I'm trying to decide how large a roller chain I need...

Does anyone know of a table that shows how much each size roller chain
stretches under increasing loads?

The application is my plasma table. I'm upgrading from cable tension drive
to roller chain.

Karl

Karl Townsend wrote:

I'm trying to decide how large a roller chain I need...

Does anyone know of a table that shows how much each size roller chain
stretches under increasing loads?

The application is my plasma table. I'm upgrading from cable tension drive
to roller chain.

Karl

Rack and pinion drive is the most common / popular for most plasma
tables. Plenty of sources out there for the components and plenty of
info on CNCZONE.

Rack and pinion drive is the most common / popular for most plasma
tables. Plenty of sources out there for the components and plenty of
info on CNCZONE.

Yea, I spend more time over there than here. rack pinion is best but I'm
refitting an existing machine with a clever cable drive. Won't be a big
deal to replace pulleys with sprockets and cable with chain.
lots of machines have been built with roller cahin drive over there also.
But, no sign of mechanical design for chain size.

Karl

On Thu, 11 Jun 2009 22:05:03 -0500, "Karl Townsend"
wrote:

I'm trying to decide how large a roller chain I need...

Does anyone know of a table that shows how much each size roller chain
stretches under increasing loads?


The chain mfrs list the maximum allowable tension for low speed
drives, but I don't recall ever seeing tabulated values for the
"stretchiness" of chain. It'd be easy enough to estimate by treating
the sideplates as a solid strip.

For example, the sideplates of #40 chain are .059 x .472.
..059 x .472 x 2 = .05 in^2

Young's modulus, stress over strain = 30E6 (lb/in2)/(in/in) for steel

..05 in^2 x 30E6 (lb/in2)/(in/in)) = 1.5E6 lb (in/in)

In other words, if you had an imaginary chain made of steel with
infinite yield strength, 1.5 million pounds would stretch a length of
#40 chain to twice its original length. In other, other words, a 100
inch length of real #40 chain will stretch about .007" under a 100#
load.

--
Ned Simmons

"Karl Townsend" wrote:

I'm trying to decide how large a roller chain I need...

Does anyone know of a table that shows how much each size roller chain
stretches under increasing loads?

The application is my plasma table. I'm upgrading from cable tension drive
to roller chain.

Karl



www.brecoflex.com

I was moving an heavy injection head between 2 presses over 22 ft via belt drive using
their product. You can get a timing belt any length you desire. Give it a look.

As far as chain, about anything will do, plasma isn't that fast, head is not that heavy.

Wes

On Thu, 11 Jun 2009 23:57:32 -0400, Ned Simmons
wrote:

On Thu, 11 Jun 2009 22:05:03 -0500, "Karl Townsend"
wrote:

I'm trying to decide how large a roller chain I need...

BTW, you can find this data on steel corded timing belts, if you want
to compare. The metric AT profile belts are generally stiffer and
stronger than the trapezoidal toothed belts. I know Breco, for one,
has this data in their catalogs.

--
Ned Simmons

Karl,
There are many, many different chain types for any given size and each have
their own use parameters. I use www.ustsubaki.com for my chain solutions.
Here is a tip, never use keyed sprockets for bi-directional loads, as the
keyways will eventually loosen. Tsubaki markets sprockets with compression
(friction) drive hubs and they are brilliant. Another tip, metric and US
standard chain sizes are practically interchangable and that fact is never
stated anywhere.
Steve

"Karl Townsend" wrote in message
anews.com...
I'm trying to decide how large a roller chain I need...

Does anyone know of a table that shows how much each size roller chain
stretches under increasing loads?

The application is my plasma table. I'm upgrading from cable tension drive
to roller chain.

Karl

On Jun 12, 9:09*am, "Steve Lusardi" wrote:
Karl,
There are many, many different chain types for any given size and each have
their own use parameters. I usewww.ustsubaki.comfor my chain solutions.
Here is a tip, never use keyed sprockets for bi-directional loads, as the
keyways will eventually loosen. Tsubaki markets sprockets with compression
(friction) drive hubs and they are brilliant. Another tip, metric and US
standard chain sizes are practically interchangable and that fact is never
stated anywhere.
Steve

"Karl Townsend" wrote in message

anews.com...

I'm trying to decide how large a roller chain I need...

Does anyone know of a table that shows how much each size roller chain
stretches under increasing loads?

The application is my plasma table. I'm upgrading from cable tension drive
to roller chain.

Karl


Karl,

Machinerys Handbook is your friend for this information... I use this
info, with appropriate safety factor, for certifying assembly line
lifts in automotive plants.

Just be aware that chains introduce some pulsing into the linear
motion.

As was pointed out above you can get wire reinforced timing belting in
straight and practically unlimited lengths. You might want to compare
costs between chain and belt.

Wolfgang

On Jun 11, 11:57*pm, Ned Simmons wrote:

The chain mfrs list the maximum allowable tension for low speed
drives, but I don't recall ever seeing tabulated values for the
"stretchiness" of chain. It'd be easy enough to estimate by treating
the sideplates as a solid strip.

I wonder if this is a valid model

In other words, if you had an imaginary chain made of steel with
infinite yield strength, 1.5 million pounds would stretch a length of
#40 chain to twice its original length. In other, other words, a 100
inch length of real #40 chain will stretch about .007" under a 100#
load.

Specifically, I would expect that play in the plain bearing between
the
links would add up to more than .007

On Fri, 12 Jun 2009 07:07:43 -0700 (PDT),
wrote:

On Jun 11, 11:57*pm, Ned Simmons wrote:

The chain mfrs list the maximum allowable tension for low speed
drives, but I don't recall ever seeing tabulated values for the
"stretchiness" of chain. It'd be easy enough to estimate by treating
the sideplates as a solid strip.

I wonder if this is a valid model

Why wouldn't it be adequate for an estimate? I'd be surprised if you
couldn't get within 20% of the real value with a little care.


In other words, if you had an imaginary chain made of steel with
infinite yield strength, 1.5 million pounds would stretch a length of
#40 chain to twice its original length. In other, other words, a 100
inch length of real #40 chain will stretch about .007" under a 100#
load.

Specifically, I would expect that play in the plain bearing between
the
links would add up to more than .007

That's a different issue than the elastic behavior of the chain.
Presumably the chain would be pre-tensioned to eliminate the play.

--
Ned Simmons

On Jun 12, 10:21*am, Ned Simmons wrote:

Specifically, I would expect that play in the plain bearing between
the
links would add up to more than .007

That's a different issue than the elastic behavior of the chain.
Presumably the chain would be pre-tensioned to eliminate the play.

I would expect the elongation due to bearing play to be at least
somewhat
load dependent. I would not be surprised if this overshadows what
you
calculate from the solid elasticity model. But I could well be wrong.

On Fri, 12 Jun 2009 08:19:30 -0700 (PDT),
wrote:

On Jun 12, 10:21*am, Ned Simmons wrote:

Specifically, I would expect that play in the plain bearing between
the
links would add up to more than .007

That's a different issue than the elastic behavior of the chain.
Presumably the chain would be pre-tensioned to eliminate the play.

I would expect the elongation due to bearing play to be at least
somewhat
load dependent. I would not be surprised if this overshadows what
you
calculate from the solid elasticity model. But I could well be wrong.

I can see how pin clearance in the sideplates would cause some bending
of the plate around the hole, which would not be accounted for by my
approximation, but it would be an elastic effect. An extreme example
would be regular lifting chain. In that case there's clearly a
significant bending component in the curved segment of the loop. I
guess the question is, how big is this effect with a close fitting
pin? My gut sense is that it'll be pretty small, but I'll wait 'til
someone runs an FEA on it before I dig my heels in. g

--
Ned Simmons

ciditad had written this in response to
http://rittercnc.com/metalworking/st...in-184943-.htm
:
Hi Karl,

Roller chains do not "stretch" under load - the "elongation" is called
wear.
What happens to the chain is the pins inside each of the chain link's
bushing
gets worn as time go on with each revolution of the chain around the
sprockets
and loses material, and that's why you see "stretching" or "elongation".
Chains
are not supposed to stretch like rubber, and if your chain stretched then
it's
not made with the proper material.

As for chain sizes, I suggest going to Diamond Chain's website:

http://www.diamondchain.com/

Under the "Product Support" tab, you can choose to download a very useful
program that will help you identify the proper size chain for your
application.

-------------------------------------
Karl Townsend wrote:


I'm trying to decide how large a roller chain I need...

Does anyone know of a table that shows how much each size roller chain
stretches under increasing loads?

The application is my plasma table. I'm upgrading from cable tension
drive
to roller chain.

Karl







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wrote in message
...
On Jun 11, 11:57 pm, Ned Simmons wrote:

The chain mfrs list the maximum allowable tension for low speed
drives, but I don't recall ever seeing tabulated values for the
"stretchiness" of chain. It'd be easy enough to estimate by treating
the sideplates as a solid strip.

I wonder if this is a valid model

In other words, if you had an imaginary chain made of steel with
infinite yield strength, 1.5 million pounds would stretch a length of
#40 chain to twice its original length. In other, other words, a 100
inch length of real #40 chain will stretch about .007" under a 100#
load.

Specifically, I would expect that play in the plain bearing between
the
links would add up to more than .007

But the OP will be pretensioning the chain to eliminate backlash, surely?

"ciditad" wrote in message
m...
ciditad had written this in response to
http://rittercnc.com/metalworking/st...in-184943-.htm
:
Hi Karl,

Roller chains do not "stretch" under load

*Everything* stretches under load

But roller chains "stretch" badly after use in a a lousy (read dirty)
environment. Seems to me Karl's application would slowly go out of
tolerance as the chain wore and "stretched)

newshound wrote:


"ciditad" wrote in message
m...
ciditad had written this in response to
http://rittercnc.com/metalworking/st...in-184943-.htm

:
Hi Karl,

Roller chains do not "stretch" under load

*Everything* stretches under load

Seems to me a chain drive will slowly drift out of tolerance as the
chain wears. Move it x turns/links/whatever it will move a larger and
larger distance as it wears.

Karl Townsend wrote:
I'm trying to decide how large a roller chain I need...

Does anyone know of a table that shows how much each size roller chain
stretches under increasing loads?

The application is my plasma table. I'm upgrading from cable tension drive
to roller chain.

Karl

On Jun 12, 10:42 pm, RoyJ wrote:

Seems to me a chain drive will slowly drift out of tolerance as the
chain wears. Move it x turns/links/whatever it will move a larger and
larger distance as it wears.

A friend who is a serious bicycle commuter told me that not only did I
need to replace my "stretched" chain, but also the sprocket sets that
had been worn-in to its out-of-spec pitch.

"Steve Lusardi" wrote in message
...
Karl,
There are many, many different chain types for any given size and each
have their own use parameters. I use www.ustsubaki.com for my chain
solutions. Here is a tip, never use keyed sprockets for bi-directional
loads, as the keyways will eventually loosen. Tsubaki markets sprockets
with compression (friction) drive hubs and they are brilliant. Another
tip, metric and US standard chain sizes are practically interchangable and
that fact is never stated anywhere.
Steve

"Karl Townsend" wrote in message
anews.com...
I'm trying to decide how large a roller chain I need...

Does anyone know of a table that shows how much each size roller chain
stretches under increasing loads?

The application is my plasma table. I'm upgrading from cable tension
drive to roller chain.

Karl

Just call up the nearest chain supplier and ask them the question.
They will have a set of specifications as long as your arm.
Some of the details will be of no value to you but a simple stress vs strain
would be somewhere near the top of the sheet

wrote in message
...
On Jun 12, 10:42 pm, RoyJ wrote:

Seems to me a chain drive will slowly drift out of tolerance as the
chain wears. Move it x turns/links/whatever it will move a larger and
larger distance as it wears.

A friend who is a serious bicycle commuter told me that not only did I
need to replace my "stretched" chain, but also the sprocket sets that
had been worn-in to its out-of-spec pitch.

Apperent stretch in roller chain is usually NOT stretch in the sideplates,
but wear in the roller/pin assembly.