Sample cuts in
various materials using a Sherline lathe
A large chip peels off a piece of steel as Fred Smittle does a test cut. See videos of various materials being cut by clicking on the links below. Below the chart is a section that includes a video explaining what causes tool "chatter" and shows you how to eliminate it. (Click on photo to view larger image.)
We are often asked, "Can Sherline tools cut hard materials?" The answer is "yes," but it is better to show you than to tell you. Some people (particularly those living in apartments or working in the kitchen or den) also want to know how noisy the machine is. The following video links will show about 30 seconds each of cuts on materials from Delrin to Titanium and even Inconel. You will get a feel for how quiet the machine is and how it cuts various materials. At the bottom of the page we have also given a demonstration of what "tool chatter" is and how to eliminate it.
Use of coolant
In some cases, we have cut the material dry rather than make a mess in the photo studio using coolant, but tool life can usually be extended and smoother finishes obtained with the use of coolant. With experience you will be able to make cuts like these, because Sherline machines are rigid and the DC motor supplies a lot of torque, particularly at low speeds where it is really needed for machining. Don't let the small size fool you into thinking these are not serious metal cutting machines. They are rigid, powerful and precise.
About the setups used in these cuts
The 4400 lathe used in the video sample cuts linked below is a stock machine right out of the box. We have kept the material size fairly large, part overhang low and tool overhang minimum. Tools are sharp and set to proper height. Cuts are made near the headstock end of the bed where bed flex is minimal. This is an ideal setup that allows the machine to cut at its maximum capacity. Some of the cuts are quite large in order to demonstrate what the machine can really do. Many times your particular setup will require less than ideal part or tool positioning. In those cases, you will have to scale back dramatically on the depth of cuts used compared to these examples. In some cases, for example, you may only be able to take 10% of what we show here. Additional support with the use of a live center, a steady rest or a follower rest can help alleviate these types of problems. Remember what Joe Martin says in his book, Tabletop Machining: "I've never seen anyone ruin a part by taking too light a cut." Take cuts that you are comfortable with and that yield the surface finish you are looking for. Don't be in a hurry. Your leadscrews, cutting tools and spindle motor will last longer if you are not constantly pushing your machine to maximum capacity. Consider this like a road test where we are showing you how fast a new car can turn the quarter mile, even though you will hopefully not be driving it every day like you are at the race track.
Viewing the Videos
Click on the underlined links in the left-hand column of the table below to view a video. Two versions of each video are supplied. The WMV version is a smaller file size but can only be viewed on Windows computers. The MPEG1 (MPG) version is about 2-3 times the file size but can be viewed on other platforms like the Macintosh. With slower Internet connections it might be best to right click on the link and use the "save-as" command to save it to your desktop. The video can then be played from your own hard drive for smoother replay.
| MATERIAL (Click on video link) |
DIA. OF STOCK | RPM | DEPTH OF CUT | AMOUNT REMOVED FROM DIAMETER | CUTTING TOOL | COOLANT | COMMENTS |
| DELRIN WMV version (2.1 Mb file size) MPG version (5.5 Mb file size) |
0.650" 16.51 mm |
650 | 0.100" 2.54 mm |
0.200" 5.08 mm |
1/4" HSS | No (Not needed in non-commercial applications) |
An easy to cut plastic similar to Nylon, but long chips tend to "birds nest" near the cutter and must be cleared with a brush periodically |
| WOOD (Maple) WMV version (2.15 Mb) MPG version (5.40 Mb) |
Cut #1: 3/4" square Cut #2: 5/8" round |
2000 | 0.100" 2.54 mm |
0.200" 5.08 mm |
1/4" HSS | No | The harder the wood the better. Interrupted cut on square 3/4" blank shown first, then a smooth cut on round 5/8" stock. A toggle switch dust cover is recommended if you cut a lot of wood. |
| BRASS WMV version (2.1 Mb file size) MPG version (6.2 Mb file size) |
0.625" 15.88 mm |
800 | 0.050" 1.27 mm |
0.100" 2.54 mm |
1/4" HSS | No (Brass is normally cut dry) |
NOTE: Tiny chips can get in speed control and cause a short. A toggle switch dust cover is recommended if you cut a lot of brass or wood.. |
| ALUMINUM
(6061-T6) WMV version (2.14 Mb) MPG version (5.17 Mb) |
0.75" 19 mm |
1000 | 0.050" 1.27 mm |
0.100" 2.54 mm |
1/4" HSS | No (Kerosene makes a good coolant for cutting aluminum.) |
A charcoal lighter fluid that contains odorless kerosene
can also be used. As Fred adjusts his feed rate slightly he begins to get a better chip as the cut progresses. |
| STEEL (12L14) WMV Version (1.76 Mb) MPG Version (5.17 Mb) |
0.625" 15.88 mm |
500 | 0.030" 0.76 mm |
0.060" 1.5 mm |
1/4" HSS | No (But coolant is recommended) |
A light cut. This is a free machining leaded steel that cuts well, leaves a good finish and can be heat treated. Note the slight second cut as the cutter is withdrawn. This is due to a little tool flex and is normal. |
| STEEL (12L14) WMV Version (1.91 Mb) MPG Version (5.17 Mb) |
0.625" 15.88 mm |
800 | 0.065" 1.65 mm |
0.130" 3.30 mm |
1/4" HSS | Yes | A heavier cut with coolant shows some smoke from hot chip and tool. Note that the part is supported by a live center for more rigidity. |
| STEEL (12L14) WMV version (2.23 Mb) MPG version (5.17 Mb) |
0.625" 15.88 mm |
500 | 0.100" 2.54 mm |
0.200" 5.08 mm |
1/4" HSS | Yes | A very heavy cut. Starts with .035" deep cut until it comes to .065" shoulder, then continues taking .100" cut (.200" off diameter). Note the machine does not even slow down or chatter. |
| STEEL
("Stressproof") WMV Version (2.10 Mb) MPG Version (6.30 Mb) |
.75" 19.05 mm |
350 | .010" .25 mm |
.020" .51 mm |
1/4" HSS | No (But coolant is recommended) |
A tougher steel that takes hardening well. This sample happens to be a cutoff from the material we use to make the worm gear for the rotary table. A live center is used for additional support. |
| CAST
IRON WMV Version (2.05 Mb) MPG Version (5.78 Mb) |
.75" 19.05 mm |
450 | .0250" .64 mm |
.050" 1.27 mm |
1/4" HSS | No | A short video of Fred's hand turning the handwheel is included so you can get a feel for the feed rate. It is about .06"/minute in this case. Cast iron chips tend to be small, dirty (fropm carbon) and gritty. |
| 01
TOOL STEEL WMV Version (1.93 Mb) MPG Version (6.66 Mb) |
1.0" 25.4 mm |
250 | .010" .25 mm |
.020" .51 mm |
1/4" HSS | No (But coolant is recommended) |
Note that Fred uses an even slower feed rate than for cast iron, but once he gets it just right, the chip comes off in one continuous coil. After this cut, one chip was almost 3 feet long. |
| STAINLESS STEEL (303) WMV Version (1.69 Mb) MPG Version (5.55 Mb) |
3/8" 9.53 mm |
500 | .030" .76 mm |
.060" 1.52 mm |
1/4" Brazed Carbide | No (But coolant is recommended) |
Though often feared, cutting stainless with carbide tools is not all that difficult. |
| TITANIUM
(Normal cut) WMV Version (2.07 Mb) MPG Version (5.17 Mb) |
0.50" 19 mm |
400 | 0.025" .64 mm |
0.500" 1.27 mm |
1/4" HSS | No (But coolant is recommended) |
Carbide tools work well on stainless steel and titanium, but HSS is used here to show it can be done. Smoke means the chips are HOT. |
| TITANIUM
(Heavy Cut) WMV Version (1.07 Mb) MPG Version (2.93 Mb) |
0.40" 10.2 mm |
400 | 0.050" 1.27 mm |
0.100" 2.54 mm |
1/4" HSS | No (But coolant is recommended) |
This is a very heavy cut in a tough material done with High Speed Steel rather than a carbide tool. This is not something you would do every day, but does show the capacity of the machine. CAUTION: Chips can catch fire and burn like magnesium. Clear excess chips from machine often. |
|
HARDENED STEEL
(End Mill Shank) WMV Version (2.12 Mb) MPG Version (5.15 Mb)
|
3/8 Shank (5/16" end mill--very
hard tool steel) 9.53 mm |
2800
(Full speed, and a relatively fast feed rate as well.) |
.010" (.25 mm) |
.020" (.51 mm) |
Ceramic insert in Sherline P/N 2267 holder | No Coolant is never used with ceramic inserts. It will cause them to shatter. |
Note the nice finish this cutter provides. An end mill was used because most people know how hard they are. End mills usually need to be ground rather than machined. Note also the blue color of the chip that came off the part. That means it was HOT! |
| INCONEL
(625) WMV Version (1.91Mb) MPG Version (5.80 Mb) |
.375" 9.53 mm |
300 | .015" .38 mm (A light cut, but a nice finish.) |
.030" .76 mm |
1/4" Brazed tip carbide | No
(But coolant is recommended) |
A real challenge to machine. One of a family of superalloys used in extreme high heat environments like jet engines. Work hardens very easily. Not commonly found in normal applications, but if you can cut this, you can cut about anything. |
Fred Smittle shows what chatter is and then how to eliminate it in the short video clip linked below. (Click on photo to view a larger image.)
Tool chatter occurs when the cutting tool is bouncing off the part and cutting intermittently rather than cutting continuously. The normal reaction upon hearing the screeching or rumbling sound of tool chatter is to back off and take a less aggressive cut. This is exactly the opposite of what it will take to solve the problem and get the tool cutting again. The solution is to either reduce the RPM or feed the cutter into the part at a faster rate—either or both of which will serve to take a larger chip. In the following demonstration, our machinist, Fred Smittle will purposely get the tool to chatter by attempting to take a large cut at too slow a feed rate. Then, without adjusting the RPM, he will simply increase his feed rate by turning the handwheel faster, taking a bigger bite of the spinning part. This will stop the tool chatter and begin cutting a good chip. Remember the rule: "If the tool chatters, DECREASE SPEED and/or INCREASE FEED."
NOTE: The cut shown here is a very large cut. With the right setup, sharp tools and good technique the Sherline lathe can do it, but we do not recommend it for a beginner as there is a chance you could pull the part out of the chuck, jam a tool or damage your equipment until you have more experience. For your test cut to induce and then eliminate chatter, try a depth of cut of about .060".
Video Clips
CLICK HERE for the .WMV (Windows) Version (4.17 Mb file size)
CLICK HERE for the .MPG (Mac or Windows) Version (9.38 Mb file size)
Material: 12L14 Steel; Speed: 700 RPM
Click on this image to enlarge it so you can better see the "chatter marks" on the left-hand side of this piston for a hydraulic scale. This is where the cutter was bouncing off the part and not cutting continuously. Then notice on the right-hand side of the part how the surface looks smooth once the RPM was slowed down and the tool started cutting properly. Chatter is not a problem unique to small machines. This part was made on a large CNC lathe in our factory and is about 1.13" in diameter.
It sounds wrong, doesn't it? How could slowing down the RPM actually increase the amount of metal you remove with a given feed rate? Think about it, though. If you advance the cutter at a given rate at a certain RPM, in one revolution of the part, the cutter will move a certain distance. (The chip will be a certain thickness.) If you cut the RPM in half and advance the cutter at the same rate, the cutter will move twice as far into the material during that one revolution compared to before, making the chip twice as thick. It accomplishes the same thing as turning the handwheel twice as fast while leaving the RPM the same. Either way, you get a bigger bite into the metal and a chip that begins to peel off like paper off a role instead of a half-hearted attempt that just causes the tool to bounce off the material, which is what produces that screeching sound we call "chatter." Experiment with it like Fred did to get a feel for your machine.
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