Oct 24View SourceCharlie/Mark.Another way to achieve a flat bottom shoulder,bore out to the final size incrementallylaying off to the final depth by 0.005/0.010".This will create a ploughed field effectat the bottom.Turn the power off the machine,put into neutral,wind back the tool to centeror clearing the smaller bore,set to the final depth,then with a tee handle allan keyin the head dial adjuster,use it as a tommy bar but also slowly turning the key till it touches the final bore,you could go a little farther creating a small undercut,or a sharp corner.Then wind back a turn and lift up the quill.JohnSpain
On Friday, October 25, 2013 7:00 AM, "mark.kimball2@..." <mark.kimball2@...> wrote:
Charlie-Yes it seems a bit surprinsing. The pain of using a boring bar for making a flat-bottomed hole did come through, though. Wow, just think about stepping a boring bar across the bottom using the head's micrometer adjustment. I'd go for a counterbore scheme before trying that.Owning a lathe & being able to easily move a boring bar across the bottom of the hole just seems so simple in comparison to using a miller. Right tool for the job....BTW I haven't had my boring head all THAT long!
---In GrizHFMinimill@yahoogroups.com, <email@example.com> wrote:Hi, Mark,I'm surprised that the "not often really needed" came up, because it seems to me it would be a common operation. For example, it seems to me that any time that you were going to mount a bearing, you would want to bore such a hole with a very flat lip so the bearing was properly aligned. But, with a bearing, you're only dealing with a lip, so you could probably use John's first suggestion.As John also pointed out, there is a special type of boring bar that can also face. From what I understand, it costs some serious bucks...Thanks for researching it... the fact you've never used yours leaves me wondering if I need one. I'll probably just wait until I have a need before buying...Thanks,CharlieNJ, USA
---In firstname.lastname@example.org, <mark.kimball2@...> wrote:Doing an internet search on the subject was interesting. Most opinions ran something like "not easy to do", "not often really needed", or "do it on a lathe". RT's+endmill, and CNC also came up a lot.Being the owner of an un-used boring head (so far), this subject was of particular interest to me. Thanks for bringing it up!Mark