On 2010-07-07, Searcher7 wrote:
On Jul 5, 10:40 pm, "DoN. Nichols" wrote:
On 2010-07-05, Searcher7 wrote:
[ ... ]
Ok. I have to learn a graphics app to make explanations easier.
Yes -- but make sure to get one which produces (or can produce)
an open format image, not something which is Windows specific, because I
won't be able to view it. :-)
PDF is quite easy to view on any system.
Ideally a vector program and a way to convert to PDF.
Yes. And ideally -- a free one. I can point you to one written
in Java (which means you might have to add java to your computer), which
works both on my Sun workstations under Solaris and on a Mac Mini -- the
same copy runs on both.
[ ... ]
That is why I always type in a test document(Notepad), with frequent
saves when I am typing something long.(But I don't have to worry about
"Google Groups" crashing).
Normally, my saves are automatic. My newsreader invokes the
editor of my choice (jove, FWIW) for composing articles, and if the
system crashes (most often from power failure -- the OS is rock stable),
it saves the data to recover.
I don't have power failures.(Which is amazing, considering the old
wiring in this complex). It's usually software that screws me up.
We have power failures -- usually associated with thunderstorms.
Lots of above-ground wiring and sometimes trees fall on the high voltage
lines to take them down.
I have several UPSs to maintain power under the various server
computers as well as my wife's and my workstations. Plenty of time to
shut the computers down gracefully if power fails.
[ ... ]
Yes. A realistic comparison for my lathe would be between ER32 and 3C
http://littlemachineshop.com/product...ProductID=2228
http://littlemachineshop.com/product...ProductID=1991
Note that the ER set would cover *all* sizes between the 1/8"
and the 3/4", while 3C (or 5C) collets only work close to their nominal
size.
Ok. Just to get this straight. Even with every 1/64th I'd could still
have work holding issues with the 5C/3C collets, correct?
IIRC, 5C collets have a grip range on the order of 0.007".
1/64" is easy to calculate -- 0.015625"
This is why I bought a 5mm collet -- nothing close enough in
inch sizes.
So -- the question is -- "Do you *need* to hold non-standard
dimensions? Typically -- collets are used to hold standard sized stock
and feed it through the spindle. Also -- if you want to hold short
pieces, design them to fit standard collets. Forget about holding the
world.
(I know the clamping range of an ER40 collet is .040").
Right -- 1mm. The "ER" stands for "Extended Range". Totally
different design to allow it to change this much while keeping the sides
of the bore parallel.
(The 3C would need the collet closer).
For feed-through the spindle, you would have to make your own
nose flange mount body using the other (MT-3) one as a pattern to be
able to feed through the spindle. For short things, however, you could
hold them with the MT-3 shanked adaptor and a solid drawbar.
But the real question is whether you can cut a Morse thread with
a 1.5 mm pitch. Without that, you could make everything else right, but
not be able to make something which would accept the nosepiece. The
precise thread in inch units would be 16.9333 TPI. 17 TPI would be
close but not close enough 0.0667" error in a 1" thread with 0.058" per
thread, so it would be over a full thread in error.
And 17 TPI is not likely to be found on any lathe gearbox
anyway. 16 TPI is common, 18 TPI fairly common, but 17 you would have
to find gears for -- or better metric conversions gears for the lathe.
And since it has an inch leadscrew pitch, you could not use the
threading gauge -- you would have to keep the half-nuts engaged and hand
crank the spindle backwards to the start of each threading pass.
It's a good thing I got that rotary table and making gears is at the
top of my list. :-)
Bear in mind that a real metric conversion gear set has a 127
tooth gear stacked on a common arbor with a 100 tooth gear. These tend
to get rather large compared to the design of the banjo, so there are
various approximations to true metric conversion which do fit, sort of.
And a standard dividing head won't produce 127 tooth gears from
the standard plates. The same likely applies to your rotary table, so
you will have to run a spreadsheet to print out a list of angles to set
-- lots of chances for mistakes. :-)
[ ... ]
And would ER40 instead be a problem? The sizes it covers would be
close to what my 5C set covers, so if I had to transfer work between
these collets, ER40 would seem to be the best bet.
I checked eBay, and ER-40 is available in MT-3 holder format, so
that is where you start.
Now -- I spent some time looking up the thread for the nosepiece
for an ER-32 collet holder. I don't know what the pitch is for the
ER-40, and I'll leave it to *you* to find that out. :-)
Since I now have 5C and R8 covered for milling purposes and the
discussion has moved toward ER collets, and I correct in assuming that
you think I should put the priority on getting ER instead of 3C, which
was a bigger priority than MT3?
I consider 3C to be a very good thing to have. It allows
through the spindle stock feed, and is convenient to use.
The ER is for holding larger workpieces -- up to the maximum
which will fit through the spindle, and larger for short pieces.
[ ... ]
Now -- the question is whether the end mill happens to be
sharpened properly on center. Well -- you won't be able to blame the
collets, anyway. :-)
I found myself getting heavily the whole tool-making/grinding/
sharpening area. And I'm keeping my eyes open for a tool cutter/
grinder.(Surface grinders are out, because I don't think they make
them small enough). :-)
Actually -- I've got one which is small enough. I can carry it
(with the table removed -- barely). But -- it is too small to use with
a tool and cutter grinder spindle -- or even with the end-mill
sharpening fixtures which use 5C collets.
[ ... ]
BTW Relative to an earlier part of this thread -- the Lyndex
collets. I needed a 5/8" hex collet (I had most other
hex sizes, but not the one I needed) so I ordered one from MSC
(new of course). Well ... it arrived today. The box looks the
same pattern as yours, so they must be newer than what I
originally had. Anyway -- there is no marking of Lyndex on the
collet anywhere, and from MSC, I would not expect a
substitution, especially in the same packaging. So you can feel
comfortable with the set you got.
BTW. Here are those 5C Royals I'm getting: 120585499838
O.K. Why am I looking at them? Why do I need to look at them?
[ ... ]
And you want the holding grip at the free end, not where the
holder mounts to the chuck.
Anyway, I have plenty of time to worry about this. But take a look at
the 5C collet chuck he http://www.cdcotools.com/
That is so tempting, because I have never seen it so cheap. But since
the MLA-21 is a better option I guess I should stick with that idea,
unless I definitely find out this would be too large for my lathe. If
so, then perhaps all these 5C options we're discussing are to large.
It *claims* to be precise to 0.0004 TIR -- but if it isn't,
they'll blame the backplate and mounting which you have to do to use it.
:-)
To my mind 5C collets in any adaptor are too large for your
lathe. The MLA-21 is probably the closest fit.
That's the MLA-21. The conventional 5C collet chuck. And the 5C collet
chuck that is usually held in chuck jaws.(Then there is that direct
"into the spindle" idea).
(Like I mentioned, the ability to flip the work around, center, and
machine it seamlessly to match the opposite half is what I'm after).
Then you want to turn between centers. I don't think that you
will get seamless with *any* collet system.
Cut the threads and the taper before you slit it. To slit it,
you would need the rotary table with some means of mounting the cylinder
to it. You *could* drill through the base for Allen head cap screws to
reach through the spindle flange to accept nuts. You could probably
tighten the screws with a long Allen key through the cylinder before
sliding in the collet adaptor. That would be more convenient I think.
I think I understand, but I'll have to read this a few more times. I'm
assuming you don't think a tightening ring/collar can be tighten the
grip on the chuck body effectively *without* a tool, correct? (I'm
thinking about the drawbacks of a thicker, heavier ring).
Well ... it could have a built-in tool of sorts. The ring could
be split with a pin coupling the two ends with a lever operating a cam
to clamp it. But this would mean something which is not perfectly
balanced, so it would make the lathe dance at higher spindle speeds.
And the ring I described could be loosened and tightened with
the same tool that the collet closer part is -- so one fewer thing to
deal with. Just slide in the pin, twist, and done.
The great thing is that I wouldn't need to thread the bar. The turned
down end fits in the un-threaded holes.
Yes. You actually *have* the bar you need already. The
threaded holes would only make sense when using it as part of a fixture
on a mill, where it is not rotating.
[ ... ]
I don't like the slits in the rear half. That makes it less
rigid. Make the back half as close a sliding fit as possible, and slit
the open end so the ring can clamp at that end -- closer to the place
where the cutting forces are applied.
The body is 2.750" long and the idea was to use the forward .750".
The rear 2" would seat. And a .500" collar on the front would screw
rearward only .250" max., wedging itself between the 5C chuck and
front part of hold it is seated in.(But again, I'll get back to all of
this).
I really think that putting *anything* between the chuck and the
front part is poor planning. Squeeze the adaptor body down at the nose
end with a tapered fit and ring and slits.
Or better -- forget it until you have a way to use 5C collets
anyway. :-)
I agree that the MLA-21 would be the better choice. What
remains to be seen is how difficult the machining is to make it from the
castings.
[ ... ]
I'm starting to think that this should be my first project.
I think perhaps the first *serious* project -- after you have
turned a lot of metal into chips playing with the lathe to learn it
first. Remember -- proper project castings cost more than cheap metal
to play with.
Ok. BTW. I received a reply back from Andrew concerning the MLA-21. He
said that my lathe does strike him as being a bit small for the collet
chuck, both for mounting it and making it.
I agree. You really need a larger lathe for a lot of what you
want to do.
If you had a friend in the area who had a larger lathe, he could
help you to build the MLA-21, leaving only the problems of actually
using it.
Well, you mentioned that it should be made on my lathe. correct?
I mentioned that the taper inside the nose and the bore should
be turned on your lathe. Those can be the last things to do.
[ ... ]
Why? It will be a bit easier to move around and examine without
the pallet. This is a lathe small enough so you should be able to lift
it by yourself, after all. The pallet was to keep the lathe from
shifting around in the box and damaging parts packed around it.
Right now it is next to my mill/drill in the kitchen on this big
butcher block table I won off eBay for $60. :-)
O.K. Still in the box -- or do you have it out of the box now?
Is your lathe the green one, or the blue one?
It's the red one. I think the new ones now are grey.
Oh -- collect a whole rainbow. :-)
I guess it's a marketing thing. But they do now have a 7" x 16". The
biggest difference being the 500 watt (0.67hp) adjustable-speed
brushless DC motor. As opposed to my 350 watt (0.47 hp) adjustable-
speed commutator-equipped DC motor with digital readout. (My machine
is still a little heavier).
I'm not at all sure that a longer one is that good an idea,
especially with more horsepower, as it increases the chance of the bet
winding up under heavy cutting.
Really -- changing out the spindle for one which will accept 5C
collets directly is something *well* beyond your reach where you are
living.
Ok. Let me throw out one more idea. What would be the plausibility of
a new spindle design with enough mass at the front to allow a threaded
bore that accept a 5C collet directly, eliminating the need for a
collet chuck, and still allowing pass-through of .75" and under?
How big is the diameter of the register in front of the
chuck-mount flange? Compare that to the diameter of the front of the
collet -- and add the thickness of enough steel to make it strong. If
you make such a change, you will probably have to make an entire new set
of back plates for chuck mounting.
If this is possible, a back plate or two would be the least of my
worries. :-)
(BTW. I also wouldn't be able to use reverse with the collets in such
a set up).
I don't like it.
[ ... ]
Remember -- your chucks can hold things very nicely. If you
want to avoid marring from the grip of the jaws -- perhaps you should
think of building a collet nosepiece for some ER style collets.
Generally, the nose cap is the hardest thing to make -- so get just the
nose cap, or the nose cap and a MT-3 shank body, and use the MT-3 shank
one as a pattern when making a body to fit your spindle nose. You have
the options of an ER series just big enough to pas the 3/4" workpieces
through the spindle, or a larger one which could be used for gripping
short workpieces.
O.K. ER-25 goes up to 5/8" from a start of 1/16". A little
small for your 3/4" through passage.
ER-32 goes up to 3/4"
This eBay auction (and lots of others) is a ER-32 collet chuck
with a MT-3 shank:
390084614108
And some ER40 options:
330372938101
390216414569
140424332828
I won't bother tracing them. Just make your choice and move.
*Use* the lathe. Until you do work with it, you won't really
know what it can and can't do.
Good luck,
DoN.
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