I drilled a 5/8" hole through 1/4" wall steel tubing today, and the drill caught while penetrating the second wall. The chuck stopped, but the motor kept going. Later with the belt guard open I found that the splined shaft that travels up and down was able to turn relative to the stepped pulley. There is a nut at the top of the pulley through which the splined shaft runs, and it was finger loose. Playing with it a little I found that it has a lefthand thread, and tightening it as hard as I could with greasy fingers got the chuck and pulleys much more firmly linked together by hand feel.
What am I supposed to do with that nut? Do I tighten it with a wrench as tight as I can while holding the pulley by hand, figuring that it coming loose was a malfunction? Or is it supposed to adjust some sort of slip clutch, for safety or something?
By the way, I did already pull the chuck off the Jacobs taper on the arbor, when the drill bit caught passing through the first wall. I’m surprised, as I’ve been using the drill press for months, though not that heavily and never for this big a bit. I wiped down both parts with acetone/toluene mix, and heated the chuck to 50 C, and sprayed the arbor with freezing spray, and pushed them together firmly by hand. I guess this mounting with a temperature difference was much stronger, as it got something else to come loose on that second wall.
I don’t know about drill presses large enough to have a taper, but milling machines frequently have a nut on top to pull on a rod that threads into the taper, and so have the same problem. In my experience, they have either a brake lever (used for other braking needs as well), or for smaller mills a hole drilled in the side of the housing so that you can insert a rod. The rod fits into a hole or spline on the shaft to lock it while tightening the nut. I don’t suppose you have either of those?
On those milling machines, you use a wrench to tighten the draw bar into the collet (while holding the brake), but you are definitely not supposed to wrench it “as tight as you can”.
Got a picture or model # of press? I’m having a hard time picturing where the nut is/is on. Is the splined shaft the spindle shaft around which a splined pulley is placed allowing the spindle shaft to move vertically through the pulley? If so I’d expect some kind of retainer to keep the pulley in line with the drive but not a nut.
The last part makes it sound like the you were slipping between the chucks male taper and the spindle.
Is it a Morse taper machine with a jacobs taper arbor to hold a jacobs chuck or something like that?
This is a Shop Fox W1680 drill press. There’s a manual here:
On Page 24 is an exploded view. The nut in question is 75, “PULLEY NUT”. Looking at the drawing makes me think the nut is pulling the pulley (76, “SPINDLE PULLEY”) down onto a tapered body (77, “INSERT PULLEY”). I’m wondering more specifically if the nut is supposed to be as tight as I can get it so that the pulley cannot slip on this taper, or, is slippage on that taper a safety feature? If I’m picturing everything correctly, torque on the pulley is trying to loosen that nut, which is an odd design choice (especially considering the extra trouble to put left-handed threads there, which I did just go and confirm). So, the idea that it’s a safety feature makes a little more sense.
“Is the splined shaft the spindle shaft around which a splined pulley is placed allowing the spindle shaft to move vertically through the pulley?” Yes. This shaft is 89 “SPINDLE” in the drawing.
“The last part makes it sound like the you were slipping between the chucks male taper and the spindle […] a Morse taper machine with a jacobs taper arbor to hold a jacobs chuck”
I was slipping between the chuck’s female Jacobs taper and the male Jacobs taper on the arbor, and indeed the chuck actually dropped into the work, exposing the male Jacobs taper on the arbor. The arbor’s other end is a male Morse taper that goes up into the female Morse taper of the machine, and this connection held.
I would expect it to needs to be snug. Maybe wrench tight with an easy hand. I wouldn’t expect a taper locked pulley to slip by design. But I could see wanting something to slip, maybe the belts.
The left hand nut would tend to tighten itself on initial startup, or at least not fly off and away, since the thing is starting in right hand rotation.