Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Default Coupling misaligned shafts

This is related to my dynamometer thread. We didn't find anything, so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment, which
has no solid external reference points to provide for good alignment to
the shaft on the device under test (or, for that matter, a really easy
way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to couple
the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is said
and done the coupling needs to transmit torque accurately -- it can't
just be efficient, it has to not have any severe differential gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in use.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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Default Coupling misaligned shafts



"Tim Wescott" wrote in message
...

This is related to my dynamometer thread. We didn't find anything, so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment, which
has no solid external reference points to provide for good alignment to
the shaft on the device under test (or, for that matter, a really easy
way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to couple
the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is said
and done the coupling needs to transmit torque accurately -- it can't
just be efficient, it has to not have any severe differential gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in use.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

================================================== ====

You'll probably need to be closer than 5 degrees, as Lloyd said, but two
simple couplings are the Lovejoy that he mentioned, and the Oldham coupling.
The Oldham allows quite a bit of shaft misalignment, but *not* angular
misalignment.

You might get away with a rag joint -- a steering-column coupling.

Ed


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Default Coupling misaligned shafts

On Tue, 08 Jul 2014 15:50:31 -0500, Tim Wescott
wrote:

This is related to my dynamometer thread. We didn't find anything, so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment, which
has no solid external reference points to provide for good alignment to
the shaft on the device under test (or, for that matter, a really easy
way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to couple
the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is said
and done the coupling needs to transmit torque accurately -- it can't
just be efficient, it has to not have any severe differential gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in use.

=============
Lovejoy
http://www.use-enco.com/CGI/INSRIT?P...FSxo7AodjjsAqw

cnc zero backlash coupler
http://www.tpa-us.com/shaft-coupling...FXNo7AodKRwAKw

What have you considered for the absorber?

electric motor/generator?
http://freeideas.bizhat.com/drives/feedback/index.htm

hydraulic pump?
http://www.micropump.com/pump_overview.aspx

magnetic clutch with scale and tach?
http://www.youngssurplus.com/clutches.htm

--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"


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Default Coupling misaligned shafts

On Tue, 08 Jul 2014 16:31:25 -0500, F. George McDuffee wrote:

On Tue, 08 Jul 2014 15:50:31 -0500, Tim Wescott
wrote:

This is related to my dynamometer thread. We didn't find anything, so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment, which
has no solid external reference points to provide for good alignment to
the shaft on the device under test (or, for that matter, a really easy
way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to couple
the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is said
and done the coupling needs to transmit torque accurately -- it can't
just be efficient, it has to not have any severe differential gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in use.

=============
Lovejoy
http://www.use-enco.com/CGI/INSRIT?P...Didit-_-SEM-_-

GglProd-_-
GglProd&003=18299132&010=990-4046&gclid=CJPGvbjRtr8CFSxo7AodjjsAqw

cnc zero backlash coupler
http://www.tpa-us.com/shaft-couplings.html?

gclid=CLbY26zTtr8CFXNo7AodKRwAKw

What have you considered for the absorber?

electric motor/generator?
http://freeideas.bizhat.com/drives/feedback/index.htm

hydraulic pump?
http://www.micropump.com/pump_overview.aspx

magnetic clutch with scale and tach?
http://www.youngssurplus.com/clutches.htm


I'm probably going to use a motor. I need to drive as well as absorb.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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Default Coupling misaligned shafts

On Tue, 08 Jul 2014 15:50:31 -0500, Tim Wescott wrote:

This is related to my dynamometer thread. We didn't find anything, so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment, which
has no solid external reference points to provide for good alignment to
the shaft on the device under test (or, for that matter, a really easy
way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to couple
the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is said
and done the coupling needs to transmit torque accurately -- it can't
just be efficient, it has to not have any severe differential gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in use.


And, if this sounds interesting and you're within driving distance from
Portland, Oregon, send me an email -- I can do all the work myself, but
farming it out may be better for my customer, if you've got the right
skill set.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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"Tim Wescott" wrote in message
...
This is related to my dynamometer thread. We didn't find anything,
so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment,
which
has no solid external reference points to provide for good alignment
to
the shaft on the device under test (or, for that matter, a really
easy
way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within
an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to
couple
the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is
said
and done the coupling needs to transmit torque accurately -- it
can't
just be efficient, it has to not have any severe differential
gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in
use.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com


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


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Default Coupling misaligned shafts

On Tue, 08 Jul 2014 15:50:31 -0500, Tim Wescott
wrote:

This is related to my dynamometer thread. We didn't find anything, so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment, which
has no solid external reference points to provide for good alignment to
the shaft on the device under test (or, for that matter, a really easy
way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to couple
the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is said
and done the coupling needs to transmit torque accurately -- it can't
just be efficient, it has to not have any severe differential gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in use.

#2 is called a belt.


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Default Coupling misaligned shafts

On Tue, 08 Jul 2014 15:50:31 -0500, Tim Wescott
wrote:

snip
The thing would need to work with an existing piece of equipment, which
has no solid external reference points to provide for good alignment to
the shaft on the device under test (or, for that matter, a really easy
way to get centered onto a shaft).

/snip
=====================
This simply adds another spec/requirement. You will have to
have some way to rigidly mount the test assembly. This
seems to indicate that either the test assembly mount and/or
the absorber mount must be adjustible in the XYZ directions
and rotations about the X and Y axis. Then you will need a
gage set-up to align the two shafts.

There are a ton of videos on YouTube on shaft alignment
heres one to start
https://www.youtube.com/watch?v=9JCbdDNyUPQ

A sleeve with reamed holes [several diameters deep] for the
shafts may be accurate enough. If not, here are some URLs
that may give you some ideas [most likely you already have
the drop indicators] or align off the couplings if you use
flange gear type couplings with external driving bands..


http://www.google.com/search?q=dial+...w=1207&bih=523
http://www.mitchellinstrument.com/me...arter-kit.html
http://www.solarstop.net/mrshims/shaftalignment.asp
http://www.skf.com/group/products/ma...a11/index.html
http://www.skf.com/group/products/ma...a20/index.html

http://www.google.com/url?sa=t&rct=j...,d.aWw&cad=rja



--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"
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Default Coupling misaligned shafts

fired this volley in
:

A timing belt drive is extremely efficient


Yup.
L
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Default Coupling misaligned shafts

On Tue, 08 Jul 2014 20:26:30 -0400, clare wrote:

On Tue, 08 Jul 2014 15:50:31 -0500, Tim Wescott
wrote:

This is related to my dynamometer thread. We didn't find anything, so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment, which
has no solid external reference points to provide for good alignment to
the shaft on the device under test (or, for that matter, a really easy
way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to couple
the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is said
and done the coupling needs to transmit torque accurately -- it can't
just be efficient, it has to not have any severe differential gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in use.

#2 is called a belt.


Not if I can't easily mount it concentric to the axis of rotation.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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On Tue, 08 Jul 2014 19:52:15 -0500, Tim Wescott
wrote:

On Tue, 08 Jul 2014 20:26:30 -0400, clare wrote:

On Tue, 08 Jul 2014 15:50:31 -0500, Tim Wescott
wrote:

This is related to my dynamometer thread. We didn't find anything, so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment, which
has no solid external reference points to provide for good alignment to
the shaft on the device under test (or, for that matter, a really easy
way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to couple
the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is said
and done the coupling needs to transmit torque accurately -- it can't
just be efficient, it has to not have any severe differential gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in use.

#2 is called a belt.


Not if I can't easily mount it concentric to the axis of rotation.


you will also hace considerable side loading which may be
important, whch will be avoided with a shaft coupling.


--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"


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Default Coupling misaligned shafts

On Tue, 08 Jul 2014 19:52:15 -0500, Tim Wescott
wrote:

On Tue, 08 Jul 2014 20:26:30 -0400, clare wrote:

On Tue, 08 Jul 2014 15:50:31 -0500, Tim Wescott
wrote:

This is related to my dynamometer thread. We didn't find anything, so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment, which
has no solid external reference points to provide for good alignment to
the shaft on the device under test (or, for that matter, a really easy
way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to couple
the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is said
and done the coupling needs to transmit torque accurately -- it can't
just be efficient, it has to not have any severe differential gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in use.

#2 is called a belt.


Not if I can't easily mount it concentric to the axis of rotation.

OK, spill the beans--- What is the application??? Picture or
diagram, or at least a good description?? How about a hunk of hose
the right size to fit the shaft, and a couple of hose clamps.
Braided hose if required. Even steel braid. You are only talking
80RPM from what I remember - and what torque, again???

And I'm assuming you mean parallel to the axis of rotation.
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On Tue, 08 Jul 2014 19:32:41 -0500, F. George McDuffee
wrote:

On Tue, 08 Jul 2014 15:50:31 -0500, Tim Wescott
wrote:

snip
The thing would need to work with an existing piece of equipment, which
has no solid external reference points to provide for good alignment to
the shaft on the device under test (or, for that matter, a really easy
way to get centered onto a shaft).

/snip
=====================
This simply adds another spec/requirement. You will have to
have some way to rigidly mount the test assembly. This
seems to indicate that either the test assembly mount and/or
the absorber mount must be adjustible in the XYZ directions
and rotations about the X and Y axis. Then you will need a
gage set-up to align the two shafts.

There are a ton of videos on YouTube on shaft alignment
heres one to start
https://www.youtube.com/watch?v=9JCbdDNyUPQ

A sleeve with reamed holes [several diameters deep] for the
shafts may be accurate enough. If not, here are some URLs
that may give you some ideas [most likely you already have
the drop indicators] or align off the couplings if you use
flange gear type couplings with external driving bands..


http://www.google.com/search?q=dial+...w=1207&bih=523
http://www.mitchellinstrument.com/me...arter-kit.html
http://www.solarstop.net/mrshims/shaftalignment.asp
http://www.skf.com/group/products/ma...a11/index.html
http://www.skf.com/group/products/ma...a20/index.html

http://www.google.com/url?sa=t&rct=j...,d.aWw&cad=rja



Haw about a prony brake that fits right on the shaft of the motor??
Again, we really need a picture, or at least a better description of
what you are working on.
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On Tue, 08 Jul 2014 15:50:31 -0500, Tim Wescott
wrote:

This is related to my dynamometer thread. We didn't find anything, so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment, which
has no solid external reference points to provide for good alignment to
the shaft on the device under test (or, for that matter, a really easy
way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to couple
the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is said
and done the coupling needs to transmit torque accurately -- it can't
just be efficient, it has to not have any severe differential gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in use.



"Helical coupler" is what you are looking for.

http://www.rocomcorp.com/

etc etc

What size shafts are you going to be using? I have a drawer full of
all different sizes. Let me know and I can find something for you.

Gunner

--
"Living in the United States now is like being a Tampon.
We're in a great place, just at a bad time."
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On Tue, 08 Jul 2014 22:38:27 -0400, clare wrote:

On Tue, 08 Jul 2014 19:52:15 -0500, Tim Wescott
wrote:

On Tue, 08 Jul 2014 20:26:30 -0400, clare wrote:

On Tue, 08 Jul 2014 15:50:31 -0500, Tim Wescott
wrote:

This is related to my dynamometer thread. We didn't find anything, so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment,
which has no solid external reference points to provide for good
alignment to the shaft on the device under test (or, for that matter,
a really easy way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to
couple the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is said
and done the coupling needs to transmit torque accurately -- it can't
just be efficient, it has to not have any severe differential gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in
use.
#2 is called a belt.


Not if I can't easily mount it concentric to the axis of rotation.

OK, spill the beans--- What is the application??? Picture or
diagram, or at least a good description?? How about a hunk of hose the
right size to fit the shaft, and a couple of hose clamps. Braided hose
if required. Even steel braid. You are only talking 80RPM from what I
remember - and what torque, again???

And I'm assuming you mean parallel to the axis of rotation.


It's for a customer, so I have to be all secretive. Which is a pain, I
know.

Things could, in theory, be mounted dead center on a shaft on the device
under test, but doing so would require some disassembly and reassembly to
do the test. I'll go there if I must, but I'd much rather have something
that'll work anywhere, anytime.

50 newton-meters, whatever that works out to in 'merican units.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
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Default Coupling misaligned shafts


"Tim Wescott" wrote in message
...
This is related to my dynamometer thread. We didn't find anything, so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment, which
has no solid external reference points to provide for good alignment to
the shaft on the device under test (or, for that matter, a really easy
way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to couple
the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is said
and done the coupling needs to transmit torque accurately -- it can't
just be efficient, it has to not have any severe differential gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in use.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Perhaps a roller chain coupling would be suitable if the angular
misalignment is not severe.


--
Regards,

Chas.

(To email me, replace "xxx" with letters tango papa golf.)




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Default Coupling misaligned shafts

On Tuesday, July 8, 2014 8:50:31 PM UTC, Tim Wescott wrote:

The thing would need to work with an existing piece of equipment, which

has no solid external reference points to provide for good alignment to

the shaft on the device under test (or, for that matter, a really easy

way to get centered onto a shaft).




Tim Wescott

Wescott Design Services

http://www.wescottdesign.com


This is just a wild idea, but how about a hydraulic pump driving a hydraulic motor. They could be sized so there is a speed up of the RPM's. It would solve all the alignment problems. Or just a hydraulic pump with a needle valve as the load. Use a optical tachometer from China to get the RPM and a pressure transducer on each side of the pump to get the torque.

Dan

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Default Coupling misaligned shafts

On Tuesday, July 8, 2014 4:50:31 PM UTC-4, Tim Wescott wrote:
This is related to my dynamometer thread. We didn't find anything, so

I'm working on plan B, which is to roll my own.



The thing would need to work with an existing piece of equipment, which

has no solid external reference points to provide for good alignment to

the shaft on the device under test (or, for that matter, a really easy

way to get centered onto a shaft).



I'm visualizing getting something that can locate things to within an

inch, and within five or ten degrees, then having one of two things:



1: A foot-long shaft with U-joints (probably CV) at each end, to couple

the dynamometer to the device under test, or



2: A much shorter mechanical gizmo, which is currently labeled in my

mental sketches as the "magic coupler".



The important thing in all of this blathering is that when all is said

and done the coupling needs to transmit torque accurately -- it can't

just be efficient, it has to not have any severe differential gearing

effects that would mess up torque readings.



So, do you think #1 would work? Is there a name for #2, and could I

count on it, or should I just stick with #1?



As suggested by my foot-long shaft idea, space is not a huge issue,

particularly if the thing can be stowed away compactly when not in use.


Hi Tim, I didn't chase down all the links others posted,
so perhaps it's already been mentioned, but I used a bellows shaft coupler.
(not cheap)
Link to the first hit on google.
http://www.rw-america.com/products/bellows_couplings/

George H.


--



Tim Wescott

Wescott Design Services

http://www.wescottdesign.com

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Default Coupling misaligned shafts

Tim Wescott wrote:
This is related to my dynamometer thread. We didn't find anything, so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment, which
has no solid external reference points to provide for good alignment to
the shaft on the device under test (or, for that matter, a really easy
way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to couple
the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is said
and done the coupling needs to transmit torque accurately -- it can't
just be efficient, it has to not have any severe differential gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in use.


How about directly coupling the unit to the shaft? If that isn't
possible how about a sprocket and chain?

The problem with any types of angles in the connection is that it will
screw with your measurements.

--
Steve W.
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Default Coupling misaligned shafts

On Tue, 08 Jul 2014 23:09:12 -0500, Tim Wescott
wrote:

On Tue, 08 Jul 2014 22:38:27 -0400, clare wrote:

On Tue, 08 Jul 2014 19:52:15 -0500, Tim Wescott
wrote:

On Tue, 08 Jul 2014 20:26:30 -0400, clare wrote:

On Tue, 08 Jul 2014 15:50:31 -0500, Tim Wescott
wrote:

This is related to my dynamometer thread. We didn't find anything, so
I'm working on plan B, which is to roll my own.

The thing would need to work with an existing piece of equipment,
which has no solid external reference points to provide for good
alignment to the shaft on the device under test (or, for that matter,
a really easy way to get centered onto a shaft).

I'm visualizing getting something that can locate things to within an
inch, and within five or ten degrees, then having one of two things:

1: A foot-long shaft with U-joints (probably CV) at each end, to
couple the dynamometer to the device under test, or

2: A much shorter mechanical gizmo, which is currently labeled in my
mental sketches as the "magic coupler".

The important thing in all of this blathering is that when all is said
and done the coupling needs to transmit torque accurately -- it can't
just be efficient, it has to not have any severe differential gearing
effects that would mess up torque readings.

So, do you think #1 would work? Is there a name for #2, and could I
count on it, or should I just stick with #1?

As suggested by my foot-long shaft idea, space is not a huge issue,
particularly if the thing can be stowed away compactly when not in
use.
#2 is called a belt.

Not if I can't easily mount it concentric to the axis of rotation.

OK, spill the beans--- What is the application??? Picture or
diagram, or at least a good description?? How about a hunk of hose the
right size to fit the shaft, and a couple of hose clamps. Braided hose
if required. Even steel braid. You are only talking 80RPM from what I
remember - and what torque, again???

And I'm assuming you mean parallel to the axis of rotation.


It's for a customer, so I have to be all secretive. Which is a pain, I
know.

Things could, in theory, be mounted dead center on a shaft on the device
under test, but doing so would require some disassembly and reassembly to
do the test. I'll go there if I must, but I'd much rather have something
that'll work anywhere, anytime.

50 newton-meters, whatever that works out to in 'merican units.

about 35 ft lbs., at 80 RPM that's only half a HP. I'd say just pull
the motor and test it. Save you a lot of work in the long term.
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