Vertical spindle Blanchard-style: Trade Shows & Events

Dear Doc: You don’t write much about vertical spindle Blanchard-style grinding. Why is that?

The Doc replies: I haven’t written much because Blanchard-style grinding drives me nuts. There just aren’t a lot of options to play with when that vertical spindle (solid wheel or segments) plunges down onto workpieces mounted on the rotating magnet.

Having said that, here are some observations and general trends:

1. The effective depth of cut is calculated by plunge velocity in ipm divided by bed rpm. If you’re plunging at 6,000 a minute on a bed rotating at 20 rpm, that’s effective DOC = 0.006/20 = 0.0003″.

2. The wheel/segment is going to develop two tapers: a larger taper on the outside and a smaller taper on the inside. The larger taper height will be about two-thirds the effective depth, and the inside taper will be about one-third the effective depth.

3. The two tapers will converge quickly to a point, which means that your surface finish Ra will be high. That’s why Blanchard-style is considered a stock removal operation, not a high-precision or fine-surface operation.

4. Try to keep the grinding power steady. If your power is increasing gradually, followed by wheel screaming, followed by no screaming, then you’re not self-sharpening your wheel well enough. Increase the grit penetration depth to get better self-sharpening.

5. Increasing the plunge velocity will increase your grit penetration depth.

6. Increasing the plunge velocity will increase your workpiece surface temperature.