Model Engineers’ Workshop – July 2019

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Lathework for Beginners

July 2019

The simple toolpost of a C0 lathe

Standard 4-way toolpost
The basic toolholder supplied with
most lathes is the four way toolpost
shown in photo 2. Tools are placed
in the slots and secured in place,
usually with two or three of the
clamping screws. These toolposts
have the major advantage of being
very rigid. In principle it is possible
to fi t four tools, but in practice this
can prove impractical, depending on
the choice of tool, and oft en they
end up being used with just one or
two tools fi tted most of the time.
Height setting is achieved using
packing – one source of suitable
material is a drink can, cut into strips,
although I prefer to use a single,
slightly thicker piece of aluminium
sheet photo 3. If you use tipped
tools you will probably fi nd that
the same packing will suffi ce for all
the tools of a particular shank size,
but for HSS tools or others, such
as parting tools, that may have
diff erent tip heights it makes sense to keep
the packing with the tool.
Radial adjustment of tools can be
adjusted by rotating the toolpost – useful
if you need to present a tool at an unusual
angle. Oft en, they have a simple ratchet
allowing the toolpost to be repeated turned
to the four diff erent stations so setting

One of Richard Smith’s ‘Prototype’ holders My shop-made QCTP

the tool accurately allows this feature to

speed up tool changing. Most such posts

have an accurately square centre pillar, if

the ratcheting is also accurate you can

align many tools simply by pushing them

against the centre pillar before securing

them in place.

Some small lathes have a simplifi ed

toolpost that just takes one or two

tools, but is otherwise similar to a

four way post, photo 4. Four-way

toolposts with height adjusting ‘boats’

are also available.

Lammas Toolpost

A design that was popular with

hobbyists until relatively recently was

the David Lammas’ design for a three-

way toolpost, fi rst published in Model

Engineer in 1985, fi g. 1. This design

allows three tools to be held with less

interference with each other and the

work than a four way toolpost. The

design also appeared in MEW issue 27,

January/February 1995. Castings for

these are still available on line, but they

can be milled from solid bar or even

fabricated from a ‘sandwich’ of three

pieces at the expense of a little rigidity.

Richard Smith ‘Prototype’

System

It’s worth mentioning this system that

has featured in several articles in MEW over

recent years. It uses oversize toolholders for

carbide inserts that clamp to a central pillar,

photo 5, allowing easy angular adjustment;

a screw allows repeatable height setting.

Quick Change Toolposts

For industry, where time spent changing

The SC4 dedicated quick-change toolpost

Special purpose QCTP toolholders, a knurling/toolholding combined

holder and 000 and 100 parting tool holders

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