[mlinkadelsol]

Good day, having problem with removing collet chuck from MAZAK QT18 lathe.
I managed to unscrew 3 out of 4 bolts with impact wrench, but the 4th holds like nuts.
Is there special procedure to remove the collet?
I am thankful for any advice.
Attachment 413022

[deadlykitten]

hi mlinkadesol

hammer it a bit, just like shown in image 1, maybe a bit of play will be created

considering that the hexagon of the screw is in good condition, take an allen key, kick it with the hammer, and when the hammer is touching that allen key, right in that moment, try to rotate it : this procedure requires 2 people : one will hold the hammer and kick with it, and the other should rotate the key when the hammer is at full force of impact : those 2 persons must work in syncronization, unless you can do it alone this is showed in image 2, left side; my advice would be to use a "custom T-shape allen key", with a disc wellded on side, so to have a bigger contact area for the hammer (n image 2, right side ), and also use a strong long pipe, that should fit the allen key; the "key" for this to work is the sync action, thus rotatting the pipe+allen key, exactly when the hammer is kicking; also, a good quality allen key is required, not those cheap ones, that get wear imediatly

if hexagon of screw is not in good condition, then try to weld the key inside the screw; carefull, i am not an expert about welding on cnc's, so maybe is not a good idea

also, the hydraulic cilinder should be somewhere at the middle position, thus you need to be sure that it is not creating tension inside the collet chuck; so far i have not used collet chucks like yours, and i don't know exactly what parts are there, but, in any case, you should avoid having pressure inside it from the hidraulic cilinder; you may push the foot pedal to start moving it, and push emergency stop when it is somewhere near the middle

one last resort is also a portable edm, but since you are on a cnc, try to use the live tool, so to drill / mill the entire screw out; if you have live tooling, give it a try / kindly

[mlinkadelsol]

hi mlinkadesol

hammer it a bit, just like shown in image 1, maybe a bit of play will be created

considering that the hexagon of the screw is in good condition, take an allen key, kick it with the hammer, and when the hammer is touching that allen key, right in that moment, try to rotate it : this procedure requires 2 people : one will hold the hammer and kick with it, and the other should rotate the key when the hammer is at full force of impact : those 2 persons must work in syncronization, unless you can do it alone this is showed in image 2, left side; my advice would be to use a "custom T-shape allen key", with a disc wellded on side, so to have a bigger contact area for the hammer (n image 2, right side ), and also use a strong long pipe, that should fit the allen key; the "key" for this to work is the sync action, thus rotatting the pipe+allen key, exactly when the hammer is kicking; also, a good quality allen key is required, not those cheap ones, that get wear imediatly

if hexagon of screw is not in good condition, then try to weld the key inside the screw; carefull, i am not an expert about welding on cnc's, so maybe is not a good idea

also, the hydraulic cilinder should be somewhere at the middle position, thus you need to be sure that it is not creating tension inside the collet chuck; so far i have not used collet chucks like yours, and i don't know exactly what parts are there, but, in any case, you should avoid having pressure inside it from the hidraulic cilinder; you may push the foot pedal to start moving it, and push emergency stop when it is somewhere near the middle

one last resort is also a portable edm, but since you are on a cnc, try to use the live tool, so to drill / mill the entire screw out; if you have live tooling, give it a try / kindly

Thank you for your detailed answer, its unique.
I did try everything and in the end had to drill the bolt out.
Thank you again for your help.
Best regards.

[RCaffin]

I had a slightly similar problem with a whole row of allen head bolts. The steel had siezed in the aluminium over 10 - 15 years. Problem was they were button heads, so the key size was very small.

I gave each bolt a good spray of WD40 and a few drops of oil, and left them for a day. Then I stuck a GOOD brand of allen key in the bolt head, torqued it by hand, and then tapped the end of the key with a ball peen hammer. Got all 12 out OK.

I also replaced the button heads with standard cap heads AND put anti-sieze on the threads.

Cheers
Roger