Collet Help

ddickey

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H-M Supporter Gold Member
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I need to be educated in collets. I'm interested in buying an ER-40 collet for my lathe. I will have to buy a back plate and mount the collet to it. My mill has R8 collets. I have a small rotary table that has a MT2 center. My question, is there a system I could use that would accomodate more than just my lathe or just my mill? Ideas or suggestions are always appreciated.
 
ER collets and Morse taper collets are more universal. With ER collets you need to think about the advantages of being able to put long stock through them, and some ER chucks will not allow that. MT collets will work with lathe, some milling machines, and drill press, but they will not allow stock through them. Milling machines and drill presses almost always do not allow stock through the spindle anyway, but lathes often do, and it is a major advantage for a collet set to have that feature if they can also be used on your lathe. ER collets are better at handling random sizes. 5C collets require work within about .005" from the nominal size. Both have other advantages and disadvantages...
 
Can the collet themselves be used for both mill and lathe if you have a different collet chuck, one that has a draw bar? I already have several R8 collets for the mill. Probably no reason to go with an ER system for the mill.?
 
Some collets can be used on different machines, so for the ER system I use an R-8 ER-40 holder on the mill and a MT3 ER-40 collet holder on the tailstock of the mill, they can also be used with an ER-40 chuck mounted to the spindle. The MT3 holder was for a drawbar (threaded), but I machined a threaded tang so it would not turn in the tailstock. They sell other sizes of MT holders for ER40 chucks, so it could be used in a rotary table with a MT2 ER-40 holder.There are 5C and ER collet blocks in square and hex, very helpful for machining flats on round stock.

Never have seen an R-8 collet used on the lathe. Only seen 5C for the lathe. On the mill, especially if you do not have a power draw bar, an ER system may be easier to switch collets. I have a nice set of R-8 collets and almost never use them.
 
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Not sure what you mean about using a backplate. To be able to use an R8-ER32 collet chuck on my lathe, which has an MT5 socket in the spindle, I modified a soft MT5 to MT3 sleeve. With the sleeve mounted in the spindle, the internal MT3 taper was recut to R8 dimensions.
 
There are MT5 to ER40 chucks for $50-80, but would require a drawbar system and would not allow stock to pass through the collet. There are also D1-3 and D1-4 direct spindle mount ER40 chucks, and also those that would require a back plate, both will allow up to 1" stock to pass through. These are an adaptations of the ER collet system to hold stock, there are also some limitations as to holding very short pieces of stock in ER collets. So ER collets would be interchangeable between machines, but the ER collet holders would be more machine specific.
 
No, it is a MT5 spindle with a D1-5 camlock for the chuck. Was looking at the Tormach ER-40 collet fixture which would require a back plate.
Thanks for the link.
 
hmmm....I figured they'd make MT-5 collet sets with a hollow draw bar to still allow a good sized thru hole.
I was wrong, I guess I've never looked for sets that big.

Good Luck, and please let us know what you decide.

-brino
 
Regarding ER-40 collet set: I see lots of 23 piece metric sets of ER-40 but not much in imperial. I use the inch system
for most of my work. Would a metric set work for my needs? Maybe someone has a good source for an imperial set
without spending a lot of money.
 
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