Workshop Projects 1
Major Workshop Accessory Projects
Dividing Head (Designed by George Thomas) and Engraving Tool (Hemmingway
design)
I consider this to be one of the finest engineering designs ever produced for
the home workshop. The castings and gears (zero clearance) plus book provide
the maker with a precision dividing head capable of producing any divisions
including all odd numbers. The photo also shows the engraving tool which is
normally used in conjunction with the dividing head.
I
have built a rear stand to accommodate the dividing head direct to the lathe
spindle rather than using the bull wheel gear which in the case of my lathe is
an unfriendly number to work from. Setup time is 1 minute. The Dividing Head is
mounted on a rear support and an expanding mandrel fits from the head into the
lathe spindle. 
It
is not necessary to fix the head to the rear support other than take up any
free movement using the jacking studs. These need only to be taken -up by hand
pressure to remove any rocking of the mounted dividing head. After use, the
rear support can easily be rotated down to enable access to the gear change
cover. I also use the basic head on a base unit on the mill to enable quick
development of square and hex from round sections by transferring the lathe
chuck and work to the dividing head.
This shows the Dividing Head set up on the Mill for cutting a 40 tooth, 40DP
bronze gear which is eventually to be the cam shaft gear in the
'Seal' engine. The gear blank is bored for a taper fit and was then loctited to
a mating taper on a turned mandrel held in the chuck. Later, a little local
heat destroyed the loctite and the gear was separated. The single tool, fly
cutter was made from silver steel using two buttons to form the gear tooth
shape. This cam gear drives two steel 20 tooth gears which were also made using
this setup.
Four Way Tool Post & Rear Tool
Post
I built the Four Way Toolpost designed by George Thomas. This
toolpost is excellent in use and I have found it can repeat position very
accurately. Although the current trend is for the drop on tool holders I prefer
the indexing four way toolpost. After many years of using the lathe I found
that I always seemed to use the same two or three tools to do most jobs. Once
they are packed to height which takes little time they are instantly available
on the index and it takes considerably less time to index the toolpost than
unloading and loading a drop on tool. I have a rear toolpost (see below) which
takes drop on tool holders so the unusual tools are pre-mounted ready for use.
Rear Tool Post
GA Drawing ,- drawings available
on request
There are many designs around for rear tool posts and to be honest most are
much the same. Being a simple, but very convenient tool, I have attempted to
alter many established designs with convenience in mind. The main changes are
the use of a fixed base unit, which comprises a base and pillar onto which
fixes either tool block. The base unit can, of course be removed from the
cross-slide, but even with the short slide it rarely gets in the way. The tool
blocks can be removed in seconds and I have incorporated a socket to the pillar
nut so that one only has to use the chuck key rather than find a spanner - this
saves a lot of time. The tool holders for general square tools, all mounted up
side down, are easily made and do not have to be a perfect fit to the dovetail.
At present I have about ten of these all with tools that I only use
occasionally, such as a radius tool.
This basic design has developed over the years and I now have two
types. One is used only for parting-off work whilst the other for a variety of
turning and boring tools. The parting-off tool post is designed as a solid
block and holds a single 1/8" wide x 3/4" cutter ground for
clearances and mounted upside down. The tool commercially produced so it has
the correct form. This might seem a little thick for a Myford but as the
parting-off cutter is inverted it provides extra rigidity and tool strength.
Parting-off is now one of those tasks which is routine and easy. Rarely do I
find it necessary to reduce speed but care has to be taken to maintain a steady
cut but not too aggressive and no more chatter no problems! The use of suds
helps enormously.
The other rear tool post comprises of a block with a
dovetail tongue to take matching dovetailed tool holders similar to
conventional drop-on tools. The tool holder is adjusted for height location by
a top screw and locked in position on the dovetail joint by two pressure
screws. The main use for this tool holder is for a variety of turning tools. I
have arranged for the tool block fastening bolt to be tightened using the 3 jaw
chuck key which saves time looking for a spanner. When other tools are required
the tool holder is swapped over. This is not a precision tool holder where
positional repeatability is needed but it does the job I want - speed and
convenience.
In both cases the tool block is seated on a base pad plus column (to protect
the slide table) and after use, rotated out of harms way but is always
available when needed. These tool blocks are easy to make out of stock mild
steel and as the cutting tools are inverted they can withstand heavy cutting
forces. My ML7 has the standard length cross-slide table but even so I usually
leave the rear tool block attached. Removal in any event takes but a few
seconds.
Quick Release of Screw Engagement on Lathe
This mechanism is based on an article which was in one of the
ME magazines. I think it was designed by Ken Metcalfe. I modified it so that an
automatic release could be set and added a quick action lever placed to the
right of the saddle. This is a much more convenient place for the release lever
and requires just a slight tap to operate. On the opposite side is the
automatic release which is a small button. I find that this button is very
convenient to operate by using my left hand to release engagement from a screw
cutting task in conjunction with the release of the Screw Cutting Tool (which
in my case requires my right hand to operate).
Essentially a simple design which enables end mills to be sharpened in minutes.
Seen in the photo is the double headed spindle with cup and normal grinding
wheels. This is useful in that the two grinding wheels are available at all
times. The main use for this tool is the sharpening of endmills and small
drills. I have successfully sharpened a number 70 drill! The first accessory is
a jig to hold end mill cutters for sharpening the end teeth. This was designed
by Derek Brooks and was described in the MEW- No. 16 & 17. I have made some
minor changes - the collets are pulled tight rather than using a front
ring.
The second accessory is
a jig to sharpen the side flutes of endmills. This is to my own design and
enables the cutting edge to be retracted away from the grinding wheel surface
on completion of each forward stroke. Without this facility it is impossible to
turn the tool to the next flute without damage to the cutting edge.
Drawing 1,- drawings available
on request
see article describing the design
of this Tool Rest - drawings
available
on request
see article describing the use of
these jigs to re-grind end mills
Boring & Facing Tool (MEW feature design)
Designed by Don Unwin. This was described in detail
including all drawings in the 1991 Aug/Sep edition of MEW pages 8-15. Excellent
design and a very interesting tool to make with the added advantage that it
will be used frequently. This tool has the advantage that the feed can be added
whilst the tool is in motion. By lightly gripping a feed ring the feed is
advanced by audible clicks each representing 0.00125". The photo shows the
tool with a 5/8" dia. shank for fitting on the milling machine. A Myford
spindle shank (to the right of tool) is used in the lathe.
Myford Lathe Alternative Clutch (to my design)
This is such a simple attachment (can be made
in about an hour) and yet provides exactly the same control as the Myford coned
clutch. The design principle utilizes the belt tension lever to operate
engagement. When the lever is relaxed the belt is "held" so that it
is lifted away from the driving pulley and so no wear occurs. Some minor
adjustment can be made to 'hold' the belt by altering the diameter of the front
belt guide. If you inspect the enlarged image it can just be seen that the belt
is lifted out of the pulley 'V' thus even though the countershaft is rotating
no motion is imparted to the belt drive. A small spring is fitted in a pocket
recess at the back of the guide rail which eliminates any vibration noises. I
have operated with the same belt for 20 years!
It is important to switch off the motor before
attempting to change the belt pulley diameters or touch the belt. Although a
limited amount of 'slip' control can be achieved by the tension lever it is not
recommended as this will cause belt wear and friction heat.
drawing 1- drawings available on request
Additional close up details (large
files)
Myford Gearbox
This
gearbox is supplied from Hemmingway (designed by D Machin) as a set of castings
and drawings. Very good design and have used mine constantly for screw cutting
and fine feeds for 15 years. As part of the kit and along with drawings come a
detailed set of construction notes. These are very good and the use of special
jigs (drawings and castings optionally provided) which enabled me to appreciate
a different way of tackling this project. A great deal was learned from this
project.
GA Drawing
- drawings available
on request
I designed this attachment based on the
standard Myford version but instead of the pivot point being centered it is
from either end. The basic principle is following a Sine Bar and a spacer is
used at one end to set the angle of taper. The register points on the table are
10in. apart so the spacers can provide very accurate tapers if made to
0.0001" accuracy.
The lathe must be correctly levelled and
true. The attachment is initially set to turn parallel and then the spacer is
placed at either end (depending on taper direction) and the main slide then
clamped. The significant advantage of this approach is the simplicity of
setting known angles with no dials or witness marks to judge.
First test using a spacer for a Morse 2
taper proved to be spot on when tested in the lathe. A basic set of 7 spacers
provides for angles from 1 to 7 degrees in quarter steps, Morse 2, and standard
taper pin.
I have changed the design for clamping the Cross-slide extension to the jig.
Originally, as shown in the picture (right), the clamping method was by a cap
screw. This method works OK but requires an accurate spacer washer below to
ensure the clamped are is not distorted. The new design does away with the
single large cap screw and spacer washer. A post is now permanently fixed to
the slide and a recess in the top of it provides space for a washer which is
clamped to the arm with 2 small cap screws. This method automatically adjusts
for height and ensures the Arm remains un-distorted. In addition, the Arm is
now attached using an angle piece which fastens to the cross slide table rather
than the back end of the cross slide. This modification enables the Arm to be
secured more easily. See GA Drawing (above pdf file)
Small Drill
- I made this based on the
George Thomas version. The chuck takes up to 5/32" diameter drills but
these are really too big. It is perfect for drilling very small holes
(<3/32" dia.) and allows a sensitive 'feel' to the drilling operation.
The drill head is easily removed to enable the tapping arm to swing round from
the back. This feature ensures tapped holes are perfectly square to the tapping
surface and hopefully reduce tap breakage.
More Workshop Projects
Knurling Tool to fit on ML7 Cross
Slide
Shaper Tool
to fit on Myford ML7
Retractable
Screw Cutting Tool
Drill Grinding
Jig (1/8" - 1/2")
Rotary Table
for Mill
Small
Drill Grinding (< 1/8")
Broaching
Tool
Ball Turning
Jig
All of the above tools
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