BASIS OF PRESENTATION (Details)	3 Months Ended		6 Months Ended
	Oct. 31, 2018 USD ($) item	Oct. 31, 2017 USD ($)	Oct. 31, 2018 USD ($) item	Oct. 31, 2017 USD ($)	May 01, 2018 USD ($)	Apr. 30, 2018 USD ($)
Revenue from Contracts with Customers
Number of primary product revenue streams | item	2		2
Revenue from contracts with performance obligations satisfied over time	90.00%		90.00%
Assets
Contract assets	$ 365,000		$ 365,000		$ 102,000
Equity
Accumulated deficit	(8,652,000)		(8,652,000)		(8,641,000)	$ (8,743,000)
Net sales	4,874,000		9,347,000
Cost of goods sold	3,200,000	$ 3,322,000	6,194,000	$ 6,596,000
Gross profit	1,674,000	1,362,000	3,153,000	2,618,000
Income (loss) from operations	71,000	(269,000)	37,000	(565,000)
Income (loss) before benefit for income taxes	47,000	(282,000)	(11,000)	(590,000)
Benefit for income taxes	15,000	(111,000)		(226,000)
Net loss	$ 32,000	$ (171,000)	(11,000)	(364,000)
Contract assets and liabilities			(455,000)	(22,000)
Net cash provided (used) in operating activities			$ (277,000)	$ (673,000)
Aerospace and defense industries
Revenue from Contracts with Customers
Percentage of revenue	90.00%		90.00%
Industrial and commercial
Revenue from Contracts with Customers
Percentage of revenue	7.00%		7.00%
ASU 2014-09 | Balances Without Adoption of ASC 606
Equity
Net sales	$ 4,406,000		$ 8,879,000
Cost of goods sold	2,995,000		5,989,000
Gross profit	1,411,000		2,890,000
Income (loss) from operations	(192,000)		(226,000)
Income (loss) before benefit for income taxes	(216,000)		(274,000)
Benefit for income taxes	15,000
Net loss	(231,000)		(274,000)
Contract assets and liabilities			(192,000)
Net cash provided (used) in operating activities			(277,000)
ASU 2014-09 | Effect of Change Higher/(Lower)
Assets
Contract assets	365,000		365,000		102,000
Equity
Accumulated deficit					$ 102,000
Net sales	468,000		468,000
Cost of goods sold	205,000		205,000
Gross profit	263,000		263,000
Income (loss) from operations	263,000		263,000
Income (loss) before benefit for income taxes	263,000		263,000
Net loss	$ 263,000		263,000
Contract assets and liabilities			$ (263,000)