08-14-2010, 08:07 PM
Long post warning.
While paint is drying, I started cleaning up the bench and workspace because I'll be working with mostly clean stuff from here on out. So I thought.
Ughh... there's that chuck that has been soaking in mineral spirits ever since the night I popped it off the spindle. It has been absolutely frozen solid, I mean won't budge even the slightest bit, with the jaws completely recessed. In order to see if it can be restored, I HAVE to get the jaws to move, because the outer sleeve can't come off unless the jaws are moved towards their outwards, or closed, position. If they won't move from fully open, I'll have to cut off the outer sleeve and replace it with one from a previous parts chuck that was sacrificed a long time ago. My actual backup plan, rather than put a makeshift chuck on this drill press, was to repurpose another good one that I recently picked up on *bay for pocket change because it was mislabeled and nobody else seemed to notice or bid. Then I would work on this one later.
But before going that route, I wanted to see what could come of this one with a little effort. I've been picking it out of its MS bath every few days and fiddling with it to see if it would break loose at all. Today, I finally went after it with more force and some tools, in combination with a chuck key. BTW, repeating something I said way back earlier, a guy has a great website about Jacobs chucks that I go back and visit every time I work on one of these.
http://www.beautifuliron.com/jacobs.htm
Back and forth, a little more pressure each time, what's this... movement? A couple more tries... half an inch of rotation. Ok, now we have some potential for the first time yet with this thing. A few minutes later and it has come all the way closed. Good news, because I know what do from here, although I don't know what I'll find when I get it apart. The last one I took apart was found to have broken teeth up and down one of the jaws, which are completely unusable.
The process for cleaning or repairing one of these chucks is to nearly close the chuck jaws, press off the outer sleeve, remove the split nut, pull or punch out the jaws, clean everything up, and put it back together in the reverse order.
Time to get out my little arbor press to remove the sleeve. You only have to move the sleeve about half an inch to break the press fit, then it slips off (with some fiddling) the rest of the way by hand. A tip from the OWWM guys after I posted this makes a lot of sense and is something I'll do from now on... slip a pipe fitting or something similar around the jaws so that you press directly on the chuck body rather than on the jaws themselves. I close the jaws all the way as shown below so that they can support each other and provide some stress relief when pressing on them. That would not be needed if using a round tube to avoid pressing on them in the first place.
You may have to spin the sleeve around to some particular location, I've never really figured that part out, and it will eventually slip off. The split nut will probably fall off at this point, but the jaws aren't likely to go anywhere.
The jaws usually need a little prompting to come out of the main body, which means a small punch. These happen to pull out by hand, most likely because they've been soaking in MS for two weeks. Once they're out, the chuck is apart... seven total parts: the sleeve, both halves of the split nut, the three jaws, and the main body.
A quick inspection shows that the split nut appears to be intact and the jaw teeth are all there. That's good news, but we won't know for sure until they're cleaned up on the wire wheel. After cleaning, the jaws appear to be in surprisingly good condition.
If you look closely at the second photo above, you'll notice slight differences in the jaw teeth from left to right. Specifically, look at the first step/tooth up from the solid jaw. These matter, because they are required to go into the main body in a certain orientation to each other so that the split nut will line up everything correctly. On the main body, where the jaws are inserted, there are numbers 1, 2, and 3 stamped respectively. I've lined up the three jaws above accordingly. Slot #1 gets the jaw that has a little half first tooth, slot #2 gets the jaw with the full tooth, and slot #3 gets the jaw with no first tooth. The "beautiful iron" site that I linked to above has a nice discussion about these.
Anyways, the parts all clean up nicely.
The jaws slip into their respective slots, tooth-side facing outwards. At this point, each jaw should smoothly slide its full length of travel in and out relatively easily by hand. If it sticks, catches, or binds, spend some time cleaning or troubleshooting the bore or the jaw, because it isn't going to get any better on its own once it's back together.
And now, one of the trickiest steps of all... orienting the jaws to install the split nut. The split nut is machined as a single piece and fitted to the jaw design as I described above. Then it is literally split in half, roughly, to be able to go onto the jaws and into the channel on the main body. Installing this thing takes some trial and error pretty much every time.
The first problem is that the jaws slide up and down on their own when you'd really like them to stay in one place... aligned with one another if possible. Second, when you put the first half of split nut on one or more of the jaws, it's going to intersect with the jaw teeth and move that jaw. After some fiddling, you eventually get what will feel and look like a good fit.
Once you have one half in place, don't lose your grip on that half and that jaw (or jaws). Carefully slip the other side of the split nut into place, making sure that the bottoms of the jaws are all lined up properly. At this point, holding tight to both sides of the split nut, you should be able spin the assembly and watch the jaws move in and out. Drop it, though, and you have to start over.
Carefully slide the outer sleeve back over the assembly, without anything moving, until it gets a slight grip internally on the split nut.
Back to the arbor press to press the sleeve back into place. There is one bit to pay attention to here, and that is how far to press the sleeve back on. Not quite far enough and you can't get a chuck key into place, too far and the chuck key will slip. After pressing to make sure there's a solid bite, I sort of gradually work my way to the proper depth and check it with a key a couple times as I go. Once the key slips in smoothly but tightly, that's it.
Run the chuck open and closed a few times, and this one turns out to be as flawless (knock on wood) and smooth as any that I've ever had apart. There is a little bit of external pitting on the exposed portions of the main body, but that's cosmetic only. The chuck itself appears to be pretty darn good, considering its original condition. To be honest, that's a big and pleasant surprise... I had pretty well assumed this thing had little chance of surviving for use, and was figuring at best I might be able to salvage the jaws and/or split nut for parts another time. Turns out to be as good or better than any I have in use on other machines.
Total time from start to finish, a bit less than 90 minutes, and one of the biggest pleasant surprises so far.
While paint is drying, I started cleaning up the bench and workspace because I'll be working with mostly clean stuff from here on out. So I thought.
Ughh... there's that chuck that has been soaking in mineral spirits ever since the night I popped it off the spindle. It has been absolutely frozen solid, I mean won't budge even the slightest bit, with the jaws completely recessed. In order to see if it can be restored, I HAVE to get the jaws to move, because the outer sleeve can't come off unless the jaws are moved towards their outwards, or closed, position. If they won't move from fully open, I'll have to cut off the outer sleeve and replace it with one from a previous parts chuck that was sacrificed a long time ago. My actual backup plan, rather than put a makeshift chuck on this drill press, was to repurpose another good one that I recently picked up on *bay for pocket change because it was mislabeled and nobody else seemed to notice or bid. Then I would work on this one later.
But before going that route, I wanted to see what could come of this one with a little effort. I've been picking it out of its MS bath every few days and fiddling with it to see if it would break loose at all. Today, I finally went after it with more force and some tools, in combination with a chuck key. BTW, repeating something I said way back earlier, a guy has a great website about Jacobs chucks that I go back and visit every time I work on one of these.
http://www.beautifuliron.com/jacobs.htm
Back and forth, a little more pressure each time, what's this... movement? A couple more tries... half an inch of rotation. Ok, now we have some potential for the first time yet with this thing. A few minutes later and it has come all the way closed. Good news, because I know what do from here, although I don't know what I'll find when I get it apart. The last one I took apart was found to have broken teeth up and down one of the jaws, which are completely unusable.
The process for cleaning or repairing one of these chucks is to nearly close the chuck jaws, press off the outer sleeve, remove the split nut, pull or punch out the jaws, clean everything up, and put it back together in the reverse order.
Time to get out my little arbor press to remove the sleeve. You only have to move the sleeve about half an inch to break the press fit, then it slips off (with some fiddling) the rest of the way by hand. A tip from the OWWM guys after I posted this makes a lot of sense and is something I'll do from now on... slip a pipe fitting or something similar around the jaws so that you press directly on the chuck body rather than on the jaws themselves. I close the jaws all the way as shown below so that they can support each other and provide some stress relief when pressing on them. That would not be needed if using a round tube to avoid pressing on them in the first place.
You may have to spin the sleeve around to some particular location, I've never really figured that part out, and it will eventually slip off. The split nut will probably fall off at this point, but the jaws aren't likely to go anywhere.
The jaws usually need a little prompting to come out of the main body, which means a small punch. These happen to pull out by hand, most likely because they've been soaking in MS for two weeks. Once they're out, the chuck is apart... seven total parts: the sleeve, both halves of the split nut, the three jaws, and the main body.
A quick inspection shows that the split nut appears to be intact and the jaw teeth are all there. That's good news, but we won't know for sure until they're cleaned up on the wire wheel. After cleaning, the jaws appear to be in surprisingly good condition.
If you look closely at the second photo above, you'll notice slight differences in the jaw teeth from left to right. Specifically, look at the first step/tooth up from the solid jaw. These matter, because they are required to go into the main body in a certain orientation to each other so that the split nut will line up everything correctly. On the main body, where the jaws are inserted, there are numbers 1, 2, and 3 stamped respectively. I've lined up the three jaws above accordingly. Slot #1 gets the jaw that has a little half first tooth, slot #2 gets the jaw with the full tooth, and slot #3 gets the jaw with no first tooth. The "beautiful iron" site that I linked to above has a nice discussion about these.
Anyways, the parts all clean up nicely.
The jaws slip into their respective slots, tooth-side facing outwards. At this point, each jaw should smoothly slide its full length of travel in and out relatively easily by hand. If it sticks, catches, or binds, spend some time cleaning or troubleshooting the bore or the jaw, because it isn't going to get any better on its own once it's back together.
And now, one of the trickiest steps of all... orienting the jaws to install the split nut. The split nut is machined as a single piece and fitted to the jaw design as I described above. Then it is literally split in half, roughly, to be able to go onto the jaws and into the channel on the main body. Installing this thing takes some trial and error pretty much every time.
The first problem is that the jaws slide up and down on their own when you'd really like them to stay in one place... aligned with one another if possible. Second, when you put the first half of split nut on one or more of the jaws, it's going to intersect with the jaw teeth and move that jaw. After some fiddling, you eventually get what will feel and look like a good fit.
Once you have one half in place, don't lose your grip on that half and that jaw (or jaws). Carefully slip the other side of the split nut into place, making sure that the bottoms of the jaws are all lined up properly. At this point, holding tight to both sides of the split nut, you should be able spin the assembly and watch the jaws move in and out. Drop it, though, and you have to start over.
Carefully slide the outer sleeve back over the assembly, without anything moving, until it gets a slight grip internally on the split nut.
Back to the arbor press to press the sleeve back into place. There is one bit to pay attention to here, and that is how far to press the sleeve back on. Not quite far enough and you can't get a chuck key into place, too far and the chuck key will slip. After pressing to make sure there's a solid bite, I sort of gradually work my way to the proper depth and check it with a key a couple times as I go. Once the key slips in smoothly but tightly, that's it.
Run the chuck open and closed a few times, and this one turns out to be as flawless (knock on wood) and smooth as any that I've ever had apart. There is a little bit of external pitting on the exposed portions of the main body, but that's cosmetic only. The chuck itself appears to be pretty darn good, considering its original condition. To be honest, that's a big and pleasant surprise... I had pretty well assumed this thing had little chance of surviving for use, and was figuring at best I might be able to salvage the jaws and/or split nut for parts another time. Turns out to be as good or better than any I have in use on other machines.
Total time from start to finish, a bit less than 90 minutes, and one of the biggest pleasant surprises so far.
... 
