mbraddock
Hot Rolled
- Joined
- Jul 17, 2008
- Location
- Gainesville, FL
We just bought a Doosan 2600SY CNC lathe with 77mm (~3.03") bar capability on the main and 50mm (~1.97") bar capability on the sub. We want to install a pair of collet chucks that allow the use of quick change collets and S-series master collets and top pads. We plan to run a servo-style 4' bar feeder on the machine. We're getting quotes from Microcentric, Royal, and Hardinge and want to ask a few questions so we’re not disappointed with our choice. I’ve read about a bunch of threads on the forum on quick change collet chucks, and I didn’t really see these questions answered, so thanks in advance to anyone who can answer from experience...
1. We were planning to go with an 80mm (3.15") collet chuck on the main and a 65mm (2.56") collet chuck on the sub, but we see that Royal offers 80mm chucks for the A2-5 spindle nose on the sub. Since our sub has a fairly sophisticated parts ejector installed (that we don’t want to remove), is it worth considering going with the 80mm collet size on the sub at the expense of more expensive collets and a larger chuck nose? Or would you suggest sticking to a smaller collet chuck on the sub and when necessary cut emergency collets or reinstall the regular chuck and just cut soft jaws?
2. We were planning to buy dead-length chucks for both the main and sub, but I read many posts stating the dead-lengths are not as accurate (understood due to more moving parts) and possessed lower clamping force. I can understand them being less rigid due to the additional moving parts, but can aggressive turning or drilling in tougher materials really overcome the drawbar pushing force, causing the material to slide back in the collet significantly more than pull-back style chucks? And if so, are serrated collets or top pads adequate to prevent this, or is a pull-back style chuck the only solution? I’m not trying to take 1/2" depth cuts or feed at 0.02 ipr with a 2" indexable drill in cobalt chromium, but I don’t want to have to baby a 30hp machine either. My interpretation of the threads I’ve read about this question is that modern dead-length chucks should be fine, and if you need more, use serrated hardened top jaws on the factory 3 jaw chuck.
3. In hindsight, were there any surprises / disappointments with the quick change chucks you purchased that would change your purchasing choice if you had it to do over?
Thanks!
Mike
1. We were planning to go with an 80mm (3.15") collet chuck on the main and a 65mm (2.56") collet chuck on the sub, but we see that Royal offers 80mm chucks for the A2-5 spindle nose on the sub. Since our sub has a fairly sophisticated parts ejector installed (that we don’t want to remove), is it worth considering going with the 80mm collet size on the sub at the expense of more expensive collets and a larger chuck nose? Or would you suggest sticking to a smaller collet chuck on the sub and when necessary cut emergency collets or reinstall the regular chuck and just cut soft jaws?
2. We were planning to buy dead-length chucks for both the main and sub, but I read many posts stating the dead-lengths are not as accurate (understood due to more moving parts) and possessed lower clamping force. I can understand them being less rigid due to the additional moving parts, but can aggressive turning or drilling in tougher materials really overcome the drawbar pushing force, causing the material to slide back in the collet significantly more than pull-back style chucks? And if so, are serrated collets or top pads adequate to prevent this, or is a pull-back style chuck the only solution? I’m not trying to take 1/2" depth cuts or feed at 0.02 ipr with a 2" indexable drill in cobalt chromium, but I don’t want to have to baby a 30hp machine either. My interpretation of the threads I’ve read about this question is that modern dead-length chucks should be fine, and if you need more, use serrated hardened top jaws on the factory 3 jaw chuck.
3. In hindsight, were there any surprises / disappointments with the quick change chucks you purchased that would change your purchasing choice if you had it to do over?
Thanks!
Mike