Hi jihhwood
It maybe your jig is just off a bit,the best one I have found is the the Oak-Park box jigs,quick and easy.
Here's a link to a jig I use and it works great with the Oak-Park jigs.
http://www.routerforums.com/jigs-fixtures/3543-deluxe-push-block.html
Plus here's a tip I use when I run into chip out,I used some 1/8" MDF stock on both sides of the slot.I put on some double sided carpet tape and stick the MDF on, the MDF will make a chip breaker front and backsides.MDF is cheap unlike cherry or other hardwoods.
But if you are using up to 1/2" stock you may want to take a look at the bit below,it's works great on hardwood like cherry because the bit cleans out the slot quicker and cleaner.
Box Joint Bit
http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bt_windo.html
Make perfect box joints with speed and ease by using our precision carbide cutters.
Strong, beautiful box joints are ideal for jewelry box drawers, humidors and a variety of small projects.
The long 1/2" arbor holds 5 (5/32") three-wing, carbide-tipped slot cutters, 4 spacers and a ball bearing guide. Use in router table only.
The bearing is designed for 1/2" depth of cut, but make shallower cuts by adjusting your router fence.
Use stock up to 1/2" thick.
For stock from 1/8" to 3/8" replace bearing with bearing #12111- #12114.
Bj
