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Learning how to build Lotus Seven replicas...together!
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PostPosted: October 16, 2018, 12:12 pm 
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Hey Airframefixer, thanks for the advice. I picked up some West Systems 105 epoxy, and some woven mat that I will try out on the seats. I will check out this Jeffco stuff you speak of for next time, from looking at your glass work you would be the guy to listen to!!
Your build log was one that actually inspired me to do my own glass hood, I figured if I could get something 5% as good as your bodywork I would be more than happy with it!
For the foam roller trick, do you do it on every layer? or just the final layer of glass mat?

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PostPosted: October 16, 2018, 9:57 pm 
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Thank you for the compliments.. what you dont see in my log was the learning curve i went through to get to some of the better products. Trust me.. I have trashed alot of parts. It was comunicated to me early on with composites: "you control the process, or the process controls you". I paid to get that advice, and paid again because I didnt take it. I bit off more than I could chew a few times.

Did you get woven roving.. if so that is a very difficult one to wet out.. and it will eat resin. Forgot to mention the heat gun thing i do.. use a heat gun to briefly raise the temperature of the resin. This will reduce the viscocity achieving both a faster wet out and easier release of air bubbles. If I could give myself advice years ago it would be start small. As in get some melamine board as a flat mold, wax it and experiment with saturating the cloth and rolling out the resin with some simple flat panels. That will give you a benchmark for how much material you can work based on your conditions.

Other wise.. my process is:
1 cut the glass dry with a rotary knife on a melamine backing
2 lay that on your part/form/mold
3 brush on equal weight resin as the cloth
4 roll it in with an aluminum roller or dapple it in with a brush.
5 ensure complete saturation.
6 apply second ply of cloth
7 repeat steps 3 and 4
8 repeat with another ply
9 run the foam roller over it to remove excess resin.

I dont like to go more than 3 plies at a time ad the cloth can bunch up with too much working. If your seats are going to be foam core, you really only need a 3 ply facing either side.. this will give incredible stifness.

Hope this can save some of the headaches, and expense, I endured.

Let us know how you do on the practice runs. Dont be afraid to post the mistakes, someone will chime in and steer you in the right direction.

Cheers
Andrew

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PostPosted: October 17, 2018, 11:06 am 
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Joined: August 21, 2017, 7:37 am
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Location: Pittsburgh, PA
Im pretty happy with my Corbeau DFX seats, probably the cheapest name brand quality seat out there. They're a one piece seat with side mounts and bottom mounts. Steel framed with regular oem type suspension and padding. They might be on the bigger side though. I think i gave myself 21" for seats and they take up most of it

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PostPosted: October 17, 2018, 12:44 pm 
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Hey Terryjr, I looked into the Corbeau seats but they were all too wide. I only have 17.5" and the only seats that I could find that would fit were the Lotus Exige seats, or the Cobra FIA Historic. Both of those options are super expensive (1500$ CAD for one seat) so I am going to try the build option first.

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PostPosted: October 17, 2018, 2:02 pm 
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Joined: July 29, 2006, 9:10 pm
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Location: Oregon, usually
LeftFootFirst wrote:
I picked up some West Systems 105 epoxy, and some woven mat that I will try out on the seats.<snip>For the foam roller trick, do you do it on every layer? or just the final layer of glass mat?
Oh em gee, not mat! I've tried some epoxy/mat experiments and it did not work at all for me! It was many years ago but I'll bet the problem remains.

The problem is/was, the adhesive that bonds fiberglass mat into a mat is soluble in styrene, which is why fiberglass mat stays the shape it was cut for a while, but after it's saturated with polyester resin, gradually falls apart and conforms to whatever shape you put it into. Cloths are held together by friction, so they don't conform as well as (saturated) mat into compound curves, but...ah, I'm getting a bit pedantic; it's time to switch to the Executive Summary:

Short form is, epoxies won't saturate ordinary fiberglass mat, so don't.

If technology advanced when I wasn't looking, please, somebody, correct me...but I figure an immediate Dire Warning can be corrected more easily than a big mess of epoxy and mat on that lovely styrofoam seat.

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PostPosted: October 19, 2018, 6:12 pm 
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Hey Jack
Sorry for the confusion, what I have is cloth, I called it "woven" mat because I didn't know the proper name for it. I actually learned not to use the chop mat from a forum post somewhere on this site, proving the usefulness of this site.
If you see me screwing something else up please speak up, i know i will make more mistakes as this goes on.

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PostPosted: November 26, 2018, 5:39 pm 
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Hey Gents
Sorry for the long wait on the update, things got real busy on the home front and I had to choose between working on the car or updating the build log.
I have been working on welding the chassis joints that have been just tacked up to this point as I am going to lose my borrowed welder in December and want to get it as far as possible before then. While attempting to TIG the rear 4-link brackets onto the rear axle I have been getting terrible welds, likely due to air contamination from the backside at the high heat required for these thick plates.
Attachment:
Bad Welds.JPG

I will work to fix this problem, or possibly switch to MIG for these problem welds. The welding on the chassis has been going well.
Attachment:
Good Welds.JPG

and we are making good progress on the chassis.
Attachment:
Frame on Side.JPG


I need to get the spindles machined out to fit my ball joints still then it should be onto the front suspension.


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PostPosted: November 27, 2018, 9:35 am 
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Joined: August 12, 2011, 1:46 pm
Posts: 85
About that TIG weld .
Make sure everything is clean, base metal, filler even the tungsten . That process can pull dirt from interesting places .
I had pores like that after sharpening my tungsten on the same wheel I sharpen my carbide tools, so now I dress the wheel before every sharpening .
Argon contamination is also a possibility .
Also not every paint thinner is good for degreasing .


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PostPosted: May 9, 2019, 10:40 am 
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Hey Guys, it has been a long time since I updated this build thread!
I am making good progress on the car and am about to move on to the front suspension. I got my RX8 spindles machined out to accept tie rod ends as ball joints, and have come up with what I think is pretty good geometry for the A-arms using Vsusp.
http://vsusp.com/?tool=2d#0.8%26project_name%3Adefault%20values%26trim%7Bbody_roll_angle%3A0%7Cfront.left_bump%3A0%7Crear.left_bump%3A0%7Cfront.right_bump%3A0%7Crear.right_bump%3A0%7D%26front%7Bframe.susp_type%3A0%7Cframe.bottom_y%3A15875%7Cframe.center_to_upper_mount_x%3A33020%7Cframe.bottom_to_upper_mount_y%3A24130%7Cframe.center_to_lower_mount_x%3A27622%7Cframe.bottom_to_lower_mount_y%3A2540%7Ccontrol_arms.upper_length%3A24383%7Ccontrol_arms.lower_length%3A34290%7Cknuckles.hub_to_upper_x%3A13207%7Cknuckles.hub_to_lower_x%3A8636%7Cknuckles.hub_to_lower_y%3A12065%7Cknuckles.hub_to_upper_y%3A12700%7Cknuckles.hub_to_strut_axis%3A14000%7Cknuckles.strut_incl%3A8000%7Csteering.active%3A0%7Csteering.hub_to_outer_tie_rod_x%3A7620%7Csteering.hub_to_outer_tie_rod_y%3A7620%7Cwheels.offset%3A4000%7Cwheels.diameter%3A1800%7Cwheels.diameter_expl%3A35000%7Ctires.size_convention%3A0%7Ctires.section_width%3A19500%7Ctires.aspect_ratio%3A4500%7Ctires.diameter_expl%3A50000%7Ctires.width_expl%3A7620%7Ctires.compression%3A0%7D%26rear%7Bframe.susp_type%3A0%7Cframe.bottom_y%3A9200%7Cframe.center_to_upper_mount_x%3A28500%7Cframe.bottom_to_upper_mount_y%3A24000%7Cframe.center_to_lower_mount_x%3A17000%7Cframe.bottom_to_lower_mount_y%3A2400%7Ccontrol_arms.upper_length%3A24800%7Ccontrol_arms.lower_length%3A37500%7Cknuckles.hub_to_upper_x%3A15000%7Cknuckles.hub_to_lower_x%3A13000%7Cknuckles.hub_to_lower_y%3A13000%7Cknuckles.hub_to_upper_y%3A13000%7Cknuckles.hub_to_strut_axis%3A14000%7Cknuckles.strut_incl%3A8000%7Csteering.active%3A0%7Csteering.hub_to_outer_tie_rod_x%3A7620%7Csteering.hub_to_outer_tie_rod_y%3A7620%7Cwheels.offset%3A4000%7Cwheels.diameter%3A1500%7Cwheels.diameter_expl%3A35000%7Ctires.size_convention%3A0%7Ctires.section_width%3A19500%7Ctires.aspect_ratio%3A4500%7Ctires.diameter_expl%3A50000%7Ctires.width_expl%3A7620%7Ctires.compression%3A0%7D%26pref%7Bdiag1.px_per_mm%3A200%7Cdiag1.front_or_rear%3Afront%7Ctab.active%3A1%7Cunits%3A0%7Cshow.f%3A1%7Cshow.ca%3A1%7Cshow.k%3A1%7Cshow.st%3A1%7Cshow.stl%3A1%7Cshow.w%3A1%7Cshow.t%3A1%7Cshow.rc%3A1%7Cshow.rcl%3A1%7Cshow.ic%3A1%7Cshow.icl%3A1%7Cshow.fvsa%3A0%7Cshow.tl%3A0%7Cshow.kpil%3A0%7Credraw_during_drag%3A1%7Cchart.x_axis_center%3A0%7Cchart.x_axis_window%3A10%7Cchart.x_axis_num_steps%3A21%7Cchart.x_axis_field%3Atrim.body_roll_angle%7Cchart.y_axis_fields%3A%5BFR%5D.general.roll_center.y%7D

The next step is building some jigs for the a-arms and cutting some tabs.
Since it has been so long since I posted pictures i went and grabbed some screen cap to show progress.
I got the hood buck all built and coated with PVA in preperation for molding.
Attachment:
Hood with PVA.PNG

I fiberglassed a hood shell on the mold, using the male mold process. It worked "ok" but I will have to re-do it with the female mold system.
Attachment:
Hood Fiberglass.PNG

The first female mold i made for the fiberglass firewall came out pretty good, this was practice for when we make the molds of the hood
Attachment:
First fiberglass mold.PNG

With the hood on and a tire mocked up it started to look like a car.
Attachment:
Wide with Wheel.PNG

I built a jig to hold the spindle where it needs to be in space so that we could measure it up for suspension.
Attachment:
Front Spindle Jig.PNG

And I built the skeleton for the dash, going for a Caterham CSR style dash
Attachment:
Dash Bars.PNG


Let me know what you think.
Cheers


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PostPosted: May 9, 2019, 10:46 am 
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Location: Carlsbad, California, USA
Nice work on that dash frame. It looks tricky to do.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


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PostPosted: May 9, 2019, 2:35 pm 
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Joined: May 1, 2016, 2:59 pm
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Location: Alberta
Hey Lefty, long time no see!

Love the dash! You're totally stealing my thunder with the one piece/fiberglass front end, but considering you actually have one and mine only exists in my head I guess that's fair! It's really taking shape - great work!

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PostPosted: August 6, 2020, 3:59 pm 
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Well I guess I should realy update this forum more than once a year!! I have been making really good progress on the car but have been too busy to keep both the youtube build series and this thread up to date.

Since last time I posted we have completed a female mold for the hood and cowl and produced a good fiberglass hood.
Attachment:
Hood Mold.jpg


The original concept was a one piece hood and nose cone system that would flip foreward however the hinge system required to keep the nose from smashing the ground is not something I wanted to deal with so I have since cut the finished piece into two parts.

In order to make getting in and out of the car easier I knew I wanted a structure of some sort to grab onto and pull myself out so I built a bolt on cage. I know there is a debate on cages and helmets and how if you drive a caged car more than 5 feet without a helmet it is certain death etc, but I have placed the bars far from my head, plan on using high back seats, and will use a 4 point belt system so I am comfortable with not wearing a helmet.

Attachment:
Roll Cage.jpg

Attachment:
Cage on Front.jpg

Attachment:
Cage on Rear.jpg


The cage is also a bolt on system for if it is an issue during inspections or if I want to change the design in the future. The design and tubing selection was made using the SCCA rule book, however the rear down bars are supposed to be straight however they would be at way too steep an angle so I put the bend in for aesthetics. If I was going to autocross this it would need a forward facing downbar into the passenger footwell.

I have mounted up the brake and clutch pedals, and now just need to find a deal on a 5/8" wilwood master for the clutch.
Attachment:
Pedal Box.jpg


The steering shaft is getting built right now and is quite the snaky system to thread between the pedals as the brake pedal ends up right in the center of the cockpit.

I have also finalized the rear suspension. I had to change from equal length parallel 4 link bars to unequal lengths. The top bar is now 4" shorter than the bottom in order to move the axle mount forward on the tubes so that the brake caliper would fit. I ran the axle through a full articulation and did not notice any binding issues, and the travel will be much less once the shocks and bumpstops are in place.
Attachment:
Articulation Side.jpg

Attachment:
Articulation Rear.jpg



I will try to update this build thread more often, but I also post weekly build videos on youtube if you want an update more than once a year!


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