Note J - Business Segments and Foreign Operations - Geographic Information (Details) - USD ($)	12 Months Ended
	Jun. 30, 2026	Jun. 30, 2025
Net Sales	$ 381,270,000	$ 340,738,000
Long-lived assets	85,044,000	89,582,000
Reportable Geographical Components [Member] \| UNITED STATES
Net Sales	106,207,000	87,549,000
Long-lived assets	36,324,000	39,949,000
Reportable Geographical Components [Member] \| NETHERLANDS
Net Sales	61,888,000	52,735,000
Long-lived assets	10,400,000	11,426,000
Reportable Geographical Components [Member] \| FINLAND
Net Sales	32,695,000	24,618,000
Long-lived assets	16,561,000	15,660,000
Reportable Geographical Components [Member] \| BELGIUM
Long-lived assets	7,563,000	8,184,000
Reportable Geographical Components [Member] \| CHINA
Net Sales	29,100,000	28,666,000
Reportable Geographical Components [Member] \| CANADA
Long-lived assets	4,870	5,952
Reportable Geographical Components [Member] \| AUSTRALIA
Net Sales	20,356,000	22,358,000
Reportable Geographical Components [Member] \| Other Countries [Member]
Net Sales	117,913,000	114,392,000
Long-lived assets	9,326,000	8,411,000
Reportable Geographical Components [Member] \| ITALY
Net Sales	$ 13,111,000	$ 10,420,000