# How Can I Reduce Parting Tool Chatter



## Rannunzi (Sep 21, 2021)

I've got an Atlas Craftsman 12x36. Whenever cutting with my carbide insert parting tool it seems to create a lot of chatter if I don't go incredibly slowly. I took care to ensure that the blade is at 90° to within ~0.002", but the workpiece wants to vibrate a fair bit while cutting. Today I was using it to make a groove for a piston seal o-ring but the resultant groove is quite messy. The ID of the groove looks like a series of flat faces rather than a cylindrical surface. What can I do to improve the cutting? Thanks.


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## Larry$ (Sep 21, 2021)

I think chatter is usually a case of flex. Lack of rigidity! Two suspects: the work or the tool. Both could contribute with too much stick out. If you are working close to the chuck and your machine bearings are tight then it is likely a tool problem. Is the tool mounted correctly? Minimal stick out? Cutting at center? Tool holder held solidly to tool post? Tool post mounted solidly to compound. Compound not extended & locked? RPM & feed rate suitable for the tooling? Most inserted carbide tools require a depth of cut to keep whatever radius they have on the cutting edge cutting deep enough to keep forming a chip and not slipping out of the cut due to that ease of the cutting edge. 

Try HSS in a tool holder designed to hold the tool at a positive cutting angle. (top of tool pointing upwards a few degrees.)

If you use a T shaped tool Make sure it stays vertical. Some people use a shim on the side to make sure the tool is straight up. 

Took me a while to write this so there is probably another answer by now.


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## Mitch Alsup (Sep 21, 2021)

Cutoff tool: minimum stick out that reaches the final cutoff point.
Rigid compound and turning directions.
The above makes the lathe as stiff as possible for parting off.

Cutting edge sharp, possibly up to 7º cutting rake for easier cutting.
Lots of cutting fluid, continuously applied.
Slower RPMs than when turning. ~= /2

Once the tool starts cutting, make sure the pressure on the point of cut stays constant.
This generally means driving the blade in harder than you think you should.
If the pressure on the cutting point varies, the cutting point will go down as the blade cuts, and come back up when there is no material to cut. This is what causes chatter.


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## benmychree (Sep 21, 2021)

Also, the tool should not overhang the front side of the compound if possible.  HSS tool, plenty of cutting fluid, a bit of back rake and slower speed and moderate feed rate, and/or a more rigid machine.  A carbide insert parting tool has no place on a machine such as yours, and carbide insert tools need speed, and you do not have th machine to give it what it likes.


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## savarin (Sep 21, 2021)

Remove to top slide/compound and replace it with a solid plinth to mount the tool post to.
This single change solved all my parting woes in one swoop.
I only replace the top slide now when I need to cut short tapers.
As has been mentioned use very sharp HSS tool bits.
I regularly part mild and stainless with no worries up to 1.5 inches thick.


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## Nutfarmer (Sep 21, 2021)

You are fighting a losing battle to part with carbide on an atlas lathe. I just remove the part and cut off on the horizontal band saw. Saves a lot of frustration. I know some will tell you it will part off just fine. I am only relating what I do. If you want to run production parts and part off as part of the process watch what a heavy screw machine will do. Most of us use what we have. I have seen some beautiful work by some of the members here with an Atlas lathe. Some times it's just easier to work with the limits of what we  have.


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## Dhal22 (Sep 21, 2021)

I wonder if @chatter chatter cut cut would have an answer?


: )


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## mickri (Sep 22, 2021)

What type of tool post/tool holder are you using?  A picture of your setup will help you get better answers to your question.  I have a Craftsman 12x36 and parting was not fun to begin with.  I solved my parting woes by first lining the compound up with cross feed and locking the compound in place so it can't move.  I also tightened the gibs on the cross slide. This helped a little.  Next I made a tool holder just for parting based on the design in Winky's Workshop.  



  This solved my parting woes and now parting is no big deal.  Just another operation on the lathe.


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## chatter chatter cut cut (Sep 22, 2021)

with my 7x14 no name chinese i have to lock everything down and still have problems . if i feed too fast the lathe stalls if too slow it stops cutting. iv sharpened the hss tool on diamond hones through 5 steps til it is very sharp! changing the angle is something i will try


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## WobblyHand (Sep 22, 2021)

Tried to part some 1.5" 304 and my 7x16 mini-lathe met its match today.  Actually burned one edge due to work hardening.  And chipped the other side.  Chatter, stalling, you name it.  It would cut for a short time then dig in and stall.  Just not rigid enough setup.  Everything was reefed down.  I had parted 1.5" 1045 with minimal problems.  Right side was the edge that burned back.


Gave up and pulled the part from the lathe.  Put it in my modified power hacksaw and it cut through no problem.  Going to make a plinth to get rid of the compound.  One less thing to shake, rattle and roll.


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## pineyfolks (Sep 22, 2021)

I just got one of these Armstrong cutoff holders  and they work great on older machines with lower hp and slower spindle speeds.  They really reduce the chatter.


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## AGCB97 (Sep 23, 2021)

See post # 32 in this thread








						Another Parting off Thread
					

I guess I'm confused with terminology, I was thinking the blade and the part had to be exactly parallel on the face, as in no tangents. to cut straight. That would make them perpendicular.




					www.hobby-machinist.com
				



Aaron


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## SLK001 (Sep 23, 2021)

With problems like this, you need to post pictures of your setup.  You say your workpiece is chattering, which is a different problem from your tool chattering.


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## benmychree (Sep 23, 2021)

304 is not at all pleasant to work with, 303 is the way to go.


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## mattthemuppet2 (Sep 23, 2021)

most people that have problems parting run the part too fast and feed too slow. Run slow (I was at 75rpm for a piece of 2.6" stainless today), feed HARD until you see nice little curls popping out of the cut and flood the cut with cutting oil (steel) or kerosene/ WD40 (alu). 

I have a couple of those MGEHR parting tools, one with a molded insert and the other with a ground insert. Haven't had a whole bunch of success with them to be honest.


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## Janderso (Sep 23, 2021)

pineyfolks said:


> I just got one of these Armstrong cutoff holders  and they work great on older machines with lower hp and slower spindle speeds.  They really reduce the chatter.


Did you mount this to your QCTP or the lantern style post?


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## Janderso (Sep 23, 2021)

I don't have any parting issues with my lathe but I sure did in the past.
I took David's advice, This tool is incredible.



			https://www.latheinserts.com/5-8-PARTING-GROOVING-TURNING-TOOL-4310000755.htm


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## WobblyHand (Sep 23, 2021)

benmychree said:


> 304 is not at all pleasant to work with, 303 is the way to go.


True enough.  I like using 303, but 303 isn't considered food safe, and 304 is.

304 on a mini-lathe is even less pleasant to work with.  I've been slowly uncovering things as I go.  The gibs had loosened up, so I adjusted them. Today I found a raised ridge around the compound stud, which prevented the QCTP from fully seating on the compound.  Stoned off the circular burr on the compound around the threads to allow the QCTP to bottom out on the compound.  There's lots of this kind of stuff on these little lathes. Basically, even the good mini-lathes still need work.  Been a frustrating day.  In the second photo, if you zoom in you can see the chatter in the groove.



The parting tool holder for mini-lathe isn't particularly a great design either.  Blade is only pinched in a short area, the rest of the blade is unsupported.  There is a 1mm gap between the top edge and the top of the blade.


Going to make a Winky style holder.  (Seen in the video earlier in the thread.)  Today, I squared off a 7075 block to make a plinth.  That way I can eliminate the compound as a source of movement.  Plan to bolt the Winky holder to the plinth.


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## WobblyHand (Sep 23, 2021)

mattthemuppet2 said:


> most people that have problems parting run the part too fast and feed too slow. Run slow (I was at 75rpm for a piece of 2.6" stainless today), feed HARD until you see nice little curls popping out of the cut and flood the cut with cutting oil (steel) or kerosene/ WD40 (alu).


Towards that end, I am installing a digital tach/eBay special on my mini-lathe.  At least then I will be able to make sure the SFM is appropriate for the material.  Hope it shows up within a week.  Estimating speed from a potentiometer position is not accurate.


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## rabler (Sep 23, 2021)

Doesn’t look like that parting tool holder has any upward angle.  Most of the ones I’ve seen do to provide a bit of postitive angle.  Does mean that changing the stick-out means resetting the tool height.


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## davidpbest (Sep 23, 2021)

Read the attachment in this post.









						Becoming hobby machinist in the near future.
					

Cool, Congrats on your first thread.  :encourage:




					www.hobby-machinist.com


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## WobblyHand (Sep 24, 2021)

davidpbest said:


> Read the attachment in this post.
> 
> 
> 
> ...


Appreciate the time and effort you put into making this document.  Hadn't thought out the plinth completely, so your post comes at a good time. Like the idea of using locating pins.  A mini-lathe won't ever have the rigidity of a PM1340, but doing these things will definitely help.


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## pineyfolks (Sep 24, 2021)

Janderso said:


> Did you mount this to your QCTP or the lantern style post?



I use it in a lantern toolpost. I don't even own a QCTP. I'm old-school all the way.


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## keeena (Sep 28, 2021)

I had similar problems with my first couple lathes (Grizzly G9972Z 11x26 and Grizzly G4003G 12x36) using both HSS and cheap import carbide. For me, switching to brand-name quality carbide inserts made a big difference. I'm using Iscar SGFH/R/L blades with GTN/GTR inserts in the 1, 2, and 3mm widths. These sizes span a cut width of 0.063" up to 0.139" depending on blade/insert; I use the 2mm most frequently. I also make sure to get the grade meant for unstable conditions and slower F&S - IC328 is the one I can recall. They will run about $5/insert on eBay but I have yet to burn one up. Any big brand is probably similar; I only started using Iscar because I received some blade holders in a cabinet I bought at auction.

Someone linked the Iscar Heligrip - that could be a good option and maybe better value since you get 2 cutting edges vs 1 with the SGFH. Somewhat limited DoC tho.

This is after all the other (good) recommendations like parting right next to the chuck, proper tool height, lock cross-slide and compound, etc... I also played with turning with the blade upside-down to aid in chip clearance (this didn't really help me at all). With SS you have to feed to get the cut. Too slow or dwell and you'll smoke the bit. All these recommendations helped, but for me a quality insert made a big improvement.


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