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Advantages of collet chucks over regular chucks?
- Thread starter Nelson
- Start date
I think that these replies sort of fall short and simply confuse the beginner- so far.
Workholding in the lathe is a long subject that cannot be dashed off in a series of one liners.
The beginner will soon realise that his newly acquired lathe with its single three jaw self centreing chuck isn't a fat lot of use.
He will find that it cannot repeat workholding of a truly parallel piece round metal. At best, it is probably running out by 3 thous-- or worse. Moreover, if the thing is rotated it will give a variety of results rotating it around the three separate jaws. This, I must emphasise, is for a brand new chuck which is all bright and shiny and straight from the maker be it American or Chinese or whatever.
The normal alternative to accuracy is a 4 jaw independent chuck which will hold a piece of round accurately- or a misshapen piece. The fault is that it is not easy to perform the act- pushing it backwards and forwards with the opposite keys-- and a piece of chalk or a clock gauge.
A collet chuck will hold far greater accuracy but like the soft jaw alternatives- only on one dimension. A 1/2" collet will only hold something more or less .500 concentric. If the piece of round is nominally manufactured it will probably be 0.497 or worse. It will, believe me, either slip or defoprm or crack the collet. Some of the collets can accept a wider tolerance but at a poorer accuracy than that offered by a decent fixed dimension collet.
OK, I use all of these but for varying needs. I also use a faceplate and something which is not in general use, a tee slotted one. Indeed, I made one.
Importantly, I'm not a professional machinist or someone with a fancy lathe or workshop. I have basically a very old Myford lathe, a Unimat clone and a cheap mill drill plus a almost scrap tool and cutter grinder and tools which I mainly made myself.
Norman
Workholding in the lathe is a long subject that cannot be dashed off in a series of one liners.
The beginner will soon realise that his newly acquired lathe with its single three jaw self centreing chuck isn't a fat lot of use.
He will find that it cannot repeat workholding of a truly parallel piece round metal. At best, it is probably running out by 3 thous-- or worse. Moreover, if the thing is rotated it will give a variety of results rotating it around the three separate jaws. This, I must emphasise, is for a brand new chuck which is all bright and shiny and straight from the maker be it American or Chinese or whatever.
The normal alternative to accuracy is a 4 jaw independent chuck which will hold a piece of round accurately- or a misshapen piece. The fault is that it is not easy to perform the act- pushing it backwards and forwards with the opposite keys-- and a piece of chalk or a clock gauge.
A collet chuck will hold far greater accuracy but like the soft jaw alternatives- only on one dimension. A 1/2" collet will only hold something more or less .500 concentric. If the piece of round is nominally manufactured it will probably be 0.497 or worse. It will, believe me, either slip or defoprm or crack the collet. Some of the collets can accept a wider tolerance but at a poorer accuracy than that offered by a decent fixed dimension collet.
OK, I use all of these but for varying needs. I also use a faceplate and something which is not in general use, a tee slotted one. Indeed, I made one.
Importantly, I'm not a professional machinist or someone with a fancy lathe or workshop. I have basically a very old Myford lathe, a Unimat clone and a cheap mill drill plus a almost scrap tool and cutter grinder and tools which I mainly made myself.
Norman
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Using colletts for close up work will eliminate the chance of running the carriage into the chuck,,, and eliminate the chance of getting something caught in the spinning chuck jaws??
Opinions guys??
Opinions guys??
B34VD link=topic=2243.msg14801#msg14801 date=1306101386 said:
Of course, I mentioned a tee slotted faceplate but you can do the thing but incorporate a set of clamping screws like a 4 jaw chuck- but only bigger.
Actually I have three faceplates which fit the Myford and don't really involve fiddling with the 4 jaw as mentioned.
I DID say that is a BIG subject
Cheers
Norman
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Advantages:
Concentricity
Repeatability
No/low damage to finished surfaces
No time spent indicating a part true
Little to snag fingers or tools, or clothing
No/little loss of holding power at high spindle speed
I never use them.
Concentricity
Repeatability
No/low damage to finished surfaces
No time spent indicating a part true
Little to snag fingers or tools, or clothing
No/little loss of holding power at high spindle speed
I never use them.
I used collect chucks for production on turrett lathe. The one my boss had you pulled the stock forward and a stop mounted in the turrett tailstock push it back to the set lenght. I think the collect was about an inch of jaw lenght to hold the bar stock. It all depends on the diameter of the part being made. On the larger turrett lathe he had we used a three jaw chuck since the material was about 1.5 " OD. Hope I didn't confuse the issue.
I use them all the time; a 5C as a matter of fact, which can only hold stock up to 1-1/8. Tony and others pretty much hit the nail on the head. I work on a lot of shafts and most are finished when I get them but damaged on the end or the bearing race is worn-out. Almost always, they're between 1 to 1-1/8 inch (about half of them are a metric diameter). The holding ends are precision machined and polished and thus cannot be damaged by a regular chuck. They usually come to me straight as arrows so when you chuck e'm in a collet they line-up basically dead-on with the center.
A few more positive aspects: The chuck is usually pretty small and you get to use more of the bed if needed. Likewise, most lathes can accommodate a 5C collet right in the spindle -giving you even more usable bed length. When you do that though, the shaft cannot protrude into the spindle because of the collet closing mechanism resides there. Also, the chucks tend to balance very well. My 5C balances so well, the machine simply doesn't vibrate at any speed.
So, instead of the upsides that Tony pointed-out, the downsides are that you need a full set in 1/64" increments to hold all possible size shafts. That's something like 50+ collets (at 6-10 bucks each). You cannot use them to turn tapers with the tailstock method (taper attachements work fine with them) -but this is also true of any jawed chuck. Limited range (For 5C, 5/64" I think at the small end and 1-1/8 at the large end). They can be damaged easily. If a piece spins-out, that could be the end of that collet. I believe someone else mentioned this but, you can't put rusty/scaley stock in them if you care about them, lest you transfer pit marks in the surface. If you're not careful, it's possible to get a collet stuck in the chuck (knock on wood, it hasen't happened to me) and getting them un-stuck can be an ordeal.
I like e'm... they save me a lot of time.
Ray
A few more positive aspects: The chuck is usually pretty small and you get to use more of the bed if needed. Likewise, most lathes can accommodate a 5C collet right in the spindle -giving you even more usable bed length. When you do that though, the shaft cannot protrude into the spindle because of the collet closing mechanism resides there. Also, the chucks tend to balance very well. My 5C balances so well, the machine simply doesn't vibrate at any speed.
So, instead of the upsides that Tony pointed-out, the downsides are that you need a full set in 1/64" increments to hold all possible size shafts. That's something like 50+ collets (at 6-10 bucks each). You cannot use them to turn tapers with the tailstock method (taper attachements work fine with them) -but this is also true of any jawed chuck. Limited range (For 5C, 5/64" I think at the small end and 1-1/8 at the large end). They can be damaged easily. If a piece spins-out, that could be the end of that collet. I believe someone else mentioned this but, you can't put rusty/scaley stock in them if you care about them, lest you transfer pit marks in the surface. If you're not careful, it's possible to get a collet stuck in the chuck (knock on wood, it hasen't happened to me) and getting them un-stuck can be an ordeal.
I like e'm... they save me a lot of time.
Ray
I'm about to put in lathe number 3, so I am considering collets, although somehow I always envision collet work as being generally smaller than most of what I actually need to do, so not convinced just yet. These are all larger lathes, and don't have the high speeds needed to turn miniature work anyway. I dunno, maybe I'll just put a 4 jaw on one of them and build a collet chuck to use in it when I need one. I have a 5-C set already, grabbed from a t&c grinder I missed out on. I use them in a collet block once in a while.
Tony,
Well heck then, just get one of these...4000 R's fast enough for you? I can send you the price quote if you want. You'll want to be sitting down before you read it...
Ray
Well heck then, just get one of these...4000 R's fast enough for you? I can send you the price quote if you want. You'll want to be sitting down before you read it...
Ray
Same here. I tend to use collets on smaller stuff but the smaller stuff is rare and sometimes I don't care what the part runout is so the three jaw is just fine if I can get it to hang onto the part. I've been known to mount an ER collet in the large three jaw to turn something tiny in a pinch. I don't have a drawbar on my Mori so I don't use 5C's like I used to on my Clausing (10years ago) so collets aren't as easy to use as they used to be in the past which causes me to not use them as much as I might. I guess it all depends on your uses for a lathe.