Works OK for me. I also have the Delta mortising attachment. It does what it says. I would bet a dedicated mortiser would make a cleaner hole, but who cares? You can't see it anyway.
For the weekend hobbiest, I think it fits the bill.
Yes, I've tried it. Want one? I'll send you this one for the cost of shipping.
The bit bores a round hole using an electric motor and the square chisel cuts the four sides by using downward force using lever action. On a drill press the downward lever is short and the pressure on the square chisels is not effective. On a dedicated mortiser the square chisel is driven downward with a much longer lever arm mounted on a much larger rack and pinion. So when you lower the lever down while boring the round hole the square chisel cut effectively and smoothly.
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