau of Labor Statistics)
$26.25/hr * 4.5hr = Total Labor Cost = $118.13 per screwdriver
(note: this is given that pre-cast screwdriver blanks are given/ordered)
Raw Material Cost
3/8″ O1 tool steel round was pre-cast in aluminum from a supplier in mass, given to each student by the EMECH. Assuming this wasn’t the case, the following is an estimation of what each screwdriver would cost in raw material.
Aluminum Handle
Raw Aluminum (4.75″ length * 1.25″ diameter = 18.55 in^3 ) = 0.000304 m^3 rough volume
Aluminum Density: 2710 kg/m^3
Approximate Mass: 0.8238 kg
Price of Aluminum (as of December 11): ~$2.90 / kg
Price per Screwdriver: $2.39 per Aluminum Handle
O1 Tool Steel Rod
Assuming final length of approximately 8.1″ for the entire screwdriver and 3.5″ exposed length (which was specified in the assignment) I will assume a raw material length of 6″ of steel per screwdriver. This is leaving room for grinding and error in casting, and over 2″ of steel within the aluminum cast which is an assumed length.
Supplier: OnlineMetals – 3/8″ Tool Steel Drill Rod O1 Precision Ground
Price of 36″ stock: $21.84
Price per Screwdriver: $3.84
Total Raw Material Cost for Single Flathead Screwdriver Production:
$6.23
Improving Production Efficiency, and theoretical production of 10,000 Cast and Knurled Screwdrivers
To improve production efficiency, the drop forging, heat treatment, and tempering should all be done in completely automated processes. Using an assembly line, or even a 6-DOF robotic arm, the screwdriver ends would be automatically heated, checked by temperature sensor, and drop forged. Using camera sensors, desired thickness would be measured, and all ends would be ground identically. This removes massive losses in material from human error, and perfect flatness each time. The same kind of controlled processes could then be followed for heat treatment and tempering as well, utilizing thermal imaging and sensors to reach ideal heat each time and remove wasted material.
In a perfect world, all screwdrivers like this would be injection molded, as the process is extremely quick, cheap, and easy compared to the machining process used here. Knurling must be set up in CNC, which I could imagine would be difficult due to the manual process undertaken. The cost of a production like this adds up quick, giving more credence to injection molding process as a whole vs. aluminum handle.
All lathing processes could be accomplished through CNC milling vs. manual milling, saving time and money. I believe this process, if fully automated, would only require around 3 minutes of manual labor moving from machine to finishing areas/other machine processes if the process was optimized.
Production Cost: 10,000 screwdrivers
O1 Tool Steel Rod
Given the increase in amount of material, O1 tool steel rounds would be ordered at greater lengths and in bigger quantities.
Supplier: OnlineMetals – 3/8″ Tool Steel Drill Rod O1 Precision Ground
Price of 144″ stock: $68.41
Stock Needed: 5,000 ft (60,000″) (417 units of 144″ steel round)
Cost for 10,000 screwdrivers: $28,526.97
Aluminum Handle
Aluminum Required: 8238 kg
Price of Aluminum as of December 11, 2025 (source: dailymetalprice.com): ~$2.90 / kg
Cost for 10,000 screwdrivers: $23,890.20
Total Material Cost: $52,417.17
Total Labor Cost, based on 3 minutes per screwdriver in loading/unloading operations in an automated process (500 hr for 10,000 screwdrivers) (Based on Colorado DLSS Minimum wage of $14.81): $7,405
TOTAL COST FOR 10,000 FLATHEAD SCREWDRIVER MASS PRODUCTION: $59,822.17
This brings the material cost of each screwdriver from $6.23 in manual processing to $5.98 in automated processing, with additional room for bulk discount ordering. The labor cost decreased substantially as well, from $118 per screwdriver down to just $0.74!