On 2010-06-11, Searcher7 wrote:
On Jun 10, 1:26*am, "DoN. Nichols" wrote:
On 2010-06-10, Searcher7 wrote:
[ ... ]
Unfortunately...far far too many importe (Asian) collets are under or
over sized. A 5C collet has at most..a .015 grip range..and most of them
are .006. Ive seen far too many of them that were in that 15 thou
range..but a .500 collet may open to .485, and close to .497....which
really doesnt help much when your stock is .502 +/- .004
Hardinge, Lyndex, Royal, etc etc and several other german or polish made
brands are Good stuff.
* * * * [ ... ]
Ok. So I should concentrate on getting common sizes from Hardinge,
Lyndex, and Royal. Do these manufacturers make collets for MT2, MT3,
and R8?
* * * * R8 -- yes. *MT2 and MT3 are less common these days. *Hardinge
*might* still make them, but probably not the others. *And be sitting
down before you ask for the price of *any* Hardinge collet. :-)
That's the reason I got the imported collets to begin with. :-)
Understood. They may be all that is available these days.
* * * * And R8 is not a work-holding collet -- it is a *tool-holding*
collet -- specifically end-mills.
Yes. I had decided to not get the R8 end mill holders and get the R8
collets instead.
The end mill holders are better. R8 collets holding end mills
tend to slip with heavy cuts, causing the end mill to walk deeper and
deeper into the workpiece -- or even *through* it and into the mill table
or the vise.
I don't have an R8 spindle machine, but for end mills I prefer
end mill holders for the NTMB-30 and NTMB-40 tapers for my two machines
(with an adaptor allowing me to use the 30 taper holders in the larger
machine as well.)
* * * * As for the MT-2 and MT-3 -- the most likely place to find them
is from the same people who sell the import machine tools which
currently use them.
My mini lathe has a .787 spindle bore, so I figured I would get an
MT-3(3MT) set so I wouldn't need a collet chuck for that range up to
3/4".: http://littlemachineshop.com/product...ProductID=1948
With the disadvantage that you can't pass long workpieces
through the spindle as you can with 5C (or even 3C) collets. The
drawbar for those is hollow, while the drawbar for what you got is solid
(it uses internal threads in the collet back, while the 3C and 5C use
external threads instead.
And a set of R8 collets to cover the endmills for my mill/drill.:
http://littlemachineshop.com/product...ProductID=2872
I just have to determine what sizes are best to get that give me a
good range of options for end mills.
(But not necessarily the collets in these links, since they are also
imports).
The only disadvantage of the end mill holders is the extra
length. But remember my warning about the R8 collets slipping with
heavy cuts.
I would have considered these if I had gotten that Vertex dividing
head: http://littlemachineshop.com/product...ProductID=2999
But that particular set only goes up to 1/2" anyway.
Look for a good 3-jaw chuck to fit it instead.
I'm not sure of what, if any MT2 collets I should get. (My lathe
tailstock and rotary table center bore are MT2).
http://littlemachineshop.com/product...ProductID=1752
I would not bother. There are special collets for drill bits
for use in a drill press or tailstock ram -- but they expect a ground
flat on the end of the drill shank to prevent it spinning. And you can
get drill bits with a Morse Taper shank which is better than trying to
use drills in a collet anyway.
And these don't have the tang needed for extracting them from a
tailstock ram in a lathe. I can see you having to remove the ram from
the tailstock, clamp it in the 3-jaw chuck, and reach in through the
leadscrew hole with a rod to knock it out -- *every* time. Those are
not for use in a lathe tailstock.
And I don't see a use for collets in a rotary table bore.
Just because something *has* a Morse (or other) taper does not
mean that it is worth while getting collets to fit it. The tailstock
taper for a lathe is for centers -- or for drill chucks on an arbor, or
drill bits fitted with a Morse Taper shank.
As for 5C. I still have that "poor man's" 5C collet chuck, spin
indexer, hor/vert. collet fixture, and collet blocks.
http://littlemachineshop.com/product...ProductID=3842
I'm thinking 1/8", 1/4", 3/8", 1/2", 5/8", 3/4", 7/8", 1" "precision"
collets.(In round, square and hex).
Getting all these collets from a quality manufacturer will be tough.
It will also be *expensive* -- especially from Hardinge. :-)
(The various spindle and bore standards are killing me).
One reason to avoid getting collets for things which don't need
them.
[ ... ]
BTW. How accurate can one expect to make collet blocks for other sizes
where they are not available?
* * * * You can *expect* any degree of accuracy you can imagine.
Whether you will *get* it depends on your skill and the accuracy of the
machines you are using to make them.
Randy said that the problem he's found with the cheap collets is that
they are all undersized.
And someone else (quoted above) said that in *his* experience,
some are undersized and others oversized.
If this is generally true I wonder if it
would be a plausible project correct the inaccuracies of at least some
of the imports. Of course, there will be concentricity as well as bore
size issues.
And if they are *sufficiently* undersized, you can fix both the
size and concentricity problems in one operation. Note that the collets
are hardened, so don't expect to turn them right -- you will have to
grind them to the right size, using a toolpost grinder on the lathe.
You will have to spend quite a bit of time protecting the bed
and other precision surfaces from the abrasives from the grinding
operations.
And every time you change out one collet for another, you will
need to clean the taper and bore of the collet adaptor or some grit will
hold the next collet off-center so it will wind up no better, and
perhaps worse than before.
I would suggest that you not worry about the accuracy of the
collets until you *need* it. Normally, even the inexpensive collets are
significantly better that a 3-jaw chuck.
(Which reminds me, I have to get a taper attachment).
For what projects? And is one available for your lathe? You
may have to make one from scratch.
Another issue is that my set of 5C collets were packed in four
different kinds of packages, which would probably mean they are even
more inconsistent.
http://s290.photobucket.com/albums/l...t=IMG_0165.jpg
Or perhaps they were selected as the best (or the worst) of what
came in. If the different packaging means different makers, it may
still not make much difference -- they may still all be pretty good.
Good Luck,
DoN.
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