First off, I really don't want to start a fight and I absolutely agree that, all things being equal, collets are infinately more accurate than any type of scroll chuck.
But......let's discuss the merits of each before we decide what is best for each of us and also before we tell someone that they really need collets if they want a round pen. Some people really don't have a lot of money and often need tooling that can perform more than one function.
I don't have collets but I am saving to get a set for my metal lathe. But we are generally talking about using them on wood lathes.
My scroll chuck came with two sets of jaws. One set is still in the box as I rarely turn stuff that require them. The pin jaws have been in it since I got it.
I just did a test.... I removed the jaws and lightly clamped a transfer punch in the chuck just with the jaw holders ( is there a proper name for them? ) I don't have a proper Test Rod
I mounted a dial indicator and was very impressed with the result.
I got a difference of 0.06mm ( 0.002 in ? ) Now that isn't bad by any standards.
Now I replaced the jaws making sure the numbers on them matched.
Mmmm...0.26mm ( 0.010 in ? ) Pretty poor by machine standards and if that was on a metal lathe, I'd be worried.
But lets think about that for a minute. Just how much IS 0.26mm?
And let's not forget that the actual 'out of round' is half that. So how much is 0.13mm? I hunted around to find something that we all are familiar with.....a sheet of paper from my printer. Bang on almost at 0.14mm.
Now as John so clearly showed in his great video, if the blanks isn't squared perfectly to the tube then it will be out of round. Can you really get that accurate with a pen mill? Home made sander jig? MMmmmm
I took a pic of my jaws and I'm sure you will agree that they are not pretty and have had a lot of abuse. But I will dress them up with a Dremel this weekend for sure. I will use my metal lathe to do this, but there are methods on the web that show you how.
My wood lathe is the worst type in the world.....a pipe lathe. This is the type that has a a round tube as the bed and the tailstock can swivel from 11 to 1 oclock position without a problem. ( cool if you need a nice taper:redface: ) So you can see that it would be a complete waste to fit a precision collet chuck to this lathe.
But I have also yet to see any wood lathe where the tailstock can travel and remain perfectly aligned to the headstock. To get any benifit from collets, the TS must always be equally or better accuracy than the headstock. If you have a nice collet chuck and your TS quill flops around like a fish out of water then you have wasted your money. No doubts.
So what can a collet chuck do in a wood lathe that a half decent scroll chuck can't? In my opinion, absolutely nothing.
A scroll chuck on the other hand can do lots. With only two sets of jaws against a large full set of collets there is just no contest. You can hold virtually any irregular shape from round to oblong.
I've waffled enough and it's obvious where I stand, but I'd like to hear from the other side too. If you can state a good case for collets in a wood lathe then please do so.:biggrin:
But......let's discuss the merits of each before we decide what is best for each of us and also before we tell someone that they really need collets if they want a round pen. Some people really don't have a lot of money and often need tooling that can perform more than one function.
I don't have collets but I am saving to get a set for my metal lathe. But we are generally talking about using them on wood lathes.
My scroll chuck came with two sets of jaws. One set is still in the box as I rarely turn stuff that require them. The pin jaws have been in it since I got it.
I just did a test.... I removed the jaws and lightly clamped a transfer punch in the chuck just with the jaw holders ( is there a proper name for them? ) I don't have a proper Test Rod
I mounted a dial indicator and was very impressed with the result.
I got a difference of 0.06mm ( 0.002 in ? ) Now that isn't bad by any standards.
Now I replaced the jaws making sure the numbers on them matched.
Mmmm...0.26mm ( 0.010 in ? ) Pretty poor by machine standards and if that was on a metal lathe, I'd be worried.
But lets think about that for a minute. Just how much IS 0.26mm?
And let's not forget that the actual 'out of round' is half that. So how much is 0.13mm? I hunted around to find something that we all are familiar with.....a sheet of paper from my printer. Bang on almost at 0.14mm.
Now as John so clearly showed in his great video, if the blanks isn't squared perfectly to the tube then it will be out of round. Can you really get that accurate with a pen mill? Home made sander jig? MMmmmm
I took a pic of my jaws and I'm sure you will agree that they are not pretty and have had a lot of abuse. But I will dress them up with a Dremel this weekend for sure. I will use my metal lathe to do this, but there are methods on the web that show you how.
My wood lathe is the worst type in the world.....a pipe lathe. This is the type that has a a round tube as the bed and the tailstock can swivel from 11 to 1 oclock position without a problem. ( cool if you need a nice taper:redface: ) So you can see that it would be a complete waste to fit a precision collet chuck to this lathe.
But I have also yet to see any wood lathe where the tailstock can travel and remain perfectly aligned to the headstock. To get any benifit from collets, the TS must always be equally or better accuracy than the headstock. If you have a nice collet chuck and your TS quill flops around like a fish out of water then you have wasted your money. No doubts.
So what can a collet chuck do in a wood lathe that a half decent scroll chuck can't? In my opinion, absolutely nothing.
A scroll chuck on the other hand can do lots. With only two sets of jaws against a large full set of collets there is just no contest. You can hold virtually any irregular shape from round to oblong.
I've waffled enough and it's obvious where I stand, but I'd like to hear from the other side too. If you can state a good case for collets in a wood lathe then please do so.:biggrin: