On 2008-03-12, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:
On 2008-03-11, Joseph Gwinn wrote:
[ ... ]
It's a city thing, as we live off the residue of what had been a
technological civilization.
Well ... I'm pretty close to a city -- but not one engaged in
manufacturing of anything other than legislation. :-)
So, the necessary tool is a snowblower? Or a ****shovel.
Yep -- not much use in our shops.
And the Chinese are learning how to make these as well.
But -- are they learning to make them *well*?
Not yet, but they will soon enough. You remember when Made in Japan
meant junk. Now it's the good stuff.
Oh yes -- I remember my set of butter-steel drill bits. :-) This
was around 1961 or so, IIRC. But since I was driving them with a
hand-cranked eggbeater drill, they still served fairly well for my needs
at the time.
Yep. The Chinese will figure it out before the Indians do, it seems.
I believe so.
[ ... ]
Well, file a flat, before hardening.
Or -- use my surface grinder to grind the flat -- since I used
the surface grinder to grind the Acme profile with custom relief angles
for the particular thread pitch and diameter which I was cutting. The
final pass was grinding back the tip until it fit the Acme thread gauge
for width.
Surface grinders can be had around here for reasonable money, but no
place to put one.
Mine is a 4x8" one (or is it 4x6" -- a benchtop one made by
Sanford (now out of business but in business when I got the grinder, so
I got perhaps the last set of manuals from them before they went under.
[ ... ]
All we want are their bits, not their lathes.
But you were saying "Jewelers and clockmakers do this kind of
stuff all the time" -- suggesting that "this kind of stuff" meant
internal threading -- and I was pointing out that they were unlikely
to be threading -- internal or external -- on their lathes.
I think clockmakers do cut threads.
Not with jeweler's lathes. They use "screw plates" (multiple
dies on a single piece of steel to cut external threads, and taps for
cutting internal threads.
The axis perpendicular to the bed ways is also loose, but far less so.
While my compound leadscrew was quite tight (and still is),
while the cross-slide was the one with 0.075" backlash (3/4 of a turn of
the crank).
Wonder why. Demands of production, I suppose.
Certainly. Remember that the lathe had a bed turret, so most
cutting was done with the tooling on the turret. The cross-slide was
power feed and used for parting off -- and probably nothing else -- so
it got used a lot, while the crank on the compound was likely used only
for fine tuning of cutter position vs a bed stop. Probably set up
parallel to the ways.
The Clausing does have the power cross-feed, but the top (compound) axis
is the loosest.
But in your lathe, since it did not have a bed turret, the
compound was used a lot more relative to the cross-slide. In
particular, it is used a lot when doing single-point threading, cutting
bevels, cutting short steep tapers, and sometimes set up parallel to the
ways for fine position adjusting relative to a bed stop.
It was *because* mine was supplied with a bed turret that almost
all of the wear was on the cross-slide -- under power feed to part off
parts formed by the turret tooling.
[ ... ]
Ahh. Interestingly, the Dorian Tool catalog of toolposts has an
annotated drawing of a lathe naming the various parts of said lathe.
And what names do *they* use? I don't have that catalog.
Moving up from the bed ways, the items are called the cross-slide and
the compound respectively. Same as your terminology.
Good!
[ ... ]
So, even within Clausing, the nomenclature varies. Thus the
confusion.
I think that the "cross slide" is a stable term, and anything
else is presumed to be the compound.
OK. As good a rule as we are likely to find.
Good -- we agree on this.
[ ... ]
I still think that "cross slide" is sufficiently unambiguous.
OK. Perhaps that term is stable enough to be used without obsessive
explanation. What's above the cross slide seems to be the issue.
At least what it is called. :-)
[ ... ]
I'm going to Aloris as well.
The better way for almost everything. Unless you get to one of
those really expensive toolposts which let the tool holders lock at 15
degree intervals. :-)
Like the MultiFix.
Yes. I never seem to remember the name of that one. If I had
one, I would be searching for more tool holders on eBay, so I would have
the name refreshed easily.
I'm sorely tempted by a #22, the theory being that this replaces a
number of individual toolholders, and I'm more interested in flexibility
than simplicity.
Hmmm ... I would have to dig into the MSC catalog to figure out
a #22.
O.K. I see what it is now. It might be nice for occasional
tasks where a weird angle is needed, but for most purposes, I find the
BXA-16N to handle things nicely, with a pair of holders with straight
ahead mounted tools to cut bevels. The BXA-22 looks like a pain to
re-set in the middle of a task, so having it as the only one is not what
makes sense to me -- kind of like having a 3-in-1 machine where you have
to tear down the milling setup to turn a part needed for completing the
milling. :-)
Interesting. Why 16N versus plain 16?
Simple -- with the plain 16, you have to use inserts which have
a relief angle ground on them. With the 16N, the relief is formed from
right-angle edges by tilting the insert to provide the negative rake.
When used with inserts with the proper chipbreaker groove, it is in
effect cutting with a positive rake, even though the insert is held in a
negative rake position. Since the edge of the insert is square to the
plane of the insert, it can have a chipbreaker groove on each side, so
the triangular insert can provide six working points, instead of three
-- you use the first three, then you flip it over to use the second
three. At the price of good inserts, this is a worthwhile saving.
Plus, it will let me try true negative rake inserts some of these days
to see how they do in my machine.
And -- I was *already* using negative inserts with the positive
chipbreaker groove (and had 200 of them) with previous tooling, two of
them straight ahead, which provide two equal angles on either side of the
tip making them good for beveling edges, and one each of the right and
left turning holders, which have been mostly retired with the 16N tool
holder, which holds two inserts -- one for turning, and one for facing,
with a single common height adjustment working for both.
The BXA-22 strikes me as disturbing the indexing of the tool
every time you change its angle, which negates one of the major benefits
of the quick-change toolpost -- that each time you replace the tool, it
in precisely the same position, so when you are making a production run
on something which requires multiple tools you can keep using the same
readings on the dials or on a DRO or dial indicators mounted to display
cross-slide position.
I'm also sore tempted by a #5C, which accepts 5C collets and allows me
to utilize all those round shank tools.
Hmm ... I've got whatever the holder is which offers a 3MT
socket (matching the tailstock socket) which lets me put in anything
which I can use in the tailstock -- including drill chucks, of course.
I've thought of that, but I have lots of tools with cylindrical shanks,
especially boring bars.
Well ... there is a holder specifically for the larger boring
bars. The BXA size has a 1" bore, plus a sleeve to reduce it to the
next size down.
For smaller boring bars with round shanks (e.g. the kind used
in boring heads) the BXA-2 holders have a shallow 'V' in the bottom of
the tool slot to keep round-shanked boring bars from rotating as you
tighten the setscrews. And the good solid carbide boring bars (with the
brazed on steel head to accept inserts) have a flat ground on the top
and the bottom, so the standard BXA-1 tool holders are a good choice
there. The same applies to the insert holders for internal threading
inserts. And for most purposes, the BXA-2 holders work well enough for
square shanked tools as well, since the bottom 'V' is not full width.
Hmm ... the BXA-1S would be nice to have a few of, too.
But mostly, a collection of BXA-1 and BXA-2 tool holders is the
most useful general thing to have -- enough so each tool you use can
live in its own holder so the height adjustment can be left set for that
tool. Aside from the normal turning tools, there are inside and outside
threading tools (the outside threading tool is in my one BXA-13 holder,
since it gives support closer to the insert when you have it extended
enough to thread close to a live center. If I had one of the
four-station toolposts with the indexable base I would want a BXA-13L to
get even closer to the end of the workpiece.
I also have a BXA-6 which I expect to set up to both part off
one workpiece and groove the next in one pass next time I go into
production mode with the turret. (The #6 will hold multiple tools at
once).
BTW -- I note that the BXA-4 does not specify how far the
centerline of the bore is from the dovetail, so the are not promising
that you could use a set of them as a replacement for a turret. :-)
Note just above the 5C holder is the #35, which holds a drill
chuck, but in such a way as to have better clearance from the the end of
the workpiece in a short bed leg. (Yes, I am looking through the PDF
file of the catalog.)
Note that the BXA-22 also uses negative rake inserts, so if you
get that, it would be worth while also having the 16N so you could share
a single stock of inserts between both holders.
The #23 looks interesting -- offering two different angles of
attack in a single holder.
Hmm ... the #15 looks as though it would hold the PCD
(PolyCrystaline Diamond) inserts which I have. Those are very nice for
non-ferrous workpieces, but not for ferrous.
The #19 knurling tool I have and like. The #10 I only use for a
facing toolholder, not for knurling.
The #7 cut-off tool holder is good with the right blades.
I would like to have the #71 or the #77, but I don't, yet.
Hmm ... the BXA-H looks interesting for mounting a rear parting
tool.
[ ... ]
It'll be a few years before the issue becomes salient for me. I'm still
chasing down causes of and cures for chatter.
Interestingly enough, the 5418 does not seem to experience much
chatter.
The latest observation is that if I pry the workpiece up wrt the
cross-slide, the workpiece moves far more than the 3-jaw chuck, so it
may be that the workpiece is too irregular for the 3-jaw to get a firm
grip on.
Hmm ... this sounds like bell-mouthed chuck jaws -- ones more
worn at the tailstock end than at the headstock end, so it can't keep
the workpiece from tilting a bit under load.
Does your three-jaw chuck have two-piece jaws? If so, the first
test is to install soft top jaws and bore them to a reasonable fit on
the workpiece before clamping the workpiece. If this makes a big
difference, it is time to get a new set of hardened top jaws for general
use, and use the soft jaws when it really matters.
This was discovered while I was trying to figure out why the
cutoff bar in the BXA-7 holder chattered so badly. This theory that
it's the workpiece will be tested. What will also be tested is cutoffs
using a collet chuck. I did tighten the various gibs a bit, to no avail.
Did you try something soft, like mild aluminum or better soft
copper between the jaws and the workpiece?
Good luck,
DoN.
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