I was thinking about your comments on knee automation and had this thought.
Do you really need to CNC control the knee in order to get the positioning
you wanted except maybe for an extremely few parts? Why not just put a DRO
of some type on that knee. Maybe not a fancy made for application one.
Just a simple digital caliper (over sized for your ap of course) like used
by a lot of the mini lathe guys on their tail stock. Or you could shop for
deals until you find a fancy DRO at an auction somewhere.

I'm dealing with a lot of these same ideas on the Hurco retrofit, and I
started with the concept of using an independent control just for raising
and lower the knee, but then I thought, "Gee. Its not that hard to crank,
and even if I do need to move it its only going to be once or twice during a
fairly complex part." If it were hard to crank I could throw any old DC
servo on it that's strong enough and power it from a variable voltage power
supply for speed to move and slow speed to position with a DPDT spring
loaded toggle switch. Maybe some diodes for protection of the switch.

Bob La Londe wrote:

I was thinking about your comments on knee automation and had this thought.
Do you really need to CNC control the knee in order to get the positioning
you wanted except maybe for an extremely few parts? Why not just put a DRO
of some type on that knee. Maybe not a fancy made for application one.
Just a simple digital caliper (over sized for your ap of course) like used
by a lot of the mini lathe guys on their tail stock. Or you could shop for
deals until you find a fancy DRO at an auction somewhere.

I'm dealing with a lot of these same ideas on the Hurco retrofit, and I
started with the concept of using an independent control just for raising
and lower the knee, but then I thought, "Gee. Its not that hard to crank,
and even if I do need to move it its only going to be once or twice during a
fairly complex part." If it were hard to crank I could throw any old DC
servo on it that's strong enough and power it from a variable voltage power
supply for speed to move and slow speed to position with a DPDT spring
loaded toggle switch. Maybe some diodes for protection of the switch.



You don't even need a DRO on the knee if you're doing tool touchoff to
set the tool length offset. Indeed a single touchoff of a previously
measured tool after a knee reposition will give you the offset to apply
to the rest of the previously measured tools. There really isn't any
reason to power the knee unless you plan to lock off the quill and use
the knee as your Z.

On 2011-01-18, Bob La Londe wrote:
I was thinking about your comments on knee automation and had this thought.
Do you really need to CNC control the knee in order to get the positioning
you wanted except maybe for an extremely few parts? Why not just put a DRO
of some type on that knee. Maybe not a fancy made for application one.
Just a simple digital caliper (over sized for your ap of course) like used
by a lot of the mini lathe guys on their tail stock. Or you could shop for
deals until you find a fancy DRO at an auction somewhere.

I'm dealing with a lot of these same ideas on the Hurco retrofit, and I
started with the concept of using an independent control just for raising
and lower the knee, but then I thought, "Gee. Its not that hard to crank,
and even if I do need to move it its only going to be once or twice during a
fairly complex part." If it were hard to crank I could throw any old DC
servo on it that's strong enough and power it from a variable voltage power
supply for speed to move and slow speed to position with a DPDT spring
loaded toggle switch. Maybe some diodes for protection of the switch.

Bob, I am still stuck working on my 4th axis and I do not want to get
into too much detail in the knee.

But I already have a nice servo ready DC gearmotor with a shaft for
the encoder. All I will need to do to automate the knee is

1) Put encoder on the DC motor
2) Make a bracket to mount DC gearmotor
3) Add limit switches to the knee
4) Configure EMC

and I think that what I will get amounts to a huge value for not too
much cost. The motor cost me $40 and the limit/home switch $40 IIRC.

There are very many parts where tool length differs by more than 4.5
inches, and without CNC knee, I would have to split programs into
pieces to get done with what I want, plus I have to re-zero positions
etc.

i

On Jan 18, 10:11*am, Ignoramus5053
wrote:
On 2011-01-18, Bob La Londe wrote:


I was thinking about your comments on knee automation and had this thought.
Do you really need to CNC control the knee in order to get the positioning
you wanted except maybe for an extremely few parts?

There are very many parts where tool length differs by more than 4.5
inches, and without CNC knee, I would have to split programs...

How accurate is the table level as a function of knee height? Are
there any options for implementing the knee lock, then re-zeroing the
work position?

"Pete C." fired this volley in news:4d35d419$0
:

There really isn't any
reason to power the knee unless you plan to lock off the quill and use
the knee as your Z.


Well, Pete, actually there is a good reason.

I don't know what Iggy does, but I do a LOT of work where I have to find
the center of existing old parts to machine new features in them. Many
are plastic, which means I have to use a centering indicator instead of
an edge finder.

Being that my centering indicator is more than 4" taller than my longest
cutting tool, that puts me in the mode of _continually_ cranking the knee
up and down to make headroom for it, then going back to my usual machine
Z for the cutters. It gets wearisome. I will eventually power my knee,
but I see no reason for DROs and the like. I just go (as was said) for a
touch-off of a known tool, and done.

LLoyd

whit3rd fired this volley in news:807bb7b6-2f38-4804-
:

Are
there any options for implementing the knee lock, then re-zeroing the
work position?


GOOD question! The one thing you don't want to do is work a critical
piece without locking the knee, and the OTHER thing you don't want to do
is start slewing that knee under CNC control while it's locked!

I definitely don't think you can count on the bed being dead-level until
the knee is locked.

LLoyd

On Tue, 18 Jan 2011 18:54:47 -0600, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

"Pete C." fired this volley in news:4d35d419$0
:

There really isn't any
reason to power the knee unless you plan to lock off the quill and use
the knee as your Z.


Well, Pete, actually there is a good reason.

I don't know what Iggy does, but I do a LOT of work where I have to find
the center of existing old parts to machine new features in them. Many
are plastic, which means I have to use a centering indicator instead of
an edge finder.

Why can't you use an edge finder on plastic? I do it all the time

Mike

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote:
whit3rd fired this volley in news:807bb7b6-2f38-4804-

Are
there any options for implementing the knee lock, then re-zeroing the
work position?

GOOD question! The one thing you don't want to do is work a critical
piece without locking the knee, and the OTHER thing you don't want to do
is start slewing that knee under CNC control while it's locked!

I definitely don't think you can count on the bed being dead-level until
the knee is locked.

FWIW, depending on the characteristics of the knee joint, my bike has a
lever that holds the front axle to the fork - the axle has the two nuts,
but the one nut has a locking lever which is just an eccentric; I can
release the lever, and get the wheel off by hand.

Just an idea, thinking about the knee lock.

Cheers!
Rich

In article ,
wrote:
Why can't you use an edge finder on plastic? I do it all the time

.....probably has one of those electrical edge finders.

--
Cats, coffee, chocolate...vices to live by

fired this volley in
:

Why can't you use an edge finder on plastic? I do it all the time

I'm in the fireworks business; my hearing ain't that great when there ISN'T
a BP spindle running.

(yes, I have both "clickers" and electrical edge finders...) I can still
hear the mechanical ones on steel, but have trouble hearing the edge on PVC
or polyethylene.

LLoyd

On 2011-01-19, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
"Pete C." fired this volley in news:4d35d419$0
:

There really isn't any
reason to power the knee unless you plan to lock off the quill and use
the knee as your Z.


Well, Pete, actually there is a good reason.

I don't know what Iggy does, but I do a LOT of work where I have to find
the center of existing old parts to machine new features in them. Many
are plastic, which means I have to use a centering indicator instead of
an edge finder.

Being that my centering indicator is more than 4" taller than my longest
cutting tool, that puts me in the mode of _continually_ cranking the knee
up and down to make headroom for it, then going back to my usual machine
Z for the cutters. It gets wearisome. I will eventually power my knee,
but I see no reason for DROs and the like. I just go (as was said) for a
touch-off of a known tool, and done.

Yes, as soon as the difference between tool lengths is too great, it
means constantly going up and down and touching off. Gets tiring very
quickly.

i

On Tue, 18 Jan 2011 19:57:12 -0600, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

fired this volley in
:

Why can't you use an edge finder on plastic? I do it all the time

I'm in the fireworks business; my hearing ain't that great when there ISN'T
a BP spindle running.

(yes, I have both "clickers" and electrical edge finders...) I can still
hear the mechanical ones on steel, but have trouble hearing the edge on PVC
or polyethylene.

LLoyd

got it

Ignoramus5053 wrote:

On 2011-01-19, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
"Pete C." fired this volley in news:4d35d419$0
:

There really isn't any
reason to power the knee unless you plan to lock off the quill and use
the knee as your Z.


Well, Pete, actually there is a good reason.

I don't know what Iggy does, but I do a LOT of work where I have to find
the center of existing old parts to machine new features in them. Many
are plastic, which means I have to use a centering indicator instead of
an edge finder.

Being that my centering indicator is more than 4" taller than my longest
cutting tool, that puts me in the mode of _continually_ cranking the knee
up and down to make headroom for it, then going back to my usual machine
Z for the cutters. It gets wearisome. I will eventually power my knee,
but I see no reason for DROs and the like. I just go (as was said) for a
touch-off of a known tool, and done.

Yes, as soon as the difference between tool lengths is too great, it
means constantly going up and down and touching off. Gets tiring very
quickly.

i

No problem, just sell me your Interact with it's inadequate Z travel for
a decent price, and then go find yourself something like a Mycenter 1
with longer travels, more horsepower, ATC and a footprint that isn't a
lot larger I'll help you with the rigging and moving...

"Lloyd E. Sponenburgh" wrote:

whit3rd fired this volley in news:807bb7b6-2f38-4804-
:

Are
there any options for implementing the knee lock, then re-zeroing the
work position?


GOOD question! The one thing you don't want to do is work a critical
piece without locking the knee, and the OTHER thing you don't want to do
is start slewing that knee under CNC control while it's locked!

I definitely don't think you can count on the bed being dead-level until
the knee is locked.

LLoyd

Considering that these are "knee" mills and in their manual form are
intended to use the knee as the primary precision Z axis, I think you
are way off base thinking that the knee needs to be locked.

On 2011-01-19, Pete C. wrote:

Ignoramus5053 wrote:

On 2011-01-19, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
"Pete C." fired this volley in news:4d35d419$0
:

There really isn't any
reason to power the knee unless you plan to lock off the quill and use
the knee as your Z.


Well, Pete, actually there is a good reason.

I don't know what Iggy does, but I do a LOT of work where I have to find
the center of existing old parts to machine new features in them. Many
are plastic, which means I have to use a centering indicator instead of
an edge finder.

Being that my centering indicator is more than 4" taller than my longest
cutting tool, that puts me in the mode of _continually_ cranking the knee
up and down to make headroom for it, then going back to my usual machine
Z for the cutters. It gets wearisome. I will eventually power my knee,
but I see no reason for DROs and the like. I just go (as was said) for a
touch-off of a known tool, and done.

Yes, as soon as the difference between tool lengths is too great, it
means constantly going up and down and touching off. Gets tiring very
quickly.

i

No problem, just sell me your Interact with it's inadequate Z travel for
a decent price, and then go find yourself something like a Mycenter 1
with longer travels, more horsepower, ATC and a footprint that isn't a
lot larger I'll help you with the rigging and moving...

How generous of you ;-)

I like my Interact VERY much.

i

"Pete C." fired this volley in news:4d365f7a$0$14607
:

Considering that these are "knee" mills and in their manual form are
intended to use the knee as the primary precision Z axis, I think you
are way off base thinking that the knee needs to be locked.

Pete, the little training I have had taught that the knee shall _always_ be
locked during machining. I'm not sure why the locks would be there at all,
unless they serve a functional purpose.

LLoyd

"Lloyd E. Sponenburgh" wrote:

"Pete C." fired this volley in news:4d365f7a$0$14607
:

Considering that these are "knee" mills and in their manual form are
intended to use the knee as the primary precision Z axis, I think you
are way off base thinking that the knee needs to be locked.

Pete, the little training I have had taught that the knee shall _always_ be
locked during machining. I'm not sure why the locks would be there at all,
unless they serve a functional purpose.

LLoyd

That's bad or misinterpreted training. The knee is your Z in normal
manual machining, not the quill and you have to have it unlocked to do
any machining with a Z move. What you may be misinterpreting is the
recommendation that you lock and axis you aren't moving for a particular
machining operation, which applies to X and Y as well. Locking any axis
you aren't moving will increase rigidity by locking out the backlash in
the axis, as well as protecting it from you accidentally bump the handle
when reaching for something.

"Pete C." fired this volley in news:4d36e6a5$0
:

Locking any axis
you aren't moving will increase rigidity by locking out the backlash in
the axis, as well as protecting it from you accidentally bump the
handle
when reaching for something.


And your point? I do not move the knee except to get to a position.
Once in that position, I lock it. Manual or CNC -- lost motion is your
enemy.

And normally, one would not (say) drill with the knee crank, one would
lock knee-Z at the clearance point, and peck with the spindle feed. Knee
feed is for "getting there", even if the holes are deeper than the
spindle extension length.

I believe _any_ axis not being moved during a cut should be locked. It
would normally be quite inconvenient on a manual mill to lock X or Y
unless you were only doing straight lines, but the opportunities to lock
the knee gibs are often and many. FWIW, I do not guess, but know, that
the table is not level and true on my old Cincy #2 until the knee locks
are tight enough that you _cannot_ easily move it with the crank. Can't
tell you that for sure on the R2E4, though, because I've never checked
the whole table end-for-end and side-to-side for planarity.

LLoyd

"Lloyd E. Sponenburgh" wrote:

"Pete C." fired this volley in news:4d36e6a5$0
:

Locking any axis
you aren't moving will increase rigidity by locking out the backlash in
the axis, as well as protecting it from you accidentally bump the
handle
when reaching for something.


And your point? I do not move the knee except to get to a position.
Once in that position, I lock it. Manual or CNC -- lost motion is your
enemy.

And normally, one would not (say) drill with the knee crank, one would
lock knee-Z at the clearance point, and peck with the spindle feed. Knee
feed is for "getting there", even if the holes are deeper than the
spindle extension length.

It's a mill, not a drill press. On a manual knee mill the quill is there
for quick drill type operations, while the knee is intended for use as
the precision Z axis for milling operations (with the quill locked). My
point is that if the knee needs to be locked to make the table level,
your gibs on the knee need to be adjusted, that is not a normal
condition. Since your CNC mill is based on a manual knee mill design,
the same applies there as well.

Interesting discussion. I don't think I've "ever" locked the knee.

On both my mills, I trammed in the head by using a dial indicator
several inches out from the quill and adjusted till perfect in both X
and Y. I always watch when using a large face mill to verify that the
head in still in perfect tram. There's nothing that shows out of tram
quicker than a skim cut with a large face mill.

I can see where locking the knee might change this. If you're getting
good results with out locking the knee I think it would be best to
never do so.

However, I bet many machines out there have more wear at the center of
travel and using a face mill with the knee all the way down would
produce different results than at the center of travel. In this case,
always locking the knee would improve things.

My two cents

Karl

On Wed, 19 Jan 2011 20:33:09 -0500, Karl Townsend
wrote:

Interesting discussion. I don't think I've "ever" locked the knee.

On both my mills, I trammed in the head by using a dial indicator
several inches out from the quill and adjusted till perfect in both X
and Y. I always watch when using a large face mill to verify that the
head in still in perfect tram. There's nothing that shows out of tram
quicker than a skim cut with a large face mill.

I can see where locking the knee might change this. If you're getting
good results with out locking the knee I think it would be best to
never do so.

However, I bet many machines out there have more wear at the center of
travel and using a face mill with the knee all the way down would
produce different results than at the center of travel. In this case,
always locking the knee would improve things.

My two cents

Karl

I never lock mine either. I've checked with an indicator to see if the
front of the table moves relative to the head when the locks are
tightened -- it doesn't. But, it has box ways and the locks clamp on
the side of the ways, so I wouldn't expect the table to move even if
the ways were worn. I'm pretty sure you could detect some movement on
my old dovetail way Bridgeport. Perhaps relevant to this is that BP
manuals point out that the table on a new machine is fitted so that
the front of the table is about .0005 high.

--
Ned Simmons