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invision 09-01-2011 02:35 PM

"The Next One" - Handcrafted Mid-Engine Sports Car
 
I really appreciate everyone's enthusiasm for Rhythm's fabrication thread. That really shows the passion you guys have for not only your projects underway in your garages but as well as other members' rides. Thanks very much.

This is an all new thread that I'm starting so as to share the progress for 'the next one' - our second hand-crafted mid-engine sports car. Like Rhythm's build, it's something that both my dad and I are involved with...I wouldn't have it any other way.

The Idea

Rhythm was in the final stages of assembly and as crazy as it sounds in the back of my mind I found myself already tossing around the idea of creating a second mid-engine vehicle. However, taking into account what had been learned over the course of the building Rhythm, I decided that if and when this new project began, fabrication would have to be approached from an entirely different perspective.

You may have previously seen that Rhythm’s body was essentially hammered and dollied out entirely by hand. While this sounds impressive and taught me how sheet metal behaves, it was immensely time consuming – not something I wanted to repeat. So an English wheel would have to be bought or built to help in creating the panels. I decided to build one. Also, with 'the next one', a fixture would have to be developed to not only provide a base for shaping the body panels, but to also ensure higher fabrication tolerances. For the non-metal shapers out there these fixtures are usually referred to as bucks and can be created many ways including carving a full-scale shape out of foam or building a wooden buck. To meet our requirements we decided to create a wire frame buck. This buck would provide the flexibility to alter particular aspects of the design features relatively easily if it was ever necessary. To ensure that the buck was always square and remained true during the sheet metal shaping process an extremely rigid frame table was necessary. I dislike doing things over again, so the frame table was designed and built in such a way that it was fully adjustable in all 3 planes and to not only work for this project but for others as well.

Here are a few photos of the table:

http://i1099.photobucket.com/albums/.../INVFT-012.jpg
The frame table is being assembled. The main longitudinal beams are 15ft long - the cross members with fully adjustable legs/pads are 6ft across.

http://i1099.photobucket.com/albums/.../INVFT-022.jpg
The table is kept square with the use of triangulation gussets which work on a friction system. Once the bolts are tightened...thats it...she's not going anywhere. To move the table around, the rear legs pop out and wheels slip into the pockets.

http://i1099.photobucket.com/albums/.../INVFT-032.jpg
With a comfortable height set, sliding jigs are being created to mount the engine/trans, seats, and suspension components. It took a bit..well actaully a lot of work to fabricate the table, but we(my dad and I) wouldn't go back to anything else. And when another project needs to come into the bay the wheels can be installed within a few minutes and the table with what ever is sitting on top is rolled out.

Vehicle Design Overview

Starting out as a fresh sheet of paper design, ‘the next one’ loosely resembles Rhythm. Simply called R2, the lines have been re-proportioned and tightened up resulting in a modern aggressive appearance. Since it’s being built as a driver, we want a final fit and finish that only a metal body can provide. An LS6/LS7 engine mated to a Porsche G50 transmission called for a redesign of the chassis for increased rigidity as well. Rolling on 275/35/R18s in the front & 315/30/R19s rear R2 is 28” shorter, 6” narrower, and a little over 900lbs lighter for a total weight of about 2800lbs. The final horsepower to weight ratio is expected to come in around 6lb/HP.

Here are the specifics:
http://i1099.photobucket.com/albums/...SpecSheet2.jpg

Creating the Wire Frame Buck

Once R2’s final design was established and renderings completed 2-dimensional construction drawings were created. These were then taken to a print shop and scaled to full size side, top, front & rear views and posted on our shop’s ‘build board’. Then the exciting part began. To create the wire frame buck, the wheelbase, engine/transmission, seating position, and front windscreen locations were set using sliding jigs on the frame table based on design dimensions from a common datum point. Construction of the wire frame buck began by simultaneously working with four drawings and translating reference dimensions from the ‘build board’ into 3D and 'stump shaping' steel rods, square-stock, and flarbar to match the appropriate feature curves.

Initial 20 minute mockup... I grabbed some parts from storage to get an idea of the new proportions. Ahh.. no worries, those won't be the final wheels... :D
http://i1099.photobucket.com/albums/...cation02-1.jpg

We're into the thick of it with the fabrication of the wire frame buck. The various lengths of box tubing were fabricated to slide along the frame table, then lock into place at set positions. Other lengths were tacked to them.
http://i1099.photobucket.com/albums/...ication012.jpg

To make room for another job, R2 is rolled out of the bay and covered up. At this point, with most of the wire frame completed, the tarp actually created a temporary surface on the buck and outlined some of the body lines.
http://i1099.photobucket.com/albums/...derWraps12.jpg

Just to clarify, the wire frame is a temporary structure. Once all the inner & outer panels have been created it will be removed and all the panels re-assembled on their own.

Jacob 09-01-2011 07:33 PM

1 Attachment(s)
It will be interesting to see a new project take shape!

I was on autoblog and i saw this Russian concept car with the most unusual doorshttp://www.blogcdn.com/www.autoblog....ncept-lead.jpg.
That's right, they slide up through the body and cross over in the back.
Wanna give it a try?

HEATNBEAT 09-01-2011 09:00 PM

Looks like a good start!

invision 09-02-2011 06:48 AM

Thanks Gents,

It was a huge step forward taking the design from 2D into 3D. The key was to make the buck as accurate as possible since it translates any errors directly to the sheet metal stage...and potentially slow that process down.

It's great to play with concepts...those slide-up doors are trick. R2 has butterfly doors incorporated into the design...on a single hinge. The issue one always has to tackle when creating doors for a hotrod/custom car is in creating a wind/watertight seal with existing production door deals. We're running with two seals - an interior one as well as a knife edge seal around the exterior perimeter.

Thanks for looking.

Kerry Pinkerton 09-02-2011 07:24 AM

Excited you're building #2 Nick. I envy your time working with your Dad.

Couple questions/comments:

1- What software are you using?

2- How did you bend & weld the wire for the wireform buck. When I tried welding the 1/4" rod, it pulled and caused a kink in the flow.

3- Do you have any images of the overall design?

4- What are you going to use for the transaxle?

idickers 09-02-2011 09:42 AM

Quote:

Originally Posted by invision (Post 40329)
We're running with two seals - an interior one as well as a knife edge seal around the exterior perimeter.

Really cool project. Could you describe your weather seal solution in a little more detail? I'm trying to figure out how to upgrade some ancient weather seals, and am interested to learn more about current methods.

ShawnMarsh 09-02-2011 11:33 AM

That looks like it will be not only an amazing feat of craftsmanship, but also an amazingingly fast street car. What type of suspension will you be using to keep the wheels on the pavement?

invision 09-02-2011 01:59 PM

Quote:

Originally Posted by Kerry Pinkerton (Post 40331)

Couple questions/comments:

1- What software are you using?

The majority of R2's initial design was done old school...with pencil and paper... sketches, 1/4 scale 2D build drawings, and final renderings. I feel I have more freedom to alter my designs quicker on paper. However, to confirm that there were no awkward areas in the overall body I used Rhino 3D to model the vehicle digitally. For structural components and hinges I use AutoCAD, Solidworks and Inventor. Photoshop comes in handy as well for tweaking some of the renderings as well.

2- How did you bend & weld the wire for the wireform buck. When I tried welding the 1/4" rod, it pulled and caused a kink in the flow.

To bend/shape the 1/4" and 1/2" rod, flatbar, and squarestock I use the end of an 8"x8"x34"LG wooden stump that has had the centre hollowed outafter repeated use. As for welding the 1/4", you're spot on when it comes to the rod taking on a mind of it's own and developing a kink. I just get my heat cranked up on the machine and "stick" the rod in one shot...then as the rod is cooling I pull it in the direction that opposes the pull. Occasionally, I need to touch it up with a hammer and dollie.

3- Do you have any images of the overall design?

Yes, there are a few overall renderings of the final design. I really appreciate that you guys know how easily things can get shared once you post something on the net.

4- What are you going to use for the transaxle?

We have a Porsche G50 5 SPD lined up for this car, though a 6spd would really be the cat's meow.



Replies in blue :D

Thanks for checking out the build so far, if there are any more things I can answer, let me know. I like your format. :) Have a great weekend Kerry!

invision 09-02-2011 02:18 PM

Quote:

Originally Posted by idickers (Post 40337)
Really cool project. Could you describe your weather seal solution in a little more detail? I'm trying to figure out how to upgrade some ancient weather seals, and am interested to learn more about current methods.

With the weather seal design on R2, there is one rubber that slides over the pinch weld on the cab - like in most cars. This one is fairly easy to incorporate into an opening and can come with molding dyed with a colour that matches your interior.

The second seal goes on the actual door with the use of 'one way" plastic "T" clips below the shoulder line of the vehicle. The upper portion of the "T" slides onto holes in the rubber and the vertical leg pops into holes in the door. Creating the seat for this is much more challenging.

The knife edged seal goes around the top perimeter of the door ... above the shoulder line. This one usually sits in a "C channel and requires the most work to sit correctly, but totally eliminates any wind noise.

For the best way to get an idea how these seals work, drop by your local wrecker with a small section of your original door seals and check out the new vehicles - 1998 and up..for possible fits.

Hope this helps and thanks for the thumbs up.

invision 09-02-2011 02:22 PM

Quote:

Originally Posted by ShawnMarsh (Post 40342)
That looks like it will be not only an amazing feat of craftsmanship, but also an amazingingly fast street car. What type of suspension will you be using to keep the wheels on the pavement?

Its funny, but I enjoy the fabrication process more than driving them... Don't get me wrong though...driving is a blast.

As for the suspension, C5 Corvette control arms, hubs, and coil overs will be used on this project.


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