So, after implementing the ridged plate with index-pin hole to keep the
Dickson-style toolpost from rotating while performing cutoffs, and using
a 0.5x0.5" HSS tool (versus 0.25x0.25), everything was peachy until I
tried to take a cut 4" from the chuck in a mild steel bar 1-3/8" in
diameter. What a noise that made. The entire lathe shook. Even with
fairly shallow cuts. The tailstock chuck fell out of the tailstock
taper (no harm done). And the tool-slide (upper) handwheel started to
turn by itself. It was always too easy to move, and I had noted that
the reduction in work piece diameter did not match the change in
cross-slide (lower) handwheel position. Hmm. I bet it's creeping, even
when not obviously moving.

The gib between tool post slide (Clausing part number 704-033, page 30)
and the top of the compound (704-034) is the one I could not adjust, for
unknown reasons.

So, I disassembled the upper assembly, the thing that rotates to set the
cutting angle. As expected, it was pretty dirty, and there were signs
that it had been partially wet at one time.

One of the swivel bolts (055-017) had been stretched by too forceful
tightening. Filed the top off a bit so it wouldn't pinch against the
underside of the compound slide and break that thin cast-iron web. I'll
have to make a new swivel bolt.

The two 10-24x 5/8" hex socket cap screws that attach the dial hub
(382-029) to the tool post slide were mangled -- it seems that the holes
were not tapped deeply enough, or the screws were too long, but the
screws were driven home anyway. So, re-tapped the holes, and
re-threaded the cap screws.

It took some careful tapping with a drift, but got the gib (345-023) out
without difficulty. Apparently, some prior owner did not understand how
to use the gib adjusting screws (696-089) - loosen one before tightening
the other, and managed to break the critical corners of both ends of the
gib off, leaving ramps. It must have taken considerable force. So,
when one tightened the make-tighter adjuster (next to the dial hub), it
instead pinched the gib against the wall. The gib is also unevenly
worn. And was loose. So, after filing some upset areas down, turned
the gib over. It isn't perfect, but it will have to do for now.

I suppose one can make a gib by hand, although a surface grinder would
come in real handy. Two surfaces are parallel, while two taper towards
one another at a shallow angle, and the cross section is always a
trapezoid.

Anyway, put it all back together with nice clean Mobil 1 grease on the
tool post screw and thrust bearings (no oil ports for these), and Vactra
#2 way oil everywhere else, and got the tool post slide tight enough so
it does not move by itself.

Fortunately, the larger cross-slide gib (345-022) does not appear to
have been butchered. I have not yet taken that whole assembly apart,
but I have taken the cross-slide off the saddle, removing, cleaning, and
adjusted the gib.

My suspicion is that the water caused rusting of ways, and the problem
was solved with muscle, not brain.

Anyway, all this helped a lot, and I made the first part, a collar for
use in the toolpost.

Cutting that steel with a big carbide-tipped bit was absolutely
peaceful. It made hardly any noise as the chips curled off by the foot,
and left a very nice surface. I wonder if the steel was leaded. It
came with the lathe, and was rusty as hell. But it was soft to the
file, even where there had been a welding puddle, so I went ahead and
used it.

Now, I get chatter if I try to take a 0.030" to 0.050" cut with the
carbide tool, which has a nose diameter of something like 0.100" (which
is large). My question is how heavy a cut I should be able to make on
this lathe, to have some idea when I have succeeded is solving the major
problems.

Joe Gwinn

Joseph Gwinn wrote:

performing cutoffs, and using
a 0.5x0.5" HSS tool (versus 0.25x0.25), everything was peachy until I
tried to take a cut 4" from the chuck in a mild steel bar 1-3/8" in
diameter.

What!? You are making cutoffs with 12 x 12 mm bits!?
You don't have to wonder if there is chatter, noise and vibration. 4mm wide
for a 50mm deep cut is OK, but the bit has do be *considerably* higher.
My HSS-blade is 2,7 mm wide and 11mm high. Good for 40mm (diam.) cutoffs.
The carbide inserts blade is 32mm high and the width is 3mm. That is OK for
100mm diameter cutoffs.
Get real tools.

Considering the leaded (supposedly) steel with a weld. Can't be, can't weld
leaded steel. It makes bubbles while welding.


Nick
--
The lowcost-DRO:
http://www.yadro.de

"Joseph Gwinn" wrote in message
...
So, after implementing the ridged plate with index-pin hole to keep the
Dickson-style toolpost from rotating while performing cutoffs, and using
a 0.5x0.5" HSS tool (versus 0.25x0.25), everything was peachy until I
tried to take a cut 4" from the chuck in a mild steel bar 1-3/8" in
diameter. What a noise that made. The entire lathe shook. Even with
fairly shallow cuts. The tailstock chuck fell out of the tailstock
taper (no harm done). And the tool-slide (upper) handwheel started to
turn by itself. It was always too easy to move, and I had noted that
the reduction in work piece diameter did not match the change in
cross-slide (lower) handwheel position. Hmm. I bet it's creeping, even
when not obviously moving.

The gib between tool post slide (Clausing part number 704-033, page 30)
and the top of the compound (704-034) is the one I could not adjust, for
unknown reasons.

So, I disassembled the upper assembly, the thing that rotates to set the
cutting angle. As expected, it was pretty dirty, and there were signs
that it had been partially wet at one time.

One of the swivel bolts (055-017) had been stretched by too forceful
tightening. Filed the top off a bit so it wouldn't pinch against the
underside of the compound slide and break that thin cast-iron web. I'll
have to make a new swivel bolt.

The two 10-24x 5/8" hex socket cap screws that attach the dial hub
(382-029) to the tool post slide were mangled -- it seems that the holes
were not tapped deeply enough, or the screws were too long, but the
screws were driven home anyway. So, re-tapped the holes, and
re-threaded the cap screws.

It took some careful tapping with a drift, but got the gib (345-023) out
without difficulty. Apparently, some prior owner did not understand how
to use the gib adjusting screws (696-089) - loosen one before tightening
the other, and managed to break the critical corners of both ends of the
gib off, leaving ramps. It must have taken considerable force. So,
when one tightened the make-tighter adjuster (next to the dial hub), it
instead pinched the gib against the wall. The gib is also unevenly
worn. And was loose. So, after filing some upset areas down, turned
the gib over. It isn't perfect, but it will have to do for now.

I suppose one can make a gib by hand, although a surface grinder would
come in real handy. Two surfaces are parallel, while two taper towards
one another at a shallow angle, and the cross section is always a
trapezoid.

Anyway, put it all back together with nice clean Mobil 1 grease on the
tool post screw and thrust bearings (no oil ports for these), and Vactra
#2 way oil everywhere else, and got the tool post slide tight enough so
it does not move by itself.

Fortunately, the larger cross-slide gib (345-022) does not appear to
have been butchered. I have not yet taken that whole assembly apart,
but I have taken the cross-slide off the saddle, removing, cleaning, and
adjusted the gib.

My suspicion is that the water caused rusting of ways, and the problem
was solved with muscle, not brain.

Anyway, all this helped a lot, and I made the first part, a collar for
use in the toolpost.

Cutting that steel with a big carbide-tipped bit was absolutely
peaceful. It made hardly any noise as the chips curled off by the foot,
and left a very nice surface. I wonder if the steel was leaded. It
came with the lathe, and was rusty as hell. But it was soft to the
file, even where there had been a welding puddle, so I went ahead and
used it.

Now, I get chatter if I try to take a 0.030" to 0.050" cut with the
carbide tool, which has a nose diameter of something like 0.100" (which
is large). My question is how heavy a cut I should be able to make on
this lathe, to have some idea when I have succeeded is solving the major
problems.

Joe Gwinn

The depth and feed of any given cut will hinge a great deal on the power and
rigidity of the machine in question, but you can take this to the bank::
stay away from large radius tools unless they are absolutely necessary.
Anything beyond 1/16" is asking for grief on light duty machines, which
would include the Clausing. Mind you, I'm thinking of machines similar to
a Mori-Seiki, Axelson or Monarch when I judge the Clausing. I'm not
implying it's not a decent machine. It is-----it's just not heavy duty, and
not well suited to running form tools.

I might suggest that you may be able to pull a cut of .100" depth per side,
with .010" feed when roughing, in steel. Could be wrong. All depends
on how tight the machine is, and if you have the horsepower, as I stated.
I can reduce 3" steel @ .200" per side, .012" feed, negative rake, with my
3 hp Graziano Sag 12.

Harold

In article ,
Nick Mueller wrote:

Joseph Gwinn wrote:

performing cutoffs, and using
a 0.5x0.5" HSS tool (versus 0.25x0.25), everything was peachy until I
tried to take a cut 4" from the chuck in a mild steel bar 1-3/8" in
diameter.

What!? You are making cutoffs with 12 x 12 mm bits!?

No. The cutoff blade is 3/32 inch (2.4 mm) wide, and chattered
instantly, right at the surface of the rod.


You don't have to wonder if there is chatter, noise and vibration. 4mm wide
for a 50mm deep cut is OK, but the bit has do be *considerably* higher.
My HSS-blade is 2,7 mm wide and 11mm high. Good for 40mm (diam.) cutoffs.
The carbide inserts blade is 32mm high and the width is 3mm. That is OK for
100mm diameter cutoffs.

The chatter begins right at the surface.

The blade is ~12 mm high by 2.4 mm wide, and works OK in 5/8" (16 mm)
stock, but failed for 35 mm diameter stock, but by your experience it
should have worked. As discussed, I think it's some combination of
loose dovetails and the Rube Goldberg setup holding the cutoff blade.

You are implying a required ratio between blade width and stock
diameter, which makes sense. Do you have a source for such a ratio?

What we do know is that the ratio exceeds 40/2.7= 14.8:1 for the HSS
blade and 100/3=33:1 for the carbide insert blade.


Get real tools.

They are real. Loose dovetails will undermine the best of tooling, so
the dovetails are getting the attention. Followed by a better cutoff
tool for sure.


Considering the leaded (supposedly) steel with a weld. Can't be, can't weld
leaded steel. It makes bubbles while welding.

The bar was not welded to anything, but there was a frozen weld puddle
at one end. Perhaps they were testing, saw it bubble, used something
else.

Joe Gwinn

In article ,
"Harold and Susan Vordos" wrote:

"Joseph Gwinn" wrote in message
...
So, after implementing the ridged plate with index-pin hole to keep the
Dickson-style toolpost from rotating while performing cutoffs, and using
a 0.5x0.5" HSS tool (versus 0.25x0.25), everything was peachy until I
tried to take a cut 4" from the chuck in a mild steel bar 1-3/8" in
diameter. What a noise that made. The entire lathe shook. Even with
fairly shallow cuts. The tailstock chuck fell out of the tailstock
taper (no harm done). And the tool-slide (upper) handwheel started to
turn by itself. It was always too easy to move, and I had noted that
the reduction in work piece diameter did not match the change in
cross-slide (lower) handwheel position. Hmm. I bet it's creeping, even
when not obviously moving.

[snip]

Cutting that steel with a big carbide-tipped bit was absolutely
peaceful. It made hardly any noise as the chips curled off by the foot,
and left a very nice surface. I wonder if the steel was leaded. It
came with the lathe, and was rusty as hell. But it was soft to the
file, even where there had been a welding puddle, so I went ahead and
used it.

Now, I get chatter if I try to take a 0.030" to 0.050" cut with the
carbide tool, which has a nose diameter of something like 0.100" (which
is large). My question is how heavy a cut I should be able to make on
this lathe, to have some idea when I have succeeded is solving the major
problems.

Joe Gwinn

The depth and feed of any given cut will hinge a great deal on the power and
rigidity of the machine in question, but you can take this to the bank::
stay away from large radius tools unless they are absolutely necessary.
Anything beyond 1/16" is asking for grief on light duty machines, which
would include the Clausing.

I was suspicious of the radius being too large.


Mind you, I'm thinking of machines similar to
a Mori-Seiki, Axelson or Monarch when I judge the Clausing. I'm not
implying it's not a decent machine. It is-----it's just not heavy duty, and
not well suited to running form tools.

I know, the Clausing is only 1000 pounds or so, which is heavy for home
use but light by industrial standards.


I might suggest that you may be able to pull a cut of .100" depth per side,
with .010" feed when roughing, in steel. Could be wrong. All depends
on how tight the machine is, and if you have the horsepower, as I stated.
I can reduce 3" steel @ .200" per side, .012" feed, negative rake, with my
3 hp Graziano Sag 12.

The Clausing is 2 HP. I'm still tightening things up. We'll see what I
can do with a more pointed tool.


Joe Gwinn

Harold and Susan Vordos wrote:


The depth and feed of any given cut will hinge a great deal on the power and
rigidity of the machine in question, but you can take this to the bank::
stay away from large radius tools unless they are absolutely necessary.
Anything beyond 1/16" is asking for grief on light duty machines, which
would include the Clausing. Mind you, I'm thinking of machines similar to
a Mori-Seiki, Axelson or Monarch when I judge the Clausing. I'm not
implying it's not a decent machine. It is-----it's just not heavy duty, and
not well suited to running form tools.

I might suggest that you may be able to pull a cut of .100" depth per side,
with .010" feed when roughing, in steel. Could be wrong. All depends
on how tight the machine is, and if you have the horsepower, as I stated.
I can reduce 3" steel @ .200" per side, .012" feed, negative rake, with my
3 hp Graziano Sag 12.

Harold



Harold

Your pretty much right on, I usually rough with my 5904 at .100" a side
and .006 or.008" feed, and while definitely working it isn't
uncomfortable. I've pushed this machine harder but you sorta get that
'don't turn your back on it' feeling.

Regards
Paul

--
-----------------------------------------
It's a Linux world....well, it oughta be.
-----------------------------------------

"Paul" wrote in message
. ..
Harold and Susan Vordos wrote:


The depth and feed of any given cut will hinge a great deal on the power
and rigidity of the machine in question, but you can take this to the
bank:: stay away from large radius tools unless they are absolutely
necessary. Anything beyond 1/16" is asking for grief on light duty
machines, which would include the Clausing. Mind you, I'm thinking of
machines similar to a Mori-Seiki, Axelson or Monarch when I judge the
Clausing. I'm not implying it's not a decent machine. It is-----it's
just not heavy duty, and not well suited to running form tools.

I might suggest that you may be able to pull a cut of .100" depth per
side, with .010" feed when roughing, in steel. Could be wrong. All
depends on how tight the machine is, and if you have the horsepower, as I
stated. I can reduce 3" steel @ .200" per side, .012" feed, negative
rake, with my 3 hp Graziano Sag 12.

Harold

Harold

Your pretty much right on, I usually rough with my 5904 at .100" a side
and .006 or.008" feed, and while definitely working it isn't
uncomfortable. I've pushed this machine harder but you sorta get that
'don't turn your back on it' feeling.

Regards
Paul

The nature of the tool makes a huge difference. Are you using HSS? With
a proper chip breaker, that should be a nice cut, yielding a coiled chip, if
not broken. I've always accepted coils in lieu of breaking. They're much
safer to handle than strings, and are easy to clean up. Best part is, if
you're used to running negative rake at high speed, you don't get those
nasty blue chips that fly off the jaws and burn to your skin.

Harold

Joseph Gwinn wrote:

performing cutoffs, and using a 0.5x0.5" HSS tool (versus 0.25x0.25),
everything was peachy until I tried to take a cut 4" from the chuck
in a mild steel bar 1-3/8" in diameter.

What!? You are making cutoffs with 12 x 12 mm bits!?

No. Â*The cutoff blade is 3/32 inch (2.4 mm) wide, and chattered
instantly, right at the surface of the rod.

So I misunderstood that. Sorry.
Learning how to part off initially takes some nerves and maybe some blades
you will break 'till you got it.
It has been said many times:
Do not try to slowly part off. If the blade quiiiiks, feed quicker. Don't
start with scratching around, but *feed*. Increase feed until you get a
nice chip and keep that feed *constant*- That means that a automatic
cross-feed is the best. If not available, use both hands to turn the crank.
The third hand is used to lubricate. :-)

The blade is ~12 mm high by 2.4 mm wide, and works OK in 5/8" (16 mm)
stock, but failed for 35 mm diameter stock,

That should work too, depending on the material. Lubricate but don't
hesitate.

You are implying a required ratio between blade width and stock
diameter, which makes sense. Â*Do you have a source for such a ratio?

No source. Experience. Also depends on the material. I wouldn't use my
HSS-blade on 40mm aluminium. I had too many bad experiences. :-)

What we do know is that the ratio exceeds 40/2.7= 14.8:1 for the HSS
blade and 100/3=33:1 for the carbide insert blade.

It is more the stickout (to reach to the center of the bar) and height
(rigid) of the blade. If you have a bore in the bar, you can use a lighter
blade (obviously). Only the depth of cut and the required stickout
therefore counts.

They are real. Loose dovetails will undermine the best of tooling, so
the dovetails are getting the attention. Â*Followed by a better cutoff
tool for sure.

Not that much. The sloppiness in the guides doesn't count *that* much,
because cutting forces will move the parts where they have to be G. What
counts more is how rigid things are. Note that there is *no* contradiction
between sloppiness and rigidness. As long as you keep the feed constant,
the cutting force is constant. As soon as you feel uncomfortable and reduce
the feed, things will start to move and start to chatter.

A friend has the same carbide insert blade I do have (but a lighter lathe)
and he has broken already two of the holders, I'm still using the first
insert (on the first holder). I really don't know what he is doing (I'll
have to visit him to see). But when he visited me and asked me to show it
he saw that they work. Coolant on, cross feed on and off it goes. More
feed? If you want! Faster? If you want. Even faster? No, look at the chips,
they are starting to look bad, that's the limit. Slower? No, chips are
getting bad, that's the lower limit. Without coolant? Not with this RPM,
but with less, yes.
You see, you have to try it. But blades aren't that forgiving. G.


Nick
--
The lowcost-DRO:
http://www.yadro.de

In article ,
Nick Mueller wrote:

Joseph Gwinn wrote:

performing cutoffs, and using a 0.5x0.5" HSS tool (versus 0.25x0.25),
everything was peachy until I tried to take a cut 4" from the chuck
in a mild steel bar 1-3/8" in diameter.

What!? You are making cutoffs with 12 x 12 mm bits!?

No. Â*The cutoff blade is 3/32 inch (2.4 mm) wide, and chattered
instantly, right at the surface of the rod.

So I misunderstood that. Sorry.

OK. I think DoN's lathe is large enough, but not the 5914.


Learning how to part off initially takes some nerves and maybe some blades
you will break 'till you got it.

I haven't broken any blades yet. But it's a sure thing.


It has been said many times:
Do not try to slowly part off. If the blade quiiiiks, feed quicker. Don't
start with scratching around, but *feed*. Increase feed until you get a
nice chip and keep that feed *constant*- That means that a automatic
cross-feed is the best. If not available, use both hands to turn the crank.
The third hand is used to lubricate. :-)

I tried pushing harder, and it only shook harder. Unlike with the 5/8"
bar. I was also having chatter problems with ordinary cutting bits, so
my suspicions turned to loose joints.


The blade is ~12 mm high by 2.4 mm wide, and works OK in 5/8" (16 mm)
stock, but failed for 35 mm diameter stock,

That should work too, depending on the material. Lubricate but don't
hesitate.

I think that the fact that the blade is so far out from the toolpost
body, thus increasing the lever arm, is a cause of multiple problems. I
bet many problems will go away when I get a better toolpost.


You are implying a required ratio between blade width and stock
diameter, which makes sense. Â*Do you have a source for such a ratio?

No source. Experience. Also depends on the material. I wouldn't use my
HSS-blade on 40mm aluminium. I had too many bad experiences. :-)

What we do know is that the ratio exceeds 40/2.7= 14.8:1 for the HSS
blade and 100/3=33:1 for the carbide insert blade.

It is more the stickout (to reach to the center of the bar) and height
(rigidity) of the blade. If you have a bore in the bar, you can use a lighter
blade (obviously). Only the depth of cut and the required stickout
therefore counts.

OK.


They are real. Loose dovetails will undermine the best of tooling, so
the dovetails are getting the attention. Â*Followed by a better cutoff
tool for sure.

Not that much. The sloppiness in the guides doesn't count *that* much,
because cutting forces will move the parts where they have to be G. What
counts more is how rigid things are. Note that there is *no* contradiction
between sloppiness and rigidness. As long as you keep the feed constant,
the cutting force is constant. As soon as you feel uncomfortable and reduce
the feed, things will start to move and start to chatter.

Except that the compound and attached toolpost visibly tilted leftward
under cutoff loads, even when cutting the 5/8 bar. This really had to
be fixed, and things improved greatly after the dovetail was tightened.

Part the tilting was also due to that large lever arm.


A friend has the same carbide insert blade I do have (but a lighter lathe)
and he has broken already two of the holders, I'm still using the first
insert (on the first holder). I really don't know what he is doing (I'll
have to visit him to see). But when he visited me and asked me to show it
he saw that they work. Coolant on, cross feed on and off it goes. More
feed? If you want! Faster? If you want. Even faster? No, look at the chips,
they are starting to look bad, that's the limit. Slower? No, chips are
getting bad, that's the lower limit. Without coolant? Not with this RPM,
but with less, yes.
You see, you have to try it. But blades aren't that forgiving. G.

He may be spinning the work too slowly. I made that mistake at first,
and had problems with grabbing. In retrospect, part of the problem was
probably due to the toolpost tilting, but running faster nonetheless
helped greatly.

Joe Gwinn

Joseph Gwinn wrote:

Learning how to part off initially takes some nerves and maybe some
blades you will break 'till you got it.

I haven't broken any blades yet. Â*But it's a sure thing.

I don't think it is something to be ashamed of. At least, I have broken a
few too. HSS, that's cheaper. :-))


I tried pushing harder, and it only shook harder. Â*Unlike with the 5/8"
bar.

If you had the same stickout (not enough for 4" to part off) there should be
no difference.

I was also having chatter problems with ordinary cutting bits, so
my suspicions turned to loose joints.

Oh! If you look at the bed in a cross section, you do have 3 (yes, 3 not
just 2) guides. Two on top (one being roof-shaped) and one on the rear
*bottom*. Here, a guide of the saddle is gripping downwards (can't express
better) and prevents the saddle's rear from lifting off of the bed. You
really have to bend over your lathe to see that guide. Got me? Check that
guide and adjust it.


I bet many problems will go away when I get a better toolpost.

AXA AKA Multifix rulez! :-)


Except that the compound and attached toolpost visibly tilted leftward
under cutoff loads, even when cutting the 5/8 bar.

Outch! When parting off, move the top slide as much as possible to the
*right*. This way, it gets more/better support. But watch the jaws! EG

He may be spinning the work too slowly.

No, he broke his next holder after my instruction and show and tell. But he
didn't blame me for that. :-)


Nick
--
The lowcost-DRO:
http://www.yadro.de

Harold and Susan Vordos wrote:
"Paul" wrote in message
. ..

Harold and Susan Vordos wrote:

Harold

Your pretty much right on, I usually rough with my 5904 at .100" a side
and .006 or.008" feed, and while definitely working it isn't
uncomfortable. I've pushed this machine harder but you sorta get that
'don't turn your back on it' feeling.

Regards
Paul


The nature of the tool makes a huge difference. Are you using HSS? With
a proper chip breaker, that should be a nice cut, yielding a coiled chip, if
not broken. I've always accepted coils in lieu of breaking. They're much
safer to handle than strings, and are easy to clean up. Best part is, if
you're used to running negative rake at high speed, you don't get those
nasty blue chips that fly off the jaws and burn to your skin.

Harold



Actually the above is with inserted carbide, I'll generally rough with
carbide and finish with HSS. I've got one of those 'tangential' HSS
holders and usually can face or turn with the same tool setup. It does
preclude grinding chip breakers into it (at least its beyond my skill)
and it does tend to stringy chips.

When roughing I try for short coils that leave the tool tan and hit the
chip pan blue. I agree that the classic 'comma' chip lands on bare arms
and down shirt fronts all to often. If the chips are tight coils that
break when an inch long or so I like that the best. Coils that don't
break and snake down around the apron and chip pan make me nervous,
especially when you're approaching a shoulder and need to kick the feed out!

Paul


--
-----------------------------------------
It's a Linux world....well, it oughta be.
-----------------------------------------

In article ,
Nick Mueller wrote:

Joseph Gwinn wrote:

Learning how to part off initially takes some nerves and maybe some
blades you will break 'till you got it.

I haven't broken any blades yet. Â*But it's a sure thing.

I don't think it is something to be ashamed of. At least, I have broken a
few too. HSS, that's cheaper. :-))

My objective is to not break the lathe itself. But blades are
expendable.

The real problem is that when a blade breaks, whatever one is cutting
off is often ruined in the process.


I tried pushing harder, and it only shook harder. Â*Unlike with the 5/8"
bar.

If you had the same stickout (not enough for 4" to part off) there should be
no difference.

I was also having chatter problems with ordinary cutting bits, so
my suspicions turned to loose joints.

Oh! If you look at the bed in a cross section, you do have 3 (yes, 3 not
just 2) guides. Two on top (one being roof-shaped) and one on the rear
*bottom*. Here, a guide of the saddle is gripping downwards (can't express
better) and prevents the saddle's rear from lifting off of the bed. You
really have to bend over your lathe to see that guide. Got me? Check that
guide and adjust it.

You mean the hold-down plates and the carriage clamp plate. These are
under the ways and face up. The hold down plates are probably OK as
they are adjusted using shims, and so are pretty much user-proof. I do
use the carriage clamp when cutting off, and it does seat firmly. But I
will still look, just to be sure.


I bet many problems will go away when I get a better toolpost.

AXA AKA Multifix rulez! :-)

Ja! But they are pretty big. I'm leaning towards Aloris BXA.


Except that the compound and attached toolpost visibly tilted leftward
under cutoff loads, even when cutting the 5/8 bar.

Ouch! When parting off, move the top slide as much as possible to the
*right*. This way, it gets more/better support. But watch the jaws! EG

I did this, including getting too close to the chuck, but it didn't
help. Fixing the loose joints seems more direct.


He may be spinning the work too slowly.

No, he broke his next holder after my instruction and show and tell. But he
didn't blame me for that. :-)

Good. But you will need to watch him try cutoffs before you will be
able to figure out what is wrong.


Joe Gwinn

Joseph Gwinn wrote:

My objective is to not break the lathe itself. Â*But blades are
expendable.

Very good! ;-)

The real problem is that when a blade breaks, whatever one is cutting
off is often ruined in the process.

That's part of the learing process. No pain, no gain.

You mean the hold-down plates and the carriage clamp plate.

If the hold-down plates are on the rear, yes. The carriage clamp is on the
front. I mean the similar setup on the rear.
I suspect that your carriage's rear is lifting off. Why?
With a small diameter, the cutting force is projecting within the two guides
of the bed. With a big diameter, the force is moving outside of the guide
and thus tilting your carriage (lifting the rear).


I do use the carriage clamp when cutting off, and it does seat
firmly.

What I do with deep(er) cuts is to initially clamp the carriage and later
(after 1/3 or such) loosen it.
You also have to pay attention that the blade is dead at 90° to the spindle.
An easy way to check this is to move the carriage to the left until the
blade's side touches the chuck's face. No, not with the lathe running G.
Then you see how well it aligns or not.

Ja! Â*But they are pretty big. Â*I'm leaning towards Aloris BXA.

There's one size below size "A". It's "Aa". But you have to check tool
height.
I have similar ones to the Aloris on my small lathe. They aren't good with
repeatability. If you remove it and reinsert it, it is on a slightly
different place.
The Multifix really has an repeatability of 1/100mm. I tried this.


Good. Â*But you will need to watch him try cutoffs before you will be
able to figure out what is wrong.

Will happen when I help him install his VFD. But first, he has to help me
bring down my replacement lathe.
No, I didn't break it! It simply was well out of specs, so I finally got a
new one yesterday.


Nick
--
The lowcost-DRO:
http://www.yadro.de

In article ,
Nick Mueller wrote:

Joseph Gwinn wrote:

The real problem is that when a blade breaks, whatever one is cutting
off is often ruined in the process.

That's part of the learning process. No pain, no gain.

True enough.


You mean the hold-down plates and the carriage clamp plate.

If the hold-down plates are on the rear, yes. The carriage clamp is on the
front. I mean the similar setup on the rear.
I suspect that your carriage's rear is lifting off. Why?
With a small diameter, the cutting force is projecting within the two guides
of the bed. With a big diameter, the force is moving outside of the guide
and thus tilting your carriage (lifting the rear).

I'm not sure that this could be the mechanism, because even the larger
bar is well centered between the two rails of the way. Nor can I
imagine the person that allowed the dovetails to become so loose
concerning themselves with something like the hold-down plate. In fact,
I doubt that they could find such a plate in broad daylight.

But it's easy to check that the hold-down plates are correct.


I do use the carriage clamp when cutting off, and it does seat
firmly.

What I do with deep(er) cuts is to initially clamp the carriage and later
(after 1/3 or such) loosen it.

OK. By the way, the carriage clamp plate works on the front bed way
rail, and so would not much help if the back hold-down plate were loose.


You also have to pay attention that the blade is dead at 90° to the spindle.
An easy way to check this is to move the carriage to the left until the
blade's side touches the chuck's face. No, not with the lathe running G.
Then you see how well it aligns or not.

I've been using a little square between the bar to be cut off and the
blade. The 5/8 rod was in a collet, with no easy reference surface.

Hmm. Another difference in rigidity. The 5/8 rod was in a collet,
while the 1.35" rod was in a 3-jaw scroll chuck.


Ja! Â*But they [MultiFix] are pretty big. Â*I'm leaning towards Aloris BXA.

There's one size below size "A". It's "Aa". But you have to check tool
height.

I'm sure that there is a recommended size for any given lathe. The BXA
is what Aloris recommends for the 5914.


I have similar ones to the Aloris on my small lathe. They aren't good with
repeatability. If you remove it and reinsert it, it is on a slightly
different place.
The Multifix really has an repeatability of 1/100mm. I tried this.

I believe it, given the inherent averaging from clamping two zigzag
surfaces together. How bad was the Aloris clone repeatability?


Good. Â*But you will need to watch him try cutoffs before you will be
able to figure out what is wrong.

Will happen when I help him install his VFD. But first, he has to help me
bring down my replacement lathe.
No, I didn't break it! It simply was well out of specs, so I finally got a
new one yesterday.

You wore it out? I bought mine pre-worn.

Joe Gwinn

Joseph Gwinn wrote:

I'm not sure that this could be the mechanism, because even the larger
bar is well centered between the two rails of the way. Â*Nor can I
imagine the person that allowed the dovetails to become so loose
concerning themselves with something like the hold-down plate.

Two vectors of cutting force during parting off:
1.) pointing vertical downwards from the tip of the blade
2.) pointing horizontal outwards (along the blade) from the in-feed force

If you add the two vectors and the resulting vector is not pointing between
the two rails, the rear will lift. To prevent that, there is a 3rd guide
(rear, downside).


Nick
--
The lowcost-DRO:
http://www.yadro.de

In article ,
Nick Mueller wrote:

Joseph Gwinn wrote:

I'm not sure that this could be the mechanism, because even the larger
bar is well centered between the two rails of the way. Â*Nor can I
imagine the person that allowed the dovetails to become so loose
concerning themselves with something like the hold-down plate.

Two vectors of cutting force during parting off:
1.) pointing vertical downwards from the tip of the blade
2.) pointing horizontal outwards (along the blade) from the in-feed force

If you add the two vectors and the resulting vector is not pointing between
the two rails, the rear will lift. To prevent that, there is a 3rd guide
(rear, downside).

Right. I'm saying that given the small diameter stock (compared to the
spacing between way rails), it could be hard to arrange this. But I'll
look.

Joe Gwinn