long slender machining

[60case]

Trying to machine a rear wheel spoke with follow rest and can't get away from chatter. Diameter of material is 1" and trying to machine to .750. What spindle speed should i use with the rest?

[Craig A]

When that happens sometimes it's as simple as holding a gloved hand on the piece to act as a dampener.
We have even resorted to using wood blocks, a piece of rubber belting and a vee block to gently support a shaft to prevent chatter which has the same dampening effect.
The cutting tool angle and rake can affect chatter also but a slower speed will usually reduce chatter.
See what happens.....
Craig

[60case]

thanks craig i'll give it a try

[Fred_M]

I would add how tight are you gibs? A loose tool carriage will cause it big time. Also, carbide chatters more than high speed steel cutters, and larger radi on the tool causes more chatter. Sometimes moving the cutter slightly above center also helps. Fred

[Steve Adams]

Craig!!! you of all people should know that you NEVER wear gloves around rotating equipment! Not lathes, not mills, not drills, not grinders, Nothing! BAD, BAD, BAD! A friend of mine who has another shop across town had to deal with the loss of one of his guys who was KILLED on one of their lathes because he was wearing gloves. There was a burr on the part that caught his glove, pulled his arm in that came off at the shoulder, and by that time it had smashed his head off of the spinning chuck, which proceeded to spay blood and brains up the wall behind the machine. They found what was left of the body in the chip tray. It was so bad the fire department had to hose down the shop. I apologize for the graphic description, but I can't emphasize enough the gravity of the situation. This was on a 20X60 TOS. When I was still working for someone else, I had my back to a guy that was working on a 20X60 lathe and I heard the machine bog a bit and then switch off. when I turned around, Bob was standing there with no shirt on. it was wrapped around the part he was working on and he had caught his sleeve.This guy was big and luckily had the strength to pull back until the shirt ripped right off him. As I stood there asking if he was okay, the welts started coming out and after 5 minutes he looked like he had got 50 lashes. I was shaking thinking how close a call it was. NO GLOVES!!!!!!!!! if you have to do something like that to reduce chatter, use a SHORT piece of emery cloth.

[John Newman, Jr.]

AMEN! Steve.
I know most people (including me) are guilty of it at one time or another, but you should NEVER touch a moving part! No gloves, rings, watches, long sleeves.
To reduce chatter support the part the best you can, slow the RPM and increase the feedrate. You might try grinding your tool bit with a slight negative rake on top. This helps to keep the part from trying to climb up on it.

[Craig A]

I ALWAYS wear leather palmed gloves when working around machinery and always will. There's something about HOT parts on my hands that I don't like.
One doesn't, indiscriminately, just GRAB a rotating part without seeing it IS burr free and, besides, I said HOLD a gloved hand on the piece, not grab it.
Loose fitting clothes are another story. Even my Dad got his shirt wrapped up in a lead screw because he didn't have it tucked in.
No long sleeves? I don't care WHAT you are doing.....you have to think and use your head.
People die in the shower too and I can only assume they aren't wearing anything.
Be that as it may, unfortunately, accidents do happen.
As far as dangerous equipment goes, in my opinion, a press in inexperienced hands has 'em all beat.

[60case]

Thanks for the info guys

[Steve Adams]

Experience combined with complacency in an industrial enviroment can be just as dangerous as inexperience.

[Forrest A]

The advice I have always been given by my elders with machining experince is this: Chatter, decrease speed and increase feed. I will also add that the tool must be on center with the part you are turning. If you are using carbide check the cutting edge with a loop to make sure that it hasn't cracked away. I am one who thinks using any gloves on ones hands next to a spinning shaft is asking for an amputation.

Forrest A