Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended		9 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Income Statement [Abstract]
Net sales	$ 6,799,970	$ 7,661,946	$ 22,744,294	$ 23,921,627
Cost of sales	4,830,092	5,257,556	16,147,715	17,333,569
Gross profit	1,969,878	2,404,390	6,596,579	6,588,058
Selling, general and administrative expenses	725,596	663,625	2,135,293	2,097,317
Operating income	1,244,282	1,740,765	4,461,286	4,490,741
Other income
Interest and dividend income	7,301	13,926	25,716	37,396
Other	15,322	7,492	29,827	23,594
Total other income	22,623	21,418	55,543	60,990
Income before income taxes	1,266,905	1,762,183	4,516,829	4,551,731
Provision for income taxes	351,674	499,320	1,249,104	1,291,101
Net income	915,231	1,262,863	3,267,725	3,260,630
Other comprehensive income, net of tax:
Unrealized gain (loss) on investment securities	(5)	1,651	1,700	1,813
Total comprehensive income	$ 915,226	$ 1,264,514	$ 3,269,425	$ 3,262,443
Net income per share:
Basic	$ 0.41	$ 0.58	$ 1.48	$ 1.50
Diluted	$ 0.41	$ 0.58	$ 1.46	$ 1.48
Weighted average number of shares outstanding:
Basic	2,217,641	2,174,640	2,201,619	2,170,466
Diluted	2,247,599	2,196,366	2,240,181	2,197,677
Dividends per share:	$ 0.2500	$ 0.2250	$ 1.7250	$ 1.6750