Hi Guys,
I've not been totally idle for the past few weeks ! Apart from working on my van/rv conversion, I had the need to replace my old parting off toolpost. Since I could only part off 12 mm diameter with it and the need arose to be able to part off 1 inch diameter material. I happened to have a nice 1/16" inch by 3/4" inch parting off blade so I thought that I would press it into service.
I obtained a 120 mm length of 50 mm diameter bar and machined three flats on it. Using these flats I milled one end to create the key that fits into the slots on the Myford cross slide. I cheated a little and used the original clamp bar from the old toolpost, just cutting a short length of M8 all thread to suit the hight of the new toolpost.
Then carefully measuring the centre hight I machined a 3 mm deep by 22 mm wide groove across the left hand face, looking from the front of the lathe. Then I drilled two holes right through the bar with M4 clearance holes, setting the hole centres 4 mm from the top edge of the groove and 30 mm apart. Using these two holes as pilots I drilled them out 10 mm diameter with a ten degree taper 20 mm deep so that the top of the tapers broke into the machined groove by two mm. The idea being that the tapers would grab the top of the parting blade and secure it in place. In hindsight one millimetre would have been plenty. I used a 10 degree dovetail cutter to create a taper on the bottom edge of the groove and to accurately set the tool hight so that it was a couple of thou below centre hight.
I turned two tapered studs with M4 threaded shafts from silver steel, so that they would sit a few mm above the surface of the bar and the taper would grip the top edge of the parting off blade locking it into the groove.
The photographs show the various bits and pieces. I didn't take any pictures of the actual machining, mainly because of its experimental nature.
But it works and works very well. Certainly better than I expected. It makes parting off a breeze, The last picture is one of the makers details of the parting off blade.
I've not been totally idle for the past few weeks ! Apart from working on my van/rv conversion, I had the need to replace my old parting off toolpost. Since I could only part off 12 mm diameter with it and the need arose to be able to part off 1 inch diameter material. I happened to have a nice 1/16" inch by 3/4" inch parting off blade so I thought that I would press it into service.
I obtained a 120 mm length of 50 mm diameter bar and machined three flats on it. Using these flats I milled one end to create the key that fits into the slots on the Myford cross slide. I cheated a little and used the original clamp bar from the old toolpost, just cutting a short length of M8 all thread to suit the hight of the new toolpost.
Then carefully measuring the centre hight I machined a 3 mm deep by 22 mm wide groove across the left hand face, looking from the front of the lathe. Then I drilled two holes right through the bar with M4 clearance holes, setting the hole centres 4 mm from the top edge of the groove and 30 mm apart. Using these two holes as pilots I drilled them out 10 mm diameter with a ten degree taper 20 mm deep so that the top of the tapers broke into the machined groove by two mm. The idea being that the tapers would grab the top of the parting blade and secure it in place. In hindsight one millimetre would have been plenty. I used a 10 degree dovetail cutter to create a taper on the bottom edge of the groove and to accurately set the tool hight so that it was a couple of thou below centre hight.
I turned two tapered studs with M4 threaded shafts from silver steel, so that they would sit a few mm above the surface of the bar and the taper would grip the top edge of the parting off blade locking it into the groove.
The photographs show the various bits and pieces. I didn't take any pictures of the actual machining, mainly because of its experimental nature.
But it works and works very well. Certainly better than I expected. It makes parting off a breeze, The last picture is one of the makers details of the parting off blade.
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