# How to Prevent Chatter.



## jtice (Feb 29, 2004)

One of the problems I have when useing my lathe is chatter.
Especially when "Parting" a piece.

The last 2 times I have had to part a 1" dia. piece, I broke my parting tool. /ubbthreads/images/graemlins/frown.gif
I think its due to the tool not cutting properly. And kinda bounces as its trying to cut. Which I guess thats what chatter is.

I had just alittle chatter the other day while boring with a boring bar, but it wasnt too bad.

How do I reduce chatter?
Slower speeds, cut less at a time, more at a time?

Thanks alot for the info.

John


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## Rothrandir (Feb 29, 2004)

reduce vibration, use lube, make sure everything is at the right height, make sure all the angles are correct...

when parting, you need to make sure that the sides don't rub!

set your lathe to the lower gears so you get more torque, and you probably need to plunge faster than you're doing now...

what i do is start out with a parting tool, then pull out the hacksaw and while the lathe is running, i hack away furiously. that goes without saying, be careful.

or you could get a metalcutting bandsaw /ubbthreads/images/graemlins/wink.gif


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## jtice (Feb 29, 2004)

Roth,

I have used lube both times.
The parting bit was shapped properly, with sides not touching.

Lat time I used the lower gears, and I did notice, that when I got brave, and starting plunging alittle more than I ussually do, it would quiet down alittle. BUT... thats when it ends up braking my bit. It will all of a sudden catch, and BAMM!

I hate to admit this, but I have also done the hacksaw trick.
Cuts really fast, and surprisingly, makes a fairly smooth cut.
But, that tends to bounce around alot, and shakes the lathe, and entire workbench.
That cant bee good for the lathes bearings, so I think I am not going to do that anymore.


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## tvodrd (Feb 29, 2004)

Jtice,

How wide a parting tool are you using, and what sort of diameter are you trying to part? When you say "catch, and BAMM!"- been there/done that _once_ and snapped 2 1/4-28's on the holder. You need fairly continuous coolent application. Try a plastic squeeze bottle with a one hole rubber stopper and one of those "acid brushes" through the stopper. It conserves coolant by allowing you to apply it as needed. Hold the brush in the cut while squeezing gently. As to chatter, rigidity is all important. Always part as close to the chuck as practical and with the minimum amount of blade sticking out from the holder. You can also "wiggle" the tool by moving the carriage back and forth to widen the cut slightly and reduce the chance for siezeing.

Parting is such sweet sorrow! /ubbthreads/images/graemlins/icon15.gif

Larry


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## Chief_Wiggum (Feb 29, 2004)

[ QUOTE ]
Parting is such sweet sorrow! 

[/ QUOTE ] 

ROTFL!


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## jtice (Feb 29, 2004)

Larry,

The parting tool was about 0.055" thick.
First one was thicker.

I was parting about 1" OD bod.

I try to spray it often with lube, but thats not really all that constant.
I will try it with the bottle idea, to try to keep a better continuos flow.


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## unnerv (Feb 29, 2004)

It could also be that your tool is not dead center, possibly a little too low. Also you may need to sharpen the tool, and slow the lathe down. I got a lot of chatter when I 1st started, and it turned out to be a combo of all of the above. I sharpened the tool, then I got a wiggler to find the exact center of the spindle and set all my tools to that hight. I also have a guage made to the exact hight of center so if I put it on the bed rails I can set the tool to that hight and be within a couple thousands from center. Cutting at a lower speed seemed to help to. I do most of my cut off at around 100rpm.


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## tvodrd (Feb 29, 2004)

That sounds good! (Shoulda reread for the 1" dia part.) Your chips should be in little rolled-up curls. Cutter geometry is critical- parting tools are usually zero top rake with some side rake/clearance, and you set it for centerline of the stock. Do you have a link to the blade you are using?

Larry


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## jtice (Mar 1, 2004)

Larry,

Blade is home made, from a tool blank. About 0.055" wide.
I will have to double check to see if the sides are hitting at all, but I dont think they are.

I think the constant lube, and slower speed will help alot.

I also need to check for center.

unnerv,

What is a wiggler?


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## unnerv (Mar 1, 2004)

Here is a link to a wiggler, so you can see what it is and various uses. What I did was mount it in the chuck and spin it. I borrowed a precision block from my father (who is a machinist) that has two triangular blocks that slide against each other (sorry don't know the technical name for it.) The top and bottom of the two peices are exactly parallel. I placed this on the bed under the wiggler and slid the two blocks together until the wiggler stoped wiggling in the chuck. Then I measured the the hight of the block and added 1/2 the size of the wiggler tip. I then had a piece of 1" stainless cut to exactly that height, so I can quickly set my tool hight. I don't have the blocks any longer, but if you wanna see the pic of my guage I can take one tonight.


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## MoonRise (Mar 1, 2004)

Speed, feed rate, lube, rigidity, cutter geometry and set-up. /ubbthreads/images/graemlins/smile.gif

Yeah, chatter is when the tool bounces or chatters as you are machining something. Chatter is usually not good. /ubbthreads/images/graemlins/frown.gif

Speed. Find the right speed for the operation. Sometimes faster helps, sometimes slower is better. And it will vary depending on the material, tooling, and machine used.

Feed, or feed rate. Feed fast enough to have the tool take off a consistent cut. If your set-up allows it, getting a constant and consistent ribbon of material streaming off of the tool tip as you make the parting cut is neat. As long as this big wad of sharp swarf doesn't wrap itself around something and catch, scratch the workpiece, or cut your hands. /ubbthreads/images/graemlins/icon8.gif

Lube is important. Keep a constant flow going so that the tool tip is never cutting dry. The tip about the brush on the squeeze bottle is a good one.

Rigidity in the setup is important. The tool, tool holder, workpiece, and machine should be stiff enough so that they aren't flexing or vibrating during machining operations. Flexing or vibrating could be causing the chatter. Remember to have the least tool overhang out of the tool holder as possible during the machining operation so that you don't have a long lever spring flexing and bouncing in the tool holder. /ubbthreads/images/graemlins/smile.gif

Cutter geometry and set-up are important too. Maybe you didn't grind a chip relief or chip breaker into your tool? Or you don't quite have the cutter set-up so that the cutter TIP is correctly positioned with respect to the stock so that the tip is cutting nicely and the chips can get out of the way?

One inch diameter aluminum -shouldn't- be too bad to part off. Stainless steel is a *****, get the feed/cut rate wrong and you gall or work harden the stock. /ubbthreads/images/graemlins/ohgeez.gif


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## jtice (Mar 1, 2004)

unnerv,

I see what you mean now.
I thought of another way to do this.

Get a piece of AL stock, chuck it, and face it.
When facing, I wont put my little "half assed" shims under my tool bit.
This will leave alittle "tit" on the face, in the center, where the toll isnt touching.
I will then measure to the exact center of that "tit" and make the apropreate thichness shim to get to that level.

I had to shim mine, in order to face properly without leaving that "tit".
This is the same shim I use for parting. But I am thinking now, that maybe its just slightyl too high. /ubbthreads/images/graemlins/icon3.gif

Thanks for all the great tips guys. /ubbthreads/images/graemlins/bowdown.gif


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## unnerv (Mar 1, 2004)

Yeah, that should work. If you have calipers, you can measure the OD of the the "tit" and then halve that. That should give you the amount that you need to raise the tool. I have a QC toolpost , so I can just dial in the hight without shimming. That makes getting the right hight much easier as well as only taking a few seconds to change tools without haveing to worry about correct hight. Also, if you have to be a few thousands high or a few low, for the the cuttoff, a few high would probably be better since when you are low it tends to grab more and you have a better chance of stalling, or breaking the tool. Once you have the correct hight for one tool, use that tool to face off a peice of stock so you have a flat end, then place it one the bed faced side down and scribe a mark on it at the proper tool height. Re chuck, cut off at your mark and reface. This should get you a gauge that is pretty close. You can keep refacing until you have the exact hight you need.

Good luck.


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## jtice (Mar 1, 2004)

unnerv

Wow, I didnt know that QC tool holder would let you change your hieght like that.

I have been meaning to get one.
But I heard that the other one that they have, is better than that one.

What do you think of yours?
What is the sturdyness like, compared to the stock holder?

BTW, what lathe do you have?


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## unnerv (Mar 1, 2004)

I only used the stock holder for a day or two on my Homier 7x12, so I can't really compare, but I have not had any problems with mine at all. Once the cam engages, the dovetails between the two pieces lock up pretty secure. I have taken .060" off the diameter in a single cut (although the finish isn't too pretty) on aluminum without any problems. It seems to be holding up well. It was the best $100 I have spent on accessories. Once you get a QC post, you will never go back. My father has a full sized lathe at his house with a standard tool post, and it kills me to have to center up and shim everything everytime I change the tooling even with his center gauge. The QC post changing a 1 or 2 minute change to a 5 to 10 second change.


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## unnerv (Mar 1, 2004)

Here is a pic of my toolpost and the gauge.


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## Dan C (Mar 1, 2004)

unnerv, your lathe is *entirely* too clean! /ubbthreads/images/graemlins/drool.gif

Dan C


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## Chief_Wiggum (Mar 1, 2004)

Very slick height checker. I got to get around to making one of those.


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## Rothrandir (Mar 1, 2004)

what dan said!

i'm not even going to take a picture of my work area! /ubbthreads/images/graemlins/eek.gif


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## unnerv (Mar 1, 2004)

I clean it every time after I finish using it. It builds up swarf so fast, sometimes I have to clean it a couple of times while using just so there isn't crap all over it geting caught on the parts /ubbthreads/images/graemlins/smile.gif Next time I'll take the pic half way thru my job...

Here is the pic of the whole thing clean





Sorry to hijack the thread. Hope some of this helps with the chatter problems. Keep us updated.


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## MicroE (Mar 2, 2004)

Unnerv---That is a scrupulously clean set-up. If only I had more time to clean the shop.........


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## jtice (Mar 2, 2004)

Thats just rediculous.

I dont think he uses it guys,, just likes it sitting there. /ubbthreads/images/graemlins/wink.gif

Mine is a MESS !!!!
All I do is brush the piles of chips off onto the floor. lol

Yours seems bone dry also. Mines covered in oil and grease, and all the chips are stuck all over it. /ubbthreads/images/graemlins/icon15.gif


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## unnerv (Mar 2, 2004)

I use mobile 1 synthetic for the ways and it says pretty clean. Plus aluminum makes some big chips so they are easier to clean up, unlike when I work with brass. I really do use my lathe, I just like it clean after a project. /ubbthreads/images/graemlins/smile.gif

Now back to the regularly scheduled thread on chatter...


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## chalo (Mar 5, 2004)

Use as short an overhang on your parting tool as you can get away with. 

Grind a curved chipbreaker into the tip of the tool. 

Use the recommended edge rake and relief clearance for the material you are cutting. 

Autofeed at the minimum recommended IPR for the metal you are cutting. 

Flow coolant directly into the slot while cutting. 

If all else fails, turn the speed down reeeeal low. (Maintain a normal IPR). 

Chalo Colina

P.S. Insert type parting tools have made my professional life as a machinist more comfortable. (The insert is wider than the toolbar.)


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## tvodrd (Mar 5, 2004)

Chalo,

You could write the textbook! I am not a machinist but posess reasonable competency with the mill and lathe. Most of the folks here are dealing with the small "bench top" lathes and may not even have a bench grinder with a "green" wheel /ubbthreads/images/graemlins/grin.gif . Trying to enlighten them with grinding/sharpening bits (radii for surface finish, etc) will be a neverending class. I think the MMM forum should acquire some stickys for the basic "basics." What do you think? Are there textbook pics that can be "stolen" to post?

Larry


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## chalo (Mar 8, 2004)

[ QUOTE ]
*tvodrd said:*
I think the MMM forum should acquire some stickys for the basic "basics." What do you think? 

[/ QUOTE ]

Sounds good. Mike/Chief Wiggum seems to be a rich source of basic good practices. Perhaps he could be talked into archiving a fundamentals/FAQ thread. 


[ QUOTE ]
Are there textbook pics that can be "stolen" to post? 

[/ QUOTE ]

I'm sure. However, I went years as a self-taught and mentor-taught machinist before discovering that there were actually books on the subject. (Duh!) Therefore my references are limited to Machinery's Handbook and other similarly dense text-based manuals. Not any worthwhile pictures in there. 

When I'm unpacked from my recent move, I'll recover my digital camera and take in-shop pix as appropriate.

Until then, here is a picture of me in my workplace shop, riding a bike I built there. /ubbthreads/images/graemlins/grin.gif

Chalo Colina


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## tvodrd (Mar 8, 2004)

Clalo,

I'm mostly self-taught also. Years ago, I had a machining textbook that had excellent illustrations for cutter geometries and the like. (Long gone. /ubbthreads/images/graemlins/frown.gif ) That's quite a shop you have! I've been downsized twice to a Bridgeport, 15" lathe, 18" vert bandsaw, drill press, and a couple pedestal grinders. It's just an R&D support shop now.

Larry


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## gadget_lover (Jun 1, 2005)

In another thread (which I can't find now, of course) I said that I didn't have any problems with parting aluminium or mild steel. Feed slow, make sure the parting tool is at 90 degrees to the work, lube, etc....

For the last month or so, parting has been a hit and miss proposition. Sometimes
it goes well, other times it digs in and stalls the lathe. Fortunately, nothing has broken yet, but it does mess up the work and sometimes pulls it out of true.

I found the problem. It was the stinking gibs on the compound slide. When I added the DRO I also replaced the lower part of the compound that had the lower part of the dovetail. I thought the gib was adjusted securely. It turns out that it was pretty loose. Even though it was loose, normal cutting seemed OK.

The give-away symptom was that as I was parting, the bit would dig in and it almost seemed like the tool post would lean away from me. I'd checked everything except the gibs. No swarf under the tools. The cross-slide had no play. The tools were secure in the tool post. It never occured to me that the whole compound slide was lifting just a fraction of an inch.

I liberally lubed the gib and dovetails with while lithium grease and tightened the adjusting screws so there's just the slightest drag. The compound is now solid as a rock.

I posted this in the chatter thread since the gibs can also increase the chatter, leading to poor finishes.

Daniel


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## McGizmo (Jun 1, 2005)

On a recent Ti light I made, the boreing bar would "sing" if I tried a shallow cut. The carbide insert _looked_ fine and I assumed that it was mostly deflection of the boreing bar as it was extended further than ideal. New carbide insert and the Ti cut like butter. Rigid and sharp; never have too much of either, I guess. /ubbthreads/images/graemlins/icon3.gif I missed this thread but glad it surfaced. /ubbthreads/images/graemlins/blush.gif

I am self taught too and likely have taught myself some pretty stupid things! /ubbthreads/images/graemlins/rolleyes.gif


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## tvodrd (Jun 1, 2005)

They're really pricey, but you can get solid carbide boring bars that use inserts. I don't have any, but they gotta help with chatter. Rigidity (largest shank that will fit, minimum tool overhang, close to the chuck/collet as you can get, and minimum "slack" in the machine) really helps for accuracy and nice finishes!

Larry


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## Rothrandir (Jun 1, 2005)

the other day at work i was setting up some pretty big parts (15inches diameter, 7inches long, shaped kind of like the letter "T"), and the bore was 2.8305, 5.5inches back.
i was using a 1.5" boring bar (the largest diamter this particular machine will hold), sticking out just far enough to bore all the way in, and was getting lots of chatter, like we do every time we've run this part for the past xxxyears.

anyway, the boring bar is held in place by 6 tiny setscrews, maybe .250 diamter.
i drilled out the holes and tapped them for a larger setscrew size (about .400), popped the boring bar back in and secured it.
you wouldn't *believe* the difference that made. just a little bit more clamping area and pressure on that boring bar, but it made the difference between ear popping racket and a smooth cut.
same boring bar, sicking out the same amount.

rigidity is sooo important. there are so many things to consider when machining something. bar sicking out too long? sharp insert? spinning too fast? feeding to fast? spinning to slow? feeding to slow? cutting too shallow? cutting to deep? part held securly? tool rigid? tool held securly? machine secured down? machine rigid? cutting fluid? correct angles? correct insert? dirty tooling pockets? crappy tooling? currect height? enough material to be rigid?

sometimes it can be as simple as adjusting the order you do things in. for example, if you're od threading a part with a bore, simply threading before boring can provide enough rigidity to prevent chatter in the threads. the same can be said with grooves.

another thing to keep in mind when grooving, is that the sharper the tool, the better it will cut. this doesn't only mean a fresh insert, but it can also mean that using a narrower groove tool will provide less tool pressure than a wider groove tool.


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## McGizmo (Jun 1, 2005)

Larry,
I picked one of those up in a micro size. Would be nice to have in the larger sizes but I don't cut the tough stuff much anymore. /ubbthreads/images/graemlins/grin.gif

A while ago, I ran across a page Hardinge Hard Turning that makes our issues with rigidity and other considerations just pale! /ubbthreads/images/graemlins/icon15.gif

Good job Roth! /ubbthreads/images/graemlins/thumbsup.gif /ubbthreads/images/graemlins/grin.gif


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## tvodrd (Jun 1, 2005)

Hi Don,

My fireFox browser doesn't display the "items on the left" to click and "learn more." /ubbthreads/images/graemlins/frown.gif I have a good friend who _machines!_ and grinds carbide every day for header dies. You're thinking "green" carbide, but appearantly not. /ubbthreads/images/graemlins/faint.gif He says he uses carbide, not diamond tooling to do it! There are a lot of things I wouldn't care to do for a living!

Hey Roth, when you gonna move into sales for your employer, and start offering _services?_ /ubbthreads/images/graemlins/grin.gif

Larry


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## McGizmo (Jun 1, 2005)

Larry,
Here's a quote at the beginning:

[ QUOTE ]
Hard turning is defined as the process of single point cutting of part pieces that have hardness values over 45 Rc. Typically, however, hard turned part pieces will be found to lie within the range of 58-68 Rc. The hard turning process is similar enough to conventional “soft” turning that the introduction of this process into the normal factory environment can happen with relatively small operational changes when the proper elements have been addressed.

[/ QUOTE ]

One proper element is operator with brass ones! /ubbthreads/images/graemlins/icon15.gif

It goes on to discuss how hard turning can replace grinding.


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## gadget_lover (Jun 1, 2005)

Ummm, did anyone else notice that the picture to the right on that Hardinge web page showed chips that were glowing yellow? Yikes!

Larry, the "items on the left" was a drop down menu; Home, about us, products, etc.

Daniel


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## tvodrd (Jun 1, 2005)

Don, "carbide" is about 90Rc and you can cut case-hardened and full-hardened 60+Rc stuff ok. (Your cutter _will_ take a beating!) Guys like you and me resharpen with a "green wheel" (SiC) but it results in some edge property deterioration(sp?) on carbide cutters. (Diamond wheels with coolant feed are really for production shops, though diamond stones for "touch-up" are cheap and a "must!) 

Indeed, "brass ones" do help sometimes! /ubbthreads/images/graemlins/icon15.gif

Larry


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## pbarrette (Jun 3, 2005)

Hi all,

I have never had a problem with chatter while parting. Then again, I think I'm the only one here with a Sherline lathe. The Sherline parting tool is essentially a .04" thick, steel blade ground to shape and held in a special toolpost. The toolpost provides a positive rake to the blade in relation to the part.

As I understand it, the increased attack angle (as opposed to a level attack) means that there is less pressure required to cut, but the tool will lose its edge more quickly. For me, it works well. I always end up with nice long curls that are right around .04" thick. I just have to remember to back out a bit so my curls don't get too long and start wrapping around my work piece.

Here's the link to the tool to give you an idea of what I'm talking about:
http://www.sherline.com/3002inst.htm

I'd take a picture of the setup, but I just got my CNC motor mounts installed, with motors and controller in the mail. Basically, the machine is non-functional (no handwheels) until I get the motors in.

pb


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## nekomane (Jun 3, 2005)

You'll all laugh, but with the tiny lathe I have, I do a lot of parting by _furiously_ cranking away manualy on an improvised handle. Never thought that sitting in front of a lathe would be so much exercise /ubbthreads/images/graemlins/thinking.gif


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## Silviron (Jun 3, 2005)

Gee- I was going to recommend *DUCT TAPE*

That was before I read the thread and realized that you were talking about lathes, not your wife or girlfriend. /ubbthreads/images/graemlins/wink.gif

I often use one of those little "mini-hacksaws" for "quick and dirty" parting: They seem to be a little easier on the machinery and the stock than a full-size hacksaw, and a little easier to manipulate .


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## 1331 (Jun 4, 2005)

For a reference book I have "The Model Engineer's Workshop Manual" by George Thomas. It has a good section on parting and tightening of the slides. He can apparently part at 300rpm. It has a lot pictures of techniques and tools to make for the lathe, boring, threading, tool height guage ,etc.


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