In my head I have a kind of picture how a rotary table might be made.

You have a base, with a central pivot (could be bored for a taper). Around
the pivot is a gear & the table, driven by a worm.

Some of these tables are advertised to have a method by which the table can
be decoupled from the gear, to allow quick rotation without turning the
worm. I have been turning this picture around and around in my head and
cannot figure out how they do this.

Someone tell me or point to a drawing, please...

jtaylor wrote:

In my head I have a kind of picture how a rotary table might be made.

You have a base, with a central pivot (could be bored for a taper). Around
the pivot is a gear & the table, driven by a worm.

Some of these tables are advertised to have a method by which the table can
be decoupled from the gear, to allow quick rotation without turning the
worm. I have been turning this picture around and around in my head and
cannot figure out how they do this.

Someone tell me or point to a drawing, please...



The worm is mounted on a shaft which is cammed so that rotating the shaft causes
the worm's center to move away from the gear's center, effectively disengaging
it. This is a very desirable feature on RTs and in my opinion a must have.

GWE

jtaylor wrote:

Some of these tables are advertised to have a method by which the table can
be decoupled from the gear, to allow quick rotation without turning the
worm. I have been turning this picture around and around in my head and
cannot figure out how they do this.

Someone tell me or point to a drawing, please...

Mount the worm shaft in an eccentric bushing, rotate bushing, disengage
worm.

Rich

"Grant Erwin" wrote in message
...
jtaylor wrote:

In my head I have a kind of picture how a rotary table might be made.

You have a base, with a central pivot (could be bored for a taper).
Around
the pivot is a gear & the table, driven by a worm.

Some of these tables are advertised to have a method by which the table
can
be decoupled from the gear, to allow quick rotation without turning the
worm. I have been turning this picture around and around in my head and
cannot figure out how they do this.

Someone tell me or point to a drawing, please...



The worm is mounted on a shaft which is cammed so that rotating the shaft
causes
the worm's center to move away from the gear's center, effectively
disengaging
it. This is a very desirable feature on RTs and in my opinion a must have.

GWE

Aha.

There'd have to be some method of adjusting the position of the worm in the
cam (or the bearing surfaces of the worm) then.

In article . ca,
"jtaylor" wrote:

In my head I have a kind of picture how a rotary table might be made.

You have a base, with a central pivot (could be bored for a taper). Around
the pivot is a gear & the table, driven by a worm.

Some of these tables are advertised to have a method by which the table can
be decoupled from the gear, to allow quick rotation without turning the
worm. I have been turning this picture around and around in my head and
cannot figure out how they do this.

Someone tell me or point to a drawing, please...



Any method of shifting the motor/shaft such that the worm unmeshes from
the wheel would work - Here's a few I came up with "on the fly": Maybe
the whole motor/worm assembly pivots on an axis 90 degrees to the center
line of the shaft the worm is mounted on, turning it off of the wheel.
Maybe the motor/worm assembly pivots toward/away from the wheel,
allowing it to be "lifted off" the wheel. Maybe the wheel "floats" on
the pivot point the same way the clutch-disk in a car with a manual
transmission does on the tranny's input shaft - Shaft is splined, inside
of clutch disk/wheel is splined to match, but loose enough to slide, and
something similar to a car's throwout bearing (or perhaps shift-fork...)
rises and/or falls to boost and/or drop the wheel above/below the point
where it can mesh with the fixed-location worm to be driven. Maybe the
worm and wheel are permanently meshed, but something like a pair of
crown rings mesh to connect the table to the wheel - separating those
rings would accomplish the task.

The list of possibilities is probably a close relative to the Energizer
Bunny, since they both go on and on and on and...

--
Don Bruder - - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
somewhere, any message sent to this address will go in the garbage without my
ever knowing it arrived. Sorry... http://www.sonic.net/~dakidd for more info

On Mon, 13 Feb 2006 10:39:02 -0400, "jtaylor"
wrote:

In my head I have a kind of picture how a rotary table might be made.

You have a base, with a central pivot (could be bored for a taper). Around
the pivot is a gear & the table, driven by a worm.

Some of these tables are advertised to have a method by which the table can
be decoupled from the gear, to allow quick rotation without turning the
worm. I have been turning this picture around and around in my head and
cannot figure out how they do this.

Someone tell me or point to a drawing, please...

My several have the worm coming through a bushing a smidge off center,
and when I release the bushing lock and turn it..it actually pulls the
worm away from the gear inside the base. Very quick.

Gunner



"A prudent man foresees the difficulties ahead and prepares for them;
the simpleton goes blindly on and suffers the consequences."
- Proverbs 22:3

On Mon, 13 Feb 2006 10:59:32 -0400, "jtaylor"
wrote:


"Grant Erwin" wrote in message
...
jtaylor wrote:

In my head I have a kind of picture how a rotary table might be made.

You have a base, with a central pivot (could be bored for a taper).
Around
the pivot is a gear & the table, driven by a worm.

Some of these tables are advertised to have a method by which the table
can
be decoupled from the gear, to allow quick rotation without turning the
worm. I have been turning this picture around and around in my head and
cannot figure out how they do this.

Someone tell me or point to a drawing, please...



The worm is mounted on a shaft which is cammed so that rotating the shaft
causes
the worm's center to move away from the gear's center, effectively
disengaging
it. This is a very desirable feature on RTs and in my opinion a must have.

GWE

Aha.

There'd have to be some method of adjusting the position of the worm in the
cam (or the bearing surfaces of the worm) then.

Ayup..this also allows you to take out any backlash.

Gunner



"A prudent man foresees the difficulties ahead and prepares for them;
the simpleton goes blindly on and suffers the consequences."
- Proverbs 22:3

"Gunner" wrote in message
...
On Mon, 13 Feb 2006 10:59:32 -0400, "jtaylor"
wrote:


"Grant Erwin" wrote in message
...
jtaylor wrote:

In my head I have a kind of picture how a rotary table might be made.

You have a base, with a central pivot (could be bored for a taper).
Around
the pivot is a gear & the table, driven by a worm.

Some of these tables are advertised to have a method by which the
table
can
be decoupled from the gear, to allow quick rotation without turning
the
worm. I have been turning this picture around and around in my head
and
cannot figure out how they do this.

Someone tell me or point to a drawing, please...



The worm is mounted on a shaft which is cammed so that rotating the
shaft
causes
the worm's center to move away from the gear's center, effectively
disengaging
it. This is a very desirable feature on RTs and in my opinion a must
have.

GWE

Aha.

There'd have to be some method of adjusting the position of the worm in
the
cam (or the bearing surfaces of the worm) then.

Ayup..this also allows you to take out any backlash.


Um, only some - that between the worm and gear teeth. The worm might also
shift axially; need something to handle that as well.

"Gunner" wrote in message
...
On Mon, 13 Feb 2006 10:39:02 -0400, "jtaylor"
wrote:

In my head I have a kind of picture how a rotary table might be made.

You have a base, with a central pivot (could be bored for a taper).
Around
the pivot is a gear & the table, driven by a worm.

Some of these tables are advertised to have a method by which the table
can
be decoupled from the gear, to allow quick rotation without turning the
worm. I have been turning this picture around and around in my head and
cannot figure out how they do this.

Someone tell me or point to a drawing, please...

My several have the worm coming through a bushing a smidge off center,
and when I release the bushing lock and turn it..it actually pulls the
worm away from the gear inside the base. Very quick.


Do that have just one bushing at one end of the worm, or is the bush really
a pair, one each end, connected along the back side of the worm (so they'll
turn together)?

I don't have a reference drawing to point you to, although someone else
may know of one.

The RT worms that I've seen are mounted in an eccentric sleeve, so that
both ends of the worm shaft are moved the same amount of distance,
simultaneously. The worm shaft is mounted within the sleeve with
provisions for eliminating/adjusting-to-minimum the axial movement of
the worm shaft.
The eccentric sleeve better describes the visualization of the two
eccentric bushings question.

The eccentric engage-disengage sleeve/worm assembly rotates to move the
worm on/off the table gear. The rotational movement of the eccentric
sleeve may have a stop adjustment for the engage position, so that the
sleeve is set to the same position easily each time it is engaged. The
stop would be set to a point where most or all of the worm-gear
backlash is eliminated, but stops short of the point where the worm and
gear might bind.
A stop for the disengaged point isn't really required.

With the table disengaged, the table is moved freely to any point,
quickly. The degree scale around the edge of the table could be used
for low accuracy positioning without needing to dial in accurate
positions.
In theory, the table locks would prevent the table from shifting while
the machining operation is taking place, but engaging the worm before
machining would give the operator the assurance that the table will
remain locked in position.

The precision fit of parts in quality RTs allows them to perform well
with power applied to the worm shaft, from either a motor mounted to
the RT, or from a power feed shaft driven by the machine the RT is used
on.
A low quality RT will most likely present problems for the user. The
first one I bought was a cheap import that was difficult to operate.
Some other types of RTs don't utilize a worm shaft. They might be
actuated to index a certain number of stops, sometimes with pneumatic
power.

WB
.....................

jtaylor wrote:

On Mon, 13 Feb 2006 10:39:02 -0400, "jtaylor"
wrote:

In my head I have a kind of picture how a rotary table might be made.

You have a base, with a central pivot (could be bored for a taper).
Around
the pivot is a gear & the table, driven by a worm.

Some of these tables are advertised to have a method by which the table
can
be decoupled from the gear, to allow quick rotation without turning the
worm. I have been turning this picture around and around in my head and
cannot figure out how they do this.

Someone tell me or point to a drawing, please...



Do that have just one bushing at one end of the worm, or is the bush really
a pair, one each end, connected along the back side of the worm (so they'll
turn together)?

On Tue, 14 Feb 2006 09:13:27 -0400, "jtaylor"
wrote:


"Gunner" wrote in message
.. .
On Mon, 13 Feb 2006 10:39:02 -0400, "jtaylor"
wrote:

In my head I have a kind of picture how a rotary table might be made.

You have a base, with a central pivot (could be bored for a taper).
Around
the pivot is a gear & the table, driven by a worm.

Some of these tables are advertised to have a method by which the table
can
be decoupled from the gear, to allow quick rotation without turning the
worm. I have been turning this picture around and around in my head and
cannot figure out how they do this.

Someone tell me or point to a drawing, please...

My several have the worm coming through a bushing a smidge off center,
and when I release the bushing lock and turn it..it actually pulls the
worm away from the gear inside the base. Very quick.


Do that have just one bushing at one end of the worm, or is the bush really
a pair, one each end, connected along the back side of the worm (so they'll
turn together)?

That..I honestly dont know. Ive never had one apart.

Gunner



"A prudent man foresees the difficulties ahead and prepares for them;
the simpleton goes blindly on and suffers the consequences."
- Proverbs 22:3

On 14 Feb 2006 07:18:21 -0800, "Wild Bill"
wrote:

Some other types of RTs don't utilize a worm shaft. They might be
actuated to index a certain number of stops, sometimes with pneumatic
power.

WB

I have a very nice Yuasa that has this feature. Totally unused if
anyone wants to buy it from me. Its either 8 or 10" with a 3 jaw chuck
on top.

Gunner



"A prudent man foresees the difficulties ahead and prepares for them;
the simpleton goes blindly on and suffers the consequences."
- Proverbs 22:3

Gunner wrote:

On 14 Feb 2006 07:18:21 -0800, "Wild Bill"
wrote:


Some other types of RTs don't utilize a worm shaft. They might be
actuated to index a certain number of stops, sometimes with pneumatic
power.

WB


I have a very nice Yuasa that has this feature. Totally unused if
anyone wants to buy it from me. Its either 8 or 10" with a 3 jaw chuck
on top.

If it's a horizontal/vertical model, please come up with a price for me. Thanks!

GWE

On Tue, 14 Feb 2006 09:46:39 -0800, Grant Erwin
wrote:

Gunner wrote:

On 14 Feb 2006 07:18:21 -0800, "Wild Bill"
wrote:


Some other types of RTs don't utilize a worm shaft. They might be
actuated to index a certain number of stops, sometimes with pneumatic
power.

WB


I have a very nice Yuasa that has this feature. Totally unused if
anyone wants to buy it from me. Its either 8 or 10" with a 3 jaw chuck
on top.

If it's a horizontal/vertical model, please come up with a price for me. Thanks!

GWE

It is. Before I give you sticker shock ..do you know what a new one
costs?

Hummm...I thought I showed it to you when you were hear last?

Gunner



"A prudent man foresees the difficulties ahead and prepares for them;
the simpleton goes blindly on and suffers the consequences."
- Proverbs 22:3