Since most of the work on these hones will be in the fixturing and setup, it makes sense to machine more than one hone while you are at it. Each of these three 7075-T6 aluminum blocks will make both halves of one frame for a total of three hones.
The axles are all faced to 32mm long and chamfered slightly on each end. A 90° v-groove 1mm deep is then added to the center of the three main 10mm axles.
Next, six 10mm x 10mm x 10mm cubes are made from steel stock. I had some 416 stainless hardened to HRc35 so I machined the blocks from this as accurately as possible then drilled a clearance hole for the M4 setscrew through centered on one face.
The next task is to square up and size the frame stock to 107mm x 40mm x 32mm. Accuracy is important, but your main goal here is consistency so that each piece of stock will work the same in the various setups.
Here’s how the two frame halves fit into the stock. As you can see, the holes in one half are the mirror image of the holes in the other half. We’ll use this bit of information to cut our setups in half.
I’m starting with the 4mm clearance holes for the anvil retention screws. Move back 8mm from center and 36mm from the end and center drill the first position. Rotate the part 180°, flip it 180°, and spot the second hole. Repeat on the other two blanks.
Move 8mm forward from the center, and repeat the above procedure until you have four holes spotted on each blank.
You can now drill and tap M4 for the main axle setscrew along the centerline and 11mm from the end. Note that there is only one of these holes per blank and you don’t want to drill any deeper than 16-17mm.
Now, flip the block over to work on it’s 40mm side and set your zero on the back edge of the part.
At this point your blanks should look like this. The one side not shown should have the two retention screw holes but not the axle set screw hole.
Next post: sketch and saw
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CAD Files Used On This Page (AutoCAD 2010 Format)