Whether those parts can be easily manufactured, however, is another thing entirely.
One issue we often see at Macy Industries is overly tight tolerances that don’t reflect the part’s actual needs. For instance, it’s not uncommon for our fabrication shop to receive drawings with very precise machining tolerances, even when the project is a handrail, frame, bracket, rooftop component, or countertop.
But for the type of custom fabrication we specialize in, that kind of accuracy is often unnecessary. While parts need to fit, function, install cleanly, and hold up in the field, they rarely need to be measured to the thousandth of an inch.
Understanding Tolerances
Every dimension on a drawing comes with some acceptable range of variation, and that range is what a tolerance defines. For example, a part specified at 10″ ± ⅛” can vary by up to ⅛” in either direction, meaning it could measure anywhere from 9⅞” to 10⅛” and still meet the requirement. Because no manufacturing process produces a perfect theoretical dimension every time, tolerances define how close is close enough.
Where it gets more nuanced is in figuring out how tight those tolerances actually need to be. Some features genuinely require greater precision, especially if the part affects fit, alignment, sealing, movement, or assembly. That is often the case in precision assemblies for aerospace, medical devices, or robotics, where components interface with dozens of other tightly controlled parts.
But not every part requires that same degree of accuracy. For many custom fabrication applications, what matters most is that the part installs correctly, functions as intended, and looks right in its final environment.
In other words, when designing parts for fabrication, the key question is not, “How tight can this be?” but “How tight does this need to be?”
Why Macy Works in Tape Measure Tolerances
Most of what we fabricate at Macy is built for field installation and real-world site conditions, and the tolerances reflect that. The work is typically built around ±1/16″ or ±1/8″ dimensions verified with a tape measure rather than calipers or laser measurement equipment.
Our shop floor processes match that approach. For many of the parts we fabricate, operators mark bend locations directly on the material and form the part to the level of accuracy the application requires, rather than relying on automatic back gauges to hold repeatable precision-bend dimensions. For a piece of drip edge, a set of stairs, or a stainless countertop being fit to existing site conditions, that level of accuracy is appropriate. When tolerances are tighter than necessary, the impact shows up in places most designers don’t expect.
Why Overly Tight Tolerances Create Problems
When you’re designing a new product or preparing to submit a quote request, it’s worth taking a closer look at whether the tolerances actually meet the application’s needs. Whether they come from machining standards, CAD defaults, or an abundance of caution, unnecessarily tight tolerances on a fabrication drawing can create real problems:
- Higher cost: Tighter tolerances may require specialized equipment, additional fixturing, extra measuring, more setup time, and more inspection.
- Longer lead times: If a shop has to slow down, jig parts differently, laser measure larger assemblies, or verify features beyond normal fabrication requirements, the project will likely take longer.
- More back-and-forth: If a drawing calls out a tolerance that seems unrealistic or unnecessary, the shop may need to pause and ask whether that tolerance is truly critical.
- No quotes or fewer bids: Some shops will see tolerances they cannot reasonably hold and simply pass on the project. That can mean fewer bids, less competition, and fewer options.
- Inflated pricing: Even shops that do quote may price the project to cover the risk, labor, and effort of holding tolerances the part may not actually need.
There is also a material reality to consider. On larger structural or general fabrication projects, the raw material itself carries allowable variation before anyone ever cuts, forms, or welds it. For example, the same W12 beam purchased from different mill lots could measure roughly a sixteenth of an inch differently. When the base material has that level of variation, applying ultra-tight tolerances across the finished fabrication can create a mismatch between what the drawing asks for and what the material and process can reasonably deliver.
Macy’s Collaborative Approach
The good news is that many tolerance issues are easy to resolve once the fabricator and the customer have a chance to talk. The problem is that not every shop will initiate that conversation. If a fabrication drawing comes through with tolerances that seem unrealistic, unnecessary, or outside the shop’s normal process, some fabricators may simply no-quote the project and move on.
At Macy Industries, we take a more collaborative approach. If the project appears to be a good fit for the type of work we do, but the tolerances don’t seem to match the application, our first step is to reach out and better understand what the customer is actually trying to accomplish.
That conversation can make a meaningful difference. We may ask how the part will be used, which dimensions are truly critical, and whether certain tolerances can be opened up to make the part more practical to fabricate.
Before sending your next fabrication drawing out for quote, take a second look at the tolerances. If they are driven by function, keep them. But if they are driven by CAD defaults or assumptions from a different type of manufacturing, it may be worth a conversation. At Macy Industries, that conversation is part of the process.
Have a project you’d like to discuss? Request a quote, and let’s talk it through.