Boring in the mill with lots of chatter. Ideas?

[Janderso]

Shorten the shank on the boring head
Shorter boring bar.
Give us a close-up of the grind on the bar. Those brazed bars require a LOT of grinding to get the geometry suitable for a boring head. As purchased, when the cutting edge is in the right orientation to the boring head you end up with negative rake.

I thought i put the criterion tool in. It has a proper edge, the ones in the kit need a lot of work for sure.

 

[MrWhoopee]

As in, they need additional radial clearance below the edge?

No, the back rake on top of the carbide needs to be ground. As received, the top of the carbide is parallel to but above the centerline of the shank. When the bar is rotated so the cutting edge is on center with the boring head, the carbide has a negative back rake.
In this picture the bar on the left is as received, the one on the right has been ground to provide a neutral or slightly positive rake.

 

[Janderso]

As in, they need additional radial clearance below the edge?

They need to have all the clearance you would see in any normal cutting tool. The brazed carbide tools need to be shaped.

 

[Janderso]

No, the back rake on top of the carbide needs to be ground. As received, the top of the carbide is parallel to but above the centerline of the shank. When the bar is rotated so the cutting edge is on center with the boring head, the carbide has a negative back rake.
In this picture the bar on the left is as received, the one on the right has been ground to provide a neutral or slightly positive rake.
View attachment 392964

Well done.
Notice the cutting edge is way off center line on the as shipped tools.
A good example of how moch work they need.
I think my biggest problem is the 8-10” the cutting edge is from the spindle lugs.

 

[mmcmdl]

Too much hanging out of the holder and too small a boring bar .

 

[mmcmdl]

from the picture, it looks like you have the cutter facing 90 degrees to where it should be.
The cutter should be aligned with the heads sliding direction, not 90 to it.

This too !

 

[woodchucker]

No, the back rake on top of the carbide needs to be ground. As received, the top of the carbide is parallel to but above the centerline of the shank. When the bar is rotated so the cutting edge is on center with the boring head, the carbide has a negative back rake.
In this picture the bar on the left is as received, the one on the right has been ground to provide a neutral or slightly positive rake.
View attachment 392964

I have no trouble with mine being straight. It cuts perfectly well.

 

[Janderso]

I have some off shore tools but mostly Criterion and Bokun brand.
In the last pic is another example of how much work is needed just to get the carbide cutting edge to the centerline.
I’ve tried just about every tool in my box but the excessive distance is causing unbelievable chatter.
Tool on centerline, parallel with the adjustment screw, as short as possible, etc.
I thought it might be spindle bearings but the runout is within factory specs.

I sure would like to see your boring head set up!

 

[Winegrower]

I have never had to grind my import boring bars, you just have to be careful not to set too aggressive a rake angle, and make sure the bore radius is large enough for back relief. It’s possible to try to bore too small a hole for a particular bar and orientation.

 

[mmcmdl]

The bar isn't the issue . The stick out is . Think of boring on the lathe . You have a 12" boring bar , you're going to get chatter . You have a 2" bar , you're not . Cut that shank if that's the only holder it will fit .

It's looking like that is sticking out 8 inches on that little BB ?