View Full Version : Boring deep holes, how do you keep the chips from piling up on the bar?

04-30-2013, 10:46 PM
I am working on making a new cylinder ram sleeve and am working on the final job of boding out the 2" center and adding an O-ring groove in the bore. But I am having trouble with the chips piling up on the boring bar and pushing it away from the wall. I have tried boring both ways with the bar (in and out) and have been trying to get as much angle on the bar as possible to allow clearance between the bar and wall. i forgot my camera in the shop so I can't show any pics. I was able to get the chips (string) to exit the hole toward the compound until the boring bar reaches about half way down the hole and the string starts to wrap around the bar. The hole I am boring is about 4" deep and a final size of about 2". I am at 1.750" now and want to figure out how to get a clean cut before I approach the final size. I am using my home made cummins valve for a boring bar which normally works great on not so deep holes. I need to get the sleeve done tomorrow for the customer so I can't wait for some new boring bar or something to come in.

Some ideas? lol

04-30-2013, 11:01 PM
Sneak up on it. Get it all bored close and then take a real light final cut. When doing the roughing, you will have to back the bar out frequently to clear chips.

Frank Ford
04-30-2013, 11:04 PM
For boring through holes, I rig up my air gun so I can blast compressed air through the spindle - it helps direct the chips outward. With the nose of the air gun in the spindle I get a bit of a multiplier effect, so the flow is pretty strong.

04-30-2013, 11:18 PM
Grind a chip breaker just behind the cutting edge to curl and break the chips into shorter pieces. A Dremel abrasive disk will do it. Short tight curls will work their way out of a 2" dia 4" deep.

04-30-2013, 11:18 PM
If I read your description correctly, it sounds like you are getting long streamers wrapping around the boring bar. If that is the case, perhaps a chip breaker ground into the cutter of your boring bar would work.

04-30-2013, 11:31 PM
I did think of the chip breaker I hear many talk about but never actually looked one up to see what it actually is. I may have to look into that and it may work well for this.

I did try taking very light cuts and still the light strings still wrap up and eventually push on the bar.

Rich Carlstedt
04-30-2013, 11:48 PM
Reverse the boring bar by turning it upside down.
"IF" your lathe is heavy enough, and you bore on the far side , the chips fall to the bore bottom and no bar is there to tangle with.
The problem is the bar will try to lift the carriage, so a heavy carriage /lathe is preferred, but it does clear out the chips easier.


05-01-2013, 08:32 AM
I have a threaded chuck, while I do have a reverse switch wired up I haven't ever tried turning in reverse. I am sure the light cuts probably wouldn't cause a problem though. After I try cutting in a chip breaker today, if I still have some trouble I will try cutting from the back side. Thanks!

05-01-2013, 12:16 PM
I have a bar that has a "through-coolent" bore. I connect that to compessed air. Works very well. Reverse and inverted bar is my next choice.

05-01-2013, 12:39 PM
I made a attachment for a huge sealed bearing to go into the outboard of my spindle and connect a vacuum cleaner, for throughole boring.
Blind boring? ehhh. just sucks, keep a vacuum handy near the bore and freqenctly retract the bar.

Rich Carlstedt
05-01-2013, 09:00 PM
I didn't mean reversing the lathe rotation. I meant turning the boring bar over ( upside down) and raising it so the cutting edge
is on the centerline, but the body of the bar is all above the centerline and completely out of the way of chips as gravity will
cause them to drop to the bottom of the bore. The bar is cutting on the backside of the bore in normal rotation.
I assumed it was a blind hole.
For through holes, use a vacuum on the left side of the spindle to suck chips through the spindle.


05-01-2013, 09:17 PM
Well today I tried to cut a relief for a chip breaker, no dice. I tried a vacuum, no pie. I tried the blow gun, it kind of worked, but still, no soup. Then I figured it out, just use a beefier bar that the chips can't push off the material and the blow gun that sort of worked before.

I remembered the camera too!

Using all of it.


Some chips.

My small bar and how the strings were coming out till the bar would get half way down and the string would start to wrap up.

More pics in next post, just wait.

05-01-2013, 09:21 PM
The improved more rigid bar.

Nice clean bore.

How do you measure a O-ring groove inside of a bore? I ended up using playdough...

All done.

05-01-2013, 09:23 PM
Next to the old scrap one.