Griz G7946 Drill Press Runout

MontanaAardvark

MontanaAardvark

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I've had one of these drill presses for quite a while, and have lived with a lot of runout for that time. The end of a drill bit wobbles a lot. I don't have a good long tool rod, but a 3/8 drill bit as far down as the shank extends (an inch?) below the chuck has 10 mils of TIR.

I thought I'd re-seat the taper, it's a JT-33 taper, but I can't get it out. I was thinking the taper may have had some gunk in it when I set it, and it ended up at an angle. 10 mils seems like a lot even for a no name chuck.

How can I pull the chuck out of the taper? There's no way to go in through the top and tap it out with a hammer, so it's going to end up having to be pulled down at the chuck.

This is possibly a general machining question, but all help appreciated.


Thanks,
Bob
 
I can't see your spindle, but most spindles with Morse taper have slots in them, beyond the end of the inserted taper. You put a 5 to 10º (drift) wedge in the slot and hammer on it to drive out the taper.

Tom
 
Normally you can use a set of wedges to pop the chuck. Of course if your has lock title red on it like I know mine does you will have to heat it. If wedges don't work then you will need to pull the quill and put it in and arbor press. Do an Internet search on removing a Jacobs chuck. There are some very well done acetic all out there.
 
Hmm Never thought of a wedge and trying that. I know I don't have one, but maybe I can cut one on the mill or find one.

I could take pictures and all, but this is a really got start. So thanks T Bredehoft and ARKnack!
 
Hi Bob,

As Tom mentions I am not sure what step you are on.
Most drill presses I've used have a Morse taper socket in the spindle, and a Jacobs taper socket in the back of the chuck.
A double taper stub (male Morse taper on one end and male Jacobs taper on the other) connects the two; like this:
http://www.busybeetools.com/products/arbor-mt2-j6.html

see also the top-right picture here:
https://en.wikipedia.org/wiki/Machine_taper

Are you
1) removing the chuck and double-taper stub from the drill press (separating the Morse taper), or
2) removing the normally Jacobs taper stub from the back of the chuck (separating the Jacobs taper)

Here's a short video for step1):

For step 2) open up the chuck jaws and check for a screw head up the middle of it. It may or may not have one. But beware it may be a left-handed thread (lefty-tighty; righty-loosey).
Also, there are forked wedges that exist to remove the chuck.
I will post back if I can find a link/picture for those...

-brino

update: here's a link to the forked wedges, they are used in pairs to keep the pull straight out:
http://www.amazon.com/Jacobs-Wedge-Set/dp/B00HDTB6MM
 
Last edited:
brino said:
Hi Bob,

As Tom mentions I am not sure what step you are on.
Most drill presses I've used have a Morse taper socket in the spindle, and a Jacobs taper socket in the back of the chuck.
A double taper stub (male Morse taper on one end and male Jacobs taper on the other) connects the two; like this:
http://www.busybeetools.com/products/arbor-mt2-j6.html

see also the top-right picture here:
https://en.wikipedia.org/wiki/Machine_taper

Are you
1) removing the chuck and double-taper stub from the drill press (separating the Morse taper), or
2) removing the normally Jacobs taper stub from the back of the chuck (separating the Jacobs taper)

Here's a short video for step1):

For step 2) open up the chuck jaws and check for a screw head up the middle of it. It may or may not have one. But beware it may be a left-handed thread (lefty-tighty; righty-loosey).
Also, there are forked wedges that exist to remove the chuck.
I will post back if I can find a link/picture for those...

-brino

update: here's a link to the forked wedges, they are used in pairs to keep the pull straight out:
http://www.amazon.com/Jacobs-Wedge-Set/dp/B00HDTB6MM
Click to expand...

Thanks, brino -

This drill doesn't have a slot on the side like the one in the video or as Tom describes. Looking at the exploded parts diagram in my manual, it looks like my chuck must be mounted on the end of a spindle, which ends in a JT33 taper which is then wedged into the chuck. I thought it had a double taper stub like your example, but the diagram in the manual looks like the spindle is a long, straight piece with pressed on bearings farther up. It looks like this:

upload_2015-4-19_22-0-3.png
It appears some forked wedges like your Amazon link would be the ticket.


Bob
 
I have a small drill press that had a burr on the end of its taper which stopped the chuck seating well.

Stuart
 
This is from the Jacob's web site.

http://www.jacobschuck.com/drill-chuck-removal-guide


To remove chucks:

Insert wedges between the back of the chuck and the shoulder of the arbor (Illus. C). In case the mounting taper of the arbor does not provide a shoulder, a cross hole should be drilled through the neck of the arbor (illus. D.) and a cross pin inserted. Then the wedges can be used between the chuck back and the cross pin. If desired, a hole may be drilled through the soft center portion of the chuck body (Illus. D.), and a pin may then be used with an arbor press to force the arbor out of the chuck.

If it is stuck really bad, You may have to drill a hole as shoe in figure D. A hole may already be there, and press it out.
 
if it has the original Chinese chuck, my guess would be that the runout is in the chuck. Buy a decent condition 2nd hand Jacobs (33? or 6A), make sure it's clean and well lubed and I'm sure you'll get rid of the runout. I could send you a battered old 6A that I screwed up servicing that has less TIR (6thou) :)
 
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