11-27-2016, 11:57 AM
I dug through the old photos and found this one showing both the the circle-cutter and the shield I talked about above.
You can see the shoulder of the cutting tool that bound in the cut above the machined portion at the bottom. I don’t know if I had the tool this far extended, but the shoulder was definitely below the bottom surface of the central hub. If I’d kept it above, then the central hub would have bottomed first, but the cut would only have been about 5/8” deep. I’ve chosen to use a cutter similar to the one in Steve N’s picture since then.
The shield is just a flat sheet of polycarbonate in front of the cutter. It does not absolutely prevent me from reaching around and getting my fingers in the way, but it makes it difficult and awkward to do so. You can’t move your hand there instinctively.
At the time I made it, about 8 years ago, I considered instead making a semi-cylindrical PC shield along the lines of one described by Nagyszalansky in his Taunton “Jigs and Fixtures” book. I think his approach might be safer in principle, more difficult to reach around, but I thought the downside might be filling the limited volume around the cutter with chips.
I opted to make more of a reminder, not an impenetrable barrier, with more space for chips to spread out during a cut. I have not seen a need to go back and revisit the semi-circular design.
You can see the shoulder of the cutting tool that bound in the cut above the machined portion at the bottom. I don’t know if I had the tool this far extended, but the shoulder was definitely below the bottom surface of the central hub. If I’d kept it above, then the central hub would have bottomed first, but the cut would only have been about 5/8” deep. I’ve chosen to use a cutter similar to the one in Steve N’s picture since then.
The shield is just a flat sheet of polycarbonate in front of the cutter. It does not absolutely prevent me from reaching around and getting my fingers in the way, but it makes it difficult and awkward to do so. You can’t move your hand there instinctively.
At the time I made it, about 8 years ago, I considered instead making a semi-cylindrical PC shield along the lines of one described by Nagyszalansky in his Taunton “Jigs and Fixtures” book. I think his approach might be safer in principle, more difficult to reach around, but I thought the downside might be filling the limited volume around the cutter with chips.
I opted to make more of a reminder, not an impenetrable barrier, with more space for chips to spread out during a cut. I have not seen a need to go back and revisit the semi-circular design.