Statements of Comprehensive Income (Unaudited) - USD ($)	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Net sales	$ 11,531,105	$ 5,667,624	$ 19,027,528	$ 11,736,308
Cost of sales	8,455,507	4,587,479	14,490,776	9,312,416
Gross profit	3,075,598	1,080,145	4,536,752	2,423,892
Selling, general and administrative expenses	982,370	750,381	1,861,190	1,523,047
Operating income	2,093,228	329,764	2,675,562	900,845
Other income
Interest income	35,653	11,454	66,877	23,475
Other	7,636	7,201	17,808	14,203
Total other income	43,289	18,655	84,685	37,678
Income before provision for income taxes	2,136,517	348,419	2,760,247	938,523
Provision for income taxes	521,646	104,340	702,612	273,619
Net income	1,614,871	244,079	2,057,635	664,904
Other comprehensive income, net of tax:
Unrealized loss on investment securities	(569)	(570)	(850)	(1,256)
Total comprehensive income	$ 1,614,302	$ 243,509	$ 2,056,785	$ 663,648
Net income per share:
Basic	$ 0.69	$ 0.11	$ 0.88	$ 0.29
Diluted	$ 0.69	$ 0.11	$ 0.88	$ 0.29
Weighted average number of shares outstanding:
Basic	2,327,562	2,308,588	2,326,963	2,305,825
Diluted	2,335,293	2,323,604	2,333,764	2,321,295
Dividends per share:	$ 0.25	$ 0.25	$ 0.50	$ 0.50