On 2010-06-28, Searcher7 wrote:
On Jun 26, 8:17*pm, "DoN. Nichols" wrote:
On 2010-06-26, Searcher7 wrote:

[ ... ]

The small ring is knurled, but that is all.

* * * * But is it knurled deep enough to allow the pin on the end of the
small rod to act to spin it on or off?

Well, I guess so, if I wanted to damage the knurls, but the rod is not
a tight fit, and I could just as easily use a screw driver, dowel,
etc. In fact I can get the ring on tighter with my fingers while press-
turning it.

Damage the knurls? I was assuming a slip fit of the pin in
beside the ring and with light pressure being used to spin the ring on
to a reasonable position.

Since it was packaged with the collet holder, I keep trying to
find a reasonable use for it. Perhaps some previous owner had bigger
fingers and needed that to reach down into the area.

[ ... ]

* * * * Sure -- you could probably thread it on a little more if you
were pressing in the collet nose while installing the ring, but that
would limit the size range of the collet.

Well, if I pressed hard enough to hurt my fingers it would turn
perhaps 1/16" more.

No point to doing that anyway -- you've got plenty of travel
when closing the collet by the front ring.

[ ... ]

Thinking about the material, thickness, and shape of this bushing, if
would appear that it would have to be made up of two main parts.

* * * * I see it as only two parts -- a cylinder perhaps an inch larger
in diameter than the holder body, and a screw threaded in to close the
slot. *(Oh yes -- also the studs to mount it on the spindle nose and the
corresponding nuts. :-)

* * * * But it will need a tricky bit of work to cut the slit along one
size to allow the screw to clamp it onto the body. *You'll need the mill
and some way to mount the rather large piece of metal to do that.

How about three slits in a tapered sleeve that is bolted to the
spindle. The sleeve would be slightly thicker at the front end, and at
the base there would be a tightening collar that is I.D. threaded at
the rear and rounded at the front end? Screwing it forward would
tighten the sleeve around the collet chuck.

Make that a ring -- perhaps 1-1/2" thick, with a set of radial holes
drilled the same size as those in the bit black ring so the same tool
would work for either. Make 3/4" threaded, and then taper the other
3/4" a tapered surface to match the top portion of the holder. You
don't want the collar to have to thread all the way up from the bottom,
put the threads only on the last inch or so before the matching taper.
Probably make the tapers pretty close to the taper on the nose end of
the collets as a good start.

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.

Or perhaps a collar with a circular wedge that would be put on the
collet chuck body before inserting the body into a solid sleeve that
is bolted to the spindle. This way the collet chuck would seat first
and then the collar would be screwed back resulting in the circular
wedge sliding between the collet chuck body and the solid sleeve.

That sounds a bit more difficult to make to me -- but I may be
mis-interpreting what you are suggesting.

[ ... ]

So it comes down to this. Should I proceed with this collet chuck or
concentrate on the idea at this link:http://www.sc-c.com/metallathe/MLA21.html
(The MLA-21 would seem to be the best way to go).

* * * * 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.

* * * * Why not buy the drawing first to see what you will have to do.
The "lathe only" construction suggests that the side clearance holes for
the tommy bar access to the ring would be part of the casting -- though
a mill and a dividing head might be used to dress up the edges a bit.

* * * * Checking -- yes you still get partial credit for the drawings
which you purchased if you order them first, and the casting kit without
the drawings later.

* * * * One of the things which I consider best about this is that you
can mark the spindle and the casting where they join prior to turning
the closing taper and bore for the collet, so you will get the best
repeatability.

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.

I attempted to take the lathe out of it's box today. Unfortunately it
looks as though I'll have to tear the box off around it.

I was (and so were you) pointed to a set of pages which included
the information that the lathe base is secured to the bottom of the box
with a set of bolts -- ones which were probably bent in shipping. You
have to remove those before you can take the base out of the box.

Is your lathe the green one, or the blue one?

Something I
didn't want to do until I could put it in it's permanent location.(So
I won't be able to open the headstock just yet).

The photos on the web pages included enough information so I am
*sure* that you can't scale the spindle up to 5C bore without enlarging
almost everything about the lathe -- winding up with a poor copy of a
nicer lathe. The photos were those dealing with changing out the
plastic gears in the headstock for metal ones -- something which I
*really* think you should do, if you are going to put larger chucks on
the machine than come with it.

Are you set up to make cast iron castings? You would need that
capability to make the newer headstock -- and carriage -- and tailstock.
You would need both rather large scale casting to make a new bed, and
the ability to flame harden the surface of the ways and then grind it
with a large surface grinder to make good ways.

Really -- changing out the spindle for one which will accept 5C
collets directly is something *well* beyond your reach where you are
living.

[ ... ]

I expect that you will find that the entire OD of the spindle is
smaller than the needed bore through the spindle for a 5C collet closer.

This is why the idea is to replace the existing MT3 spindle with a 5C
spindle

* * * * What I am trying to say is that there is not enough metal in the
headstock to hold a large enough spindle (and the bearings) to accept 5C
collets.

* * * * Typically, everything else has to be scaled up when you scale up
the ID of the spindle. *Multiply the size of *everything* by 1.83,
including the spacing of front bed way from the rear. *

* * * * You have bearings at each end of the spindle, you have a gear
setup to switch speeds. *You *may* have a belt pulley in the headstock
as well. *(I did not see photos of the interior.) *All of these things
have to be increased in size by the same ratio.

I have now seen the photos -- and this tells me this is *not* a
reasonable project.

Use your lathe. Find out what it is capable of doing and what
it is not. Then will be the time to think of making or buying larger
machines.

[ ... ]

Without actually going down and measuring, I think that the OD of the
bearings on my Clausing 12x24" with a 1-3/8" spindle bore is on the
order of 5" -- which I think is larger than the dimensions of your
headstock in the area where the bearings live.

I'm sure *everything* is bigger on your Clausing than on my mini-
lathe. :-) (Including the bearings).

* * * * That is why it can accept 5C collets in a spindle adaptor -- it
is big enough. *Yours is *not* If you want to handle 5C collets, plan on
at least a 10" lathe -- which you will probably have to strip down to
components and carry them up one at a time.

* * * * I believe that even the South Bend "Heavy 10" will not handle
the 5C collets in the spindle -- just the 12" swing or larger.

I was wrong about this, at least.

[ ... ]

And the wedges are more replaceable than the toolpost body. :-)

They would cost less -- if you could find a place to buy them
separate from the toolpost.

Making new ones would probably be easier. (After all, I have the
templates). :-)

* * * * If you are up to cutting a three-start internal thread on an interrupted
cut. *

Well, I'm not thinking of making the internal cylinder. I won't worry
about that and concentrate on sliming down the existing wedges.

But if you have to make the wedges, you need some way to hold
them (fixture them) while you turn the partial threads on the internal
surface to engage those on the OD of the cylinder.

And look at the complexity of the other parts of the wedge. *You
have to make some of those to use for fixturing while you cut the
threads.

I'm not sure what that means. But outside of measuring everything
accurately, determining the correct cutters would seem to be the
biggest issue. I can visually see inconsistency from one thread to the
next.(The depth shape and the width). So the margin for error is
relatively high.

Maybe -- maybe not. But the question is how are you expecting
to hold a partial shape so you can machine another surface. You have to
plan the sequence carefully -- and make things that will hold those
intermediate shapes.

Nevertheless, that's a bridge I'm don't intend to cross. All I need to
do is work on the existing wedges.

Good!

But I think that they would be easier to file or sand down in the
critical area.

How about emery paper on the edge of a glass plate? (Or perhaps I can
use this item I won on eBay: 330442158063)

* * * * Hmm ... depends on the quality of the surface plate. *He says
that he checked it flat with a square. :-) To *really* check it, you
need a setup with a micro-inch reading sensor traveling on arms
supported above the surface. *The lowest grade should be flat within
0.000050" (50 micro-inches), and as the grade goes up, the number of
allowed micro-inches of deviation go down. *There is no way you are
going to check that with a square. :-)

Yes, I know. :-) BTW. This surface plate is on my next Enco purchase
list: http://www.use-enco.com/CGI/INSRIT?P...PMAKA=640-0120

(When it is no longer back ordered). :-(

O.K. That one is class-B (20 micro-inches), and dirt cheap for
the duration of the sale. It is not a 2-ledge one, which is a bit more
convenient for holding certain types of measuring tools onto it.

But once you have it -- you can use it for a check on how good
your metal one is. Smear the surface of the granite one with thinned
spotting blue (expect your hands, and everything else around to turn
blue too :-), then slide the metal upside down on the granite and look
at the pattern of transfer of the dye. Large areas with no die pickup
indicate problems -- perhaps something has hit the surface of the metal
plate and forced bulges around a dent. (That is one benefit of the
granite -- it just makes a tiny hole, with no bulges.)

Be sure to clean both surfaces properly when you are done, and
rub the metal one down with an oil to prevent rusting.

* * * * But if it is not sufficiently accurate, it should work fine for
your task. *(Be sure to keep the abrasive grit from getting on the
surface anyway.)

* * * * A piece of glass perhaps 1/4" or 3/8" thick should suffice for
the purpose of adjusting the wedge. *Remember to keep trying it
frequently for fit, or you could get too small.

Thanks.

I'm assuming that a jig wouldn't be needed to accurately remove
material equally along the length of the wedges.

If you have a flat surface on the wedge which meets the
dovetail's angles surface, you can probably simply slide that face flat
on some fine emery paper on a hard flat surface.

Yes, that's the plan.

* * * * I would still go for tuning the gap in the wedge myself. *Or --
sell it on eBay and get a better one.

I wouldn't want anyone else to run into the same difficulty I have, so
I concentrate on fixing the problem.

O.K.

(I've also been following a thread on another site concerning a
related project involving someone making their own toolholders.
http://madmodder.net/index.php?topic=3206.0).

Interesting -- including the false start of wanting to make
holders of brass. Bronze -- maybe. Brass -- no!

BTW * * There has been a discussion of Shars tools on the local
* * * * metalworking mailing list, and the general opinion is that
* * * * they are very good -- with specific good reports on the
* * * * clone of the Kurt vises.

I have only corresponded with ne individual after seeing a thread of
his on one of these type vise, and he told me to run from the Shars,
and get the one from Little Machine Shop instead.(They were on sale at
the time and I didn't get my answer before the sale ended). His
message to me is as follows:

"I would turn and RUN from the Shars vise. Look at the cutouts in the
side, back near the handle, how ragged the casting is. Then look at
the key that aligns the fixed vise with the main casting. I would rate
the LMS vise out of the box at a 5 out of 10, and an 8 after rework. I
give the Shars vise a 3 out of the box and would fear having to
rebuild it. Just my honest opinion."

O.K. Different opinions -- and I have not personally seen the
vise, but the owner (a local mailing list member) seemed to be very
happy with his -- after checking precision everywhere that mattered.

[ ... ]

* * * * Essentially, you are rotating a feeler around the center point
of the spindle and measuring how much it goes up or down. *Since the
table is interrupted by the T-slots, something of precise thickness and
ground smooth (e.g. a bearing outer race) can give a surface for the
feeler to travel over without problems.

Ok. I understand. I'm considering something cheap(eBay) from
Shars(Discount_Machine): 330353712711

And as usual, 800watt, which sells the same tools as Shars is cheaper:
140419776972

Note that the first price is a buy-it-now, so you know what it
will cost while the other is a starting bid -- and if they have shills,
you may not get it for anything near that amount.

Shipping seems to be close to the same with the first being
shipped to my zip code, not yours (since I don't know it nor do I want
to know it) and the other a fixed shipping price.

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---