Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands	3 Months Ended
	Jul. 31, 2011	Jul. 31, 2010
Cash flows from operating activities:
Net income	$ 791	$ 6,211
Adjustments to reconcile net income to net cash used in operating activities:
Amortization and depreciation	3,956	3,408
Loss on sale of assets	239
Provision for/(recoveries of) losses on accounts receivable	(345)	134
Deferred income taxes		329
Stock-based compensation expense	587	568
Change in contingent consideration		(2,530)
Excess book deduction of stock-based compensation	(249)	(215)
Changes in operating assets and liabilities:
Accounts receivable	(4,915)	2,833
Inventories	(5,847)	(11,910)
Other current assets	(834)	(2,269)
Income tax receivable/payable	387	2,426
Accounts payable	(7,140)	(4,938)
Accrued payroll	1,195	(2,728)
Accrued taxes other than income	(1,056)	(842)
Accrued profit sharing	1,244	1,439
Accrued other expenses	(5,215)	(3,233)
Accrued product/municipal liability	(174)	(93)
Accrued warranty	57	(19)
Other assets	1,815	180
Other non-current liabilities	192	(686)
Net cash used in operating activities	(15,312)	(11,935)
Cash flows from investing activities:
Payments to acquire patents and software	(28)	(245)
Proceeds from sale of property and equipment	153	1
Payments to acquire property and equipment	(5,102)	(2,040)
Net cash used in investing activities	(4,977)	(2,284)
Cash flows from financing activities:
Proceeds from loans and notes payable	1,532	1,365
Cash paid for debt issue costs	(1,837)
Proceeds from energy efficiency incentive programs	225
Proceeds from exercise of options to acquire common stock	180
Taxes paid related to restricted stock issuance		(50)
Payments on loans and notes payable	(421)	(271)
Net cash (used in)/provided by financing activities	(321)	1,044
Net decrease in cash and cash equivalents	(20,610)	(13,175)
Cash and cash equivalents, beginning of period	58,292	39,855
Cash and cash equivalents, end of period	37,682	26,680
Cash paid for:
Interest	287	1,649
Income taxes	$ 398	$ 632