Note 10 - Plant Restructuring (Details Textual) - USD ($)	3 Months Ended
	Sep. 26, 2020	Jun. 27, 2020	Sep. 28, 2019	Jun. 29, 2019
Closing of Northeast Plant [Member]
Restructuring Charges, Total	$ 24,000	$ 263,000
Closing of Northeast Plant [Member] | Employee Severance [Member]
Restructuring Charges, Total		219,000
Closing of Northeast Plant [Member] | Lease Impairments [Member]
Restructuring Charges, Total		$ 44,000
Closing of Midwest and Northwest Plants [Member]
Restructuring Charges, Total			$ 1,146,000	$ 4,806,000
Closing of Midwest and Northwest Plants [Member] | Employee Severance [Member]
Restructuring Charges, Total			386,000	586,000
Closing of Midwest and Northwest Plants [Member] | Lease Impairments [Member]
Restructuring Charges, Total			2,230,000	2,245,000
Restructuring Credits, Total			1,875,000
Closing of Midwest and Northwest Plants [Member] | Equipment Moves [Member]
Restructuring Charges, Total			$ 405,000	$ 1,975,000