doing stuff some people say you can't do

rockcitycafe

rockcitycafe

I make things.
just designed and built a new boring bar for my bridgeport, the old one was just a 5/8 bar in a narex boring head, was easy to adjust but not all that rigid and boring a cylinder without chatter required 80 rpm and very small cuts. I did a few blocks this way but wanted to make something better, so I machined an r-8 collet onto the end of a 1.5" steel bar, then bored a crosshole to put a carbide holder I made in, the carbide holder puts the cutting edge at dead tangent of the bore, so things are more predictable and it's spring loaded, so adjustment is done with a micrometer and set screw, not as easy as the narex, but the thing is super rigid and lets me bore at the recommended cutting speed for that cutter and cast iron. rough stock removal is done at 325-600 rpms and .006" feed, it'll easily rough .010" in one pass and finish passes leave a very smooth bore, honing .001" removed all tooling marks. the finish bore is within .0002" taper and round, and after honing is just about perfect (see video), my honing skills are still a bit rough, so I put the cylinder .0002" out of round at the bottom...

bridgeport_cylinder_boring.JPG

bridgeport_boring.JPG

http://www.youtube.com/watch?v=zuK5Hd0zyrU&list=HL1391864247&feature=mh_lolz
 
where I got mine, they had some units with smaller tables for $700, considering what some people spend on flashy bling, I'd rather have the faster machine ;)
 
can you show that the bore is square to the base of the block? Sure you can bore a hole with a Milling machine, but how square is the head when the head has both forward and side tilt. you might be smarter than the average person, but the average person won't check for or even know how to check for head square. "well the arrow on the riveted plate was pointing at the 0*degree marks, it should be square!"
You've shown that you can get a fairly round hole, show me that it square to the base of the block and I will be happier.

I like that you think outside the box on all your stuff. good job
 
I tram the head to the table before the operation, and used a surface plate and indicator to make sure my standoffs were all the same height, I could probably figure out some gauge for checking the axis of the hole on the plate too


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So I did another setup and trammed the mill directly to the block base, and bored the cylinder upside down, I think that's going to be procedure now... I'm also going to build a micrometer head adjuster for the cutter after damn near screwing up a bore on the finishing cut


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y4yqeju8.jpg


my pride and joy, the boring bar I built for my bridgeport milling projects, now with a micrometer stop to adjust the cut depth... I love making tools :)


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