Carla spent six months perfecting her product design. The CAD files looked flawless. The pitch deck impressed investors. But when she handed the drawings to a machine shop, they came back with a list of problems. Over-specified tolerances. Parts that couldn't be assembled without custom fixtures. Features that would triple production time. She had to redesign everything from scratch, burning through budget and timeline.
Then she met someone who had worked both sides of the problem. Within three weeks, she had a revised design that cut production costs by 40 percent and shaved two months off the timeline. The difference wasn't just technical skill. It was understanding how things actually get built.
The Gap Between Design and Build
Most engineers learn to design. Fewer learn to build. That gap costs time, money, and momentum.
"If it can't be built, it's not a finished idea. You have to think about the process from the start," says Timothy Monzello, who spent 19 years at NASA's Jet Propulsion Laboratory and now teaches manufacturing and machine tool technology at El Camino College.
Monzello started as an auto mechanic and worked his way through machine shops as a grinder, honer, and CNC programmer. He moved into management roles including foreman, shift supervisor, plant manager, and quality control manager. He ran his own business for nearly three years before joining JPL, where he served first as Master Production Scheduler and later as Group Lead in Manufacturing Engineering.
"I've been on both sides. I've done the hands-on work, and I've managed teams doing it," he says. That dual perspective shaped his approach to both engineering and teaching.
Precision Only Where It Matters
One of the most common mistakes in design is over-specification. Engineers add tight tolerances to every dimension, assuming more precision equals better quality. In reality, it slows production and drives up cost.
"Not everything needs tight tolerances. I've seen designs where everything was over-specified. That slows production and adds cost. Precision matters, but only where it's needed," Monzello explains.
At JPL, where missions depend on flawless execution, planning leaves no room for gaps. But even in that environment, the principle holds. Smart design applies precision strategically, not universally.
"At JPL, you plan for everything. You don't leave gaps," he says. That same discipline applies to knowing what not to over-engineer.
Learning From Both Sides
Monzello's career path gave him insight that classroom training alone cannot provide. He started with the work itself, building skills on the shop floor before earning degrees in electronics, language arts, business administration, and an MBA from Arizona State University. He also completed certifications in Lean Six Sigma, and has been trained in Advanced GD&T, supply chain management, and project management.
"I didn't start with theory. I started with the work itself," he says. That foundation shaped how he teaches today.
For 11 years, Monzello has taught at El Camino College, starting part-time in the evenings while still at JPL. After a reduction in force ended his time at NASA, he transitioned to teaching asynchronously. "The goal was always to apply what I learned," he says. His courses focus on machine tool technology, manufacturing, geometric dimensioning and tolerancing, design for manufacturability, and quality control.
The Build It Right Framework
Monzello advocates for a structured approach to integrating manufacturability into the design process. His framework helps engineers, entrepreneurs, and students think through production before committing to a final design.
Phase 1: Start With the End Process
Before drawing a single line, map out how the part will be made. Which machines? Which tools? What sequence of operations? This step prevents designs that look good on paper but fail on the shop floor.
Phase 2: Apply Precision Strategically
Identify which dimensions truly matter for function and fit. Tighten tolerances only where necessary. Leave the rest with standard tolerances. This reduces machining time and cost without sacrificing quality.
Phase 3: Design for Assembly
Think about how parts will come together. Avoid features that require custom fixtures or complex alignment. Use standard fasteners. Minimize the number of unique components. Simpler assembly means faster production and fewer errors.
Phase 4: Validate With Hands-On Input
Get feedback from machinists, assemblers, and production planners before finalizing the design. They see problems that engineers miss. A quick conversation can save weeks of rework.
Phase 5: Document What Works
Keep notes on design decisions, supplier feedback, and production outcomes. Build a reference library of what works and what doesn't. Over time, this becomes a competitive advantage.
"Writing things down. I keep notes on what works and what doesn't. Over time, that builds a personal reference. It helps me avoid repeating mistakes," Monzello says.
Quick Wins You Can Use Today
Designers and engineers can take immediate steps to improve manufacturability without overhauling their entire process.
Check every tolerance. Ask if it truly needs to be that tight. Loosen where possible.
Use standard materials and sizes. Custom stock adds cost and lead time.
Limit the number of setups. Each time a part gets repositioned, accuracy drops and time increases.
Review designs with someone who has shop floor experience. Even a five-minute conversation can catch big issues.
Avoid features that require special tooling. Standard end mills, drills, and inserts keep costs down.
Red Flags That Signal Trouble
Certain design choices create predictable problems. Recognizing them early saves time and money.
Every dimension has a tight tolerance. This signals a lack of understanding about what actually matters.
The design requires custom fixtures or jigs. Unless you're building thousands of units, this rarely pays off.
No one from production has reviewed the design. Missing this step guarantees surprises later.
The part has features that can't be reached with standard tools. This forces workarounds that slow everything down.
The designer has never seen the part being made. Disconnect from the build process leads to unrealistic designs.
Bringing It Together
Monzello's career demonstrates the value of understanding systems from multiple angles. His time on the shop floor taught him what works in practice. His management roles showed him how decisions ripple through production. His years at JPL reinforced the importance of planning and precision. His teaching connects those lessons with the next generation of engineers and operators.
"I always believed that the more you understand the system, the better decisions you can make," he says.
That philosophy extends beyond manufacturing. It applies to any field where execution matters as much as ideas.
"You start to see the whole system. Not just your part of it," he explains.
His volunteer work at an assisted living facility reflects the same commitment to showing up and doing the work. Leadership and accountability aren't abstract concepts. They show up in how you plan, build, and follow through.
"You learn pretty quickly that you have to be accountable. No one is going to carry you," Monzello says.
Take Action This Week
If you design, build, or manage production, this framework can improve your outcomes immediately. Pick one project or design. Walk through the five phases. Identify one tolerance you can loosen. Find one feature you can simplify. Talk to one person who will actually make the part.
Small changes compound. A design that's 10 percent easier to build saves time on every unit. A part that requires one fewer setup cuts costs across the entire production run.
"I learned early that you have to keep moving forward. No one is going to do the work for you," Monzello says.
Start this week. Apply the framework to one design. Document what you learn. Build the habit of thinking about production from the first sketch. The gap between ideas and built systems only closes when you choose to close it.
About Timothy Monzello
Timothy Monzello is an Adjunct Professor at El Camino College in Torrance, CA, where he teaches machine tool technology, manufacturing, and business operations management. He spent 19 years at NASA's Jet Propulsion Laboratory, serving as Master Production Scheduler and later as Group Lead in Manufacturing Engineering. His career includes hands-on work as a machinist and CNC programmer, management roles ranging from foreman to plant manager, and nearly three years operating his own manufacturing business. He holds degrees from Citrus College, Ashford University, and Arizona State University, along with certifications in Lean Six Sigma, and training in Advanced GD&T, and project management. He has received multiple NASA honor awards, team awards, and a NASA Leadership award.
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