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Default PM 1440 - First Failure

Well, I just had my first failure with my PM 1440. The cam-lock on the
tailstock broke. This lathe has been just so amazing compared to my other
Chinese lathes that I got my feelings hurt. LOL.

It wasn't a particulary hard fix. I had to pull and split the tailstock to
remove the shaft, cam, and pull block. I found the cam was held to the
shaft with a spring pin (or roll pin if you prefer). It had broken. I know
why it had broken. Spring pins are strong, but not as strong as you might
think. When ever I do some heavier drilling (like clear a hole with a 1"
drill bit) I tend to bump the handle firmly with my hand. That cumulative
force surely is what caused the pin to break.

The other issues is the pin is in my opinion a little short for the job. I
think its a standard length pin though as I had several the same length in a
box of assorted spring pins I bought a while back for emergencies. I think
as a result the shorter than full depth engagement in the cam allows it to
flex more when I bump the handle. Since I had a pin and I was in the middle
of a project I put it back together and dialed the tailstock back in. I may
find it hard to break the habit of bumping the handle so eventually I am
sure it will fail again. When it does I would like to be ready with a
better solution. My first thought was to use a solid stainless dowel cut to
length. Throw some Loctite on it and call it a day. Drilling and reaming
for a nice light interferrence fit might be tedious, but its within my
capability. Just a few tenths so it stays in place, but can be driven out
easily enough. If the fit is to both parts, the cam and the shaft, there
shouldn't be any slop to allow the pin to cause wear. Are there any
issues with that? The other thought I had was to make a new cam that has to
be pressed onto the shaft eliminating another other possible play/wear
issue. A one piece shaft and cam is not a practical solution. I'd have to
drill out the side of the tail stock and the insert a bushing to support the
shaft. Not impossible, but a lot of unnecessary work and seriously
overkill. On the other hand it would probably outlast me. LOL.

This brings us to failure number two. After I put it back together I threw
a piece of stock in the chuck and turned a point to align the tailstock to.
Then I threw a dead center in the tail stock and started lining up the
points. When I got out my loupe I found the center was blunt. Looked like
maybe it was dropped. I couldn't see it with just my glasses on, but it was
clear to see with the loupe. Thinking maybe I dropped it and didn't
remember I got one out of the tool cart that had never been used before. It
was also blunt. It was a nice tiny dome, but it was blunt. Orders of
magnitude bigger than the tip on my turned point. Atleast it seemed uniform
so I dialed it in as best I could. I realize even with hardened and ground
steel handling is coming to take off needle tips from an object that heavy,
so maybe that's the norm. I don't know. Both centers came with the lathe so
perhaps they are just lower grade Chinese parts. Do all dead centers have a
domed tip when looked at under a glass?





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Default PM 1440 - First Failure

"Bob La Londe" wrote in message
news
...Do all dead centers have a domed tip when looked at under a
glass?


Ever hear of "Machinist's Elbow", caused by forgetting to remove the
center?

Since you may want to machine to finer precision than you can see, the
better way to center the tailstock is with a chucked indicator riding
on the conical surface. A quick check is to grab a milling edge finder
in both the spindle and tailstock chucks.
--jsw


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Default PM 1440 - First Failure

"Jim Wilkins" wrote in message
news
"Bob La Londe" wrote in message
news
...Do all dead centers have a domed tip when looked at under a glass?


Ever hear of "Machinist's Elbow", caused by forgetting to remove the
center?

Since you may want to machine to finer precision than you can see, the
better way to center the tailstock is with a chucked indicator riding on
the conical surface. A quick check is to grab a milling edge finder in
both the spindle and tailstock chucks.
--jsw


I figured I'd use an indicator to dial it in closer when I need it. Not
sure I agree about the edge finder. I am sure my tail stock drill chuck
isn't "that" good, and I tend to leave the three jaw on the head stock for
speed. I keep trying to convince myself I can learn to be as fast as the
guys showing off on YouTube with their 4 jaw, but I don't think I have
another two ot three decades to master that skill. LOL.



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Default PM 1440 - First Failure

On Monday, November 28, 2016 at 12:34:15 PM UTC-5, Bob La Londe wrote:

This brings us to failure number two. After I put it back together I threw
a piece of stock in the chuck and turned a point to align the tailstock to.
Then I threw a dead center in the tail stock and started lining up the
points. When I got out my loupe I found the center was blunt. Looked like
maybe it was dropped. I couldn't see it with just my glasses on, but it was
clear to see with the loupe. Thinking maybe I dropped it and didn't
remember I got one out of the tool cart that had never been used before. It
was also blunt. It was a nice tiny dome, but it was blunt. Orders of
magnitude bigger than the tip on my turned point. Atleast it seemed uniform
so I dialed it in as best I could. I realize even with hardened and ground
steel handling is coming to take off needle tips from an object that heavy,
so maybe that's the norm. I don't know. Both centers came with the lathe so
perhaps they are just lower grade Chinese parts. Do all dead centers have a
domed tip when looked at under a glass?


I don't know whether this is common knowledge or not, but an old machinist showed me how to get the alignment pretty damned close without a loupe. You bring the two points together, and capture a piece of flat stock between them - he used his 60 degree center gauge. Any misalignment becomes immediately obvious by the tilt of the metal.
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Default PM 1440 - First Failure


"rangerssuck" wrote in message
...
On Monday, November 28, 2016 at 12:34:15 PM UTC-5, Bob La Londe wrote:

This brings us to failure number two. After I put it back together I
threw
a piece of stock in the chuck and turned a point to align the tailstock
to.
Then I threw a dead center in the tail stock and started lining up the
points. When I got out my loupe I found the center was blunt. Looked
like
maybe it was dropped. I couldn't see it with just my glasses on, but it
was
clear to see with the loupe. Thinking maybe I dropped it and didn't
remember I got one out of the tool cart that had never been used before.
It
was also blunt. It was a nice tiny dome, but it was blunt. Orders of
magnitude bigger than the tip on my turned point. Atleast it seemed
uniform
so I dialed it in as best I could. I realize even with hardened and
ground
steel handling is coming to take off needle tips from an object that
heavy,
so maybe that's the norm. I don't know. Both centers came with the lathe
so
perhaps they are just lower grade Chinese parts. Do all dead centers have
a
domed tip when looked at under a glass?


* I don't know whether this is common knowledge or not, but an old machinist
* showed me how to get the alignment pretty damned close without a loupe.
* You bring the two points together, and capture a piece of flat stock
between
* them - he used his 60 degree center gauge. Any misalignment becomes
* immediately obvious by the tilt of the metal.

That makes perfect sense. I use a metal scale all the time to set the
height of tool holders. Don't know why I didn't think of doing that between
centers. Nice.




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Default PM 1440 - First Failure

"Bob La Londe" wrote in message
news
"Jim Wilkins" wrote in message
news
"Bob La Londe" wrote in message
news
...Do all dead centers have a domed tip when looked at under a
glass?


Ever hear of "Machinist's Elbow", caused by forgetting to remove
the center?

Since you may want to machine to finer precision than you can see,
the better way to center the tailstock is with a chucked indicator
riding on the conical surface. A quick check is to grab a milling
edge finder in both the spindle and tailstock chucks.
--jsw


I figured I'd use an indicator to dial it in closer when I need it.
Not sure I agree about the edge finder. I am sure my tail stock
drill chuck isn't "that" good, and I tend to leave the three jaw on
the head stock for speed. I keep trying to convince myself I can
learn to be as fast as the guys showing off on YouTube with their 4
jaw, but I don't think I have another two ot three decades to master
that skill. LOL.


A trick for that is to zero the indicator dial with the crossfeed on a
low jaw, rotate halfway to the high jaw, then adjust out half the
reading. Two revolutions get me within a few thousandths, then I
position the indicator for equal + and - deflections around a major
division.
--jsw


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Default PM 1440 - First Failure



"Bob La Londe" wrote in message news
The other issues is the pin is in my opinion a little short for the job.


Bob, I don't know how much trouble you want to go to on this job, but you
might consider reaming for a taper pin.

Tom

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Default PM 1440 - First Failure

On Mon, 28 Nov 2016 10:34:08 -0700, "Bob La Londe"
wrote:

Well, I just had my first failure with my PM 1440. The cam-lock on the
tailstock broke. This lathe has been just so amazing compared to my other
Chinese lathes that I got my feelings hurt. LOL.

It wasn't a particulary hard fix. I had to pull and split the tailstock to
remove the shaft, cam, and pull block. I found the cam was held to the
shaft with a spring pin (or roll pin if you prefer). It had broken. I know
why it had broken. Spring pins are strong, but not as strong as you might
think. When ever I do some heavier drilling (like clear a hole with a 1"
drill bit) I tend to bump the handle firmly with my hand. That cumulative
force surely is what caused the pin to break.

The other issues is the pin is in my opinion a little short for the job. I
think its a standard length pin though as I had several the same length in a
box of assorted spring pins I bought a while back for emergencies. I think
as a result the shorter than full depth engagement in the cam allows it to
flex more when I bump the handle. Since I had a pin and I was in the middle
of a project I put it back together and dialed the tailstock back in. I may
find it hard to break the habit of bumping the handle so eventually I am
sure it will fail again. When it does I would like to be ready with a
better solution. My first thought was to use a solid stainless dowel cut to
length. Throw some Loctite on it and call it a day. Drilling and reaming
for a nice light interferrence fit might be tedious, but its within my
capability. Just a few tenths so it stays in place, but can be driven out
easily enough. If the fit is to both parts, the cam and the shaft, there
shouldn't be any slop to allow the pin to cause wear. Are there any
issues with that? The other thought I had was to make a new cam that has to
be pressed onto the shaft eliminating another other possible play/wear
issue. A one piece shaft and cam is not a practical solution. I'd have to
drill out the side of the tail stock and the insert a bushing to support the
shaft. Not impossible, but a lot of unnecessary work and seriously
overkill. On the other hand it would probably outlast me. LOL.

This brings us to failure number two. After I put it back together I threw
a piece of stock in the chuck and turned a point to align the tailstock to.
Then I threw a dead center in the tail stock and started lining up the
points. When I got out my loupe I found the center was blunt. Looked like
maybe it was dropped. I couldn't see it with just my glasses on, but it was
clear to see with the loupe. Thinking maybe I dropped it and didn't
remember I got one out of the tool cart that had never been used before. It
was also blunt. It was a nice tiny dome, but it was blunt. Orders of
magnitude bigger than the tip on my turned point. Atleast it seemed uniform
so I dialed it in as best I could. I realize even with hardened and ground
steel handling is coming to take off needle tips from an object that heavy,
so maybe that's the norm. I don't know. Both centers came with the lathe so
perhaps they are just lower grade Chinese parts. Do all dead centers have a
domed tip when looked at under a glass?


If you are worried that the tail stock center doesn't come to a sharp
point just grind it.

Back in the days of turning between centers it was a common job for
apprentices. Make sure that both the headstock and center were clean
and had no burrs, install the tail stock center in the head stock and
re-grind it with the tool post grinder. Usually both centers were
ground at the same time.
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Default PM 1440 - First Failure

On 11/28/2016 12:34 PM, Bob La Londe wrote:
... Do all dead centers have a
domed tip when looked at under a glass?


Why would one want it to be sharp? Other than for aligning the tail stock?


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Default PM 1440 - First Failure

On 2016-11-28, Bob La Londe wrote:
Well, I just had my first failure with my PM 1440. The cam-lock on the
tailstock broke. This lathe has been just so amazing compared to my other
Chinese lathes that I got my feelings hurt. LOL.


[ ... ]

This brings us to failure number two. After I put it back together I threw
a piece of stock in the chuck and turned a point to align the tailstock to.
Then I threw a dead center in the tail stock and started lining up the
points. When I got out my loupe I found the center was blunt. Looked like
maybe it was dropped. I couldn't see it with just my glasses on, but it was
clear to see with the loupe. Thinking maybe I dropped it and didn't
remember I got one out of the tool cart that had never been used before. It
was also blunt. It was a nice tiny dome, but it was blunt. Orders of
magnitude bigger than the tip on my turned point. Atleast it seemed uniform
so I dialed it in as best I could. I realize even with hardened and ground
steel handling is coming to take off needle tips from an object that heavy,
so maybe that's the norm. I don't know. Both centers came with the lathe so
perhaps they are just lower grade Chinese parts. Do all dead centers have a
domed tip when looked at under a glass?


Well ... there are hardened centers, designed to go in the
tailstock, and mild centers, designed to go in the headstock and be
trued up before use. The hardened centers are more likely to have good
sharp tips.

But remember -- the center drills are designed to drill a small
hole followed by a 60 degree countersink so the point normally floats in
air -- or in whatever lubricant you may have put in the center hole. :-)

As an alternative way to center the tailstock -- do you have a
Blake Coax or one of the import clones thereof? If so, put the shank of
the coax in a collet or in the chuck (collet is better, if you have
them), and set the finger to either trace the ID of the Morse taper
socket in the tailstock ram -- or put the center in and trace on the OD
of it. Set the spindle to a slow speed (back gear) and adjust the
tailstock to minimize the wiggle of the needle. Note that some lathes
when new come with the tailstock just a little above center, so as the
tailstock wears, it first gets closer to center before it starts getting
worse, so you proably won't be able to find a truly wiggle free position.

Good Luck,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) 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 ---


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Default PM 1440 - First Failure

"tdacon" wrote in message
news


"Bob La Londe" wrote in message news
The other issues is the pin is in my opinion a little short for the job.


Bob, I don't know how much trouble you want to go to on this job, but you
might consider reaming for a taper pin.

Tom


That's probably the best idea yet for the next time it fails. A tapered
solid pin will be stronger, and it has the advantage of being able to be
tapped out. As opposed to a solid dowel Loctited in place that would also
require heat to knock out. It was already all back together with another
under engineered spring pin when I posted, but as I said before I expect it
to fail again.

Thank you.


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Default PM 1440 - First Failure


"John B Slocomb" wrote in message
...
On Mon, 28 Nov 2016 10:34:08 -0700, "Bob La Londe"
wrote:

Well, I just had my first failure with my PM 1440. The cam-lock on the
tailstock broke. This lathe has been just so amazing compared to my other
Chinese lathes that I got my feelings hurt. LOL.

It wasn't a particulary hard fix. I had to pull and split the tailstock
to
remove the shaft, cam, and pull block. I found the cam was held to the
shaft with a spring pin (or roll pin if you prefer). It had broken. I
know
why it had broken. Spring pins are strong, but not as strong as you might
think. When ever I do some heavier drilling (like clear a hole with a 1"
drill bit) I tend to bump the handle firmly with my hand. That cumulative
force surely is what caused the pin to break.

The other issues is the pin is in my opinion a little short for the job.
I
think its a standard length pin though as I had several the same length in
a
box of assorted spring pins I bought a while back for emergencies. I
think
as a result the shorter than full depth engagement in the cam allows it to
flex more when I bump the handle. Since I had a pin and I was in the
middle
of a project I put it back together and dialed the tailstock back in. I
may
find it hard to break the habit of bumping the handle so eventually I am
sure it will fail again. When it does I would like to be ready with a
better solution. My first thought was to use a solid stainless dowel cut
to
length. Throw some Loctite on it and call it a day. Drilling and reaming
for a nice light interferrence fit might be tedious, but its within my
capability. Just a few tenths so it stays in place, but can be driven out
easily enough. If the fit is to both parts, the cam and the shaft, there
shouldn't be any slop to allow the pin to cause wear. Are there any
issues with that? The other thought I had was to make a new cam that has
to
be pressed onto the shaft eliminating another other possible play/wear
issue. A one piece shaft and cam is not a practical solution. I'd have
to
drill out the side of the tail stock and the insert a bushing to support
the
shaft. Not impossible, but a lot of unnecessary work and seriously
overkill. On the other hand it would probably outlast me. LOL.

This brings us to failure number two. After I put it back together I
threw
a piece of stock in the chuck and turned a point to align the tailstock
to.
Then I threw a dead center in the tail stock and started lining up the
points. When I got out my loupe I found the center was blunt. Looked
like
maybe it was dropped. I couldn't see it with just my glasses on, but it
was
clear to see with the loupe. Thinking maybe I dropped it and didn't
remember I got one out of the tool cart that had never been used before.
It
was also blunt. It was a nice tiny dome, but it was blunt. Orders of
magnitude bigger than the tip on my turned point. Atleast it seemed
uniform
so I dialed it in as best I could. I realize even with hardened and
ground
steel handling is coming to take off needle tips from an object that
heavy,
so maybe that's the norm. I don't know. Both centers came with the lathe
so
perhaps they are just lower grade Chinese parts. Do all dead centers have
a
domed tip when looked at under a glass?


If you are worried that the tail stock center doesn't come to a sharp
point just grind it.

Back in the days of turning between centers it was a common job for
apprentices. Make sure that both the headstock and center were clean
and had no burrs, install the tail stock center in the head stock and
re-grind it with the tool post grinder. Usually both centers were
ground at the same time.


I might do that, but I think I'll indicate it in next time I need real
precision. I do have a cheap crap coaxial indicator and a couple decent
Last Word indicators that haven't been dropped yet. I'm sure I can make one
of the work ok.

I don't have a tool post grinder. I am working on a tool post cross drill
though.




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Default PM 1440 - First Failure

"Bob Engelhardt" wrote in message
news
On 11/28/2016 12:34 PM, Bob La Londe wrote:
... Do all dead centers have a
domed tip when looked at under a glass?


Why would one want it to be sharp? Other than for aligning the tail
stock?


Um... ok. LOL. Thanks Bob.


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Default PM 1440 - First Failure

"DoN. Nichols" wrote in message
...
On 2016-11-28, Bob La Londe wrote:
Well, I just had my first failure with my PM 1440. The cam-lock on the
tailstock broke. This lathe has been just so amazing compared to my
other
Chinese lathes that I got my feelings hurt. LOL.


[ ... ]

This brings us to failure number two. After I put it back together I
threw
a piece of stock in the chuck and turned a point to align the tailstock
to.
Then I threw a dead center in the tail stock and started lining up the
points. When I got out my loupe I found the center was blunt. Looked
like
maybe it was dropped. I couldn't see it with just my glasses on, but it
was
clear to see with the loupe. Thinking maybe I dropped it and didn't
remember I got one out of the tool cart that had never been used before.
It
was also blunt. It was a nice tiny dome, but it was blunt. Orders of
magnitude bigger than the tip on my turned point. Atleast it seemed
uniform
so I dialed it in as best I could. I realize even with hardened and
ground
steel handling is coming to take off needle tips from an object that
heavy,
so maybe that's the norm. I don't know. Both centers came with the lathe
so
perhaps they are just lower grade Chinese parts. Do all dead centers
have a
domed tip when looked at under a glass?


Well ... there are hardened centers, designed to go in the
tailstock, and mild centers, designed to go in the headstock and be
trued up before use. The hardened centers are more likely to have good
sharp tips.


I don't think eaither dead center I have is hardened. I may just have to go
out and spend a 3 dollars on one. There are times when I really need a dead
decenter rather than a live center for turning.


But remember -- the center drills are designed to drill a small
hole followed by a 60 degree countersink so the point normally floats in
air -- or in whatever lubricant you may have put in the center hole. :-)


But... But... But... I might forget.

As an alternative way to center the tailstock -- do you have a
Blake Coax or one of the import clones thereof?


Crap clone. And a couple Last Words and an inspection mirror as an
alternative.

If so, put the shank of
the coax in a collet or in the chuck (collet is better, if you have
them), and set the finger to either trace the ID of the Morse taper
socket in the tailstock ram -- or put the center in and trace on the OD
of it. Set the spindle to a slow speed (back gear) and adjust the
tailstock to minimize the wiggle of the needle. Note that some lathes
when new come with the tailstock just a little above center, so as the
tailstock wears, it first gets closer to center before it starts getting
worse, so you proably won't be able to find a truly wiggle free position.


I may try the pinched plate method just to see how it compares for results.


Good Luck,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) 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 ---



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Default PM 1440 - First Failure

On 2016-11-29, Bob La Londe wrote:
"DoN. Nichols" wrote in message
...
On 2016-11-28, Bob La Londe wrote:
Well, I just had my first failure with my PM 1440. The cam-lock on the
tailstock broke. This lathe has been just so amazing compared to my
other
Chinese lathes that I got my feelings hurt. LOL.


[ ... ]

This brings us to failure number two. After I put it back together I
threw
a piece of stock in the chuck and turned a point to align the tailstock
to.
Then I threw a dead center in the tail stock and started lining up the
points. When I got out my loupe I found the center was blunt. Looked
like


[ ... ]

so maybe that's the norm. I don't know. Both centers came with the lathe
so
perhaps they are just lower grade Chinese parts. Do all dead centers
have a
domed tip when looked at under a glass?


Well ... there are hardened centers, designed to go in the
tailstock, and mild centers, designed to go in the headstock and be
trued up before use. The hardened centers are more likely to have good
sharp tips.


I don't think eaither dead center I have is hardened. I may just have to go
out and spend a 3 dollars on one. There are times when I really need a dead
decenter rather than a live center for turning.


BTW -- at one time, a "live center" was simply the rotating
center in the headstock spindle, and the dead was one in the tailstock.
They were otherwise identical -- if the same Morse taper. Once we
started getting centers mounted in bearings so they could rotate in the
tailstock, the name drifted.

And the "live" one in the spindle was typically soft so it could
be trued *just* before mounting the workpiece. The "dead" one in the
tailstock was more likely to be hardened.

And have you ever seen a "half center"? A hardened center for
the tailstock with almost half of the diameter ground off so a facing
tool could get to the center hole to finish the end of a shaft. I've
got one of those -- but too small for my main lathe. Nice for doing
things that the ball bearing center won't allow.

But remember -- the center drills are designed to drill a small
hole followed by a 60 degree countersink so the point normally floats in
air -- or in whatever lubricant you may have put in the center hole. :-)


But... But... But... I might forget.


In which case, let it remind you. :-)

Old lathes tended to have a cavity in the casting near the front
where the ram comes out, and a plug/dipper in there. It used to be
filled with white lead to use as a high-pressure lubricant for the dead
center -- before the world got scared to death of lead and mercury. :-)

As an alternative way to center the tailstock -- do you have a
Blake Coax or one of the import clones thereof?


Crap clone. And a couple Last Words and an inspection mirror as an
alternative.


O.K. So you have those as an option.

If so, put the shank of
the coax in a collet or in the chuck (collet is better, if you have
them), and set the finger to either trace the ID of the Morse taper
socket in the tailstock ram -- or put the center in and trace on the OD
of it. Set the spindle to a slow speed (back gear) and adjust the
tailstock to minimize the wiggle of the needle. Note that some lathes
when new come with the tailstock just a little above center, so as the
tailstock wears, it first gets closer to center before it starts getting
worse, so you proably won't be able to find a truly wiggle free position.


I may try the pinched plate method just to see how it compares for results.


I didn't mention the pinched plate because of the questionable
state of your centers. I first learned about that in the manual for a
Unimat SL-1000 (where the headstock rotated instead of the tailstock
offset for turning long tapers). And they showed a double-edge razor
blade as the pinched plate. I often use a 6" scale for quick-and-dirty
center checking.

Enjoy,
DoN.

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Default PM 1440 - First Failure

On Tuesday, November 29, 2016 at 8:32:01 PM UTC-5, DoN. Nichols wrote:
On 2016-11-29, Bob La Londe wrote:
"DoN. Nichols" wrote in message
...
On 2016-11-28, Bob La Londe wrote:
Well, I just had my first failure with my PM 1440. The cam-lock on the
tailstock broke. This lathe has been just so amazing compared to my
other
Chinese lathes that I got my feelings hurt. LOL.

[ ... ]

This brings us to failure number two. After I put it back together I
threw
a piece of stock in the chuck and turned a point to align the tailstock
to.
Then I threw a dead center in the tail stock and started lining up the
points. When I got out my loupe I found the center was blunt. Looked
like


[ ... ]

so maybe that's the norm. I don't know. Both centers came with the lathe
so
perhaps they are just lower grade Chinese parts. Do all dead centers
have a
domed tip when looked at under a glass?

Well ... there are hardened centers, designed to go in the
tailstock, and mild centers, designed to go in the headstock and be
trued up before use. The hardened centers are more likely to have good
sharp tips.


I don't think eaither dead center I have is hardened. I may just have to go
out and spend a 3 dollars on one. There are times when I really need a dead
decenter rather than a live center for turning.


BTW -- at one time, a "live center" was simply the rotating
center in the headstock spindle, and the dead was one in the tailstock.
They were otherwise identical -- if the same Morse taper. Once we
started getting centers mounted in bearings so they could rotate in the
tailstock, the name drifted.

And the "live" one in the spindle was typically soft so it could
be trued *just* before mounting the workpiece. The "dead" one in the
tailstock was more likely to be hardened.


It's good you brought that up. A lot of more recent home machinists may not realize this. A live center is one driven under power. A tailstock center with ball bearings is...a ball-bearing dead center. d8-)

For precise work, you mount the live center and turn a new point on it with the lathe compound. Then punch a witness mark on it, and a matching one on the center collet, so you can line them up again later for less-precise work.



And have you ever seen a "half center"? A hardened center for
the tailstock with almost half of the diameter ground off so a facing
tool could get to the center hole to finish the end of a shaft. I've
got one of those -- but too small for my main lathe. Nice for doing
things that the ball bearing center won't allow.

But remember -- the center drills are designed to drill a small
hole followed by a 60 degree countersink so the point normally floats in
air -- or in whatever lubricant you may have put in the center hole. :-)


But... But... But... I might forget.


In which case, let it remind you. :-)

Old lathes tended to have a cavity in the casting near the front
where the ram comes out, and a plug/dipper in there. It used to be
filled with white lead to use as a high-pressure lubricant for the dead
center -- before the world got scared to death of lead and mercury. :-)


Mine is still filled with white lead (1945 South Bend 10L). My tin of it is almost empty, though.

--
Ed Huntress



As an alternative way to center the tailstock -- do you have a
Blake Coax or one of the import clones thereof?


Crap clone. And a couple Last Words and an inspection mirror as an
alternative.


O.K. So you have those as an option.

If so, put the shank of
the coax in a collet or in the chuck (collet is better, if you have
them), and set the finger to either trace the ID of the Morse taper
socket in the tailstock ram -- or put the center in and trace on the OD
of it. Set the spindle to a slow speed (back gear) and adjust the
tailstock to minimize the wiggle of the needle. Note that some lathes
when new come with the tailstock just a little above center, so as the
tailstock wears, it first gets closer to center before it starts getting
worse, so you proably won't be able to find a truly wiggle free position.


I may try the pinched plate method just to see how it compares for results.


I didn't mention the pinched plate because of the questionable
state of your centers. I first learned about that in the manual for a
Unimat SL-1000 (where the headstock rotated instead of the tailstock
offset for turning long tapers). And they showed a double-edge razor
blade as the pinched plate. I often use a 6" scale for quick-and-dirty
center checking.

Enjoy,
DoN.

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Default PM 1440 - First Failure

On 29 Nov 2016 04:28:36 GMT, "DoN. Nichols"
wrote:

On 2016-11-28, Bob La Londe wrote:
Well, I just had my first failure with my PM 1440. The cam-lock on the
tailstock broke. This lathe has been just so amazing compared to my other
Chinese lathes that I got my feelings hurt. LOL.


[ ... ]

This brings us to failure number two. After I put it back together I threw
a piece of stock in the chuck and turned a point to align the tailstock to.
Then I threw a dead center in the tail stock and started lining up the
points. When I got out my loupe I found the center was blunt. Looked like
maybe it was dropped. I couldn't see it with just my glasses on, but it was
clear to see with the loupe. Thinking maybe I dropped it and didn't
remember I got one out of the tool cart that had never been used before. It
was also blunt. It was a nice tiny dome, but it was blunt. Orders of
magnitude bigger than the tip on my turned point. Atleast it seemed uniform
so I dialed it in as best I could. I realize even with hardened and ground
steel handling is coming to take off needle tips from an object that heavy,
so maybe that's the norm. I don't know. Both centers came with the lathe so
perhaps they are just lower grade Chinese parts. Do all dead centers have a
domed tip when looked at under a glass?


Well ... there are hardened centers, designed to go in the
tailstock, and mild centers, designed to go in the headstock and be
trued up before use. The hardened centers are more likely to have good
sharp tips.

But remember -- the center drills are designed to drill a small
hole followed by a 60 degree countersink so the point normally floats in
air -- or in whatever lubricant you may have put in the center hole. :-)

As an alternative way to center the tailstock -- do you have a
Blake Coax or one of the import clones thereof? If so, put the shank of
the coax in a collet or in the chuck (collet is better, if you have
them), and set the finger to either trace the ID of the Morse taper
socket in the tailstock ram -- or put the center in and trace on the OD
of it. Set the spindle to a slow speed (back gear) and adjust the
tailstock to minimize the wiggle of the needle. Note that some lathes
when new come with the tailstock just a little above center, so as the
tailstock wears, it first gets closer to center before it starts getting
worse, so you proably won't be able to find a truly wiggle free position.

Good Luck,
DoN.

Good post and good advise.

I simply use the razorblade method of tailstock center adjustment.
Works fine for most of my work, which is .000/+.001 at most


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Default PM 1440 - First Failure

On Tuesday, November 29, 2016 at 10:12:54 PM UTC-5, wrote:

snip

BTW, traditionally, dead centers are hardened only for the last 1/4 inch or so. All of mine are, and they're 60 years old or more. The hardening leaves a distinctively different color to the steel -- the result is a cone 1/4" long on the very end -- so it's easy to tell when one is a hardened center or not.

--
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Default PM 1440 - First Failure

On 30 Nov 2016 01:31:13 GMT, "DoN. Nichols"
wrote:


And have you ever seen a "half center"? A hardened center for
the tailstock with almost half of the diameter ground off so a facing
tool could get to the center hole to finish the end of a shaft. I've
got one of those -- but too small for my main lathe. Nice for doing
things that the ball bearing center won't allow.


I probably have 10 of those, from #1 MT to #5 MT..the headstock size
on my 15x58


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Default PM 1440 - First Failure

On 2016-11-30, Gunner Asch wrote:
On 30 Nov 2016 01:31:13 GMT, "DoN. Nichols"
wrote:


And have you ever seen a "half center"? A hardened center for
the tailstock with almost half of the diameter ground off so a facing
tool could get to the center hole to finish the end of a shaft. I've
got one of those -- but too small for my main lathe. Nice for doing
things that the ball bearing center won't allow.


I probably have 10 of those, from #1 MT to #5 MT..the headstock size
on my 15x58


O.K. But does it also match the tailstock? I can't see using a
half-center in the headstock. :-)

Enjoy,
DoN.

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