A lathe without the accessories would be a fairly useless machine tool. It is the
many accessories that go along with the lathe that expands the uses. This section
on accessories is entitled Tool Holding.
|Two basic types of toolholders are used on engine lathes: the
standard tool post and the quick change tool post (Figure 1).
Figure 1 Standard tool post
|The standard tool post is used in conjunction with high speed steel tooling. This type
of tool post can only be used where cutting forces are kept low because they have a
tendency to move around under heavy cutting pressure. The standard tool post uses a
toolpost clamp screw to hold the tool holder down onto the rocker. The rocker is used to
adjust the tool height to the center of the spindle. The standard tool holders which
accompany this toolpost are shown in Figure 2.
Figure 2 Quick change tool post
Figure 2 Right hand, Straight, and left hand tool holders
|The quick change tool post is used primarily with carbide cutting tools.
The dovetail slide construction of the quick change tool post makes it much faster, more
accurate, and more rigid than a standard tool post.
The quick change tool post uses a
clamp actuated by the large handle you see in Figure 2 to wedge the dovetails on the tool
posts and the tool holders together. There are a wide variety of tool holders which can be
purchased for the quick change tool post (Figure 3). Knurling, boring, cutoff and turning
tool holders are only a few of the different types of tool holders available.
Figure 3 Quick change tool holders
|There are a variety of cutoff and parting tool holders which are associated with both
standard and quick change style toolposts (Figure 4).The tool holders are equipped with a
knurled stud called an adjustment collar. This collar is used to adjust the tool height.
Figure 4 Parting tool holders
|Boring is a very common operation associated with the lathe. In the following
you will see assorted types of boring tool holders.
Figure 5 Light duty boring bar holder
|This type of light duty boring bar holder is used with the standard style
of toolpost. The clamp type boring bar holder shown in Figure 6 is used for heavier type
boring operations. This clamp style of boring bar holder is also used in conjunction with
the standard style of toolpost. Clamp style boring bar holders come in single size and
Figure 6 Clamp style boring bar holder (single size)
Figure 7 Clamp style boring bar holder (adjustable)
|Quick change style boring tool holders create a rigid set up for carbide tooling, but
are not as versatile in their size accommodations as some other types of boring tool
holders (Figure 8).
Figure 8 Quick change boring bar holder
|A self-holding taper has an angle of only 2 or 3 degrees. The tailstock of the lathe
is equipped with a self-holding taper called a Morse taper. The taper shank of a tool with
a Morse taper seats so firmly that there is a large amount of friction to keep the tool
from spinning. There are many lathe accessories available with Morse tapers. The drill
chuck, equipped with a Morse taper, is one of the most common tool holders associated with
the lathe tailstock (Figure 10).
Figure 10 Drill chuck equipped with a Morse taper
|The drill sleeve is another common tool holder associated with the tailstock of the
lathe (Figure 11). The drill sleeve (or just sleeve) is used to increase the diameter of the
tapered shank of the tool to match the size of the tailstock spindle of the lathe. Some of
the more common tools using sleeves are tapered shank drills and tapered shank reamers.
|Tools with taper shanks bigger than the tailstock spindle of the lathe can be
accommodated using a socket (Figure 12). Drill sockets allow you to use large drills and
reams in smaller machines.
Figure 12 Drill socket
|The drill driver provides another method of holding a large taper shank tool in a
tailstock spindle (Figure 13). The drill driver not only holds the tool , but also keeps
the drill from spinning through the use of the drive handle. The drive handle is placed
against the toolpost to absorb the cutting forces.
Figure 13 Drill driver
|There will be times when you will need to ream a hole on the lathe. Because the
tailstock on the lathe is not in a fixed position and the tailstock base is susceptible to
wear, the center of the tailstock spindle is not perfectly aligned with the headstock
spindle. If you try to ream a hole on a lathe and the tailstock and the headstock are not
in perfect alignment, the hole will be cut oversize. By using a floating reamer holder, the
ream will float to the center of the drilled hole (Figure 14)and the hole size produced will be
much more accurate.
Figure 14 Taper shank floating reamer holder