Statements of Comprehensive Income - USD ($)	3 Months Ended		9 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Net sales	$ 5,324,104	$ 7,217,922	$ 17,060,411	$ 20,739,378
Cost of sales	4,195,599	5,069,699	13,508,014	15,034,792
Gross profit	1,128,505	2,148,223	3,552,397	5,704,586
Selling, general and administrative expenses	784,589	781,248	2,307,636	2,285,856
Operating income	343,916	1,366,975	1,244,761	3,418,730
Other income
Interest income	39,911	4,240	63,385	22,303
Other	7,488	12,712	21,691	57,263
Total other income	47,399	16,952	85,076	79,566
Income before provision for income taxes	391,315	1,383,927	1,329,837	3,498,296
Provision for income taxes	112,142	411,459	385,761	1,032,871
Net income	279,173	972,468	944,076	2,465,425
Other comprehensive income, net of tax:
Unrealized (loss) gain on investment securities	(247)	4,357	(1,503)	5,231
Total comprehensive income	$ 278,926	$ 976,825	$ 942,573	$ 2,470,656
Net income per share:
Basic	$ 0.12	$ 0.43	$ 0.41	$ 1.08
Diluted	$ 0.12	$ 0.43	$ 0.41	$ 1.08
Weighted average number of shares outstanding:
Basic	2,317,838	2,259,529	2,309,771	2,273,401
Diluted	2,327,797	2,274,781	2,323,431	2,290,927
Dividends per share:	$ 0.25	$ 0.25	$ 0.75	$ 0.75