Good point, Steve. I had the same problem. I was less resourceful than you however and gave up. I was on a mission to create a keyway and didn't take the time to troubleshoot the shaper problem until I got it right. Instead I just let the shaper chatter its heart out and cleaned up the slot with a hand file afterwards. I think the bottom line is making a keyway full width requires a machine with more mass to eliminate chatter. I also suspect that instead of using a square tool the size of the width of the keyway we should instead get a really big (in depth) tool like those used for cutoffs on large lathes. But this is an open request to all the Gazette readers who have shapers. Please email or write me and tell me how you accomplish slotting without chatter. I'm hopeful that the collective wisdom of our many shaper owners can shed some additional light on this problem.
Keep sending email with questions and interesting shaper stories.
My email address is KayPatFisher@gmail.com.