I'm doing a cnc conversion on a 13x40 gearhead lathe.

My Z servo will be belt driven, so I think I can handle that.

Do any of you have a recommendation for a zero backlash coupling for the X
drive, which will be direct?

(metric AC servos)

LLoyd

"Lloyd E. Sponenburgh" wrote:

I'm doing a cnc conversion on a 13x40 gearhead lathe.

My Z servo will be belt driven, so I think I can handle that.

Do any of you have a recommendation for a zero backlash coupling for the X
drive, which will be direct?

(metric AC servos)

LLoyd

That depends on how accurately you can mount the servo. The big CNC
machines I used to work on had rigid couplings with precisely located
motors. For a retrofit you are probably looking at a coupling that will
accommodate some misalignment. I'd look at the helical couplings or the
flex disk couplings. I wouldn't even consider anything like the lovejoy
or similar with any sort of insert.

Try Mcmaster.com, flexible shaft couplings, catalog page 1165.

On Tue, 16 Aug 2011 07:36:23 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

I'm doing a cnc conversion on a 13x40 gearhead lathe.

My Z servo will be belt driven, so I think I can handle that.

Do any of you have a recommendation for a zero backlash coupling for the X
drive, which will be direct?

(metric AC servos)

LLoyd

I like Oldham couplings for this sort of thing. They're much cheaper
than higher performance options like bellows couplings, less fragile
and cheaper than helical beam couplings, and usually good enough in
all but the most demanding motion control apps. McMaster has a limited
selection; Lovejoy and Huco have much more. Lovejoy has some
comparison info in their catalog.

http://www.lovejoy-inc.com/products/...couplings.aspx

--
Ned Simmons

On Tue, 16 Aug 2011 09:32:29 -0500, "Pete C."
wrote:


"Lloyd E. Sponenburgh" wrote:

I'm doing a cnc conversion on a 13x40 gearhead lathe.

My Z servo will be belt driven, so I think I can handle that.

Do any of you have a recommendation for a zero backlash coupling for the X
drive, which will be direct?

(metric AC servos)

LLoyd

That depends on how accurately you can mount the servo. The big CNC
machines I used to work on had rigid couplings with precisely located
motors. For a retrofit you are probably looking at a coupling that will
accommodate some misalignment. I'd look at the helical couplings or the
flex disk couplings. I wouldn't even consider anything like the lovejoy
or similar with any sort of insert.

Try Mcmaster.com, flexible shaft couplings, catalog page 1165.

Hmm. I like the lovejoy for retrofits. Easy to disassemble. The only
possible solution on a couple locationsI've had. I suppose a purist
would say there's an RCH of backlash in them. IMHO, a tinsy fraction
of the total system backlash. I suppose if your building parts for
NASA or Medtronic it might not be good enough.

Just my 2 cents

Karl

Ned Simmons wrote:

On Tue, 16 Aug 2011 07:36:23 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

I'm doing a cnc conversion on a 13x40 gearhead lathe.

My Z servo will be belt driven, so I think I can handle that.

Do any of you have a recommendation for a zero backlash coupling for the X
drive, which will be direct?

(metric AC servos)

LLoyd

I like Oldham couplings for this sort of thing. They're much cheaper
than higher performance options like bellows couplings, less fragile
and cheaper than helical beam couplings, and usually good enough in
all but the most demanding motion control apps. McMaster has a limited
selection; Lovejoy and Huco have much more. Lovejoy has some
comparison info in their catalog.

http://www.lovejoy-inc.com/products/...couplings.aspx

Those are not zero backlash couplers. McMaster has zero backlash
flexible couplers specifically intended for servo use. They aren't
particularly cheap, but if you only need one of them they should be
acceptable.

On Tue, 16 Aug 2011 09:32:29 -0500, "Pete C."
wrote:


"Lloyd E. Sponenburgh" wrote:

I'm doing a cnc conversion on a 13x40 gearhead lathe.

My Z servo will be belt driven, so I think I can handle that.

Do any of you have a recommendation for a zero backlash coupling for the X
drive, which will be direct?

(metric AC servos)

LLoyd

That depends on how accurately you can mount the servo. The big CNC
machines I used to work on had rigid couplings with precisely located
motors. For a retrofit you are probably looking at a coupling that will
accommodate some misalignment. I'd look at the helical couplings or the
flex disk couplings. I wouldn't even consider anything like the lovejoy
or similar with any sort of insert.

Try Mcmaster.com, flexible shaft couplings, catalog page 1165.

Helical couplings for sure.

One of my clients... good **** Maynard

http://www.rocomcorp.com/

Gunner

--
"The danger to America is not Barack Obama but a citizenry
capable of entrusting a man like him with the Presidency.
It will be far easier to limit and undo the follies of an
Obama presidency than to restore the necessary common sense
and good judgment to a depraved electorate willing to have
such a man for their? president.. Blaming the prince of the
fools should not blind anyone to the vast confederacy of
fools that made him their prince".

On Tue, 16 Aug 2011 11:21:27 -0500, "Pete C."
wrote:


Ned Simmons wrote:

On Tue, 16 Aug 2011 07:36:23 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

I'm doing a cnc conversion on a 13x40 gearhead lathe.

My Z servo will be belt driven, so I think I can handle that.

Do any of you have a recommendation for a zero backlash coupling for the X
drive, which will be direct?

(metric AC servos)

LLoyd

I like Oldham couplings for this sort of thing. They're much cheaper
than higher performance options like bellows couplings, less fragile
and cheaper than helical beam couplings, and usually good enough in
all but the most demanding motion control apps. McMaster has a limited
selection; Lovejoy and Huco have much more. Lovejoy has some
comparison info in their catalog.

http://www.lovejoy-inc.com/products/...couplings.aspx

Those are not zero backlash couplers. McMaster has zero backlash
flexible couplers specifically intended for servo use. They aren't
particularly cheap, but if you only need one of them they should be
acceptable.

The Oldham couplings from Huco and Lovejoy are zero backlash, as are
those that McMaster stocks. There's a light interference fit between
the aluminum hubs and the delrin discs. The disc is much stiffer
torsionally than the elastomer spider in typical jaw couplings, which
also suffer from backlash. Oldhams are stiffer and have lower inertia
than a helical beam of similar torque rating. And if you bust one,
replacement discs are a couple dollars -- cheap enough to keep a
couple spares on hand.

In highly dynamic systems a disc or bellows coupling may be necessary,
but I've used Oldhams in many less demaninding apps with no problems.

--
Ned Simmons

Ned Simmons wrote:

On Tue, 16 Aug 2011 11:21:27 -0500, "Pete C."
wrote:


Ned Simmons wrote:

On Tue, 16 Aug 2011 07:36:23 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

I'm doing a cnc conversion on a 13x40 gearhead lathe.

My Z servo will be belt driven, so I think I can handle that.

Do any of you have a recommendation for a zero backlash coupling for the X
drive, which will be direct?

(metric AC servos)

LLoyd

I like Oldham couplings for this sort of thing. They're much cheaper
than higher performance options like bellows couplings, less fragile
and cheaper than helical beam couplings, and usually good enough in
all but the most demanding motion control apps. McMaster has a limited
selection; Lovejoy and Huco have much more. Lovejoy has some
comparison info in their catalog.

http://www.lovejoy-inc.com/products/...couplings.aspx

Those are not zero backlash couplers. McMaster has zero backlash
flexible couplers specifically intended for servo use. They aren't
particularly cheap, but if you only need one of them they should be
acceptable.

The Oldham couplings from Huco and Lovejoy are zero backlash,

The link you provided does not indicate the Oldham style is zero
backlash. The only three piece coupler on that page indicated as zero
backlash is the curved jaw GS series.

On Tue, 16 Aug 2011 13:02:19 -0500, "Pete C."
wrote:


Ned Simmons wrote:

On Tue, 16 Aug 2011 11:21:27 -0500, "Pete C."
wrote:


Ned Simmons wrote:

On Tue, 16 Aug 2011 07:36:23 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

I'm doing a cnc conversion on a 13x40 gearhead lathe.

My Z servo will be belt driven, so I think I can handle that.

Do any of you have a recommendation for a zero backlash coupling for the X
drive, which will be direct?

(metric AC servos)

LLoyd

I like Oldham couplings for this sort of thing. They're much cheaper
than higher performance options like bellows couplings, less fragile
and cheaper than helical beam couplings, and usually good enough in
all but the most demanding motion control apps. McMaster has a limited
selection; Lovejoy and Huco have much more. Lovejoy has some
comparison info in their catalog.

http://www.lovejoy-inc.com/products/...couplings.aspx

Those are not zero backlash couplers. McMaster has zero backlash
flexible couplers specifically intended for servo use. They aren't
particularly cheap, but if you only need one of them they should be
acceptable.

The Oldham couplings from Huco and Lovejoy are zero backlash,

The link you provided does not indicate the Oldham style is zero
backlash. The only three piece coupler on that page indicated as zero
backlash is the curved jaw GS series.

You're right, it doesn't say so specifically, but the page also
neglects to specify that the bellows coupling is zero backlash.

Here's Huco's description:

"Rotation is transmitted through a central disc that slides over the
tenons on the hubs under controlled preload conditions to eliminate
backlash."

http://www.huco.com/products.asp?cat=57

--
Ned Simmons

On Tue, 16 Aug 2011 14:17:31 -0400, Ned Simmons wrote:


The link you provided does not indicate the Oldham style is zero
backlash. The only three piece coupler on that page indicated as zero
backlash is the curved jaw GS series.

You're right, it doesn't say so specifically, but the page also
neglects to specify that the bellows coupling is zero backlash.

Here's Huco's description:

"Rotation is transmitted through a central disc that slides over the
tenons on the hubs under controlled preload conditions to eliminate
backlash."

http://www.huco.com/products.asp?cat=57

--
Ned Simmons

This is what you need

http://www.huco.com/products.asp?cat=104


Rocom provides them as well.


--
"The danger to America is not Barack Obama but a citizenry
capable of entrusting a man like him with the Presidency.
It will be far easier to limit and undo the follies of an
Obama presidency than to restore the necessary common sense
and good judgment to a depraved electorate willing to have
such a man for their? president.. Blaming the prince of the
fools should not blind anyone to the vast confederacy of
fools that made him their prince".