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February 6, 2025 · The Bloomfield Team

The Machine Shop Owner's Guide to Protecting Margins

Average gross margins for American job shops range from 28% to 42%, depending on specialization, customer mix, and operational efficiency. The spread is wide. A shop running at 28% gross margin on $10 million in revenue nets a very different owner's compensation than a shop running at 42% on the same top line. The $1.4 million difference between those two margin levels is the difference between a business that survives and a business that funds reinvestment, attracts talent, and grows.

Margin protection is the most important discipline in running a job shop. Revenue growth with declining margins is a path to a bigger, more fragile business. Margin improvement on existing revenue is pure profit.

Where Margins Leak

These six categories represent 9 to 25 percentage points of margin that leak out of the business without appearing on any report. A shop running at 30% gross margin that plugs half of these leaks moves to 35% or higher. On $10 million in revenue, that is $500,000 in additional gross profit per year.

Quoting Accuracy Is the Largest Lever

Every job that costs more to produce than the quoted price erodes margin. In most job shops, 20 to 40% of jobs come in over the quoted cost. The average overrun on those jobs runs 10 to 25%. These overruns rarely trigger corrective action because most shops do not systematically compare quoted cost to actual cost on completed jobs.

The fix starts with a monthly quote-to-actual variance report. Pull every completed job from the month, compare the quoted cost to the actual cost, and identify the top ten variances. Look for patterns: are specific part types consistently underquoted? Are setup times systematically underestimated? Is material waste running higher than assumed? Each pattern points to a specific correction in the quoting model. For a detailed breakdown of where cost estimates miss, see how to calculate true cost per part.

Customer Mix Determines the Ceiling

A shop's margin ceiling is largely determined by its customer mix. Aerospace and defense work with tight tolerances, specialized certifications, and long qualification processes commands higher margins because fewer shops can compete. Commercial work with broad tolerances and many capable suppliers commands lower margins because the buyer has options.

The most profitable shops are deliberate about their mix. They know which customer segments yield margins above their target and which ones fall below. They invest sales effort in growing the high-margin segments and manage the low-margin segments for volume and cash flow. A shop running 40% aerospace, 30% medical, and 30% commercial at blended margins of 44%, 38%, and 26% respectively is running a very different business than a shop doing 100% commercial work at 28%.

Overhead Control

Gross margin measures production efficiency. Net margin measures business efficiency. The gap between the two is overhead: front office salaries, rent, insurance, equipment payments, utilities, IT, accounting, and the accumulated cost of every system and process that supports the operation without directly producing parts.

Overhead as a percentage of revenue for a healthy job shop should fall between 18% and 25%. Shops above 30% are carrying costs that the revenue base cannot support. The most common overhead bloat comes from management layers that grew with revenue without corresponding reductions in direct involvement, software subscriptions that accumulated over years without periodic review, and facility costs that expanded faster than revenue.

Pricing Strategy Beyond Cost-Plus

Most job shops price on a cost-plus basis. Estimate the cost, add a margin target, submit the quote. That model works for commodity work where the buyer can easily compare prices across multiple shops. It leaves money on the table for specialized work where the shop's capabilities, certifications, or track record create value beyond the cost of production.

A shop with five-axis capability, AS9100 certification, and a ten-year track record of 98% OTD for a specific customer should price that value, not the cost. The customer's alternative is qualifying a new supplier, which costs them $15,000 to $50,000 in qualification effort and 6 to 12 months of lead time. Your pricing should reflect the switching cost, not the production cost.

What the Highest-Margin Shops Have in Common

They track quoted versus actual cost on every job. They know their margin by customer, by part type, and by process. They price to value on specialized work and price to market on commodity work. They review overhead quarterly and cut what the revenue base cannot support. They invest in capabilities that move them toward higher-margin work segments.

Margin protection is a system. It requires data, discipline, and the willingness to stop taking work that erodes the business even when the top line looks good. The return on building these systems compounds with every quote, every job, and every quarter. The shops that build the margin discipline now will have the financial strength to invest when the next opportunity appears.