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Learning how to build Lotus Seven replicas...together!
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PostPosted: May 11, 2007, 7:30 pm 
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That sure is a ton of progress in one month! When your done there, you could swing by my house for a week and help me out :lol:

I sure wish my shop class in HS had that kind of project going when I was there. We only had the hovercraft team *boring*


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PostPosted: May 12, 2007, 12:51 am 
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Yeah, the guy doing the welding is smokin'! The Miata teardown has been a little slow, but the guys in the auto shop only have an hour a day and they have to do some formal study in that hour. The guy doing the chassis fabrication (he's a senior and has been welding for three years) gets pretty much the full hour on this and has been doing a couple days after school too. I didn't expect him to be pulling ahead of the car crew, but he is. The car stripping is <real close> to done, though...the handbrake, some lines, and a fair bit of cleanup remain...but the carcass left the shop on Thursday (it's on blocks outside) so there will be room indoors for the build. Soon the 2k7 chassis will go where the Miata was, and parts that came off the one will start going on the other.

Meanwhile we're going by The Book* for the front section. 2k7/k7 front sections only differ by the length and angles of the (to use the Genuine Champion Book nomenclature) F tubes on the bottoms and J tubes on the top. And unlike the Champion/Gibbs frames, the G tubes are longer than the F tubes. I'll try to call out other departures from the traditional Locost as they come up.

One departure worth mentioning is, we finish weld as we go along. First we do the bottom of the cockpit; it's flat, it's square, it's finish welded. That gives us a solid base to work from. Then the sides of the cockpit, and then the sides get attached to the bottom and finish welded (if it's going to be a traditional-styled k7 with aluminum skins) or just the sides of the upright tubes left unfinished if it's getting a steel shear web for pontoons. At every major subassembly, we finish weld.

So, on to the front section. The structure is drawn on the tabletop, the F and G tubes clamped in place, and since the welds and floorboard hold the cockpit up off the table a bit, shims are put between the table and the tubes to keep them on an even plane. As you can see...

Well, one thing you can see is the side skins, which haven't been mentioned much, so I'll backtrack a bit. The side skins in this case are 22 gauge steel. I think the pontoons could be made of aluminum, but I haven't tested aluminum pontoons yet, and the steel was bought surplus for $12 per 4' x 5' sheet so it goes well with the budget. On this chassis (which is 13" high a la Champion) the side skins are 48" x 12", which puts the edges of the sheet exactly in the middle of the top and bottom cockpit rails and the front and rear uprights--an amazing coincidence!** Lay the cockpit on its side with a skin underneath, and mark where the intersections of the tubes meet the skin. Remove the cockpit frame, cut out notches in the skin <just past where the tubes butt together>, clamp the skin in place on the frame, tack and stitch weld the skin to the tubes and finish weld the sides of the tubes <through the notches>. This saves you the tedious grinding on the outside of the frame, as otherwise needed to get the skin (whether welded steel or rivited aluminum) to fit flush to the frame.

PS--I think building a Locost is a terriffic high school shop project. I was briefly a Voc Ed teacher during my otherwise misspent youth, and both the students and the instructors have my sympathies, particularly when it comes to budget for interesting and appropriate projects. I too wish we had a project like this when I was in school. The kids today wish the same thing. I'll bet if anybody on this site approached their high school autoshop with an offer similar to mine (I'm making modest donations to these classes, I'm supplying the materials, and I'm at the school a lot supervising the project) they'd take you up on it. It won't actually save you time and there will be a few dings here and there, but you may save a few students from Death By Boredom and help them learn a few real-world skills.


*That would be the 2k7 book, 1st edition,copr. 2007 J. McCornack--it's that blue spiral binder you see in the background now and then. I'll stop calling it The Book now; I was only being whimsical. I'll call it "The Plans" from here on, and even that is a bit of an overstatement.
**This would have been a 14" high chassis if we weren't on such a squeaky budget. It's easy to modify cockpit height, length and width, but smaller is cheaper, and if you're panneling the sides with 13" x 49" instead of 12" x 48" you'll have a lot of scrap when you're done.


Attachments:
File comment: If this frame were being made without the stressed skin, we'd add three more diagonals per side (not needed with this semi-monocoque cockpit).
FrontFrameLayout.jpg
FrontFrameLayout.jpg [ 20.04 KiB | Viewed 11089 times ]
File comment: A photo from early in the week. At that stage, before the backrest tube went in, this could have become an IRS or a live axle chassis.
SideSkinNotches.jpg
SideSkinNotches.jpg [ 19.03 KiB | Viewed 11090 times ]
File comment: The notches in the skin expose the spots where the tubes weld together. Make the notches tight enough that the skin is included in the bead.
SideSkinNotchCU.jpg
SideSkinNotchCU.jpg [ 13.83 KiB | Viewed 11086 times ]

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PostPosted: May 12, 2007, 2:45 pm 
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Returning to the front section. we leave the monocoque structure behind and switch to traditional space frame. An advantage of building a space frame front section (and building the cockpit and the firewall-forward in two parts) is, since the loads are passed through space frame tubes in tension/compression, one can attach the front section to the cockpit with brackets and bolts--as we did with the prototype--which makes a chassis cheap to ship (cheaper, at least) and major modifications (e.g. an engine swap) aren't a complete do-over. But I digress...we're welding the sections together on this one, since it doesn't have to be shipped and it saves about $60 in hardware over the bolt-together version.

Normally (hah! this is the second frame of the k7/2k7 series, and the first one built from the bottom up for a full body, and here I am saying "normally"--and "series" as well; pretty nervy, eh?) we build the front section before attaching the rear subframe mounts, but this time we didn't, which left the bottom of the cockpit with two bumps in the back, so the cockpit wouldn't fit right on the build table any more. We pushed the chassis and pattern back an inch and made a new 1" longer G tube so it would reach to the end of the table...but we'll cut the G tubes back after the radiator is fitted, and the clamps can be moved in an inch, so we didn't bother lengthening the other one.

Once the F and G tubes are tacked in place, they're solidly triangulated on the ground plane. They will soon be solidly triangulated vertically too, when the top tubes are added, but hopefully the engine and trans will be ready by then and we can optimize the bracing to fit the available space.


Attachments:
File comment: To compensate for the cockpit's bellypan and weld beads, the front tubes are shimmed to level; in this case with some 1/8&quot; steel parts and .060&quot; washers.
ShimmedTubes.jpg
ShimmedTubes.jpg [ 14.93 KiB | Viewed 11054 times ]
File comment: Shimming these tubes also lets the welder work without setting off the smoke alarm. The sides of the junctions are being finish welded--the new tubes are well triangulated side to side.
RaisedWeld.jpg
RaisedWeld.jpg [ 22.28 KiB | Viewed 11052 times ]
File comment: Normally (there's that word again) we'd brace the front tubes against a board (12&quot; board for a 13&quot; frame) before finish welding, but leaving them free didn't cause any problem.
FlipAndWeld.jpg
FlipAndWeld.jpg [ 31.74 KiB | Viewed 11049 times ]

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PostPosted: May 12, 2007, 3:37 pm 
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So whaddya think it weighs at this point? All that sheet steel around the driver and passenger, the 2" wide backrest tube, the 2" x 2" K3/K4 tubes, the mounting plates, the base frame of the engine compartment?

Oh go on, guess. I won't ruin the surprise, you can read what the Pelouze says in the second photo down.


Attachments:
File comment: The cockpit rides the scale. We should have been doing this all along. The 18 gauge bellypan and 22 gauge side shear webs are installed.
CockpitOnScale.jpg
CockpitOnScale.jpg [ 23.79 KiB | Viewed 11045 times ]
File comment: And here's the result.
CockpitWeight.jpg
CockpitWeight.jpg [ 21.73 KiB | Viewed 11041 times ]

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PostPosted: May 12, 2007, 4:15 pm 
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Then we flipped the frame back onto the table and set the bottom suspension carrythrough in place (roughly equivalent to tube LD in The Book). The junctions of the F and G tubes (see previous photo, four photos back) are where the pickup brackets for the rear of the lower control arms go, and the junctions of the G tubes and the carrythrough tube are where the pickup brackets for the front of the lower control arms go. The diagonal braces (not present in The Book frame) triangulate the front pickup points to the rear pickup points. The result is a base for the front suspension that is extremely rigid on the ground plane.

And that does it for the week of May 7--11. The guy putting this frame together is so quick at it, it's all I can do to take pictures fast enough, and I'm into the weekend before I'm caught up on this build log. I'll bet he'll be down to floorboards and transmission tunnel by next week.


Attachments:
File comment: The front section is rigid in two dimensions now, and we'll be going 3D starting Monday. Note the MDF top surface of the build table has a 1&quot; lip, to aid in clamping.
BottomFullyBraced.jpg
BottomFullyBraced.jpg [ 26.75 KiB | Viewed 11039 times ]

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PostPosted: June 4, 2007, 3:15 am 
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Will we get this to the DMV before graduation night? Stay tuned.

Note that some round tubing is creeping into the chassis. That's because the upper and lower frame rails are not parallel forward of the firewall, so square tubes mounted between them would have one end...unsquare. The round ends of the 1" uprights fit perfectly against the surface a 1" square tube, regardless of its orientation, and the oval ends of the diagonals fit close enough for welding.


Attachments:
File comment: Since the weld beads and bellypan keep the chassis from fitting flush to the build table, we 'float&quot; it on bits of steel tubing.
TopRailsAndRounds.jpg
TopRailsAndRounds.jpg [ 65.84 KiB | Viewed 10740 times ]
File comment: These fillets, cut from 3&quot; by 1&quot; rectangular tubing, stiffen the junction and provide a platform for the upper rear pickup tube. Note the front pickup tube can be unbolted and replaced, for anti-dive adjustment.
TubeFillets1x3.jpg
TubeFillets1x3.jpg [ 25.9 KiB | Viewed 10739 times ]
File comment: The upper control arm pickups are mounted back farther than a &quot;book&quot; frame, which improves chassis stiffness (and has other advantages we'll see later), as do the additional non-book diagonals.
PickupPoints.jpg
PickupPoints.jpg [ 32.43 KiB | Viewed 10736 times ]

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PostPosted: June 4, 2007, 4:12 am 
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Motor mounts. Man, these are easier to make with CAM than from scratch, but they're doable with hand tools--and as long as one of your hand tools is a plasma cutter, the four parts can be made to nest together pretty well. If you don't have a plasma cutter (and want motor mounts like these), you'll have to make five parts and fit them together one at a time.

The school does have a plasma cutter, so the parts were traced/cut from the pattern in the plans. The four sides were matched by tack welding them together and grinding them as a unit (then breaking them apart) and the top (not shown) and bottom parts were close enough as cut. Still, they look nicer when computer cut, and they're sure less work.


Attachments:
File comment: On the sides (two per mount), the only critical dimensions are the edges marked in red, Pick the most similar pairs and match them up.
MotorMountSides.jpg
MotorMountSides.jpg [ 23.7 KiB | Viewed 10732 times ]
File comment: To bend the bottoms, cut a slit at the bend line, leaving about 1/8&quot; of metal on each end of the slit. Bend to fit, then weld up the slit.
MotorMountBottom.jpg
MotorMountBottom.jpg [ 20.33 KiB | Viewed 10732 times ]
File comment: If cutting these parts by hand, number them for position, since there's going to be some variety to their shape. The little cutouts in the bottom part position the tang on the sides.
MotorMountBase.jpg
MotorMountBase.jpg [ 25 KiB | Viewed 10733 times ]

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PostPosted: June 4, 2007, 4:30 am 
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Mounting the mounts to the chassis. These motor mount platforms are cut from 3" by 1" rectangular tube, and the upper inside edge needs to be welded flush with the rest of the lower frame tubes. One can save a lot of grinding by bending that edge down a bit first (at last, a practical use for a big Cresent Wrench).


Attachments:
File comment: By bending the inside edge of the motor mount platform down a trifle, the bulk of the bead stays under the top of the frame tube,
MotorMountPlatform.jpg
MotorMountPlatform.jpg [ 22.17 KiB | Viewed 10729 times ]
File comment: Final flattening will take a grinder (or a flap wheel), but it shouldn't take much, and it's only needed on the inside upper edge.
MotorMtPlatformFlat.jpg
MotorMtPlatformFlat.jpg [ 32.6 KiB | Viewed 10728 times ]
File comment: Here's how the mounts sit on the platforms. For final positioning, bolt the mounts to the engine and lower the engine into the chassis; mark and drill the mounting hole.
MotorMountsPlaced.jpg
MotorMountsPlaced.jpg [ 31.53 KiB | Viewed 10765 times ]

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PostPosted: June 5, 2007, 6:12 pm 
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Man, I love Oregon.

See that photo above, the one where the engine mounts were placed in the frame? 48 minutes later the car was on the trailer, and 64 minutes after that, it was titled as a replica of a 1964 Lotus, roadster body. I know 'cause there's a time code on the photos.

Mind you, the parts went on pretty fast. The rear suspension assembly wheeled up to the chassis and plugged in; four bolts click click click click. The engine and trans assembly dropped in way too easily (there's no upper front crosspiece in the cockpit yet), the front control arms took two bolts each, we herded five athletes together (not all that easy on the last day of class for the grads) and off it went, recognizeably a car.

I was born here, and anything you grow up with seems normal, but I know there's a bit more of a bend toward personal responsibility in these parts than in many parts of the country. Heck, drop one state south and the DMV folks lead you by the hand through every aspect of getting your car legal...

Before I weird you out with how little supervision we get, let me ask, last time you titled and registered a car, did a DMV employee check to see if your turn signals worked? Probably not, if you bought your car from somebody else (a dealer, an ad in the paper). Basically, most states trust that if you have a regular car that somebody else built (in Detroit or wherever) that somebody got it right. If it's an old car you bought "as is, ran when parked" then maybe the turn signals don't work any more, but hey, if you drive it you'll get a ticket, that's an enforcement problem, not a registration problem.

Yet if you build your own car, the average DMV wants to check all kinds of things they don't bother with on a Buick. I mean hey, you can bring in the paperwork for a used car that has every light bashed in and they never even peek at your car, right? But if you <built> your car you get some guy who doesn't know where the fuses go on his Ford F-150, looking for DOT stampings on your taillight lenses, and in some cases (I'm not making this up) having you start your car so he can decide if it sounds legal.

In Oregon, the DMV responsibilities are to verify the vehicle and its components are not stolen, and that appropriate fees have been paid if you intend to operate it on public roads, and that a reputable insurer will stand up for you if you do something clumsy or dumb with it. I don't think it ever occurred to the woman at the DMV, that she was better qualified than me to inspect my car for functionality, safety, or even compliance with the Oregon Vehicle Code's equipment standards. The rules are there, if I went to this much trouble I probably read them, and it's really between me and the cops, same as it would be with any other car.

Anyway, nobody stops you from taking the turn signals off your Buick, it doesn't void your registration...but you'll be breaking the law if you drive it that way. My car will have turn signals before I drive it on the street because I don't want to pay any failure-to-signal tickets or equipment violation tickets, and because I don't want to get trampled by some other driver who didn't know I was turning...but I don't think it's the DMV's job to tell me that, and no Oregon police officer would be impressed if I said, "Turn signals? The lady at the DMV didn't tell me I needed turn signals." Sheesh, she's not my mom; my compliance with the vehicle code is my job as a driver, not her job as a registrar.

So I brought in all the receipts (including some for parts not yet installed) and what is clearly an unfinished car rather than a collection of car parts, and the only even minor glitch was that normally the Oregon DMV puts its VINs in the doorjams of homebuilt cars. A suitable alternative locationwas found and documented (upright tube near driver's left knee) and it's a done deal. I merely await a license plate panel's decision re obscenity or offensiveness, and if they're okay with it, my license will be GRM 2K7 in honor of the Grassroots Motorsports $2007 Challenge.


Attachments:
File comment: The chassis doesn't have its front shock mounts yet, so I used one wheel to hold up the other one. It was hot, she got the idea, so she didn't make me do the right side too.
ChassisAtDMV.jpg
ChassisAtDMV.jpg [ 33.83 KiB | Viewed 10626 times ]

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PostPosted: June 5, 2007, 11:43 pm 
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You call that a car? :lol: j/k. Great story. I'm glad the kids showed up to help close the deal. :thmbsup:

Where are you getting your front coilovers?

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PostPosted: June 6, 2007, 12:57 am 
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It's more a car than it is a non-car, though having only three wheels might be pushing it. Also I brought the book, and receipts for nose and scuttle materials...plus this isn't the first Locost they've had in the lot.

chetcpo wrote:
Where are you getting your front coilovers?


Well, that's the main reason the chassis doesn't have top shock brackets yet. I don't know what the front coilovers will be, but I know they're going to be cheap. GAZ shocks all around would cost 1/3 of the budget. I could do my cool double dip suspension with bike shocks, but I'm exploring the possibility of adding coils over ordinary shocks...we'll see.

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PostPosted: June 13, 2007, 9:35 pm 
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great write up on the Oregon DMV...theres a really good point in there.

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PostPosted: July 5, 2007, 9:50 pm 
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Since the GRM$2007Challenge rules discourage building at a place of business (gross simplification that) this car has moved to a hangar. Not a lot has happened, but you might be interested in this foot pedal installation.

We're using the Miata pedals, master cylinders, and pedal boxes, with minor modifications. To scrunch them toward the center of the car, the brake and clutch pedal legs are bent to the left (roughly as much as they're bent to the right in a Miata), which leaves just enough room for the steering column (which is the Miata unit as well; gotta keep under $2007) and moves the clutch box far enough to the right that it fits under the hood of a "book" Locost. The boxes are rotated 12 degrees clockwise; you can't tell with this chassis 'cause it's set up for a full body, but for a book frame this is necessary or the clutch box won't fit under the fiberglass.

The clutch reservoir is canted with the pedal box--it's too small in diameter for it to be a problem. The brake cylinder is mounted upright so the fluid won't hit the cap in left sweepers...probably not an issue but it was just as easy to draw the mounting holes level as it would have been to draw them canted, so there you are.


Attachments:
File comment: Not shown: steering column and firewall. The backs of the pedal boxes bolt to the firewall.
TopMountPedalsFtQtr.jpg
TopMountPedalsFtQtr.jpg [ 38.15 KiB | Viewed 9973 times ]
File comment: Instead of canting the brake pedal box, one could do some imaginative bending of the throttle and brake legs, but this way was easier. Note the pad for mounting the steering column.
TopMountPedalsRearQtr.jpg
TopMountPedalsRearQtr.jpg [ 31.53 KiB | Viewed 9969 times ]

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PostPosted: October 23, 2007, 4:51 pm 
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Whoa!
What happened?

Here I just found this neat thread and read it with great interest, when, suddenly, nothing.....

Is this a cliff hanger where I have to pay to find out the rest of the story?
All right! I'll pay! :D

I would sure like to know what happened after the last post. Pictures, story, and all the good, bad, and ugly details.

And the plans (book) you mentioned, I shall have to see if I can find more info on your site about that too. Very interesting. And I just happen to have a Miata.... :shock:


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PostPosted: October 24, 2007, 2:24 am 
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Just realised that I didnt get to see you at the 07 GRM-C. I would also like a progress update if there is any :)

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"the all-consuming time-sucking car, which I really enjoy working on" -KB


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