Drill press problems

[jaysonb]

I have a 12" delta bench top drill press. I was redrilling a hole in a metal plate today to make it a little bit bigger,I guess the hole wasn't lined up perfect and the bit bound up, so I just tryed to go slower but it bound up again, but this time the bit , and the chuck stayed with the metal plate!!! My question is how is the chuck held on to the drill press? There is no threads, no keyway, I see that the shaft has a small taper to it, but nothing else. Thanks for the help guys.

 

[cranky]

on the drill i use it has a tapor to get it to stay in slide the chuck in with no bit in, then put some wood between chuck and bench and push down on it pretty hard then the chuck stays in mine. not sure if thats the proper way to do but its wat i alwayd do. and i do alot because some off the bigger drill bits i use go into a sleeve the into drill hope that helps

 

[Major Ramifications]

Be sure to clean both the male and female tapers with brake cleaner to remove any trace of oil. Then do the wood thing or tap it in with a urethane deadblow hammer or similar.

 

[DocsMachine]

That's called a Jacobs Taper. And since the force of drilling always pushes in a direction which presses the taper together, it works quite well.

The problem is, the tapers (both male and female) have to be ground fairly precisely; if they're slightly off angles, or the surfaces are rougher than they should be, you lose holding power. And, no offense, but the cheap import tools are pretty notorious for poor machining.

As noted, to reinstall, all you need to do is basically press the chuck back on the spindle. But before doing so, first make sure they're clean- not just free of oil but also grit and debris, and check them closely for any nicks, spin marks, or dings.

If you find a mark or nick, lightly stone it off, then clean both halves with solvent (the aforementioned brake cleaner works fine) then just use the quill and a block of wood to press them back together.

Doc.

 

[jaysonb]

Thanks again Guys!!!!

 

[Kirbot]

You got your answer, but I just wanted to reinforce what Major Ramifications said.
If you don't happan to have any brake cleaner, carb cleaner or even 100% alcohol would do the job.

Both tapers must be absolutely CLEAN.

 

[larry_g]

I agree with all above. I would like to say that when you said

I guess the hole wasn't lined up perfect and the bit bound up

The ears picked up. Side loading the JT33 will a lot of times disengage the taper. This is why milling or running drum sanders in a drill press will cause the chuck to fall off. As Doc said they work well withstanding the drilling forces, but sideload and they fail.

lg
no neat sig line

 

[hilld]

Some chucks have a screw in the center, to check open the chuck all the way and look up in there with a small flash light (mirror might help), if there is a screw take that out first, then pry off the taper.