Mr. G. Brettin's Slow Motion Leg Hump

madwi

Thats exactly it what im talking about, final polish was the tp. I could never do it, about an hour in and I said f this and went back to my machine. Made me appreciate them that much more and always tried to get the best machined finish to start with to save time. Ran a few extra cycles in the EDM machines crisping up the sharp corners and blending in transitions.
We made the molds for inifinty, honda and others. If you ever notice the seatbelt latch covers in a viper; I made the electrodes and burned the snake's face into the mold.

Your mold looks awesome and that cowl doesnt seem like its gonna be fun to mess with.

gbrettin

The cowl will have its own challenges of getting the left and right side mirrored, but I know I can nail the gel coat process on it. That will cut 90% of the repair work out.

I'm really considering moulding some vents into the cowl as well, so that engine bay air pressure can get out too.

On my hood, I really need a small duckbill to divert air up over the windscreen which would take care of a high pressure area that builds up at the center base. I forgot where I saw that particular 3d rendering of pressure zones on this site. The duckbill/diverter really should have been baked into the hood mould but I guess that can be a challenge for a different day. There are too many spinning plates as is.

madwi

You are making good progress, keep it up and moving forward. Cant wait to see how it goes as this is no small undertaking.

gbrettin

Not a whole lot to say other than getting a perfect surface is a PITA. I was doing this by hand and then realized there are tools for this type of job... I purchased the best orbital sander I could get my hands on and haven't looked back.

The thermal process that happens after 30min or so is pretty wild in the tooling gel. I took too much time applying the first skim coat and the tooling gel melted my plastic cup.

I suspect there will be one more knock down after the last skim coat mould is really looking good now.


First complete knock down and corner rebuild:











Tooling coat thermal heat:



First skim coat of tooling gel:




Knocked out a few high areas





Gelcoat applied again to fill in low spots (will need additional coats)

gbrettin

IG@gbrettin:
Most all area are coming out great. Only a few touch up areas are needed. Tooling gel is incredibly hard. I've been at this with 60grit and changing the sanding pad many times. Moral of the story? Do your mould correct the first time. If you can't... Then you can repair with many hours of sanding. Many hours.. many many...

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All this time sanding gives me time to reflect how I would do the moulding process. Doing it again, I would start it off like this:

These steps were fine: flange construction, clay, Partel Wax and PVA.

Corrective steps:
Tooling gel coats (Weekend process):
1. In the AM. Apply 1 coat of tooling gel. (Orange or Red)
2. In the Evening. Apply 1 coat of tooling gel. (Orange or Red)
3. Next day. In the AM apply 1 coat of tooling gel. (black)
4. Afternoon - 2 layers of fiberglass (lighter fiberglass) using tooling polyester resin (2gal)

Next Weekend
5. 4 layers of heavy fiberglass. using tooling polyester resin (4gal)
6. Next day same as step 5.

Couple days later
7. evaluate for additional layers or pop mould.

I think that would yield the perfect mould or atleast have minimal repair.

This pictures below are about 6 hours of sanding. You may have asked yourself why I didn't start over? I have hundreds of dollars into the mould materials. Each tooling polyester gallon is about 40 dollars. I have about 7 gallons on my hood mould. Tooling gel costs about the same. Good fiberglass is about 4 dollars a yard. I used about 15yds (guessing). And so on. SO there is the cost but also the time of setup. Most importantly, I think it's worthwhile to fix the mould and show everyone the long road if you're new at something.

Thanks for watching my crazy build process so far.

gbrettin

Important note!

I'm waiting on parts for my hot and coldside. Not a lot happening with the engine side of things, so I'm happy I have this side project.

Hotrodz

You are killen it my friend. Can't wait to see that beast at ZDAYZ!

Sent from my SM-G965U using Tapatalk

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Rusty

Hook up a shop vac to that sander. Use a flexible hose long enough to let you move around the hood. You'll thank me later.

__________________

浪人 - 殺し屋
"The Difficult Anytime, The Impossible By Appointment Only"
http://www.the370z.com/members-370z-...o-journal.html

gbrettin

IG @gbrettin:
Knockdown, test fit and fill... Yup. Again. All the problem areas have subsided. Last time going through the rough grit on this. I can start working on wet sanding next.

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I know these posts are a bit repetitive; but, it'd rather show what actually goes into the actual mould making process.

Hotrods - The Dewalt has a little bag that has been catching 85% of the dust (which has been amazing). I just so happen to have a small shop vac at the shop. I'll hook that up!

Something to be said about the edges on the mould... I have the edges roughed out and will need to dedicate a ton of hours getting them perfect. I have been slowly building the edges up, specifically with tooling gel since it's hard AF.

It's getting there.

More sanding supplies


Test fit. Edgest will be built up.











More Sanding




Skim Coat

Rusty

I have the same DO sander. That bag doesn't catch chit. When I'm using mine. I duct tape my shop vac to it. It will also make your disks last longer too.

__________________

浪人 - 殺し屋
"The Difficult Anytime, The Impossible By Appointment Only"
http://www.the370z.com/members-370z-...o-journal.html

gbrettin

IG @gbrettin:
Needs 1 more day of cure because it's still cold here. The lines look great, no more pin holes and no more fiberglass patterns showing in the tooling gel. The perimeter needs to be cleaned up. No worries, I have a plan!---- *Runs off and makes plan*

Starting the Sunoco cowl 370z plug. Part B of my mould. Whipples and high rams rejoice!

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The mould looks to be coming to a close pretty soon so I'm ramping up on making a plug for the cowl. All the lessons I learned from the hood will be dumped into making the sunoco style cowl. The pictures below is me just roughing a mental idea out. I could draw it on paper with proper dimensions but I don't see the point. I need to visually feel out the lines to see how they make me feel.

I'm also going to make two rough plugs. The first one will be constructed from the items you see below. The second plug will be from my buddy's Mustang cowl. In all honesty, I really like the shape of the Mustang cowl so I want to give that a test first. I purchased expanding foam from Composite Envisions. The foam can be poured into the cowl portion of the hood and then I can cut/sand the foam down. Perhaps I can get out to the shop tonight and make that foam plug.

I'm in the design phase so any and all thoughts are welcome.

Dried(ing) tooling gel




Cowl construction

gbrettin

IG @gbrettin:

I plan on making two plugs. First one will be hand made and the second is a direct plug off a different hood. I'll see what works better soon. And guess what! Another coat (say it like DJ Khalid).

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Nothing new that you guys don't already know (from my IG statement). I will say this though... I ALMOST thought about dumping my foaming compound directly into the carbon fiber cowl you see below. The foam has some of the same chemicals used to lay up carbon fiber. It would have etched into the cowl ruining his hood if I didn't pull ripcord.

I'll put some plastic down and then make a plug today.

gbrettin

IG @ gbrettin:
Made me a big ol' hot pocket. �� Hot pocket ��

I needed a less dense A B foam mix and more of it. Great Stuff to the rescue. .... A few cans later... This hot pocket has been filled. ��

Rusty

Which Great Stuff did you use? The triple expanding stuff. You have to be careful of. It WILL push things apart. Don't ask me on how I know.

__________________

浪人 - 殺し屋
"The Difficult Anytime, The Impossible By Appointment Only"
http://www.the370z.com/members-370z-...o-journal.html

gbrettin

Oh yeah, she was ready to burst at the seams. lol

I filled in some pockets with MORE great stuff.