Model Engineers’ Workshop – July 2019

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

even considered using telescopic front forks
from an old mountain bike, for the sliding
action.
In the end, I decided to use one fi xed,
horizontal sliding rail exactly parallel to
the baseplate. This was created from some
rectangular steel tube approximately 19mm
x 38mm and 1.5mm thick. This was actually
an imperial measurement tube that was
0.75”x 1.5” and was left over from making a
bed frame.
The actual slide rail is shown in photo 4
and the following features are important.
The swivel point for the chop saw/angle
grinder is the hole in the side of the box
that slides along it. As the centre of the
grinder blade will be forward of this point, it
is necessary for the sliding rail to overhang
the rear of the baseplate if the grinder is
to be able to cut steel to the back edge of
the baseplate. On my machine, the useable
section of the slide rail overhangs the
baseplate by 80mm and the overall length
of the slide rail frame is 425mm. The height
of the top of the slide rail is 120mm above
the baseplate and the pivot point, shown
as an 8mm hole in photo 4 is 140mm above
the baseplate. You will also note that my
MIG welding needs a lot of practice!
I wanted to be able to easily remove

the sliding carriage from the slide rail, if

required, so I constructed the front of the

frame by fi tting an aluminium block into the

front of the rectangular tube as shown in

photo 5 and fi tting a detachable support.

The fi nal slide rail is very rigid and indeed

the whole machine may be carried by using

it as a handle.

Naturally, it is important to ensure that

the slide rail is true to the baseplate when

fi nally fi xed. The size of the sliding carriage

enclosure is 100 x 67mm and is 120mm

long. It was constructed from more of the

aluminium channel that was used to make

the angle grinder cradle. The dimensions of

my sliding mechanism were dictated by the

size of my rectangular tube.

The Sliding Carriage

The sliding carriage was constructed from

a length of 10mm square aluminium tubing

obtained from the local DIY chain, and four

pieces were cut, each 120mm long. Sixteen

budget metal-shielded, deep groove, ball

bearings 4x16x8mm were purchased and

axles were made from 5mm silver steel,

turned down on the lathe to 4mm at the

ends to fi t the 4mm bearings and threaded

for the fi xing nuts. Photograph 6 shows

one side of the carriage assembled, together

with one turned axle and a second axle

assembled with its two ball bearings.

Assembling and adjusting the working

6 7

8

9

Tilting mechanism fi xed to the enclosure

Constructing the sliding carriage Finished sliding carriage assembly

Sliding carriage enclosure