on requestDrawing 1, -
drawings available on request
I designed this tool to fit directly onto the lathe saddle.
The tool is considerably heavier section than the normal available items which
fit in the tool post. It can cope with diameters ranging up to 2" and as
small as 1/4". No strain is imposed on the lathe mandrel and the knurl
results produce perfect diamond patterns in minutes. Alternative Knurls can
easily be fitted to give different knurl patterns. This was made from standard
bar stock.
Drawing 1, -
drawings available
on request
There are many engineering
parts that require a keyway slot in them as in the case of a pulley, and making
an accurate slot is not that easy by conventional hand tools. If the slot is
long then the task is much more difficult and trying to achieve this with hand
tools such as a file, will after mainly hours of hard work, result in a slot
which characteristically is oversized, has rounded corners and uneven depth.
The solution is to make a shaper tool which attaches to the lathe cross slide
and by way of design, have the cutter, automatically at lathe centre height.
The design I came up with is basically simple to make and operated by hand. The
main ram is made from mild steel stock round bar and has a dovetail section
with an adjustable gib strip to eliminate slop and wear. The tool is also
graduated for angular requirements. Although the sliding parts are all made
from mild steel this presents no operational problems and of course saves a
great deal of money when compared with castings. So long as adequate
lubrication is made prior to using the tool then I see no reason why it cannot
withstand a lifetime of use and retain the accuracy built into the design. To
ensure the cutter part of the ram is at lathe centre the assembled parts during
manufacture are mounted on the lathe cross slide and a tool bar hole is drilled
and reamed with the drill and reamer held in the lathe chuck thus guaranteeing
the subsequent cutter bar will always be dead on centre height. In the case of
my Myford ML7 the tool is mounted towards the rear of the cross slide and in
use the cutter is advanced in very small increments (0.002"-0.005")
depending on the width of the cutter and depth of the slot to be shaped. A
fairly long operating handle is there to enable the cutting stroke to be made
with little manual effort and so long as the cutting tool edge remains sharp
then shaped corners will be square. For cutting wide keyways (>0.1875")
then it makes sense to use several cutting tools in stages.
The shaper, whilst originally designed, for cutting keyway slots can easily be adapted to other shaping needs both attached to the lathe and other machines.
Drawings to follow...
I think this is such a simple and useful tool
that I can't imagine screw cutting without it. Once again a fabulous design,
much can be learnt about design techniques and attention to detail. This tool
is available as a kit from Hemingway.
This table is
designed and supplied as a kit from Model Engineering Services in Chesterfield.
I built the Dore Westbury Mark 1 milling machine and met Ivan Law at the
'factory' where the kit parts were manufactured. Knowing how good the mill was
I had to try the Rotary table which is an excellent design and relatively easy
to make. Although the table is only 5 inches diameter the table can withstand
heavy cutting forces mainly due to the table tapered bearing seat and mating
worm and wheel. As can be seen the table can also be used in the vertical
plane.
The 'Potts' drill sharpening Jig was designed by G P Potts and
was supplied as a kit of castings and drawing by Woking Precision Models. The
jig is a bit of a challenge to make despite its outward simplicity. Some
adjustment had to be made but thereafter it performs well sharpening drills
accurately. The design of the jig is intriguing and Mr. Potts must have been an
exceptional engineer. The jig is fixed to a 59 degree half angle for the drill
point but the clever bit is the way in which the drill in it's grinding
position is offset from the rotation axis centre. This offset is automatically
set by initially using the drill in a caliper on the jig. The caliper/offset is
a sliding unit set at a 10 degree angle and it is this which alters the amount
of back-off according to the drill size. Every time I use the jig I am in awe
of the apparent simplicity of design and disguised complexity of original
design thought that went into its creation. Whilst many claim to successfully
sharpen small drills with the Jig I prefer another jig of a more basic approach
which works well especially on drills as small as a number 70.
Ball Turning Jig- Assembly
Drawing pdf - drawings available
on request
I built this jig many years ago to make the
handles on the George Thomas Dividing Head. In his Workshop Book he outlines
various types of ball turning jigs and based on a sketch he supplied of an
early design I made a similar jig. The major difference with my version is that
the cutting tool is advanced by it's own slide rather than the lathe cross
slide. This enables the cut to be easily advanced until the finished size is
reached. Also added is a thin metal sheet to protect the cross slide surface. A
feature that appealed to me with this design is that the cutting tool is
located on dead
centre in a conventional manner thus
allowing fairly substantial cuts with no hint of chatter. In operation the jig
is firmly attached to the cross slide so that the fastening bolt enables smooth
rotational movement with some frictional resistance. The centre of the
fastening bolt has a hole drilled in it for a scriber pointer to be temporarily
fitted. This is lined up with the lathe centre and the cross slide is locked.
The pointer is then removed and by moving the saddle the hole is located such
that it is directly under the mid position of the intended ball. The cutting
tool is placed to the best position to cut one half of the ball and then
re-positioned for the other half. Whilst task of resetting the cutting tool may
seem a disadvantage it does allow the optimum cutting faces to the work at all
times and prevents running into the chuck. Blending the two halves is no
problem as the finishing cuts are very small. The ball shown (right) took about
twenty minutes to make. In this case the pre-formed ball blank was loctited to
a shaft for simplicity.
As mentioned in the Potts article I use the rather basic jig for
sharpening small drills. This jig is essentially similar in concept to the
Potts but omits the offset. With very small drills I find that the benefits of
a correct backing-off angle are negligible. The difficult part in using this
jig is the initial setting of the drill position in the collet. I use an
Eclipse collet set with three collets which covers all the small drills. To set
the drill in position I use a setting-jig and a eye loupe magnifier so that the
drill tips are at the correct alignment. Sharpening is done on the Stent Tool
Cutter Grinder since a finer feed into the grinding wheel can be achieved. It
is this feed which is the most difficult since the amount to be ground is in
the region of tenths of a thou. Remarkably, the end result turns out well and
drills are once again useful. In the case of the very small number drills I am
always cautious about the resulting hole size (even with new drills) and where
size matters a test hole is drilled first.
See Article about this Jig and drawings.
This is largely based on the
one designed by George Thomas for the Myford ML7. I have made a few minor
changes as I found it difficult to lock the dial and then loosen it for
adjustment. It now needs only slight tightening to lock. Having worked with the
Myford fixed dial for many years I wonder just how I managed! This is an
essential modification and takes only a few hours to make.
This is a project to build a simple broaching tool to my
own design. Details are described in this
article