Ok I have a question for you more experienced lathe runners! For the life of me I can not get my parting tool set up right! I have it set just a hair below center bore, and all I get is chatter or it will cut good and when I try to feed it, it ether won't cut and then without me touching it, it will try and take a big bite by itself and ether complete the "bite " or break off! Is there something I'm not doing right? Thanks for your help in advance and please keep the bs comments to yourself! Thanks!
Parting tool question
- Thread starter Caleb85
- Start date
ab_bentley
I fix stuff, sometimes....
Support the material with tailstock, run in back gear with oil and constant pressure. Also I make a chip breaker right behind the cutting edge.
Adam
I am by no means claim to be anywhere close to a 'professional' but will take a stab at this. Sure others will also. Everything I have read says to set cut off tool dead nuts center line. Too low and it can or will cause the 'dig in and raise hell with everything' you are experiencing.lol Too high and it will chatter. Too fast and it might chatter. Too slow and them SOB's might chatter. Too dull and they might chatter. Not exactly at 90* to material being cut and it might chatter etc etc. Not my favorite tool but I have found it easier to use a cut off tool on my SB Hvy 10 then my Atlas/Craftsman 36". Rigidity and mass helps to prevent flex which can cause all of what you are mentioning in my experience! Also using a good cutting oil will usually make it cut smoother. However, I have had times when running it dry and slow worked better, just don't cut much at a time and allow tool and material to get very hot.
Edit to add...take your time and make darn sure you have your tool at 90*(well, not yours but you know what I mean). A shallow cut isn't real issue but get into a piece of 1" or bigger and you will get a lot of heat build up and cutting edge deflection if you are cutting on the front and friction/heat on both sides. I have a VFD on my SB and turn speed to a crawl and slowly increase speed and or inward pressure until I get the optimum cut, no chatter etc. One of the great benefits of variable speed is with a cutoff tool in my experience.
My worthless amateur 2 cents worth!
Respectfully,
Dennis
Suppose when I hit post there will be 40 replies with my slow typing that will all be opposite of my experiences.lol
Edit to add...take your time and make darn sure you have your tool at 90*(well, not yours but you know what I mean). A shallow cut isn't real issue but get into a piece of 1" or bigger and you will get a lot of heat build up and cutting edge deflection if you are cutting on the front and friction/heat on both sides. I have a VFD on my SB and turn speed to a crawl and slowly increase speed and or inward pressure until I get the optimum cut, no chatter etc. One of the great benefits of variable speed is with a cutoff tool in my experience.
My worthless amateur 2 cents worth!
Respectfully,
Dennis
Suppose when I hit post there will be 40 replies with my slow typing that will all be opposite of my experiences.lol
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Thank you !
I am by no means claim to be anywhere close to a 'professional' but will take a stab at this. Sure others will also. Everything I have read says to set cut off tool dead nuts center line. Too low and it can or will cause the 'dig in and raise hell with everything' you are experiencing.lol Too high and it will chatter. Too fast and it might chatter. Too slow and them SOB's might chatter. Too dull and they might chatter. Not exactly at 90* to material being cut and it might chatter etc etc. Not my favorite tool but I have found it easier to use a cut off tool on my SB Hvy 10 then my Atlas/Craftsman 36". Rigidity and mass helps to prevent flex which can cause all of what you are mentioning in my experience! Also using a good cutting oil will usually make it cut smoother. However, I have had times when running it dry and slow worked better, just don't cut much at a time and allow tool and material to get very hot.
My worthless amateur 2 cents worth!
Respectfully,
Dennis
Suppose when I hit post there will be 40 replies with my slow typing that will all be opposite of my experiences.lol
Thank you! I have been using viper cutting oil. I'm cutting at 70 RPM.
I have been using the Vipers Venom also lately and it works pretty decent. Also 70 rpm is about where I end up.
Very well put! And may I add no two similar scenarios are ever the same. If one attempt doesn't work, try option number 2 and always turn very slow.I am by no means claim to be anywhere close to a 'professional' but will take a stab at this. Sure others will also. Everything I have read says to set cut off tool dead nuts center line. Too low and it can or will cause the 'dig in and raise hell with everything' you are experiencing.lol Too high and it will chatter. Too fast and it might chatter. Too slow and them SOB's might chatter. Too dull and they might chatter. Not exactly at 90* to material being cut and it might chatter etc etc. Not my favorite tool but I have found it easier to use a cut off tool on my SB Hvy 10 then my Atlas/Craftsman 36". Rigidity and mass helps to prevent flex which can cause all of what you are mentioning in my experience! Also using a good cutting oil will usually make it cut smoother. However, I have had times when running it dry and slow worked better, just don't cut much at a time and allow tool and material to get very hot.
Edit to add...take your time and make darn sure you have your tool at 90*(well, not yours but you know what I mean). A shallow cut isn't real issue but get into a piece of 1" or bigger and you will get a lot of heat build up and cutting edge deflection if you are cutting on the front and friction/heat on both sides. I have a VFD on my SB and turn speed to a crawl and slowly increase speed and or inward pressure until I get the optimum cut, no chatter etc. One of the great benefits of variable speed is with a cutoff tool in my experience.
My worthless amateur 2 cents worth!
Respectfully,
Dennis
Suppose when I hit post there will be 40 replies with my slow typing that will all be opposite of my experiences.lol
I had similar issues. Using Mobilemet oil and turning at 165 rpm with a more aggressive feed stopped these issues.
spitfire_er
Silver $$ Contributor
RPM's should be ok. Make sure your bit is SHARP and on center. Support the piece with the tailstock, should cut down on vibrations quite a bit. Lock the carrage down. Setup, rigidity, RPM's and a sharp bit is all key! Make sure all gibs are snug also. Cross slide and compound. Takes practice to make sure everything is set up correct.
Caleb,
HS parting tools suck. To put it bluntly. I have a parting tool with carbide inserts that works great. Never chatters, grabs, or any other crazy stuff. Inserts last forever. I am on insert #3 and it just keeps going. I believe the HS flexes to much and chatters and grabs. Usually followed by a loud noise when it breaks. Usually profanity follows shortly thereafter. Lol.
Paul
www.boltfluting.com
HS parting tools suck. To put it bluntly. I have a parting tool with carbide inserts that works great. Never chatters, grabs, or any other crazy stuff. Inserts last forever. I am on insert #3 and it just keeps going. I believe the HS flexes to much and chatters and grabs. Usually followed by a loud noise when it breaks. Usually profanity follows shortly thereafter. Lol.
Paul
www.boltfluting.com
the work piece has to be held solidly and your pictures show it too far away from the headstock IMHO. When it's that far out you must use a live center to stabilize it. If it isn't held solid, you will not be able to get rid of the chatter in my experience. Also, a parting blade with replaceable carbide inserts works very well for me. Part close the the headstock and your results should improve. Best of luck.
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Guess I didn't pay attention whether or not your pics were there when I posted or not the first time?? Anyway if they were I never looked until now, several hours later! 
You can tell from chatter that cutoff tool isn't ground square to work piece and it is real evident when looking down at cutting edge that there is one h*ll of an angle on the cutting edge! Can't help but chatter at that angle! you need cutting edge ground square to rest of the HSS tool as well as to what you are planning to cut off. With any angle other than 90* at tip it cannot load up evenly when it contacts material. Unless lead or maybe near pure aluminum you will never get it to cut evenly and without chatter IMO.
You can tell from chatter that cutoff tool isn't ground square to work piece and it is real evident when looking down at cutting edge that there is one h*ll of an angle on the cutting edge! Can't help but chatter at that angle! you need cutting edge ground square to rest of the HSS tool as well as to what you are planning to cut off. With any angle other than 90* at tip it cannot load up evenly when it contacts material. Unless lead or maybe near pure aluminum you will never get it to cut evenly and without chatter IMO.If your toolpost allow,you can try to reverse the parting tool tip down and cut in reverse rotation?
The old swan neck parting tool was a dream in that aspect.
R.G.C
Riesel
Gold $$ Contributor
I have spent countless hours trying to do this and watched enough you tube videos
and still could not get it right. Now I just get a threading tool to cut a small groove, put the lathe in reverse at about 100 rpm and cut it with my handy dandy Harbor Freight portable metal cutting saw. Square and clean up the end and crown. No more blue in the face, or turning the air blue
and still could not get it right. Now I just get a threading tool to cut a small groove, put the lathe in reverse at about 100 rpm and cut it with my handy dandy Harbor Freight portable metal cutting saw. Square and clean up the end and crown. No more blue in the face, or turning the air blueluckyshot52
Gold $$ Contributor
Parting tool too far out of holder. Not enough rpm. All other comments also
Think rigidity. Close as possible to headstock. Keep parting bit in as far as possible....just enough to get through diameter with no clearance issues. Up RPM to 200. Keep brushing oil on while keeping steady in feed to keep nice chips rolling. Grind a slight back rake on top of bit. Center bit...not below.
shortgrass
Silver $$ Contributor
So, which one was it, the re-grind, the chip breaker, or supporting with the tailstock?
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