When Adam Eckfeldt retired in 1839, he recommended Peale as his successor.
As the Senate was not sitting, Peale was given a recess appointment as Chief Coiner of the Philadelphia Mint by President Martin Van Buren on March 27, 1839.
On January 23, 1840, after the Senate reconvened, Van Buren nominated Peale; the Senate gave its approval on February 17.
Despite his retirement, Eckfeldt continued to come to the mint every day until shortly before his death in February 1852, performing the function of Chief Coiner and leaving Peale with time on his hands.

Soon after his appointment, Peale began to engage in a private business on the Mint's premises.
 He did this by designing, striking and selling medals for private commission, using government property and labor, and the Philadelphia Mint's facilities.
Peale's enterprise was very profitable, as his expenses were minimal.
 This activity took place with the knowledge of the other officers of the Philadelphia Mint, most of whom were Peale's friends and relatives.
Clients included corporations as well as one couple celebrating a 50th wedding anniversary.
According to Robert E. Wright in his history of Philadelphia as an early financial center, the legality of Peale's business was unclear, but "the uncertainty of the situation made it almost inevitable that someone would make a stink on [Philadelphia's] Chestnut Street."

This activity has been variously characterized by numismatic writers.
According to coin dealer and numismatic author Q. David Bowers, "Peale started to abuse his position and privileges, in effect stealing services from the government".
Burdette notes, "Overall, it appears that Peale used mint equipment and employees to make medals as instructed by Congress and the mint director, and to produce copies from private and official dies for sale to anyone who was interested.
In the case of private sales, Peale seems to have used government metal, then reimbursed the bullion accounts when he collected for the medal.
Profits were not accounted for in mint ledgers and it is unknown how much went to Peale, others at the mint or into the mint's Cabinet of Coins.
The total amount was probably not large."

After scalemaker Saxton left the Mint Service in 1844, much of the work of maintaining and modifying the sensitive balances for which Saxton was responsible fell to Peale.
The Chief Coiner made a number of improvements to the scales, which he wrote up for an article in the Journal of The Franklin Institute in 1847.
These balances, sensitive to .0001 troy ounces (0.00011 oz; 0.0031 g), were protected by plate glass from air currents and dust.
When Adam Eckfeldt retired in 1839, he recommended Peale as his successor. As the Senate was not sitting, Peale was given a recess appointment as Chief Coiner of the Philadelphia Mint by President Martin Van Buren on March 27, 1839. On January 23, 1840, after the Senate reconvened, Van Buren nominated Peale; the Senate gave its approval on February 17. Despite his retirement, Eckfeldt continued to come to the mint every day until shortly before his death in February 1852, performing the function of Chief Coiner and leaving Peale with time on his hands.
Soon after his appointment, Peale began to engage in a private business on the Mint's premises.  He did this by designing, striking and selling medals for private commission, using government property and labor, and the Philadelphia Mint's facilities. Peale's enterprise was very profitable, as his expenses were minimal.  This activity took place with the knowledge of the other officers of the Philadelphia Mint, most of whom were Peale's friends and relatives. Clients included corporations as well as one couple celebrating a 50th wedding anniversary. According to Robert E. Wright in his history of Philadelphia as an early financial center, the legality of Peale's business was unclear, but "the uncertainty of the situation made it almost inevitable that someone would make a stink on [Philadelphia's] Chestnut Street."
This activity has been variously characterized by numismatic writers. According to coin dealer and numismatic author Q. David Bowers, "Peale started to abuse his position and privileges, in effect stealing services from the government". Burdette notes, "Overall, it appears that Peale used mint equipment and employees to make medals as instructed by Congress and the mint director, and to produce copies from private and official dies for sale to anyone who was interested. In the case of private sales, Peale seems to have used government metal, then reimbursed the bullion accounts when he collected for the medal. Profits were not accounted for in mint ledgers and it is unknown how much went to Peale, others at the mint or into the mint's Cabinet of Coins. The total amount was probably not large."
After scalemaker Saxton left the Mint Service in 1844, much of the work of maintaining and modifying the sensitive balances for which Saxton was responsible fell to Peale. The Chief Coiner made a number of improvements to the scales, which he wrote up for an article in the Journal of The Franklin Institute in 1847. These balances, sensitive to .0001 troy ounces (0.00011 oz; 0.0031 g), were protected by plate glass from air currents and dust.
Franklin Peale