I have a MT5 headstock on my lathe. I am toiling with the idea of buying a MT3 collet chuck and a set of ER40 collets. I want to use a MT5 to MT3 adapter between the spindle and the collet chuck. The unknown is the combined runout of the MT5/MT3 adapter plus the chuck plus the collets themselves. If anyone has been down this road, I'll appreciate their opinions. Specifically, what runouts are you able to achieve with this combination system? Thanks for your responses.
Garen Avanessian
Why not use an MT5 ER40 holder? I have one surplus to my needs, purchased for use with a former lathe. It's ETM brand, only used a few times on a tool & cutter grinder, like new but a tad dusty. Can let it go for 50% of MSC's price if you want it.
I got a nice set of ER40 collets once, and got adapters to use them on all my machines. Don't have one with a 5MT spindle any more. I have a 5MT lathe center, NOS, carbide tip too ..
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Grant Erwin Kirkland, Washington
What runouts are you able to achieve with the MT5 ER40 collet holder?
Garen
No way to test, sorry.
GWE
According to Robert Swinney :
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I don't know about that. The 5-C collet closer still needs an adaptor nosepiece -- from the MT-5 spindle socket to the 5C -- plus a protective cover over the spindle nose used for removing the adaptor. This could introduce as much runout as a well-made ER40 collet holder with a native MT-5 shank (which is what is being offered).
The benefit of the ER40 system is that a relatively few collets cover the whole range, compared to those necessary for a 5C collet system, which has a much narrower closure range, so you need more of them to cover the whole range. If everything you want to hold is of standard sizes, it is no problem -- but if you turn something do a smaller diameter, and wish to hold it in a collet -- or if you want to change between inch and metric sizes, the ER40 system can save you money.
That said -- I use 5C collets in my 12x24" Clausing, and ER-32 (I think that's the size) in my Compact-5/CNC -- simply because each came fitted with the proper adaptors. Oh yes -- also the Compact-5/CNC is too small to accept 5C collets anyway. :-)
Perhaps the original poster should post just how much runout is acceptable to him.
How much he will get -- with both the ER-40 and the 5C adaptors will depend on how true the MT-5 socket is in the spindle.
The one disadvantage that I can see to the ER40 system is that it will take up a bit more of the distance between centers than the 5C would -- unless the 5C were mounted in a collet chuck (such as what Bison offers), which is totally not needed in this case.
Good Luck, DoN.
Well, if he has a proper 5C setup, he can pass stock through the 5C collets, where the ER40 collets in a 5MT holder are blind.
GWE
I spent a while experimenting with my 5C collet adapter and a dial indicator. I found an orientation that cancels out the runout of the spindle & the adapter to a point where it was very hard to measure. I marked the adapter so that I can insert it in the spindle with the same orientation each time. It wasn't bad to start with, but it could definitely be improved by checking the combination carefully. This is partly a matter of luck, in that the errors in the two elements were close enough that they could cancel each other out. YMMV.
Doug White
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O.K. That is something which I overlooked. One reason is that the holder for the ER32 collets in the Compact-5/CNC does not have that particular problem. But with the 5MT setup, you would need a drawbar, and I don't think that a drawbar for 5MT can be made hollow and large enough to pass 1" stock through it -- even assuming that there is room within the 5MT to clear stock at least part way through.
Thanks, DoN.
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