Well, this weekend I made some significant progress on the knife grinder. In fact, I would have been making sparks and little piles of black dust if it wasn't for a faulty drive shaft. I decided to try making my own drive shaft from a piece of cold-rolled steel that I picked up at the local hardware store. I cut and installed the keyways in each end, installed the shaft on the pillow block bearings and attached the drive wheel and pulley. With much trepidation, I started up the grinder, eager to see how it would run. Everything seemed to work fine, with one exception; there was a significant amount of vibration.
I investigated where the problem was coming from and noticed how the drive shaft was wobbling around. I disassembled the power train and took a good look at the shaft. I rolled it across the table and it seemed to roll fairly smoothly. I set it on a flat surface and rolled it back and forth as I watched for gaps between the shaft and the flat surface. It turns out that the shaft had a wave which oscillated from one end to the other. Apparently the cold-rolled dowel rod from the hardware store isn't very precise. So, with a click of the mouse, I placed an order for a precision manufactured shaft. I had to place an order anyway since I was one piece of steel short that I needed to make the contact wheel arm. The following are a few photos of the build so far:
Here's the grinder after I have attached it to its plywood base. It doesn't look very impressive yet, but it will soon.
A good coat of paint will keep it looking good and keep it from rusting. I debated about what color to paint it for quite a while but finally settled on a dark grey color. I think I made the right choice.
Here are the parts for the flat platen, slack belt, and tool rest attachments after they got a good coat of color.
Here is the grinder completely assembled with the slack belt arm attached. This is right before I fired it up for the first time and before the pain of tracking down the vibration problem began. At least it looks good.
This is where I left off for the day. You can see the on/off switch has been installed to complete the build. The flat platen and tool rest arms have been attached for visual reference.
I had hoped to be finished with the grinder today so I could give it a try with a new knife build next week. But, if the supplier comes through with my order as promised, it should only take an hour or so to get the grinder running when the parts get here. Maybe I'll be making my son's knife next week after all. Thanks for stopping by the Robinson Edge.
- Brandant Robinson
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