Statements of Comprehensive Income (Unaudited) - USD ($)	3 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Net sales	$ 7,496,423	$ 6,068,684
Cost of sales	6,035,269	4,724,936
Gross profit	1,461,154	1,343,748
Selling, general and administrative expenses	878,820	772,667
Operating income	582,334	571,081
Other income:
Interest income	31,224	12,021
Other	10,172	7,002
Total other income	41,396	19,023
Income before provision for income taxes	623,730	590,104
Provision for income taxes	180,966	169,279
Net income	442,764	420,825
Other comprehensive income, net of tax:
Unrealized loss on investment securities	(281)	(686)
Total comprehensive income	$ 442,483	$ 420,139
Net income per share:
Basic	$ 0.19	$ 0.18
Diluted	$ 0.19	$ 0.18
Weighted average number of shares outstanding:
Basic	2,326,364	2,303,062
Diluted	2,332,234	2,318,986
Dividends per share:	$ 0.25	$ 0.25