Topic: My cafe seat

[seven]

OK,

Here is my the start of my seat project. What do ya think?

First I designed it on Cad, then cut out the templates, which i glued to craftwood.

Next comes expanding foam shaping, sanding, bog (Bondo) and more sanding.

Over the coming weeks I will be finishing the buck and making a copy in fibreglass.

Cheers

[FunJimmy]

Looks like a great start.
What bike is it for?

Keep the pictures coming.

FJ

[seven]

It's for my 78K:


But I want it to look like this:


Well, more or less.

[cafeconleche]

this is a great idea,
I think i may try to take a stab at your process.

thanks for sharing

[captaincrash80]

Template looks good man. I might have to try that method when I make my first seat.

[KiLO]

Looking really nice.  Can't wait to see how it turns out.

[luder]

Great idea keep us posted...luder

[stay youth]

What program are you using? Are you able to get all the curves for the data provided by the program? Looks really great.

I'm learning Solidworks now and I'm always curious how people do things

[seven]

What program are you using? Are you able to get all the curves for the data provided by the program? Looks really great.

I'm learning Solidworks now and I'm always curious how people do things

Just using autocad 2D. Basically all the curves are based on my freehand sketches. Then transferred to cad and projected on to a flat plane.

Hopefully, I'll foam fill it tomorrow. It was 46 deg C (120 deg F) here today, too damn hot to do anything but drink beer and hang out by a pool.

Cheers

[cafeconleche]

What program are you using? Are you able to get all the curves for the data provided by the program? Looks really great.

I'm learning Solidworks now and I'm always curious how people do things

Just using autocad 2D. Basically all the curves are based on my freehand sketches. Then transferred to cad and projected on to a flat plane.

Hopefully, I'll foam fill it tomorrow. It was 46 deg C (120 deg F) here today, too damn hot to do anything but drink beer and hang out by a pool.

Cheers

that sounds better than 15 degrees F here

[seven]

OK next step,

I enclosed the rear section in cardboard ready for the foam.


Then added the foam. WHAT A MESS. Wasn't ready for the result.



This is a two part Polyurethane Foam that sets hard. Available from the composites store. This stuff allows easy cutting sanding and you can apply BOG (auto filler) directly to it.
At first I thought I got a dud batch because I was adding the two parts together, mixing and pouring into mould but no action. Turns out I wasn't mixing it for long enough. Mix it a good twenty seconds then pour and it goes off like a volcano.

[walkingchaos]

It's for my 78K:


But I want it to look like this:


Well, more or less.

funny i have that exact seat in the second picture

[seven]

It's for my 78K:


But I want it to look like this:


Well, more or less.

funny i have that exact seat in the second picture

Not bad,

So where did you score this?

[seven]

Worked on it some more tonight.

Cut it up and roughly shaped it with my weapon of choice (a hand saw). Hard part about this step was cleaning up the mess before the missus spotted it.


So this is the rough form. Dotted line will be where I cut the cowl back so I can get a tail light wedged in there.


Next comes smoother shaping with a cheese grater file and then the body filler.

[Grumpol]

nice work mate, once you have that bogged up you could lay up a nice mould and make plenty of seats for others.
I reckon there might be a small market out there for this sort of thing

[Sponge Boy]

Hey Seven,

Looking great mate, your shaping is coming up well.
Did you particularly want the backstop to be angled back so far ?
I would have thought a little less would have been better.
Sure, it looks good like that but will it be practical ? After all, your bike will be a rocket when it's finished and you'll need that backstop to work.

[walkingchaos]

It's for my 78K:


But I want it to look like this:


Well, more or less.

funny i have that exact seat in the second picture

Not bad,

So where did you score this?

I was lucky in finding a local bike guy who was cleaning out his shop. he got it from a fiberglass guy in Boston tears and years ago who made 4 and that was it.

[seven]

Hey Seven,

Looking great mate, your shaping is coming up well.
Did you particularly want the backstop to be angled back so far ?
I would have thought a little less would have been better.
Sure, it looks good like that but will it be practical ? After all, your bike will be a rocket when it's finished and you'll need that backstop to work.

Thanks Sponge Boy, and welcome.

Yeah, I didn't really think about that to tell you the truth. I just wanted to make sure i clear the hump created by the inner guard. It's definitely form over function here. As for my bike being a rocket, well I don't think so. The motor is a little tired and if I do have to rebuild, it would only be stock. So, I'm not planning to go to the moon any time soon.

So what do you ride?

Cheers

[seven]

nice work mate, once you have that bogged up you could lay up a nice mould and make plenty of seats for others.
I reckon there might be a small market out there for this sort of thing

Nice arse Grumpol,

I don't know, it's all personal taste. I built the seat because I didn't really like anything that was available, that I've seen so far anyway. It would have been cheaper and less trouble to buy a ready made unit because I've already spent $360(Aus) on it.

Thanks

[seven]

It's for my 78K:


But I want it to look like this:


Well, more or less.

funny i have that exact seat in the second picture

Not bad,

So where did you score this?

I was lucky in finding a local bike guy who was cleaning out his shop. he got it from a fiberglass guy in Boston tears and years ago who made 4 and that was it.

Seems too close in design, to the storz version, to be a fluke.

[Sponge Boy]

Hey Seven,

Looking great mate, your shaping is coming up well.
Did you particularly want the backstop to be angled back so far ?
I would have thought a little less would have been better.
Sure, it looks good like that but will it be practical ? After all, your bike will be a rocket when it's finished and you'll need that backstop to work.

Thanks Sponge Boy, and welcome.

Yeah, I didn't really think about that to tell you the truth. I just wanted to make sure i clear the hump created by the inner guard. It's definitely form over function here. As for my bike being a rocket, well I don't think so. The motor is a little tired and if I do have to rebuild, it would only be stock. So, I'm not planning to go to the moon any time soon.

So what do you ride?

Cheers

I don't ride anything special mate; it's not important. I just like to check out what my compadres are doing on the forum.

You could glue a wedge of timber/MDF in front of the backstop to make it more upright. You don't need to have a rocket for the back stop to be sub standard. You want to get that right before you make your mould.
Maybe you could temporarily fit the plug you've made to your bike (you'll have to take off your rear guard) and try to sit on it to see how it will be. You'll propobably have to temporarily fit some slab foam to simulate the finished seat.

[seven]

A slight problem.

Bad for me but good for anyone contemplating doing this.

After i finished off the finer shaping with a cheese grater file, I noticed that the bumstop was no longer sitting evenly. One side had moved forward. When I measured this, the difference was around 7mm from one side to the other. So I cut the semi circular bit away from the foam and sure enough found the foam had expanded into the junction between the arched rear fins and the front semi circle. After I filed the excess away and put it back I also noticed the arched sections had come up around 5mm from where they were initially glued. I figured that the foam, which started off as a liquid, had flowed into and between the joins and then started to expand which forced the sections apart.





Next time I would seal all the junctions with silicone or paint to make sure the liquid could not get in between the joins. Now I have to cut the hump away from the base, remove the excess foam and glue it all back down with construction adhesive.

[Grumpol]

G`day seven
I suggest if you do another, rather than using the expanding foam use sheet foam.
You can use polystyrene but a high density foam would be better.
Once you have it carved to shape just paint a coat of PVA glue (white glue or woodworking glue) over it, this will prevent the resin attacking the foam. If you put a layer of body filler on it instead you will get a better finish but its more work (this is preferable if you are trying to take a mould off it)

[FunJimmy]

Seven

I would guess that as the liquid urethane foam was expanding and curing it started to bond to the surface of your ribs. Then as it continued to expand (which can continue for quite some time) it started to lift the structure from the base. The concept is still a good one as free handing a balanced shape can take forever. Don’t ask how I know.

Another way of construction would be to cover the ribbed structure with fine wire mesh secured with a glue gun. Once the frame is tighter, fiberglass cloth can be laid-up and finished with Bondo. Either way the objective is to get a symmetric shape to finish smooth and cast a mold from. Bondo work is required regardless of approach.

FJ

[volkswagendan]

or seam the wood with tape before adding the foam so it cant get into the cracks.
or sheet foam like grumpol said. that stuff is much easier to work with.

[Alan F.]

In a past life spent working as a shipper, we used expanding foam regularly.  The trick was to place a large plastic sheet over the box and tuck it inside.  (the sheet would then overlap the edges of the box by about half the box's width all around) then add the A and B components.  The plastic sheet prevented the foam from adhering to the interior of the box, but would allow it to expand upward.  Using this method you'll have individual blocks of foam that you could replace at will if an error were committed.  If that's an undesirable side affect, I'd run a bead of wood glue around the bottom of the area of the buck you're filling, then tuck a plastic sheet down inside and smooth it out against the interior, then add your A-B foam.   Clear as mud?

[seven]

Thanks for all the suggestions guys.

I didn't even think of funjimmy's idea about the foam gripping the sides of the ribs then expanding and pulling themselves away from the base. Which would mean that sealing the junctions would not be enough.

Another way would be to drill holes in the base of every section, tape the holes over and when the foam starts to expand it would force the tape away and give some pressure relief while it was in expansion mode. You still need a bond with the sides so the foam is not moving around when comes time to sand and apply the bondo.

Look to tell you the truth, the expansion is probably acceptable as long the curved ribs do their job as sanding guides or stops.

[FunJimmy]

Look to tell you the truth, the expansion is probably acceptable as long the curved ribs do their job as sanding guides or stops.

+1. You just need to take that into account.
No system is perfect.

FJ

[Jinxracing]

I was watching "Ask This Old House" the other day and Tommy was helping a homeowner install a new front door. He used an expanding foam to fill the voids between the door frame and the wall, but used what he called a "low-fill" foam to keep it from expanding too much and bowing the door frame. Using an expanding foam with a lower rate of expansion might solve the problem next time.

Jinx

[seven]

OK, just an update on my project.

While working on the cafe seat I have been side tracked by the original seat. A mate persuaded me to update the original lump which I must admit turned out OK. What do you think?







I'm still working on the original cafe seat but it's going slow. Here's a progress pic.



Here's my to do list:

1. Cafe seat (in progress) 2. Clubman bars (done) 3. Rear sets (purchased) 4. Powdercoat wheels black 5. Fit 18 inch rear rim 6. Bobbed rear fender and new front fender 7. Repaint tank black 8. Upgrade blinkers and taillight (purchased).

Cheers

[Alan F.]

Looking good Seven.
-Alan

[HedNut]

Awesome!! I gotta watch this... looks like you're doing great things here.  I'm Especially looking forward to seeing it with that K8 tank.  That's what I have to work with too.
Cheers!

[seven]

Thanks Guys,

I'm kind of hangin out to see how the seat turns out myself.

Your words are my fuel............................

[rustrocket92]

lookin good man. You have more patience than me.