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here's the latest addition to my model engineering workshop, the Myford Super 7 screwcutting Lathe,(manufactured around 1960) 3.5 inch centre height 19/20 inch between centres, 14 speeds of: 27, 39, 54, 77, 95, 135, 210, 300, 420, 600, 740, 1050,1480 and 2105 rpm, 3/4 hp single phase brooke crompton motor, with a Dewhurst reversing switch, all super 7s are fitted standard with a clutch unit and larger cross slide table which is slightly longer than the standard ML7 table, this particular lathe is the older model with the oil window on the front main spindle bearing, Myford changed this setup in the 1960's as this particular oil feed design proved too expensive to incorporate in the manufacture so the new wick feed type was and still is incorporated in the design of all their new lathes.
to give some sort of idea of measurement that we the model engineers work to:- a human hair measures 3 thousands of an inch, model engineers are cabable of working to 10ths of a thousands of an inch, thats an accuracy to 1/10th of a thousand of an inch, but only if the machine accuracy is upto it!
Machine light.
12 volt low voltage
A machine light was made from some scrap 1" x 1" hollow square section mild steel, I milled the ends out (saved a lot of hacksaw work) and drilled for the knuckle bolts (M6), a 240v fused light on/off switch was fitted and a swivel base was made to fit the switch box, a 12 volt car headlamp bulb and connector was used in line with a 12 volt supply from a mains converter, the lamp swivells in all directions and has a piece of heat resistant glass as to stop any coolant fluid splashing onto the bulb
Homemade lathe raising/leveling blocks.
2 inch washer under lathe feet
M8 bolt x 4" long
or M8 threaded bar
Lathe
leveling nut
M8 threaded bar with 2 nuts or a nut and bolt
4 x 60mm x 35mm (mild steel) bored on underside to accept locking bolt.
tray and stand
Homemade 4 way tool post.
first, you need some steel!! just like this! this is a 1 1/2" thick mild steel ship's plate, measured and marked out at 2.75" sq and placed on the 4 x 6 bandsaw.
I would have used my junior hacksaw but I run out of blades! yeh right!
the bandsaw cuts tolerances to within 2-3 thou over a 4 inch depth, a long time was spent setting up the bandsaw to do just this, (see the bandsaw page) the job then placed on to the lathe and fitted into the self centering 4 jaw chuck,(if the job had not cut accurately in the bandsaw then it would have been placed into an independent 4 jaw chuck) to be trued up on all six faces and very accurately centre drilled to accept the tool post bolt. The photo shows the job just after the roughing out stage so a number of tooling marks can be seen on the work piece faces, these tooling marks are completely removed by the finishing cuts. The chuck body itself is not rusty, although the photo would look to show otherwise, this is just mucky dust from the roughing out stage.
all trued up and ready for the milling machine to hog out the central section, this is where the cutting tool will sit, the cut will be 1/2" wide x 1/2" deep i do have the cutters to hog the steel out in one pass but they may need to be sharpened first, not to worry as I have plenty of smaller cutters that can maybe do this cut in several passes.
this is the first stage, to line the vice jaws to run parallel with the table and cutter, doing this is time well spent if a good neat accurate job is required. mill vice should be set up to within 2/10ths of a thousands of an inch.
placing the work piece into the milling vice with a round bar at the forward jaw takes any vertical error away from the vice, I know the rear jaw is true to vertical so this is a method of eliminating any vertical error when the jaws are tightened, a dial test indicator is set to the job on both axis for a true cut.
the dti should have no run out in either axis
starting the cut: fast back gear, slow feed rate, and plenty of coolant to the cutting edges of the cutting tool, if the speeds were wrong the cutting tool would let you know by producing sparks and being noisey, a nice cutting sound should be heard.
the cutting speed looks to be lot higher than it actually is, the cutter is only turning at around 200 rpm
just 3 more sides to be cut out at the same diam & depth then it's placed in the drilling machine for the lathe tool clamping screw holes to be drilled out and tapped to an m6 thread.
The 4 way tool block was marked out and drilled with a 5mm drill to accept the M6 tap, then placed into the converted cheap drill tapping machine for the first stage of tapping the threads.
The converted drill makes good use as a tapping machine, the tap enters the pre- drilled hole pretty square(a lot more sq than by hand) and so saves on the tap breaking.
Just enough threads are put into the drilled hole on the tapping machine, then the job is transfered into the bench vice for the final stages of the threading, by doing this it gives a lot more control over the tapping process.
note the tin of WD40, this is what was used to lubricate and help the tap cut its threads, special tapping lubricants can be bought at a price! but to be honest I personally have not experienced any problems while using this oil as a tapping fluid.
All done and dusted, fitted with the M6 hex bolts, a few more pictures below.
This sort of tool post is pretty outdated, there are newer types which are a lot more versitile but at a price, this homemade 4 way tool post will serve the purpose for now.
I have had quite a few emails from fellow model engineers asking how I built the coolant system, I will go into detail about this as soon as I have taken the relevent photo's.
