12 mm 6061: Strong Enough tb Pedal Spindle?

Not for a bike, but for a Hobie Mirage Drive as in
http://tinyurl.com/yb3uppbm

I keep breaking Hobie's hollow crank arms and have made some
replacements out of solid 6061.

Was going to tap them for 1/2" bicycle pedals, but now I am thinking of
using the Hobie pedals, whose attraction is that they have no bearings
to rust in salt water - just a spindle through the plastic pedal.

Hobie uses SS for their spindles, but after reading up on threading SS,
I think the path of least resistance would be to get some 6061 in the
same diameter (12mm) and use that instead.

Bottom Line: would 6061 have enough strength? ... This is more of a
recumbent-type config - i.e. the user is not standing/stomping on the
pedals.
--
Pete Cresswell

On 6/12/2017 1:06 PM, (PeteCresswell) wrote:
Not for a bike, but for a Hobie Mirage Drive as in
http://tinyurl.com/yb3uppbm

I keep breaking Hobie's hollow crank arms and have made some
replacements out of solid 6061.

Was going to tap them for 1/2" bicycle pedals, but now I am thinking of
using the Hobie pedals, whose attraction is that they have no bearings
to rust in salt water - just a spindle through the plastic pedal.

Hobie uses SS for their spindles, but after reading up on threading SS,
I think the path of least resistance would be to get some 6061 in the
same diameter (12mm) and use that instead.

Bottom Line: would 6061 have enough strength? ... This is more of a
recumbent-type config - i.e. the user is not standing/stomping on the
pedals.

We'll need a lot more information. I did one test ride in a Hobie
Mirage Drive, but I don't remember many details about the mechanism, and
the one photo you linked isn't helping much. But I didn't think I was
able to apply very much force to the pedals. ISTR wanting a higher
"gear," so to speak.

6061 T6 is way weaker than any stainless steel I know about. In
general, going to a solid cross section doesn't add much strength
compared with a hollow cross section of same outside dimensions. Just
based on that, I'm not optimistic about your proposed change.

So: Can you give us dimensions, and an explanation of how the thing
works? Where did the original break? Do you have photos? And in the
photo at the site you linked, what's the grey handle thing that seems
linked to a transverse pin?

(And I wonder if there's a kayak discussion group that might be more
appropriate.)

--
- Frank Krygowski

On 6/12/2017 3:20 PM, Frank Krygowski wrote:
On 6/12/2017 1:06 PM, (PeteCresswell) wrote:
Not for a bike, but for a Hobie Mirage Drive as in
http://tinyurl.com/yb3uppbm

I keep breaking Hobie's hollow crank arms and have made some
replacements out of solid 6061.

Was going to tap them for 1/2" bicycle pedals, but now I
am thinking of
using the Hobie pedals, whose attraction is that they have
no bearings
to rust in salt water - just a spindle through the plastic
pedal.

Hobie uses SS for their spindles, but after reading up on
threading SS,
I think the path of least resistance would be to get some
6061 in the
same diameter (12mm) and use that instead.

Bottom Line: would 6061 have enough strength? ... This is
more of a
recumbent-type config - i.e. the user is not
standing/stomping on the
pedals.

We'll need a lot more information. I did one test ride in a
Hobie Mirage Drive, but I don't remember many details about
the mechanism, and the one photo you linked isn't helping
much. But I didn't think I was able to apply very much
force to the pedals. ISTR wanting a higher "gear," so to
speak.

6061 T6 is way weaker than any stainless steel I know
about. In general, going to a solid cross section doesn't
add much strength compared with a hollow cross section of
same outside dimensions. Just based on that, I'm not
optimistic about your proposed change.

So: Can you give us dimensions, and an explanation of how
the thing works? Where did the original break? Do you have
photos? And in the photo at the site you linked, what's the
grey handle thing that seems linked to a transverse pin?

(And I wonder if there's a kayak discussion group that might
be more appropriate.)


https://www.youtube.com/watch?v=lD6OQhCeXqs


--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On Monday, June 12, 2017 at 4:51:06 PM UTC-4, AMuzi wrote:
On 6/12/2017 3:20 PM, Frank Krygowski wrote:
On 6/12/2017 1:06 PM, (PeteCresswell) wrote:
Not for a bike, but for a Hobie Mirage Drive as in
http://tinyurl.com/yb3uppbm

I keep breaking Hobie's hollow crank arms and have made some
replacements out of solid 6061.

Was going to tap them for 1/2" bicycle pedals, but now I
am thinking of
using the Hobie pedals, whose attraction is that they have
no bearings
to rust in salt water - just a spindle through the plastic
pedal.

Hobie uses SS for their spindles, but after reading up on
threading SS,
I think the path of least resistance would be to get some
6061 in the
same diameter (12mm) and use that instead.

Bottom Line: would 6061 have enough strength? ... This is
more of a
recumbent-type config - i.e. the user is not
standing/stomping on the
pedals.

We'll need a lot more information. I did one test ride in a
Hobie Mirage Drive, but I don't remember many details about
the mechanism, and the one photo you linked isn't helping
much. But I didn't think I was able to apply very much
force to the pedals. ISTR wanting a higher "gear," so to
speak.

6061 T6 is way weaker than any stainless steel I know
about. In general, going to a solid cross section doesn't
add much strength compared with a hollow cross section of
same outside dimensions. Just based on that, I'm not
optimistic about your proposed change.

So: Can you give us dimensions, and an explanation of how
the thing works? Where did the original break? Do you have
photos? And in the photo at the site you linked, what's the
grey handle thing that seems linked to a transverse pin?

(And I wonder if there's a kayak discussion group that might
be more appropriate.)


https://www.youtube.com/watch?v=lD6OQhCeXqs


--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

I hope that sharks don't mistake that for flippers.

Cheers

On Monday, June 12, 2017 at 1:51:06 PM UTC-7, AMuzi wrote:
On 6/12/2017 3:20 PM, Frank Krygowski wrote:
On 6/12/2017 1:06 PM, (PeteCresswell) wrote:
Not for a bike, but for a Hobie Mirage Drive as in
http://tinyurl.com/yb3uppbm

I keep breaking Hobie's hollow crank arms and have made some
replacements out of solid 6061.

Was going to tap them for 1/2" bicycle pedals, but now I
am thinking of
using the Hobie pedals, whose attraction is that they have
no bearings
to rust in salt water - just a spindle through the plastic
pedal.

Hobie uses SS for their spindles, but after reading up on
threading SS,
I think the path of least resistance would be to get some
6061 in the
same diameter (12mm) and use that instead.

Bottom Line: would 6061 have enough strength? ... This is
more of a
recumbent-type config - i.e. the user is not
standing/stomping on the
pedals.

We'll need a lot more information. I did one test ride in a
Hobie Mirage Drive, but I don't remember many details about
the mechanism, and the one photo you linked isn't helping
much. But I didn't think I was able to apply very much
force to the pedals. ISTR wanting a higher "gear," so to
speak.

6061 T6 is way weaker than any stainless steel I know
about. In general, going to a solid cross section doesn't
add much strength compared with a hollow cross section of
same outside dimensions. Just based on that, I'm not
optimistic about your proposed change.

So: Can you give us dimensions, and an explanation of how
the thing works? Where did the original break? Do you have
photos? And in the photo at the site you linked, what's the
grey handle thing that seems linked to a transverse pin?

(And I wonder if there's a kayak discussion group that might
be more appropriate.)


https://www.youtube.com/watch?v=lD6OQhCeXqs

Jeez, they can't be serious.

On 6/12/2017 4:51 PM, AMuzi wrote:
On 6/12/2017 3:20 PM, Frank Krygowski wrote:
On 6/12/2017 1:06 PM, (PeteCresswell) wrote:
Not for a bike, but for a Hobie Mirage Drive as in
http://tinyurl.com/yb3uppbm

I keep breaking Hobie's hollow crank arms and have made some
replacements out of solid 6061.

Was going to tap them for 1/2" bicycle pedals, but now I
am thinking of
using the Hobie pedals, whose attraction is that they have
no bearings
to rust in salt water - just a spindle through the plastic
pedal.

Hobie uses SS for their spindles, but after reading up on
threading SS,
I think the path of least resistance would be to get some
6061 in the
same diameter (12mm) and use that instead.

Bottom Line: would 6061 have enough strength? ... This is
more of a
recumbent-type config - i.e. the user is not
standing/stomping on the
pedals.

We'll need a lot more information. I did one test ride in a
Hobie Mirage Drive, but I don't remember many details about
the mechanism, and the one photo you linked isn't helping
much. But I didn't think I was able to apply very much
force to the pedals. ISTR wanting a higher "gear," so to
speak.

6061 T6 is way weaker than any stainless steel I know
about. In general, going to a solid cross section doesn't
add much strength compared with a hollow cross section of
same outside dimensions. Just based on that, I'm not
optimistic about your proposed change.

So: Can you give us dimensions, and an explanation of how
the thing works? Where did the original break? Do you have
photos? And in the photo at the site you linked, what's the
grey handle thing that seems linked to a transverse pin?

(And I wonder if there's a kayak discussion group that might
be more appropriate.)


https://www.youtube.com/watch?v=lD6OQhCeXqs

I'm familiar with that. As I said, I test rode one. It was fast, and
kind of fun to generate a serious wake.

But if we're going to do new pedal arms, I'd like to know how they
attach to the rest of the mechanism, and exactly which part broke, etc.

--
- Frank Krygowski

On Monday, June 12, 2017 at 6:59:19 PM UTC-7, Frank Krygowski wrote:
On 6/12/2017 4:51 PM, AMuzi wrote:
On 6/12/2017 3:20 PM, Frank Krygowski wrote:
On 6/12/2017 1:06 PM, (PeteCresswell) wrote:
Not for a bike, but for a Hobie Mirage Drive as in
http://tinyurl.com/yb3uppbm

I keep breaking Hobie's hollow crank arms and have made some
replacements out of solid 6061.

Was going to tap them for 1/2" bicycle pedals, but now I
am thinking of
using the Hobie pedals, whose attraction is that they have
no bearings
to rust in salt water - just a spindle through the plastic
pedal.

Hobie uses SS for their spindles, but after reading up on
threading SS,
I think the path of least resistance would be to get some
6061 in the
same diameter (12mm) and use that instead.

Bottom Line: would 6061 have enough strength? ... This is
more of a
recumbent-type config - i.e. the user is not
standing/stomping on the
pedals.

We'll need a lot more information. I did one test ride in a
Hobie Mirage Drive, but I don't remember many details about
the mechanism, and the one photo you linked isn't helping
much. But I didn't think I was able to apply very much
force to the pedals. ISTR wanting a higher "gear," so to
speak.

6061 T6 is way weaker than any stainless steel I know
about. In general, going to a solid cross section doesn't
add much strength compared with a hollow cross section of
same outside dimensions. Just based on that, I'm not
optimistic about your proposed change.

So: Can you give us dimensions, and an explanation of how
the thing works? Where did the original break? Do you have
photos? And in the photo at the site you linked, what's the
grey handle thing that seems linked to a transverse pin?

(And I wonder if there's a kayak discussion group that might
be more appropriate.)


https://www.youtube.com/watch?v=lD6OQhCeXqs

I'm familiar with that. As I said, I test rode one. It was fast, and
kind of fun to generate a serious wake.

But if we're going to do new pedal arms, I'd like to know how they
attach to the rest of the mechanism, and exactly which part broke, etc.

Frank - fun to generate a wake? God lord now I know you're a lot older than me. Moved into the retirement community yet? Do you have trouble with your dentures?

On Mon, 12 Jun 2017 13:06:32 -0400, "(PeteCresswell)"
wrote:

Not for a bike, but for a Hobie Mirage Drive as in
http://tinyurl.com/yb3uppbm

I keep breaking Hobie's hollow crank arms and have made some
replacements out of solid 6061.

Was going to tap them for 1/2" bicycle pedals, but now I am thinking of
using the Hobie pedals, whose attraction is that they have no bearings
to rust in salt water - just a spindle through the plastic pedal.

Hobie uses SS for their spindles, but after reading up on threading SS,
I think the path of least resistance would be to get some 6061 in the
same diameter (12mm) and use that instead.

Bottom Line: would 6061 have enough strength? ... This is more of a
recumbent-type config - i.e. the user is not standing/stomping on the
pedals.

6061 isn't a complete description. You need to include the "T" number
as 6061 can have a yield strength of from 14 to 35 ksi, a typical
hardness from Brinell 30 to 95 and a sheer strength of from 12 - 30
ksi, depending heat treatment.

Relative to steel aluminum is a relatively soft metal and I would
guess not be the material of choice for long wearing pedal spindles.

On the other hand a stainless and aluminum mix can cause some
astonishing commission in salt water but there are quite a selection
of barrier "stuff" to electrically isolate the two. I even used a
silicon sealant mix and a year later the parts came apart easily. I
don't recommend silicone sealant as an all purpose solution but it
does, I believe, show that the problem isn't rocket science.


--
Cheers,

John B.

On Tuesday, June 13, 2017 at 5:45:22 AM UTC-7, John B. wrote:
On Mon, 12 Jun 2017 13:06:32 -0400, "(PeteCresswell)"
wrote:

Not for a bike, but for a Hobie Mirage Drive as in
http://tinyurl.com/yb3uppbm

I keep breaking Hobie's hollow crank arms and have made some
replacements out of solid 6061.

Was going to tap them for 1/2" bicycle pedals, but now I am thinking of
using the Hobie pedals, whose attraction is that they have no bearings
to rust in salt water - just a spindle through the plastic pedal.

Hobie uses SS for their spindles, but after reading up on threading SS,
I think the path of least resistance would be to get some 6061 in the
same diameter (12mm) and use that instead.

Bottom Line: would 6061 have enough strength? ... This is more of a
recumbent-type config - i.e. the user is not standing/stomping on the
pedals.

6061 isn't a complete description. You need to include the "T" number
as 6061 can have a yield strength of from 14 to 35 ksi, a typical
hardness from Brinell 30 to 95 and a sheer strength of from 12 - 30
ksi, depending heat treatment.

Relative to steel aluminum is a relatively soft metal and I would
guess not be the material of choice for long wearing pedal spindles.

On the other hand a stainless and aluminum mix can cause some
astonishing commission in salt water but there are quite a selection
of barrier "stuff" to electrically isolate the two. I even used a
silicon sealant mix and a year later the parts came apart easily. I
don't recommend silicone sealant as an all purpose solution but it
does, I believe, show that the problem isn't rocket science.

That was some good information John. Too bad this site doesn't allow you to edit your spelling so that you could correct your spelling of "corrosion" since some of the people won't be able to figure it out.

I sort of fail to see how a flipper mechanism like that could require or absorb much power.

On Monday, June 12, 2017 at 6:59:19 PM UTC-7, Frank Krygowski wrote:
On 6/12/2017 4:51 PM, AMuzi wrote:
On 6/12/2017 3:20 PM, Frank Krygowski wrote:
On 6/12/2017 1:06 PM, (PeteCresswell) wrote:
Not for a bike, but for a Hobie Mirage Drive as in
http://tinyurl.com/yb3uppbm

I keep breaking Hobie's hollow crank arms and have made some
replacements out of solid 6061.

Was going to tap them for 1/2" bicycle pedals, but now I
am thinking of
using the Hobie pedals, whose attraction is that they have
no bearings
to rust in salt water - just a spindle through the plastic
pedal.

Hobie uses SS for their spindles, but after reading up on
threading SS,
I think the path of least resistance would be to get some
6061 in the
same diameter (12mm) and use that instead.

Bottom Line: would 6061 have enough strength? ... This is
more of a
recumbent-type config - i.e. the user is not
standing/stomping on the
pedals.

We'll need a lot more information. I did one test ride in a
Hobie Mirage Drive, but I don't remember many details about
the mechanism, and the one photo you linked isn't helping
much. But I didn't think I was able to apply very much
force to the pedals. ISTR wanting a higher "gear," so to
speak.

6061 T6 is way weaker than any stainless steel I know
about. In general, going to a solid cross section doesn't
add much strength compared with a hollow cross section of
same outside dimensions. Just based on that, I'm not
optimistic about your proposed change.

So: Can you give us dimensions, and an explanation of how
the thing works? Where did the original break? Do you have
photos? And in the photo at the site you linked, what's the
grey handle thing that seems linked to a transverse pin?

(And I wonder if there's a kayak discussion group that might
be more appropriate.)


https://www.youtube.com/watch?v=lD6OQhCeXqs

I'm familiar with that. As I said, I test rode one. It was fast, and
kind of fun to generate a serious wake.

But if we're going to do new pedal arms, I'd like to know how they
attach to the rest of the mechanism, and exactly which part broke, etc.

When it snaps, at least its soft enough to drill a pilot hole for the Easy-out.

Speaking of . . . my Roubaix has these removable removable rear fender eyelets that screw into a female boss at the end of the seat stay. The eyelet has a threaded 4mm shank and is made of aluminum. Well, I broke a rear eyelet yesterday and was looking at it in the garage last night thinking, "oh boy, I get to drill a tiny hole in a 4mm bolt stub" . . . The good part is that the metal was so soft and useless that I could grind a slot using a low speed drill and then screw it out. I had previously broken a front eyelet much higher up and bought a set of four SS replacements, so at least I had the part. I didn't like the idea of having to buy a part that should have been sold in the first place.

-- Jay Beattie.