×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Vibration problem

Vibration problem

Vibration problem

(OP)
Hi
We are trying to machine a left handed & a right handed thread each thread is 500mm long and the total shaft lenght is 1500mm long, there is a 100mm long section in the middle which is left stock 30mm . The material is EN24T we are using carbide insert tips ,speed has been tried at 500 & 250 rpm ,feed is non adjustable as set by cnc lathe
Pitch is M30 x 2mm , Passes are 15 , Spring passes are 2 , plunge angle is 29.5 degrees. The problem is we are getting alot of vibration and can't get rid of it , net result the thread looks rough
Anyone got any good ideas

Regards
Henry

RE: Vibration problem

It could be a million things;

When was the machine last leveled?
How long is the tool?
How old is the machine?
If the center of the part is left as stock is the length causing a off balance whip?

.....

Fill what's empty. Empty what's full. And scratch where it itches.

RE: Vibration problem

That's a long, skinny piece of material.  I'm not surprised you're having problems.  Have you tried putting a steady rest in the middle?

RE: Vibration problem

The problem is the tool pressures are too great. You will need a follower rest adjusted to the part OD and thread. This is the usual approach to making a thread this long on a shaft.

The other approach is to roll the thread.

RE: Vibration problem

(OP)
hi
thanks for the replys
We have now manufactured a new type of support for this job
It is mounted just infront the cutting tip and is basically a large ultrawear bush that is 0.1 clearance on thread od and about 50mm long . The bush completly surrounds the shaft so it hasn't got any chance but to do what its told ( so to speak ) The support for the bush is made from 40mm thick mild steel and the whole thing is bolted to the saddle so runs up and down nicely.
i must admit the whole thing works great and we can easily remove the bush and replace for bigger sizes

Regards
Henry

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources