1 operating challenge for the quarter was supply chain and logistics disruptions.
Our teams continue to drive margin improvement through 80/20 simplification, lean effort and through sound capex deployment.
We deployed just over $575 million in the first half of the year with our acquisitions of ABEL Pumps, Airtech and a small investment in a digitalization technology start-up within the fire and rescue space.
While we've stepped up our M&A game, we're also investing in our existing businesses with a 45% increase in capital spending through the first half of the year.
As I mentioned, order strength continued in the second quarter both compared to prior year and sequentially, resulting in a backlog build of $65 million in the quarter.
And with its backlog burn last year and significant pullback in customers' capital investments, it impacted FMT's organic sales by 11%.
In other words, FMT's organic sales for the quarter would have been 19% instead of 8%.
Q2 orders of $751 million were up 44% overall and 39% organically as we built $65 million of backlog in the quarter.
Second-quarter sales of $686 million were up 22% overall and 17% organically.
Excluding FMD, organic sales would have been up 22%.
Q2 gross margin expanded by 280 basis points to 44.6%.
Excluding the impact of $1.8 million pre-tax fair value inventory step-up charge related to the ABEL acquisition, adjusted gross margin was 44.9% and was approximately flat sequentially.
Second-quarter operating margin was 23.1%, up 340 basis points compared to prior year.
Adjusted operating margin was 24.4%, up 330 basis points compared to prior year, largely driven by gross margin expansion and fixed cost leverage, offset by a rebound in discretionary spending and investment.
Our Q2 effective tax rate was 21.3%, which was lower than the prior-year ETR of 22.7% due to benefits from foreign sourced income in the second quarter of 2021.
Q2 adjusted net income was $123 million, resulting in adjusted earnings per share of $1.61, up $0.51 or 46% over prior-year adjusted EPS.
Finally, free cash flow for the quarter was $120 million, down 25% compared to prior year and was 98% of adjusted net income.
Adjusted operating income increased $49 million for the quarter compared to prior year.
Our 17% organic growth contributed approximately $41 million flowing through at our prior-year gross margin rate.
As we return to a spend level, in line with our growth and continued strategic investments, we see year-over-year pressure of about $11 million, in line with the guidance we gave at the beginning of the year.
Even with the incremental spend, supply chain and operational issues that tempered our performance, we still achieved a robust 45% organic flow-through.
Flow-through is then negatively impacted by the dilutive impact of acquisitions and FX, getting us to our reported flow-through of 39%.
For the third quarter, we are projecting earnings per share to range from $1.57 to $1.61.
We expect organic revenue growth of 14% to 16% and operating margins of approximately 24 and a half percent.
The third quarter effective tax rate is expected to be 23% and we expect a 1% top-line benefit from the impact of FX.
And corporate costs in the third quarter are expected to be around $21 million.
Turning to the full year.
We are increasing our full-year earnings per share guidance from our previous range of $6.05 to $6.20, up to $6.26 to $6.36.
This range includes Airtech, which will contribute $0.06 in the second half of 2021, roughly $0.03 a quarter.
We are also increasing our full-year organic revenue growth from 9% to 10% up to 11% to 12%.
We expect operating margins of approximately 24 and a half percent.
We expect FX to provide a 2% benefit to top-line results.
The full-year effective tax rate is expected to be around 23%.
Capital expenditures are anticipated to be around $65 million, an increase of around $10 million versus our last call as we increase our investments in growth opportunities.
Free cash flow is expected to be 110% to 115% of net income, lower versus our last guide, primarily due to the additional capital spending and higher working capital to support our increased volume.
And corporate costs are expected to be approximately $77 million for the year.
Once completed next month, this collection of solar panels will be about one-third the size of the European soccer field and provide 30% of the electricity needs for the facility.
Not only will it help reduce our carbon footprint there, we estimate it will save the business more than EUR 67,000 in just the first year alone.
The IDEX Foundation also paid $100,000 to the German Red Cross, which has thousands of people in the region assisting those impact.

Summary:
Q2 adjusted net income was $123 million, resulting in adjusted earnings per share of $1.61, up $0.51 or 46% over prior-year adjusted EPS.
For the third quarter, we are projecting earnings per share to range from $1.57 to $1.61.
We expect organic revenue growth of 14% to 16% and operating margins of approximately 24 and a half percent.
Turning to the full year.
We are increasing our full-year earnings per share guidance from our previous range of $6.05 to $6.20, up to $6.26 to $6.36.
We are also increasing our full-year organic revenue growth from 9% to 10% up to 11% to 12%.