You can put the coupon code at check out to see if it works with out acutely ordering it. I do that just to see if the store will take it.
I don't think HF is putting out the 20% off coupons anymore. Closest I could find is 20% off a specific line like chemical sprayers in the current catalog.
In general they offer excellent value on tools but I think lathes might be an exception....
John