Afternoon in the shop: new table crank for drill press
Posted: Sun Sep 14, 2014 10:54 pm
I have this import drill press with a broken table lift crank (originally plastic). I spent this afternoon making a new crank out of steel and aluminum.
3/4" x 1" steel bar, 1/2" round aluminum, a socket head screw, re-used set screw, and a jam nut.
Handle: Lacking a lathe to turn the handle or even a V-block to clamp the round aluminum stock in the mill vise, I took a chunk of steel and milled a slot to use it as sort of a v-block. Clamped it in the vise with the aluminum rod. Eyeballed center and drilled a recess in the end for the screw head. Swapped to a 1/4" bit and drilled all the way through. Chucked the piece in a drill press and used a file and sanding sponge to soften the edges.
Crank arm: I cut the steel bar to length with an angle grinder, squared up the ends with a roughing mill, and put an angle in the backside with the same mill. Drilled for the handle screw, began tapping... Ah, crudmuffins! broke the tap (got too gorillafied with it and too long between chip-clearings).
Spent the next hour or two ruining punches trying to get the piece of tap out (turns up they're kind of cheap/crappy punches anyway). Eventually fractured the rest of the tap into little pieces and extracted them. Cleaned up the hole and (carefully) continued tapping with another tap. Drilled the big end (I don't have metric bits, so I went 31/64", tiny bit loose but close enough). Used a 1/4" end mill to start a "shelf" to drill for the set screw. Drilled and tapped M6x1 to re-use the setscrew from the old crank.
Having clamped it in a bench vise while hammering that broken tap out, it had some pretty nasty gashes in the sides so I stuck it on a belt sander to clean it up. Went ahead and belt-sanded all sides and softened the corners. Assembled and installed. Works great!
3/4" x 1" steel bar, 1/2" round aluminum, a socket head screw, re-used set screw, and a jam nut.
Handle: Lacking a lathe to turn the handle or even a V-block to clamp the round aluminum stock in the mill vise, I took a chunk of steel and milled a slot to use it as sort of a v-block. Clamped it in the vise with the aluminum rod. Eyeballed center and drilled a recess in the end for the screw head. Swapped to a 1/4" bit and drilled all the way through. Chucked the piece in a drill press and used a file and sanding sponge to soften the edges.
Crank arm: I cut the steel bar to length with an angle grinder, squared up the ends with a roughing mill, and put an angle in the backside with the same mill. Drilled for the handle screw, began tapping... Ah, crudmuffins! broke the tap (got too gorillafied with it and too long between chip-clearings).
Spent the next hour or two ruining punches trying to get the piece of tap out (turns up they're kind of cheap/crappy punches anyway). Eventually fractured the rest of the tap into little pieces and extracted them. Cleaned up the hole and (carefully) continued tapping with another tap. Drilled the big end (I don't have metric bits, so I went 31/64", tiny bit loose but close enough). Used a 1/4" end mill to start a "shelf" to drill for the set screw. Drilled and tapped M6x1 to re-use the setscrew from the old crank.Having clamped it in a bench vise while hammering that broken tap out, it had some pretty nasty gashes in the sides so I stuck it on a belt sander to clean it up. Went ahead and belt-sanded all sides and softened the corners. Assembled and installed. Works great!