Alex. Posted October 5, 2010 Report Share Posted October 5, 2010 Hi Guys and Gals, I have recently taken the plunge and bought a small lathe, just for knocking up spacers and stuff, and generally playing around with. But I seem to have one major issue (for now!). I am having trouble centering the work in the chuck so that it is all square. I have even faced the end and turned down the sides to give a square end, turned it around and put it in the chuck, but still cannot get it perfectly square! This is doing my noggin in! I have even resorted to spinning up the work, identifying the high spot and tapping it with a hammer! I'm using round bar and a three jaw self centering chuck. Can anyone give me some tips, or point out where I am going wrong? Any help and advice gratefully received... Alex. Link to comment Share on other sites More sharing options...
garage19 Posted October 5, 2010 Report Share Posted October 5, 2010 Could justbe your chuck is worn/damaged. Get yourself a dial gauge with a magnetic base. Will let you see where and how much run out you are getting. Will also give you a better idea of where to smack.. tap it with a hammer. Link to comment Share on other sites More sharing options...
spacemonkey Posted October 5, 2010 Report Share Posted October 5, 2010 You'll never get it quite right just putting it back the other way around in a normal 3 jaw. One method would be to tap it. (Use a dial test indicator.) Or grip the work in a collet which is far more accurate. Or use a four jaw and a dial test indicator. Link to comment Share on other sites More sharing options...
Alex. Posted October 5, 2010 Author Report Share Posted October 5, 2010 Could justbe your chuck is worn/damaged. It better not be, it's brand new!! You'll never get it quite right just putting it back the other way around in a normal 3 jaw. Good to know it's not just me being hamfisted then! Get yourself a dial gauge with a magnetic base. Will let you see where and how much run out you are getting. Will also give you a better idea of where to smack.. tap it with a hammer. One method would be to tap it. (Use a dial test indicator.) Or grip the work in a collet which is far more accurate. Or use a four jaw and a dial test indicator. I've got a dial tester somewhere, good call on the magnetic base. I'll have a goodplay when I'm next in the garage... Any general, or specific, advice for someone starting out? Alex. Link to comment Share on other sites More sharing options...
spacemonkey Posted October 5, 2010 Report Share Posted October 5, 2010 Get on a college course if at all possible to help you learn a few basics including safety.... Otherwise, think twice before doing anything, remember how dangerous it is, watch your fingers on the chuck jaws, etc, don't have any loose clothing, no long hair, wear eye protection, stuff like that... Get some nice, carbide tips with the sharp, polished edge for aluminium bits and don't be afraid to use really fast spindle speeds for cutting aluminium. - There's loads of info for speeds and feeds on the internet. You'll get a much nicer looking part if you do it right. Link to comment Share on other sites More sharing options...
jayRC3045 Posted October 5, 2010 Report Share Posted October 5, 2010 gripping bar in a 3 jaw with hard jaws on hobby lathes you will never get it to run true without the help of a DTI and a mallet your other option is soft jaws (if your lathe came with some) and bore them out ,done right and your job (if already round) should run within .02mm T.I.R or better Link to comment Share on other sites More sharing options...
Alex. Posted October 6, 2010 Author Report Share Posted October 6, 2010 Thanks guys, dial guage and whacking stick it is! As for aluminium, I was trying some at the weekend and it did seem to cut nicer than steel at the same speeds. This was at fairly low speed, so I'll try ramping it up for the parting off. Alex. Link to comment Share on other sites More sharing options...
spacemonkey Posted October 6, 2010 Report Share Posted October 6, 2010 Thanks guys, dial guage and whacking stick it is! As for aluminium, I was trying some at the weekend and it did seem to cut nicer than steel at the same speeds. This was at fairly low speed, so I'll try ramping it up for the parting off. Alex. Parting off might require a bit more caution! Link to comment Share on other sites More sharing options...
Alex. Posted October 6, 2010 Author Report Share Posted October 6, 2010 Parting off might require a bit more caution! I've only successfully parted off once, but that was after doing some reading! The first couple of times I was using steel tube and trying to part off towards the end of the work, away from the chuck, and the tool was slightly below centre. Didn't work too well... After a bit of reading, I tried with some aluminium bar, close to the chuck and managed to adjust the height of the tool to be in the centre, it worked much better. Just wish I had more time in the garage to practice. Alex. Link to comment Share on other sites More sharing options...
spacemonkey Posted October 6, 2010 Report Share Posted October 6, 2010 I've only successfully parted off once, but that was after doing some reading! The first couple of times I was using steel tube and trying to part off towards the end of the work, away from the chuck, and the tool was slightly below centre. Didn't work too well... After a bit of reading, I tried with some aluminium bar, close to the chuck and managed to adjust the height of the tool to be in the centre, it worked much better. Just wish I had more time in the garage to practice. Alex. Set everything up as rigid as possible, miniumum tool overhang, etc. Get the tool dead in line with the cross slide. You don't want it going in at an angle. Spindle speed wants to be lower than normal turning. Put coolant on if you can. Link to comment Share on other sites More sharing options...
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