Aug 31

August 31, 2005

Carbon fiber remote steerer and a the fairing mold is finally here!!

The 4000 lb slab of MDF arrived today. To tell you the truth, I am not thrilled about the surface finish, but hopeful that I can make it better. I made some assumptions about LaserSpec's abilities, and they made some assumptions about what kind of quality expectations I had. Totally my fault - I should have insisted on sitting down with a technical person there rather than a sales representative. The problem is when they finish sanded the surface of the mold, the glue lines (the mold is made up of a stack of 1" thick MDF sheets glued together) are harder than the wood and leave a slight line or wavy wobble behind. They sprayed a thick coat of epoxy based primer over it all and sanded again, but the slight waves are still there.

I have some vacuum forming tricks up my sleeve that could fix the problem, but if worse comes to worse, I may have to make a fiberglass plug from the mold, coat with bondo, sand down smooth and make a new mold from that.

The other problem I am having is how to drill my vacuum holes. Some places are almost 3 feet deep!!! I was told by LaserSpec that if you shape the end of a piano wire and put it into the chuck of a drill, you can drill tiny vacuum holes through a very thick slab.

I tried this and it didn't work at all. The bit spun nicely, but didn't drill into the hard MDF wood. Then I welded a 1/16" drill bit onto a 1/16" dia rod of steel welding filler. It seemed to work great, but again, the drill bit didn't want to drill though the MDF without a lot of pressing down on the bit - something you can't do when most of the bit is just a thin wire. The weld held, and actually the bit itself ended up snapping in two.

But, I have another idea, and I think this ones a keeper. I have a long 1/4" drill bit and I can weld it to a 1/4" steel rod that should be stiff enough to apply enough pressure to force it to drill through the wood slab. 1/4" is WAY too large a hole for vacuum forming, so I will fill each 1/4" hole with some bondo, sand smooth and drill through the bondo patch with a 1/16" or 1/32" bit.

This is the new carbon fiber remote steering bar that I made. I weighs WAY less than the bracket system and works VERY sweet!!! Details of the construction are in the table below.

And finally, I got an email from Kevin who asked a really great question. He wanted to know why I didn't simply build a fairing over the M5. Here is my reply:

Hi Kevin:

You know, It's been so long since the design phase that I had to stop and think about the answer to that.

1. Rolling resistance. I wanted the lowest Crr possible and that meant big wheels. The M5's small front wheel is not acceptable.

2. FWD. I wanted front wheel drive to eliminate that huge and heavy long M5 chain. Also with a RWD, you need to either route the chain up and over the front wheel which causes power loss due to the chain idlers required, or, use a mono-hub and mono-fork for the front wheel which restrict turn radius and causes the wheel to want to always turn left (I hate that the most about the M5).

3. Gearing. As a streamliner, the M5 offers no way of getting the kind of gears I need to get to speed. The FWD system offers an intermediate drive which does two things; a. Changes the drive direction to parallel the fork, and B. allows me to use the intermediate drive to step up the gears.

4. Weight - The M5 is heavier than the carbon frame, and would be even heavier will all of the fairing attachment hardware that the carbon frame does not require.

5. Stiffness - I wanted the most efficient transfer of power from the cranks to the drive wheel. The M5 frame is very flexy and some energy is lost to frame flex. The carbon frame is as stiff as a rock.

6. Steering - I prefer the remote steering to the very long tiller that the M5 uses.

7. Finally, since I planned on vacuum forming my fairing with thin PETG plastic, I needed a fairing mount that was actually part of the fairing to hold it's shape properly. Without that fairing shaped perimeter, the fairing would just flop around.

1. I bought some carbon fiber tubes from Carbon Fiber Tube Shop and was VERY impressed with their helpfulness over the phone, prompt service and delivery. The quality of the tubes is top notch.

I cut to tubes to fit, then bonded them in place using Crazy Glue.

2. This is the steering bar temporarily held together with Crazy Glue
3. I wrapped multiple layers of carbon around the joints and then wrapped the whole bundle with peel ply, breather and duct tape.
4. Here is the bar after curing and some sanding
5. My friend James machined two UHMW plastic bushings to press fit into a 3" long aluminum head tube shell (not shown).

I cut a washer from a small sheet of 1/8" thick carbon plate that I also purchased from Carbon Fiber Tube Shop.

The tube slides into the bushing, then the washer fits on, then an aluminum clamp to hold it all together.

6. This is the aluminum clamp - it's a bar end that I cut off.
7. The push/pull arm is a 1/2" carbon tube. To get the bar end joints onto the carbon tubes, I welded a nut to a small piece of 1/2" ID tubing. This tubes slides over the 1/2" carbon tube, and the bar end screws into the nut.
8. Like this.
9. This carbon push/pull rod replaces the much heavier aluminum one I was using before
10. To secure the nut, I wrapped a few layers of carbon over the end piece.
11. This shows the new push/pull rod bolted to the re-purposed bar end
12. The aluminum shell was pressed into place where the old aluminum bracket and headset used to be. Then I layered on dry carbon cloth using spray epoxy to hold it in place.
13. This shows the completed assembly.
14. The motion is equally as smooth as the old headset based one - WAY lighter.

I still need to sand the carbon smooth and fill in the edges around the head tube.

Still to do:

1. Add a rear caliper brake
2. Trace the real perimeter outline using an actual fairing half shell (when I get one!), and cut out the perimeter
3. Edge laminate the perimeter
4. Thicken the frame to avoid using the spacers on the brackets
5. Bond in the bottom brackets
6. Make new remote steering out of carbon and UHMW
7. Bond on the right hand rear wheel dome.

8. Bond fasteners to frame for the left hand wheel dome
9. Add a thin coat of epoxy to the left hand wheel disc because it is not air tight (and fill holes in the dome)
10. New carbon fork?
11. Carbon wheel disc and wheel dome for from t wheel
13. Wheel fairing
14. Seat (wait until you know exactly where you want it)

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