YAMAHA RD CAFE SEAT

[Clueless]

Hey guys Im in the process of building myself an Rd250 cafe racer, the bike has not run in a very long time ,it is a basket case which I am enjoying bringing back to life. I thought I would share with you how I have designed and made the seat.

 

[Clueless]

First I cut away the rear hoop from the frame to give myself more freedom with the design

 

[Clueless]

I then mocked up a seat useing bits of wire and masking tape until I came up with a shape I was happy with. The shape of the frame dictated the design but I wanted to cut away as little as possible from the frame.

 

[Clueless]

I then took measurements of the mock up and drew the seat in pro-engineer, then opend it in Mastercam to produce a toolpath to cut the seat on a CNC Router from polyurethane foam.

 

[Clueless]

The seat was machined from both sides.

 

[Clueless]

Once machined I gave it a coat of 2k primer.

 

[Clueless]

I then set the part up to make a fibre glass mould, I built a wall down the middle useing cardboard which I then covered with a piece of 1mm styrene, I used styrene to form walls to produce a flange on the base and front too. I used plastic screw caps to form locators, these were stuck on useing a hot glue gun.

 

[Clueless]

I gave the half to be moulded 3 layers of wax polishing each between coats. I then sprayed a thin layer of PVA release over it to act as an extra barrier. This is not really necessairy but does work very well in preventing the polyester resin from attaking the part.
Next up was the laminating, first I gave the part and flanges a coat of gelcoat, once dry enough I sprinkled choppies on to the awkward parts such as locators and sharp corners before covering with 5 layers of 350gram matt.

 

[bikeboy]

I really like that profile, and maybe I've missed something, but why are you doing this as a two-piece? It looks pretty straight-forward single piece molding to me?

cheers
ian

 

[Hoosier Daddy]

Curious as well, appears the seam right down the middle may be a PITA to hide.

 

[Tim]

Seam or no seam, that's awesome stuff. First thing I'd buy (well second, I'd need a shop for it first) after winning the Powerball is a bunch of super-cool CNC stuff, and hire someone to teach me how to use it.

I'd CNC my toast in the morning.

 

[TheChild]

Did you just make a mold of a mold?

 

[chrisf]

Gents:

He made a female mould. The male part will be pulled from the female mould. This is the real way to do composite seats which will result in a much lighter, cleaner male seat.

The seam is there so he can unbolt it, and easily pop the male seat out. Otherwise, it's a bitch.

--Chris

 

[dirtbag]

I'll take one please.

 

[HK_Sailor]

Did you only use chop strand fibre sheet?

 

[VonYinzer]

Purdy neat. When you get around to making some seats, I would certainly be interested in one.

 

[Clueless]

Hey guys I will carry on posting, the pics will explain my method. I only used chop strand matt for both the mould and the part with polyester resin.

 

[dirtbag]

will u make one for me.

 

[Clueless]

As the first side of the mould went green I trimed the excess fibre glass to the flanges with a craft knife. Once dry I removed the central carboard/styrene flange as the moulded fibre glass now forms the flange with female locators.
I then waxed and polished the part and flanges and sprayed a thin laher of PVA release and repeated the steps for the first half.

 

[Clueless]

Once again I trimed the excess to the flanges when green, once dry I gave the mould a once over with course sand paper to remove splinters. I then drilled holes in the central flanges to accept M6 bolts, these along with the locators will ensure the mould aligns perfectly. To split the mould I ran a craft knife down the central flange for the inital crack I then inserted and twisted a flat screw driver, the mould split with ease with one side popping off.
Once both sides of the mould were released from the plug/machined part I re-assembled the mould and trimmed the flanges with a hand grinder.