Clamp Style Knurling Tool
I made this clamp style knurling tool originally to fit a tool post on my Sherline lathe but it works in the quick change tool post on my new 7x lathe as well. I based this on a few different designs I found online. I felt the clamp style tool was best for my small machines since they don't have the rigidity of larger lathes. I can see a little bit of flexing in the tool when I'm knurling, but the wheels still track properly and the quality of the knurls hasn't suffered. If I remake this tool, I will consider using steel and/or a solid body to eliminate the flexing. You can click on the pictures to view larger images.
There are a few key design considerations: - The length of the arms and the placement of adjuster shafts determine how large the part diameter can be. I didn't draw the complete design in AutoCad, but I did use it to determine the arm lengths. This tool is capable of about a 2.5" diameter. - The bar that is clamped in a tool post must be sized to mimic a tool bit, unless you have an adjustable height tool post (i.e. QCTP). The bar in this design is 0.25" tall and the top sits at the center line of the lathe, since the Sherline lathe uses 1/4" tools. - The adjuster shafts need to be able to rotate in the arms, but should be as tight as possible to eliminate flexing in the tool. - The length of the wheel bushings should be a few thousandths longer than the width of the wheel. I learned this when the first bushings I made were too short. I couldn't tighten the screws all the way without pinching the wheels, and they rotated loose during use. With the longer bushings, the screw clamps them to the arms so the wheels rotate on the bushings instead of with them, so there is no twist on the screw. You also don't want the bushings to be too long, since that will allow the wheels to move along the length of the axle and they may not track correctly. |