Model Engineers’ Workshop – July 2019

42 http://www.model-engineer.co.uk Model Engineers’ Workshop

and setting tools is literally lost money,
it is not surprising that various systems
of quick-change toolpost have been
developed. These allow tooling to be set up
once and swapped in and out in moments.
Increasingly hobbyists are using QCTPs
in their workshops because not only are
they convenient and effi cient, they can
make doing runs of repetitive work vastly
less boring and more pleasant. Don’t we all
prefer to spend our time cutting metal than
swapping tools?
Several years ago, I made my own QCTP
for my mini lathe, photo 6, together with
a dozen or so holders for a range of uses
(MEW 197, December 2012 and 198, January
2013). Since then my only regret has been
that I didn’t make enough toolholders!
I was given the opportunity to try some
diff erent types of QCTP on the C4 lathe.
There is a toolpost designed specifi cally
for the SC4 that uses an ‘inverse wedge’
draw-in system, photo 7. This looks rather
diff erent from the well-known Dickson
toolpost system but has a similar working
principle but with a simplifi ed geometry. The
SC4 system only has one type of toolholder
available, but this is suitable for both round
and square-shank tooling.
It comes with a replacement pillar suitable
for the SC4 lathe. This tool post requires an
allen key for locking and only has a single
position for holders, so you have to rotate
it for some operations. It works well, and its
low height gives good view of the work. I
had to experiment with diff erent thickness

washers to get the (original SC4) toolpost

clamp handle to point in the right direction.

I also was able to try out the ‘Model XXX’

toolposts. These are available in three

sizes, 000, 100/111 and 200/222. These are

much taller toolposts with two positions

for ordinary dovetail toolholders and a

ball ended lever providing either wedge or

piston locking.

My fi rst impression of these toolposts is

that they have a better level of fi nish and

feel very smooth in operation, however,

they are much bulkier. They also have

a wider range of toolholders available

including boring tool and knurling holders,

photo 8. See my comment later about the

100 version and SC4.

The Model 000 toolpost is small wedge-

locking toolpost, suitable for lathes of about

3 ½” centre height such as mini-lathes,

photo 9, and Myford 7-series lathes. It will

fi t on a C4 lathe, but its toolholders are too

small for some tooling appropriate to the

larger lathe and its position back from the

edge of the top slide means tools have to

be overhung. Its dimensions are very similar

to my shop-made QCTP for my mini-lathe,

although the dovetails are approximately

3mm wider. In all likelihood I will modify my

shop-made toolholders to work with the

000 toolpost and keep it on my mini lathe.

The Model 100 Toolpost is a piston-lock

toolpost for 4”- 5” centre height lathes, like

the SC4, photo 10 The Model 111 Toolpost

is a wedge-locking version with the same

overall dimensions that also takes Model

100 toolholders. Again, these are very well

fi nished. Whether you prefer the piston-type

or the wedge type toolpost is very much a

choice of personal preference. Having tried

both they are equally secure and pleasant

to use. I have a marginal preference for the

wedge type as when loosened the dovetail

becomes ‘smaller’ making it marginally easier

to drop a diff erent holder in place.

As supplied the original Model 100/111

toolposts required two modifi cations to

work with the SC4, photo 11. The fi rst of

these was to turn down the end of the

supplied fi xing pillar and screwcutting the

end M12 to match the SC4 topslide. The

second problem was that the supplied

toolholders have bottom lip 11mm thick,

thicker than the base of the SC4’s standard

toolpost so I could not use 10mm shank

tools. I solved this situation by bandsawing a

3mm slice off the bottom of the toolholders

Model 000 toolpost fi tted to a mini lathe (the lathe has a 100mm
chuck fi tted, which makes the QCTP look smaller than it really is). Model 100 toolpost with piston clamping fi tted to SC4 lathe

Model 111 wedge-lock toolpost, with the
original 4-way behind

New pillar to fi t 1XX toolposts to an SC4

lathe, lying down is the original Model 1XX

pillar modifi ed to have an M12 thread.

Model 100 slim toolholder with reduced base

thickness

Inserted tip boring bar with fl ats

9 10

11 12 13

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