Statements of Comprehensive Income (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Net sales	$ 5,663,161	$ 5,324,104	$ 24,690,689	$ 17,060,411
Cost of sales	4,407,957	4,195,599	18,898,733	13,508,014
Gross profit	1,255,204	1,128,505	5,791,956	3,552,397
Selling, general and administrative expenses	895,129	784,589	2,756,319	2,307,636
Operating income	360,075	343,916	3,035,637	1,244,761
Other income
Interest income	42,684	39,911	109,561	63,385
Other	13,428	7,488	31,236	21,691
Total other income	56,112	47,399	140,797	85,076
Income before provision for income taxes	416,187	391,315	3,176,434	1,329,837
Provision for income taxes	98,423	112,142	801,035	385,761
Net income	317,764	279,173	2,375,399	944,076
Other comprehensive income, net of tax:
Unrealized loss on investment securities	(2,143)	(247)	(2,993)	(1,503)
Total comprehensive income	$ 315,621	$ 278,926	$ 2,372,406	$ 942,573
Net income per share:
Basic	$ 0.14	$ 0.12	$ 1.02	$ 0.41
Diluted	$ 0.14	$ 0.12	$ 1.02	$ 0.41
Weighted average number of shares outstanding:
Basic	2,331,697	2,317,838	2,328,518	2,309,771
Diluted	2,349,428	2,327,797	2,338,909	2,323,431
Dividends per share:	$ 0.25	$ 0.25	$ 0.75	$ 0.75