Thanks for the kind words everyone. It’s gratifying to know that others see value in a project that has consumed so much of my time for so long.
> how did you get the carbon to stay down over the leading and trailing
> edges, especially through the crown area? Looks to me like it took a LOT
> of time and patience to get it that good.
It was a slow process. I cut the carbon to the shape of a paper pattern I had fit to the fork. The joint is on the inside of the fork leg off centre. I just reversed the orientation of subsequent layers so the joints would not line up. There is also a strip of carbon fabric applied over the joint between each full layer. The final layup is 3 layers thick overall, 5 layers on the inside of the fork legs, and locally thicker under the crown and around the seat tube. Areas that were particularly stubborn were coaxed into place with electrical tape. I did one layer at a time so things wouldn’t get out of hand. The carbon I used was 5.6 oz cloth. The epoxy was Industrial Formulators G2. The fiberglass veil was 1 1/2 oz (there was a typo in my last post).
The wood core weighed 15 oz measured on a balance beam scale before adding the carbon. Each layer of carbon/epoxy added 3 oz. After all carbon and the e-glass was added the fork weighed 1 lb 9 oz. I haven’t weighed the bearing retainers or the finished fork. I’ll try to get that done for those who are curious. If a person wanted to lighten it up it wouldn’t be hard. The bearing retainers are way beefy and the fork legs could be slimmed quite a bit. I think two layers of carbon would be plenty strong given the stiffness of the core. If you use foam you’ll have to rethink the lamination schedule a bit. Pulling as hard as I can over my knee I can’t flex a fork leg at all which leads me to believe it’s a bit overdone. Vacuum bagging would give a higher fabric/resin ratio which would be even stiffer.
> Are you going to post a step-by-step how to? Id love to see it, and
> maybe even give it a go myself!
I’ve got photos throughout construction. I’ll see if I can get them scanned for people to view online. It was a tedious process but not at all difficult really. I’d encourage anyone who is generally handy to give it a go. Total material cost of the fork not including the bearing retainers was about $85.00 CAN.
Someone asked about the seat post. It came from Unicycle Source along with most of the other bits (thanks!). I looked for a brand name and found it stamped “Kalin”.
Cheers, Greg
P.S. I suspect this post will start another thread. I tried replying to a message I received from the list but got a message that the newsgroup could not be resolved whatever that means. Damn computers.
— Greg Moore <gmoore@island.net> wrote:
>
> Thanks for the kind words everyone. It’s gratifying
> to know that others see value in a project that has
> consumed so much of my time for so long.
>
> > how did you get the carbon to stay down over the
> leading and trailing
> > edges, especially through the crown area? Looks to
> me like it took a LOT
> > of time and patience to get it that good.
>
> It was a slow process. I cut the carbon to the shape
> of a paper pattern I had fit to the fork. The joint
> is on the inside of the fork leg off centre. I just
> reversed the orientation of subsequent layers so the
> joints would not line up. There is also a strip of
> carbon fabric applied over the joint between each
> full layer. The final layup is 3 layers thick
> overall, 5 layers on the inside of the fork legs,
> and locally thicker under the crown and around the
> seat tube. Areas that were particularly stubborn
> were coaxed into place with electrical tape. I did
> one layer at a time so things wouldn’t get out of
> hand. The carbon I used was 5.6 oz cloth. The epoxy
> was Industrial Formulators G2. The fiberglass veil
> was 1 1/2 oz (there was a typo in my last post).
>
> The wood core weighed 15 oz measured on a balance
> beam scale before adding the carbon. Each layer of
> carbon/epoxy added 3 oz. After all carbon and the
> e-glass was added the fork weighed 1 lb 9 oz. I
> haven’t weighed the bearing retainers or the
> finished fork. I’ll try to get that done for those
> who are curious. If a person wanted to lighten it up
> it wouldn’t be hard. The bearing retainers are way
> beefy and the fork legs could be slimmed quite a
> bit. I think two layers of carbon would be plenty
> strong given the stiffness of the core. If you use
> foam you’ll have to rethink the lamination schedule
> a bit. Pulling as hard as I can over my knee I can’t
> flex a fork leg at all which leads me to believe
> it’s a bit overdone. Vacuum bagging would give a
> higher fabric/resin ratio which would be even
> stiffer.
>
> > Are you going to post a step-by-step how to? Id
> love to see it, and
> > maybe even give it a go myself!
>
> I’ve got photos throughout construction. I’ll see if
> I can get them scanned for people to view online. It
> was a tedious process but not at all difficult
> really. I’d encourage anyone who is generally handy
> to give it a go. Total material cost of the fork not
> including the bearing retainers was about $85.00
> CAN.
>
> Someone asked about the seat post. It came from
> Unicycle Source along with most of the other bits
> (thanks!). I looked for a brand name and found it
> stamped “Kalin”.
>
> Cheers, Greg
>
> P.S. I suspect this post will start another thread.
> I tried replying to a message I received from the
> list but got a message that the newsgroup could not
> be resolved whatever that means. Damn computers.
Greg,
Where did you get the materials? Im curious, we have a
carbon fibre lab here at school (I think), where I
might be able to work. Well, next semester maybe.
That’s a pretty cool uni! I just wanted to add my praise of it.
One question though? Would it be possible to add a brake? I mean would you have to add a piece of metal for the brake studs, or would the carbon fibre be strong enough?
A local supplier, Industrial Plastics & Paints, ordered the carbon for me. I
had the epoxy on hand. Everything needed is readily available.
Nathan had asked why I chose a 26" rim and I had forgotten to reply. I
wanted the fork to accomodate the largest wheel/tire I would likely ever
want - of course now I want to build a 36", oh well. Much of my riding is
still on the street and very easy trails so I didn’t feel the extra size
would be a hindrance to me. At 135 lbs I didn’t feel the need for the
stronger 24" wheel either. I like the look of the 26" wheel as well. It
truly is a massive piece of kit. I’ve already noticed the beast is
significantly faster than my 24", the only other uni I’ve ever tried.
I’m going to be mounting the brakes in aluminum brackets doing away with the
stock Magura mounts. I’ve got aluminum tubing that will be tapped and
epoxied into the fork legs to accept the fasteners. I wouldn’t trust a
machine screw holding in carbon fibre only.
An update. Weighed the fork as best I could and I figure it’s about 2 lb 13
oz.
On another note I achieved some level of fame with the beast last evening. I
live on a sailboat in the marina here in Comox mid way up Vancouver Island.
The local stomping grounds are largely 4 foot wide concrete fingers oriented
90 degrees to each other to which the various boats are moored.
At about 7:30 pm PST something happened that has never happened before.
There was a splash that surely scared sea going creatures up and down the
coast almost as much as it did me. I UPD’d into the chuck! Damn that water
is cold. Went up to the pub for a pint after drying off and didn’t the
waitress search high and low for an umbrella for my beer! News travels fast
on the docks.
Unfortunately there are few enough unicyclists here that saying “it was the
other guy” proved a waste of time. Time to rethink that bright yellow paint
job. So I’ve spent today recovering, sheepishly riding deserted streets in
search of my self confidence.
