ballen
Diamond
- Joined
- Sep 25, 2011
- Location
- Garbsen, Germany
A few years ago, when I got my first surface grinder, Buck suggested a technique that I now use a lot.
Case in point: I cut a 50 x 400mm strip of 1.2842 (90MnCrV8 or AISI O2 tool steel) from a 10 x 150 x 400mm plate. The plate was ground parallel both sides (Blanchard) but after I cut out the strip, the strip was bowed about 0.3mm (0.012") from internal stress. It needed to be straight, and I'm no good at "heat straightening", so I needed to hog 0.35 mm (0.014") off the strip.
Following Buck's method, I used a 46 open wheel, 25mm wide, plunging straight down along the rear long edge, dropping 2 microns in each traverse, lots of coolant. When I reach full depth of 0.35mm, I then crossfed across the part, about 0.2mm per pass, pushing the part directly into the wheel. This breaks down the front corner of the wheel, but puts enough pressure on it that it doesn't tend to clog up. Then, when I got to the front of the part, I downfeed a few microns, and then crossfeed back full width in the other direction. That's it: one plunge and two crossfeeds, finished.
The point is that the front corner of the wheel gets all of the abuse from the roughing, and the rear corner of the wheel is kept in good shape for the finishing pass.
Is this a standard technique? You beat up one corner of the wheel for roughing, and baby the other corner for finishing?
Case in point: I cut a 50 x 400mm strip of 1.2842 (90MnCrV8 or AISI O2 tool steel) from a 10 x 150 x 400mm plate. The plate was ground parallel both sides (Blanchard) but after I cut out the strip, the strip was bowed about 0.3mm (0.012") from internal stress. It needed to be straight, and I'm no good at "heat straightening", so I needed to hog 0.35 mm (0.014") off the strip.
Following Buck's method, I used a 46 open wheel, 25mm wide, plunging straight down along the rear long edge, dropping 2 microns in each traverse, lots of coolant. When I reach full depth of 0.35mm, I then crossfed across the part, about 0.2mm per pass, pushing the part directly into the wheel. This breaks down the front corner of the wheel, but puts enough pressure on it that it doesn't tend to clog up. Then, when I got to the front of the part, I downfeed a few microns, and then crossfeed back full width in the other direction. That's it: one plunge and two crossfeeds, finished.
The point is that the front corner of the wheel gets all of the abuse from the roughing, and the rear corner of the wheel is kept in good shape for the finishing pass.
Is this a standard technique? You beat up one corner of the wheel for roughing, and baby the other corner for finishing?