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Small boring bars with no flats alignment?

Scribe a line on the part with the facing tool then align the tip of the bar with the line on the part. That's what I'd do.

Brent
 
You align the cutting tip on center the same way as any other lathe tool. That can be as simple as turning a point on a rod held in a chuck and lining the cutting edge up with the very tip.
 
I guess the biggest problem is the tool is only .037 in diameter.

Bust out your glasses bill :D

We used to use a lot of sandvik boring bars for stainless in this size and they had an angle ground on the end of the bar that aligned it on center in their special holders. Worked great.
 
hy :)

... mark a thin line on the toolholder, line that is perpendicular and intersecting center bore axis
... use a sleeve for collets
... clamp the sleeve inside the holder
... put the collet + nut inside the sleeve
... align the tool inside collet, so tool nose projection is among the marked line
... tighten the nut :)

use a nut with bearing ring, so to avoid / minimize tool rotation when clamping the nut :)
 
sleeve + collet + tool + normal nut > inside the chuck

use C axis so to align tool

grind a flat, small enough for a tiny screw to grip the shank

now you may clamp the tool inside a normal sleeve with screws, and put it in the holder :)
 
MOST of my boring bars are this small. As in probably 85% of them. It is only recently that I've actually had reason to use anything larger than .200" on a regular basis, actually... But I digress...

The way I do it is to install the boring bar into the various bits ( bar into holder, holder into step sleeve, step sleeve into tool block sleeve, etc... ) and then put it all on a small surface plate I have next to the turning center ( used for in process inspections and tooling set up ). Then, I do whatever math is needed and grab a gauge block ( or stack as the case may be ) to keep the flat parallel to the surface plate. I use various bits to establish it's relationship to the flats on the various bits it is all installed into. ( small angle plate, 1-2-3 block, etc... )

Once the flat of the cutting surface of the boring bar is aligned, you lock it all down and then install it in the tool block.

Clear as mud?

Oh, and once that job is complete, I do this again and grind a goddam flat on the bar so I don't have to do this again, next time. :cool: O, at least I tell myself that... there's a reason I know this procedure so damn well... :rolleyes5:

Here's a pic of a very small sample of my bars. These are just the ones I use almost every day.

FAF5159A-442B-4304-928D-57FD0D252020_zps2o3n6xxo.jpg
 
Hi All:
In my experience you've got to get your cutting edge dead nuts on center with a bar as small as 0.040"
"Dead nuts" means better than 0.001" so I set them up with an indicator on a stand directly on the machine.
I grind my micro bars so the plane of the cutting edge is exactly in the center of the blank.
I can double check my bar height by clocking the body of the bar with a DTI in the spindle, just like I'd clock in a drill or a reamer.
A twitch too high is better than a twitch too low, because the side clearance on these tiny bars is so minimal.
If you're too low you'll rub the bar on the bore and often break the bar.

I've got a gang chucker with a nice big flat table and a known center height, so it's easy on my machine.

Turret machines are harder because there are fewer flat reference faces to locate from and they're all a lot more awkward to clock from.
It's not too bad if your turret has convenient flats on it you can set a mag stand on and pick up a pin in the collet.

Scribed lines and eyeballing to a point and pushing the tip up against a flat are pretty good for bigger stuff, but not quite there for the tiddlers in my experience.
Even the solutions like PHorn modular tooling fall short if your setscrews shift the tip a thou or more in the wrong direction when you snug it all up.
Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
www.vancouverwireedm.com
 
Hi Old Friend,

In my experience you've got to get your cutting edge dead nuts on center with a bar as small as 0.040"

< snippage >

A twitch too high is better than a twitch too low, because the side clearance on these tiny bars is so minimal.
If you're too low you'll rub the bar on the bore and often break the bar.

Exactly. That's precisely why I've taken to using the gauge blocks on a surface plate for doing this.
And, for what it's worth - I too sweep the pockets and the tools with a coax in effort to make sure that things are where they need to be.

( seems you and I had that same conversation a few years back. Eh? :) )
 
I second that, surface plate, gage blocks and indicators is the way to go. on center to .001" above. If you have to change regularly, use a sleeve and grind a flat on the bars after setting on surface plate.I

For bigger bars i agree with rotating to a flat or eyeball, light facing cut, rotate, face again to check. Much faster for a more forgiving situation.

Sent from my KFGIWI using Tapatalk
 
What would you do if your boss hands you a carbide boring bar without a flat and tells you to grind a flat on the shank?
 
Not sure how to grind a flat the entire length of a boring bar in a vee block.
Where does the clamp go?
I just use a grinding vise. Height gauge to rotate tool tip to 1/2 diameter on a plate, clamp and run.
I know people get crazy land about this but if .001 off a problem and your tool bigger that .010 something is so not right in the design or use.

There is only one cutting centerline for a boring bar. Tool tip to center of rotation. This may be your slide axis or way off from it.
This can be used to make your .001 infeed dial become a .0001 size dial. The same is done in boring heads.
Is that confusing? Think way, way off center to the machine slide. Try 80 degrees off. What happens then?
How does the actual cutting geometry and clear rakes change? 80 degrees, I don't think so.
Bob
 








 
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