boring bar chatter

[Geof]

Did the chatter start when you began using material cut from a different bar? I have had a similar thing happen with leaded steel and my conclusion was that one bar was slightly different. maybe a little bit harder or something, tool deflection also changed and sizes changed.

[len walker]

attach some lead wheel balancing wieghts to the back of the boring bar as close to the tip as possable. use hose clamps to secure the whieghts if the hole size allows or masking tape if hole is close to the bar.

[HuFlungDung]

What kind of tool mount system is used on this lathe?

What diameter bar?

What insert are you using?

[chipproducer]

Thanks for all your help guys.
Sorry I have not replied in so long, but I was very bussy with these jobs.
We have found that there is probably the material being different with every bar like was mentioned. Apperantly, the tolerances for the ingredients of materials is quite loose, so they vary.

[SeaSchell]

Not suprising......
last placed I worked we had parts we had been making for years...never a problem. Then we had a batch that had all kinds of issues, finish,warping after cuts, holding size, etc. Turns out even though we bought material, (2024-T4) from same supplier as always we hadn;t specified "Domestic". They substituted "Offshore". Even though it was certified & met all chemicals & properties the variences caused the above referenced issue. It is why when at all possible I specifiy "Domestic" material. Why cause myself grief.

[msomerville]

I don't know how much room you have to work with, but a set of vise grips clamped onto the back of the bar does wonders.

[jani]

Sometimes a good way getting vibration marks off the part is using low rpm and much higher feed.

[-jon-]

Been a long time since I operated a lathe or CNC machning centre, 20 odd years since I left the trade, but I recall we used to use all of the above methods and also lifting the bar slightly above centre sometimes helped.

[chipproducer]

lots of good advice. some We tried already and some new.
The biggest mistery of the job was why it worked perfect for the first 30 odd pieces and not all.
We are looking into the material certs to find differences but in the mean time, we will try some of the tricks of the trade learned here.

[Wiseco]

Does the boring bar have been removed, manipulated, drop on the floor after the first 30 pieces? A trick that I use sometime when all tricks metionned above doesn't work is to take a honing stone and rub it on the corner radius of the insert to dressed the clearance angle a bit. It will round a bit the cutting edge which in some case does miracle with chattering issue.