Let's Reinvent the Seat!

I’ve got a clay prototype of a seat handle. I need some ideas for fabricating a
seat handle in the same shape as the clay model.

Idea 1: Cut the rough shape from foam, then layer with fiberglass cloth & fill
with epoxy.

Idea 2: Obtain short pieces of glass fiber, mix with 5 or 30 minute epoxy at a
ratio of about 30% fiber/70% matrix, put it all in a ziploc bag and hold it in
the desired shape until it sets. Rip the plastic off after it’s cured.

I’m leaning toward the second method, since some sections are thin already, so a
core would make it too thick when done.

Has anybody ever done this before? Send your experience this way

Chris

Re: Let’s Reinvent the Seat!

Chris Reeder wrote:
>
> Has anybody ever done this before? Send your experience this way

I have a carbon fiber and kevlar endcap on my unicycle that I made a year ago.
It’s made for the old style miyata seat which doesn’t have the handle. The
handle will complicate things.

I made mine by making a plug from another seat bumper by putting some fiber
glass mat inside the bumper where the bumper wraps around the seat. Then I
finished up the plug so there were no extra fiber glass sticking around and
extended the front of the plug for the bumper so the carbon fiber and kevlar
lays flat over it.

Then I waxed it up and layed the carbon fiber over that followed by a layer of
Kevlar. I had a bag with warm water that I put over it after I layed up the
composite to keep the air out and make it flat against the plug. When that was
hardened, I finished it up by cutting and sanding off the extra composite
material to look right and to fit the seat.

That’s pretty much it. I hope it makes sense, if not, let me know. The one I
made has lasted a year now, but it could use another layer of kevlar on there as
it is wearing through to the carbon fiber.

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Re: Let’s Reinvent the Seat!

Chris,

A solid mould would last well but remember to put on a lot of release agent and
coat with a thick jel coat first to give you a good finish. We do casting
regularly and I would try and find some casting silicone. I comes as a gloopy
liquid with a hardener. It is not cheap though, but is one of the best ways to
make moulds. Here is a brief description how to produce
it.Create a casting box. - temporary glue wooden panels together giving about 1
1/2" all the way around the model. Use a glue gun and seal the corners. Place
your model in the box supported on 2 columns. These should be fixed to the
high points on the model because they will be used as the pourer and air vent
when casting. Use a glue gun again for fixing. Mixed the silicone and pour in.
Now you need to de-gas it… we do it in a autoclave but can be done by gently
tapping it to get the bubbles to raise to the surface. When dry pull the
casting box apart to get the silicon out. Cut the model out with a sharp knife
and get as ragged a line as you can because you want to have a good key to
re-align the 2 halves. Pull out the model. re-assembly the mould using packing
tape and then re-assemble the casting box. Put the silicon in so that the air
holes are vertical. Pour in the the casting resin… wait for it to cure and
you have your handle.

Good luck

Roger


The UK's Unicycle Source <a href="http://www.unicycle.uk.com/">http://www.unicycle.uk.com/</a>

----- Original Message ----- From: “Chris Reeder” <reed8990@uidaho.edu> To:
<unicycling@winternet.com> Sent: Thursday, November 23, 2000 7:04 AM Subject:
Let’s Reinvent the Seat!

> I’ve got a clay prototype of a seat handle. I need some ideas for fabricating
> a seat handle in the same shape as the clay model.
>
> Idea 1: Cut the rough shape from foam, then layer with fiberglass cloth & fill
> with epoxy.
>
> Idea 2: Obtain short pieces of glass fiber, mix with 5 or 30 minute epoxy at a
> ratio of about 30% fiber/70% matrix, put it all in a ziploc bag and hold it in
> the desired shape until it sets. Rip the plastic off after it’s cured.
>
> I’m leaning toward the second method, since some sections are thin already, so
> a core would make it too thick when done.
>
> Has anybody ever done this before? Send your experience this way
>
> Chris

Re: Let’s Reinvent the Seat!

On Thu, 23 Nov 2000, Chris Reeder wrote:
>I’ve got a clay prototype of a seat handle. I need some ideas for fabricating a
>seat handle in the same shape as the clay model.

Got any photos?

Greg

Re: Let’s Reinvent the Seat!

Not yet. It’s still pretty rough, but it’s got the basic idea. I just squeezed
the clay to the shape of my hand for the handle part. The part that troubles me
is how to attach it to the carbon fiber seat base. The Miyata gains strength
from having webs on either side of the seat. That makes them a little wider than
I like, and they eventually wear out my pants.

One way to simplify attachment is to cut out the front lip of the c.f. seat base
so that the handle doesn’t have to go so far down, then turn around, and finally
straight back to the bolt holes. Without having webbing like the Miyatas, it
would have to be fairly thick right there where it goes aroundthe corner. So the
fewer corners the better.

Chris

have to Greg House wrote:
>
> On Thu, 23 Nov 2000, Chris Reeder wrote:
> >I’ve got a clay prototype of a seat handle. I need some ideas for fabricating
> >a seat handle in the same shape as the clay model.
>
> Got any photos?
>
> Greg


Chris Reeder reed8990@uidaho.edu

Re: Let’s Reinvent the Seat!

Pics are up at www.uidaho.edu/~reed8990/h2bday/handle.html

Chris Reeder wrote:
>
> Not yet. It’s still pretty rough, but it’s got the basic idea. I just squeezed
> the clay to the shape of my hand for the handle part. The part that troubles
> me is how to attach it to the carbon fiber seat base. The Miyata gains
> strength from having webs on either side of the seat. That makes them a little
> wider than I like, and they eventually wear out my pants.
>
> One way to simplify attachment is to cut out the front lip of the c.f. seat
> base so that the handle doesn’t have to go so far down, then turn around, and
> finally straight back to the bolt holes. Without having webbing like the
> Miyatas, it would have to be fairly thick right there where it goes aroundthe
> corner. So the fewer corners the better.
>
> Chris
>
>
>
> have to Greg House wrote:
> >
> > On Thu, 23 Nov 2000, Chris Reeder wrote:
> > >I’ve got a clay prototype of a seat handle. I need some ideas for
> > >fabricating a seat handle in the same shape as the clay model.
> >
> > Got any photos?
> >
> > Greg
>
> –
> Chris Reeder reed8990@uidaho.edu


Chris Reeder reed8990@uidaho.edu

Re: Let’s Reinvent the Seat!

Hi,

My feeling on a new seat handle is that it must be upgraded in a couple of
key areas:

  1. strength. I’ve broken several Miyata handles. All of them split along the
    perimeter of the part that bolts to the seat, starting at the rear edges. I
    don’t think that having 3 bolts in the current location is the best solution,
    engineering wise, because it places so much stress on this area. I added two
    additional bolts that go thru the handle sides and the lip of the seat frame,
    on either side.

  2. size and shape. The handle needs to be slightly longer out front for MUni,
    and a slightly different shape (maybe more triangular, with the “top” of the
    triangle at the front). Not much bigger (maybe 1/2" or so).

What about this solution: Forget about a plastic Miyata style front handle.
Instead, redesign the seat base so that it includes a integral handle in the
front. It would not have to be smoothed or rounded (which I’m guessing would be
hard to make); rather the seat would just extend further forward than before.
Then you could just have a plastic cap that fits over this to prevent abrasion
of the seat frame, and round out the corners a bit. Perhaps having the handle as
an integral part of the seat, and the bumper as just that, only a bumper, might
significantly increase the strength of this unit.

The rear bumber could be improved as well this way, by extending the bumper
around the sides at the back. The main purpose of this would not be to actually
function as a “bumper” on the back sides of the seat, but rather to round out
the bottom lip of the seat in this area (making it much more comfortable for
seat-out-in-front hopping).

Any takers? (Roger…?)

-Kris

— Chris Reeder <reed8990@uidaho.edu> wrote:
> Not yet. It’s still pretty rough, but it’s got the basic idea. I just squeezed
> the clay to the shape of my hand for the handle part. The part that troubles
> me is how to attach it to the carbon fiber seat base. The Miyata gains
> strength from having webs on either side of the seat. That makes them a little
> wider than I like, and they eventually wear out my pants.
>
> One way to simplify attachment is to cut out the front lip of the c.f. seat
> base so that the handle doesn’t have to go so far down, then turn around, and
> finally straight back to the bolt holes. Without having webbing like the
> Miyatas, it would have to be fairly thick right there where it goes aroundthe
> corner. So the fewer corners the better.
>
> Chris
>
>
>
> have to Greg House wrote:
> >
> > On Thu, 23 Nov 2000, Chris Reeder wrote:
> > >I’ve got a clay prototype of a seat handle. I
> need some ideas for
> > >fabricating a seat handle in the same shape as
> the clay model.
> >
> > Got any photos?
> >
> > Greg
>
> –
> Chris Reeder reed8990@uidaho.edu


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RE: Let’s Reinvent the Seat!

Chris,

Definitely make a mold if you can.

Then you can make more when you need them.

Then you can make even more…and we can buy them!

John Foss, the Uni-Cyclone http://www.unicycling.com

SIGN IN A FIELD: “The farmer allows walkers to cross the field for free, but the
bull charges.”

RE: Let’s Reinvent the Seat!

> The Miyata gains strength from having webs on either side of the seat. That
> makes them a little wider than I like, and they eventually wear out my pants.

You know, we put too much stress on the fronts of our seats. To keep them from
breaking, it means making the seats real stiff and strong. This makes them
heavy. Perhaps we should think like bicycles, and put the strength under the
seat. In other words, reinvent the seat post.

Then we can make seats that are comfortable, without having to withstand any
stress other than body weight (and impact with any part that touches the
ground). The seat post can be an upside down “L” shape, or even a “T” shape, to
provide protection to both ends of the seat. To the front of this post, handles
and accessories can be attached. These could include computers, lights, water
bottles, toolkits, or even narrow storage bags. You could put a bigger storage
bike on the back, long as you keep it out of the way of your heels.

I just think 'em up. Hopefully somebody will try this…

Stay on top, John Foss, the Uni-Cyclone http://www.unicycling.com

SIGN IN A FIELD: “The farmer allows walkers to cross the field for free, but the
bull charges.”

Re: Let’s Reinvent the Seat!

Kris wrote:

> What about this solution: Forget about a plastic Miyata style front handle.
> Instead, redesign the seat base so that it includes a integral handle in the
> front. It would not have to be smoothed or rounded (which I’m guessing would
> be hard to make); rather the seat would just extend further forward than
> before. Then you could just have a plastic cap that fits over this to prevent
> abrasion of the seat frame, and round out the corners a bit. Perhaps having
> the handle as an integral part of the seat, and the bumper as just that, only
> a bumper, might significantly increase the strength of this unit.

It is worth noting why the current design is as it is. The seat has a separate
bumper for a cost reason. If the seat were made totally from the same material
as the bumper rather than ABS it’s cost would be horrendous. This is not just a
streight cost of material but also a cycle time in the machine. What they have
done with the existing seat with the webs up the side is give the component some
steighth back. It is the vertical component of the seat and handle that give it
the streingth and what Miyata have done is place both in the same horizontal
plain by having one outside the other. The seat must be on the inside, if you do
not want it on the outside then the only place we can put it is below it - which
would make the seat a lot deaper and heavier… or we could always remove the
cover from the front and extend the bumper mound through to probably the
reinforment of the steel because we have destroyed the steigth in the seat by
taking it’s vertical compent away. I could show this a lot better with a pen,
paper and calculator. The problem is that both components, the seat and the
bumper must have a vertical component of about about 20mm without that even the
CF seat base would break. There is the additional point that the Muni guys want
the handle on the seat the freestyle guys do not and if we are doing a new seat
it should allow for both. I am not going to say that there is not a way round
this because there will be, but it is not an problem and is likly to cost. It is
worth remembering that to tool up for the seat it would cost between $10,000 and
$25,0000 and demand a large production run. Lets see what happens.

Roger

> The rear bumber could be improved as well this way, by extending the bumper
> around the sides at the back. The main purpose of this would not be to
> actually function as a “bumper” on the back sides of the seat, but rather to
> round out the bottom lip of the seat in this area (making it much more
> comfortable for seat-out-in-front hopping).
>
> Any takers? (Roger…?)
>
> -Kris
>
> — Chris Reeder <reed8990@uidaho.edu> wrote:
> > Not yet. It’s still pretty rough, but it’s got the basic idea. I just
> > squeezed the clay to the shape of my hand for the handle part. The part that
> > troubles me is how to attach it to the carbon fiber seat base. The Miyata
> > gains strength from having webs on either side of the seat. That makes them
> > a little wider than I like, and they eventually wear out my pants.
> >
> > One way to simplify attachment is to cut out the front lip of the c.f. seat
> > base so that the handle doesn’t have to go so far down, then turn around,
> > and finally straight back to the bolt holes. Without having webbing like the
> > Miyatas, it would have to be fairly thick right there where it goes
> > aroundthe corner. So the fewer corners the better.
> >
> > Chris
> >
> >
> >
> > have to Greg House wrote:
> > >
> > > On Thu, 23 Nov 2000, Chris Reeder wrote:
> > > >I’ve got a clay prototype of a seat handle. I
> > need some ideas for
> > > >fabricating a seat handle in the same shape as
> > the clay model.
> > >
> > > Got any photos?
> > >
> > > Greg
> >
> > –
> > Chris Reeder reed8990@uidaho.edu
>
>
> __________________________________________________
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