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Learning how to build Lotus Seven replicas...together!
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PostPosted: June 21, 2017, 12:22 am 
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Toyotaphobe
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Now I understand about the wiper, I was thinking it was on the gun somehow and I couldn't figure that out.

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mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.


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PostPosted: June 21, 2017, 8:50 am 
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Your local welding supply will have what is call "Chem-Wipe" for clean the drawing oil off the welding wire. One small plastic box will last a life time for hobby welding. I would also recommend that you clean the drive roller once in a while with a Q-tip and alky. Dave W


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PostPosted: June 21, 2017, 8:07 pm 
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Have my theoretical mounting bracket locations worked out.. These keep the arms perfectly level at 5" ride height. Of course, the center of the balljoint pivot point is slightly (5/16") above the center of the arm, so geometrically speaking they aren't actually level. I'll have to look at what the motion looks like. Right now the model is being somewhat uncooperative.

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PostPosted: July 4, 2017, 9:12 pm 
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Okay, back from vacation and back to work. Model looks pretty good now. I had to tilt the ball joint sleeve inward to allow the stud to sit more centered within the cup. Hopefully it's enough.

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Does this look about right? I had to modify the angle of the rear bar to line up nicely. This gets me a wheelbase of about 90.5" assuming the rear axle is centered right under the rear upper shock mounts.

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Also spent some time cleaning up my axle housing while I modeled it up.. Cut the brackets off but gouged a bit into the tube in one spot. Might add a bit of weld there just to make myself feel better.

I don't have rear brake rotors yet.. Anybody know if I can assume the centers to be about as thick as the fronts? I want to add them to the rear but I want to make sure my true WMS-WMS is as accurate as possible.


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PostPosted: August 22, 2017, 9:35 pm 
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Sigh.. Got my upper balljoints and adapters, so the front suspension is pretty much designed and ready to start building. Jack's kit should work well with just a few modifications to accomodate the Mustang spindles.

I have decided that the welds on my frame are such garbage that I'm not even going to bother trying to fix them. And after buying and practicing with a gas bottle, I am confident I can do better welds. The good news is that I can get steel very cheap through work, so I'm going to build a frame from scratch, and maybe use the one I have to create jigs, maybe salvage some of the bent round tube, etc. Working like a dog at my day job right now, but should have some much-needed time off soon, and during that time I plan to build the frame and get the suspension done.

In the meantime, I am getting more acquainted with my new toy:

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And for fun, and some motivation, I picked this up:

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So that's all. Another non-update, but I'm not giving up and actually glad for the opportunity to make my frame my way. Okay, off to design a MDF torsion box..


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PostPosted: August 23, 2017, 11:35 am 
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Man, that lathes looks cool. :drool:

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: September 3, 2017, 2:40 pm 
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Always Moore!
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Nice lathe. Is that Busy Bee's version of the G0602?

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PostPosted: September 3, 2017, 9:18 pm 
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a.moore wrote:
Nice lathe. Is that Busy Bee's version of the G0602?


Good eye! That's it exactly. I've just about finished turning the parts to make my trailing arms (heim joint on one end, bushing on the other) and it's been great.

Also finished building my table today. Very happy with how it turned out. Time to skin the top with some thin plate and get welding!

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PostPosted: September 30, 2017, 9:58 pm 
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Alright. I have a pile of steel in the garage and am taking next week off work (entirely with banked hours). I used one sheet of steel to skin the build table which makes it very convenient to tack things down, as well as acting like a ground.

The next order of business was to make sure I had my welder settings correct. I could make a decent looking weld, but wanted to make sure I had full penetration. So I welded a couple samples and took them to the lab at work where we did some tensile and bend testing. Boy am I glad I did that. I didn't have the heat up high enough at first, which was evident during the bend tests:

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Turned the heat up, tried again, and produced a result which looked good. Forgot to take a picture though. D'oh.

Anyway, have started on the new chassis. Have the bottom part fit and tacked up. Hoping to make a lot of progress in the next few days. The one thing I'm not sure about but have to figure out soon is how to do the compound angle cuts on the front end.

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PostPosted: October 1, 2017, 10:26 am 
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It's great that you checked your welds. I wish I'd had a more scientific may of testing my own as I went along. Good on ya!

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: October 17, 2017, 4:16 am 
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When I was learning to weld, my uncle told me to set the machine hot enough to blow a hole in the material and use enough motion not to .
Nothing beats a destructive test though .

Cheers from Bulgaria


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PostPosted: October 26, 2017, 1:08 am 
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Whoops, forgot to update for a bit. Finished the bulk of the chassis but hurt my back, so I wasn't able to do anything for a week or so. Better now, and back at it. Very happy with how it looks so far! And everything is nice and square and dimensionally accurate. Managed to get FU1/2 in and rotated them to be parallel with the lower rails for better control arm connection geometry.

Image

My ghetto tube notcher:
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Perfect!
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Also got some decent bends out of the tube bender I snagged:
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I have the trailing arms designed (bushings on one end, heim joints on the other) and just finished 3D printing a jig to tack them together. Hoping to have the rear axle mounted this weekend? Then I want to get the motor in, take it to a shop for a driveshaft, and build the tunnel around it.

Working on my front suspension geometry as well. Playing with roll center, etc. Does this look reasonable? I think I will plan to give myself some decent adjustment of both front and rear RC. Still need to work out what it does in the corners. For that I just ordered two books on my wife's Amazon Prime account for $180 worth of light weekend reading. :)
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PostPosted: October 29, 2017, 11:13 am 
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Your diagram looks good. It's a real debate about what ride height to run. It's more for practical reasons (like scraping your oil pan) that suspension performance. I'm sure you know that you need both sides of the diagram finished to locate the static roll center at ride height. The static values are 100% accurate until you move the car [LOL], but a good indicator of the general characteristics you have.

What books did you order?

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: October 29, 2017, 12:57 pm 
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Lonnie-S wrote:
you need both sides of the diagram finished to locate the static roll center at ride height.


Uh oh, I did not realize that. Assumed since it was a mirror image I could use the centerline as a reference. I will look into it more. That's why I bought the books, because I don't feel like I fully grasp the relationships between RC, RH and CoG in particular. Further, I need to figure out what will be ideal for this car. The next step from there is looking at how it changes during cornering. Oh, and steering ackerman. :)

I had my wife order these on her Amazon Prime account, hopefully they get here soon..

https://www.amazon.ca/gp/product/047051 ... FN49&psc=1
Image

https://www.amazon.ca/gp/product/184584 ... 4ISS&psc=1
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PostPosted: October 30, 2017, 10:35 am 
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No, you got it right. You just need to construct the lines from the right side (looking at your graphic), and they should meet at the centerline at the 3.72" height you indicated. Not seeing the construction lines, I wasn't sure you understood that.

That first book looks very interesting. The only thing I've seen like it is the older text by Bastow from about 1980. Computation was not part of the text back then. Are you a programmer too?

I have the original edition of the second book. The great thing about it is that it gives you good practical targets to shoot for in your design, and later alignment regimen. There are so many individual things to worry about when designing suspension. Hammill's book give you some practical idea of the consequences of altering things too.

Probably the best quote I've ever found with respect to design and engineering is, "All design is compromise." I can't remember who said it, or where I read it, but it's true. I think the full quote is more like, "All design is compromise. He who makes the best compromises creates the best design."

You're going to be the prisoner of some decisions someone else made in the past for reasons you'll never know. For example, if you choose a particular donor front spindle to use on your Locost, you're got certain characteristics built into it that you can't change - unless you want to design and build your own spindle, or make large modifications to it - assuming you can. So, be prepared for imperfections and learn how to make the best compromises with what you've got.

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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