Statements of Comprehensive Income - USD ($)	3 Months Ended		9 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net sales	$ 7,217,922	$ 6,470,286	$ 20,739,378	$ 17,860,841
Cost of sales	5,069,699	5,032,752	15,034,792	12,354,493
Gross profit	2,148,223	1,437,534	5,704,586	5,506,348
Selling, general and administrative expenses	781,248	765,900	2,285,856	1,997,279
Operating income	1,366,975	671,634	3,418,730	3,509,069
Other income
Interest income	4,240	9,362	22,303	26,416
Other	12,712	5,024	57,263	25,618
Total other income	16,952	14,386	79,566	52,034
Income before income taxes	1,383,927	686,020	3,498,296	3,561,103
Provision for income taxes	411,459	179,651	1,032,871	924,431
Net income	972,468	506,369	2,465,425	2,636,672
Other comprehensive income, net of tax:
Unrealized gain (loss) on investment securities	4,357	(259)	5,231	(1,672)
Total comprehensive income	$ 976,825	$ 506,110	$ 2,470,656	$ 2,635,000
Net income per share:
Basic	$ 0.43	$ 0.22	$ 1.08	$ 1.16
Diluted	$ 0.43	$ 0.22	$ 1.08	$ 1.15
Weighted average number of shares outstanding:
Basic	2,259,529	2,271,105	2,273,401	2,269,157
Diluted	2,274,781	2,297,071	2,290,927	2,286,312
Dividends per share:	$ 0.25	$ 0.25	$ 0.75	$ 0.75