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Discussion Starter · #1 ·
I need help designing a mold for this seat plug. I need to figure out whether it will be fiberglass or plaster, two parts or one, and how to incorporate the bottom.

The seat pan will be made out of aluminum and will rivet to the fiberglass bump stop.

The bottom will need to be a separate part, as the front will need to be made attached to the top part for strength.

The bottom will be made of either aluminum, or more likely, fiberglass. I want to make it flush with the end, but don't know how I'd attach it to the rest of the seat (probably more rivets).

Here's pictures of the desired result, seat plug, seat pan, and bottom.
http://imgur.com/a/YMBlq#2bD96

Thanks.
 

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There are three parts to this video. This is the first. see if it helps.


Use thin fiberglass at first and if you REALLY feel the need to beef it up some you can back it up with some expanded steel (steel mesh).
 

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Thin/ thick doesn't matter. Poor craftsmanship will break

Steel mesh = no no. Rivets will fail with vibration

I am being mr negative. Sorry dude.
 

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Thin AT FIRST so it will follow the contour of the ropes used in the video. Use multiple layers of Fiberglass as described in the video for added strength. No one said anything about rivets. You can epoxy the steel mesh for added structure as if it were another layer of Fiberglass. You aren't being negative, I just wasn't complete. I counted overly much on the video to do much of my talking.
 

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Discussion Starter · #5 ·
I doubt the rivets would fail, if they can hold an airplane together, they can hold a cafe seat together.
 

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quote:Originally posted by Kevvo16

I doubt the rivets would fail, if they can hold an airplane together, they can hold a cafe seat together.
the actual rivet may not fail (unless you use some really bad cheap pop rivets), but the fiberglass around it will due to the local stress.
 

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I'm a retired aviation structural mechanic with alot of experience with joining metals with composite material (fiberglass, graphite and reinforced plastics). The biggest issues that I can see with this seat is cracking the fiberglass while installing rivets. If youre using cherrymax (pop rivets), it is critical to ensure you have the correct length and use a washer under the bucktail, otherwise there is a strong chance of pulling the rivet through the glass. If using solid rivets, which I'd recommend since you can get to both sides of the material, use small washers under both the head as well as the bucktail to spread the stress over a larger area. Bottom line, always use a washer between the rivet and fiberglass. It doesnt have to be very thick or be a whole lot larger that the rivet head. Rule of thumb, the washer diameter is 1.5 times larger than the rivet head diameter.

Just my thoughts and experience...

By the way, thanks for the video link Kevvo...I love watching Herm work. The guy is good! do you have a link for part 3? I only found 1 and 2 on youtube.
 

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That's pretty darn interesting Kafe. I have other uses for that little tidbit about the washer size. Thanks
 

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Rather than riveting together a bunch of different pieces.... Construct parts correctly the first time

Yes I have about 16 years in composites construction and repair
 

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Good morning
I am building a cafe racer and the seats I found are a bit smaller mine is 340mm by 620mm. Does anyone have contacts or links to websites of professional builders with a reasonable price range. Thank you and have a good day
 

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