Saturday, August 11, 2018
Refined Baldor 7 Inch Bench Grinder
I've really wanted a nice bench grinder since 2010, when I used the baldor in the high school shop. I bought one nearly two years ago, but didn't get to it until now. I put together a nice belt grinder with VFD, but a belt grinder is just not as refined. Grinding cutters on a quiet and stable bench grinder has to be one of the most relaxing activities.
The Baldor came pretty rough from the factory and I resolved to make it nice. The tool rests were crooked and wobbly, and the wheel flanges/bushings weren't very accurate. The shaft was pretty concentric through, so it was worth fixing. For accurate grinding of drills and cutters, a solid and flat tool rest is helpful. I set mine 1/2" below wheel centerline. I can put spacers beneath the item to be ground to accurately set a grind angle.
I made the rests of 1/2" mild steel using hacksaw and file, and the Taig lathe to mill the slot and drill the screw holes. I machined the bushings all on the Taig lathe.
I used the Oneway balancing kit to balance the wheels. It works alright; the balancing stand is not very sensitive but the flanges are nice and accurate.
You can see it running here.
I set up a fixture for sharpening a drill, and for the first time I split the point on a twist drill effectively. Sharpening drills freehand is a controversial topic because people have such wildly varying ideas of what a twist drill should be able to do.
I've had many US-made machine-sharpened drills which are sharpened worse than I could do by hand. Obviously, machines can do a much better job than I can do freehand too. You basically get what you pay for--a $25 twist drill is bound to be alright.
For accurate drilling in home shop, I like Chicago-Latrobe screw-machine length drills. They have a super crisp split point and their short length can actually take advantage of a rigid setup. They don't tend to make lobed hole during start unlike jobber-length bits (when used without guide clamped to surface).
Next challenge is grinding a brad-point bit for sheet metal :)