The dowel jig is meant to align holes that will be about one inch in depth.
8 inches is another story. Spade type bits are famous for going around corners; very difficult to drill a straight 8 inch hole
with one of these. Better off with an auger type bitt. Or.....is it too late to make these holes using the drill press.
Dave

I only have the very small DP, but I have augers and braces. The tenons are cut
but not all finished... some still need to be cut down to length. I get the impression
that auger bits tend to wander off the straight line while in use.

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Alex - newbie_neander in woodworking
cravdraa_at-yahoo_dot-com
not my site: http://www.e-sword.net/