Post By Brian@VersaMil
Post By cnctoolcat
Post By Weasel
I am removing the 8" Kitigawa chuck from our Haas SL-20 and I am having a little trouble getting the chuck to unscrew from the drawtube.
Does anyone have any good advice on this topic.
We had one stuck pretty good on a used machine we bought. We wound up making a wrench to attach to an air impact wrench and that did the trick.
Getting a Kitagawa chuck off of a lathe can be TORTURE! I have a Daewoo Puma 230 that uses a Kitagawa 10 inch chuck, and had MAJOR problems getting it off the first few years. There is a tool to grip the slots in the chuck to unscrew it, but the big problem on my lathe was the two slots in the drawtube, that are for removing the drawtube after the chuck is off. The bright boys that designed these drawtubes, aren't thinking clearly, to put two slots right where all the swarf is going to collect in the drawtube threads! The instant you start unscrewing the chuck, this swarf jams up in the threads. It can jam up so tight that you can unscrew the entire drawtube from the actuater, so you're drawing out both the chuck and an upwards of four foot long tube.
I ended up cutting off the slots in the end of my drawtube, which has helped alleviate the problem of removing the chuck. I also made a removal tool that I can put a 1 1/4 wrench on, rather than use the stock Kitagawa tool, that just has a crossbar. In the first few years of removing my chuck, I destroyed the slots in the threaded ring in the Kitagawa chuck, so I removed the ring and milled two more slots at 90 degrees to the first two. These have hung in there. Certainly the entire design sucks! A lathe chuck should be able to be EASILY removed, instead of turning into an hour and a half battle.
I had the same problem, as I often have to swap chucks fro a Kitigawa to a collet chuck, In the Kitigawa there is a free wheeling joiner that screws onto the draw tube, this is where the trouble lies, It has 2 small cutouts, I fashioned a tool using 10 mm keyway steel with a offset handle to allow the end to fit in on an angle then come parrell to fit into both cutouts, works like a breeze, I then turned a shaft that fits snug, but not tight into the draw tube and also into the chick, this allows the Kitigawa to stay parrell to the thread on the draw tube, once it starts on the thread, I remove the shaft and fit my 'magic' tool, I swap chicks in less than 10 minutes - before I would take hours, let alone the frustration.
I've had the same trouble. Haven't made my own removal tool yet, but I will now. The design is lousy. I can say this, after you get it off, clean the hell out of it. Does any one know if I can switch to a Powerhold or straight Gamet without much trouble or $?
When reinstalling the Kitagawa, I always coat the male drawtube threads and the female chuck adaptor threads completely with anti-seize.
The anti-seize obviously helps when removing later, but also works to "fill the void" between threads. This helps to keep chips and swarf out from between the threads, facilitating easy removal next time.
Anytime you remove a chuck, you should completely disassemble the chuck and clean thoroughly. You will be amazed at the crap that gets inside of your chuck. This "crap" is what degrades the accuracy of your chuck over time.
Of course you should always keep your chuck well greased. US Shop Tools sells a grease specifically made for 3-jaw power chucks.
Could you post some photos of your custom tools? I'm thinking about getting a collet chuck for our new Duraturn, and like the idea of a 10min switch between the 8" Kitigawa and the collet chuck. Do you have to do any alignment or truing when changing over?
Thanks for your replies
I didnt realize that you had to cycle the chuck between open and closed to remove the pressure from the drawtube. Once I figured that out it was "relatively" easy. I dissasembled the chuck and man was it full of crap.
I just took my kitagawa on my Daewoo apart. Same story. But I knew I had to play with the drawbar to get it off.
I have a nice old Mazak QT10 ATC, and I am having the same issue changing out from a Kitagawa B08 to a ATS 3J collet nose.
Made a tool for the slotted nut, but I am definitely experiencing a wrestling match with the chuck.
Time and patience....
After wrestling with a drawtube nut for a few hours, I took an impact socket that would just slide into the hole in the chuck (with the sleeve removed of course) and milled the end to make a couple ears to fit the slots. Couple good burps with a strong 1/2" impact wrench and it loosened right up. I'd previously ripped the ears off a couple other makeshift tools, and assumed the socket was made of the right material with the right heat treatment to take a real beating. Couldn't even tell it had been used after it had loosened the nut.
We ended up milling 2 more slots in the nut on our SL-30 chuck, and made a tool with 4 tabs instead of 2. Works much better now.
I curse whoever designed this system every time I change over the lathe....
Sounds like the OP has it figured out.On our Daewoo Lynx, we had trouble unscrewing the drawtube from the chuck until I decided that the drawtube doesn't have to bottom out tight when you put the chuck on. We always stop about a full turn before the threads bottom out,that way, it's never really tight. When removing, the jaws always get taken off first, and we blow the connection off real good before putting the wrench on.Haven't had a problem since.
Some tips, a coupe of which were alluded to.
Spray the thread area with penetrating oil well in advance of when you intend to dismount the chuck.
Realize that drawtube pressure is trying to either close or open the jaws, which is helping to "lock" the threads. This is the same theory behind torquing a bolt. I turn the hyd pressure very low (so the drawtube strokes slowly), then in the rough middle of travel while closing or opening, turn the pressure to minimum, which should stop the drawtube movement. Now you have the chuck master jaws in a "neutral" position, with no load on the threads. This alone will help them unscrew.
Dig the crap out of the slots in the drawnut so the ears on the wrench will fit in full-depth. This is basic mechanics. If you don't do this, the ears are much more likely to pop out of the slots, and round everything off in the process.
Note that when you have unseated the chuck from the spindle nose, all the weight of the chuck is hanging on the end of 3.5 to 4 feet of drawtube. That short little thread at the opposite end, engaging the hydraulic cylinder, is the only thing doing all the support, and it's now taking a helluva sideload to the threads, nor is it helping the cylinder. I like to put a piece of tubing or barstock through the chuck into the drawtube at least 1.5 feet deep. Then, support the end sticking out of the chuck. This helps unload those threads at the other end. Of course, this must be done after first using the chuck wrench to unscrew several turns. At that point, the chuck body can usually be rotated to continue unscrewing the chuck off the drawtube. The tubing going through has another very beneficial use. If you do something wrong and the chuck comes off the end of the drawtube unexpectedly, it won't fall, if you have the tubing set right. I saw a guy standing inside a lathe trying to catch the chuck as it came off. It dropped, smashing his hands between the chuck and bed. OMG, it hurt just to see. Cannot imagine how much pain that was.
Clean the chuck while it's off!!!! If you don't do it now, you'll never take it off just to clean it. Unless, of course, it quits moving. Yep, seen that one. Lots of crap gets inside, and can make so much friction that the hyd pressure can't overcome it. You'll also find a clean chuck will stroke at a much lower minimum pressure, which is great help when holding thin-wall parts. That same crap can also build up between the spindle ID and drawtube OD and cause a lot of friction. I've seen that also bring a chuck to a halt. Very often, the grease passages inside the chuck get clogged. So, you're pumping in grease, but it's not going to all the right places.
When you put it back on, use the anti-seize, as mentioned. Makes a world of difference in getting it off on the next round.
If the chuck absolutely won't come off without the drawtube unscrewing from the cylinder, so be it. Take the assembly off, clamp the drawtube in a vise (no more than necessary pressure) and you should now be able to separate them. (Try to avoid jaw marks in the drawtube, as these could be stress-risers.) Clean the cylinder-end drawtube threads really well, then screw the drawtube back in with removable Loctite on the threads. This and the anti-seize at the chuck should make it come apart properly next time. Some drawtubes have a thin-wall locknut on the threads at the cylinder end. It should do a good job at preventing the drawtube from unscrewing. Unfortunately, these locknuts aren't on all machines.
Worst-case scenario is the chuck just WON'T come off. A customer had never pulled the chuck off their 25-year old Mori. Damn, that was stuck. It took heating with a torch to persuade it. Obviously, this is an extreme measure and requires some caution and common-sense. But, it worked with no damage.
Liberal usage of profanity will not help the threads unscrew, but it might make you feel better.
I never have too many problems with removing a chuck. As I do it so often, it never as time to gum up or corrode. I switch from the chuck to collet chuck at least once a week, if not more. I use the "wrench" that came with my machine(SL20). It's just a piece of tube with two tabs that correspond with slots in the draw nut.
I've done that also, but then realized, if you unbolt the chuck, then put the chuck in the closed position, (so the draw bar is pushing outward) the threads should have no pressure on them at all. That is provided, you've popped the chuck off the taper.
I turn the hyd pressure very low (so the drawtube strokes slowly), then in the rough middle of travel while closing or opening, turn the pressure to minimum, which should stop the drawtube movement. Now you have the chuck master jaws in a "neutral" position, with no load on the threads. This alone will help them unscrew...
Just a simple weld job.
I also use anti seize on the threads, and make sure I clean all the chips out of the chuck adaptor before unscrewing. I tighten the drawtube and chuck adaptor, but I don't go nuts on it. Just a little past snug.
It is a pain to hold the chuck with one hand and the tool in the other and unscrew the chuck adaptor. I bought a socket head cap screw the same size as the shcs used to mount the chuck but about an inch longer. I cut the head off the shcs and screw it into one of the spindle mounting holes. Then I slide the chuck on the shcs. That takes the weight of the chuck while I fumble with the adaptor.