[darrellx]

We have an older Daewoo Lynx 200L that the chuck has quit running true. Our guess is someone crashed it and bent the draw tube. We are trying to remove the chuck and draw tube to repair it but we can not get it to break loose. Has anyone had this problem and if so, any suggestions on how to break it loose and remove it. At wits end.

Thanks in advance for your help.

Darrell Ross

[deadlykitten]

hy if your chuck has high tir, then it may be possible that the flange is still true to the spindle, only that the chuck is not true to the flange, thus i consider that there is a flange betwenn spindle and chuck

drawtube, up to a point, can handle high chuck tir, without bending, thus within elastic deformation

depending on configuration, it may be possible to simply unbolt the chuck, then pull it forward, while the plunger nut and wedge plunger will remain stuck to the drawtube

if all fails, then last resort is to machine the interference between drawtube and drawnut, then remove hydraulic cilinder and dismount drawtube; it is not tricky, you can machine another drawnut, and refresh the drawtube, so to re-use them

kindly

[darrellx]

Thank you for your reply. We will give that a try.

[Algirdas]

Mr. deadlykitten described very well: take away all bolts holding the chuck to spindle nose and take the chuck and draw bar together.
There is other method also.
The idea is that hydraulic pressure builts high tension on the thread betwenn chuck nut and draw bar. So the sequence as follows:
1. Make the hydraulic pressure as low as possible. Draw bar should travel forward / back, that's enough. No more pressure needed.
2. take the front cover out of the chuck nose. The opening should reveal the access to chuck nut face with slots. Check if your key fits to the slots well.
3. prepare to operate ( pedal ) chuck open close continuously.
4. command the action of draw tube, let's say close.
5. turn the nut while draw bar is on travel - its a couple of seconds only.
6. command draw bar to opposite direction.
7.turn the nut while draw bar is on travel - its a couple of seconds only.
and so on.
Is that clear? It is very hard to turn the nut when hydraulic pressure is applied - at the end of stroke, doesn't matter which. Easy to turn the nut while the draw bar is moving.

[deadlykitten]

hello again mr egg bunny i forgot one thing, just like you mentioned, about hydraulic stroke :
... a recomanded setup, on a new lathe, for od clamping, is like this :
...... when jaws are closed, there still has to be room for the hydraulic cilinder travel, thus, without the chuck, the hydra cilinder must travel more than with the chuck on; thiss assures that there will still be pressure, even if chuck has reached full travel, otherwise, parts may fly out
...... when jaws are opened, there has to be no more room for the hydraulic cilinder travel , otherwise, it means that on machine idle, the hydraulic cilinder tends to throw your chuck away from the spindle; a method to check this, is to open the chuck, and try to find clearance between master jaws and chuck : simply force them a little, with your hand; if there is clearance, like a few 1/10 of a mm, then is ok; however, in time, as chips/swarf gets inside the chuck, this clearance will be smaller, as all gaps will be filled with residue

*in other words : hydra cilinder left < chuck full travel < hydra cilinder right < chuck full open; things depends also if there is a flange, or not

about using low pressure, there is a catch, since it may be hard to rotate the drawbar while it is traveling, because, even at low pressure, travel duration is short; one method to deal with this, is to push emergency stop when travel is arround middle, then block the hydra cilinder from behind, in order to rotate the drawbar in front; this may require to clamp a flange on the back of you hydraulic cilinder, and use a wrench or something, in order to prevent it's rotaton; this has to be done carefully, because on the back, there are small screws, like M6 or M8 etc, so steady hands and sharp sense are required, in order to avoid breaking those tiny screws

before making worries, if your drawtube is allready tilted, just look behind your chuck, and see if there is a flange; if it is, then perhaps is all ok otherwise, it may mean that your chuck is bolt directly to spindle, and in such cases, if the chuck has tir, then the spindle nose is wrecked, so again, no reason to worry for the drawtube kindly

[darrellx]

Thanks for your reply. We will give it a try.

- - - Updated - - -

Thanks for sharing that. we will give it a try.

Darrelll

[deadlykitten]

if you wish, share a few images, or a short video, with spindle, then hydra cilinder, maybe someone sees something

also, if your chuck wrench / joint handle fails, simply re-cut its shape, then flame it, and drop it in oil; at some moment, i had to do that, because the original one got wear, or got lost another thing that i have encountered, is when the drawtube was spiniing togheter with the drawnut, and in that moment, i have used 2 wrenches, one inside the other, one for keeping the drawnut stable, and the 2nd for spinning the drawnut

hope you will fix that soon

[darrellx]

I think we got it. Thanks for all of the replies.

Darrell