Dbd13, being a piping designer I've worked with structural engineers. As far as the brace is concerned i would suggest gussets at the X all four sides and four more gussets at the big X corners opposite the small triangles. And I invite Mad R's(SWMBO) response. 
I think you want the "horizontal" part of the "L" channel (bed frame?) to be "down" so that it's furthest from the body... then it'll be doing "the most work" vs being tucked up against the body. Although, I'll defer to Mad R's wife... I'm a bit {ahem} rusty on structures visualization.
if you gusset, you might gusset the tops... since that'll make a more "I" beam like structure. Leaves you the option of more easily skinning the bottom with AL at some point (good for Aero, and good for increase torsion resistance).
you're tying (bolting?) the uprights of the braces sides into the 2x2 box channel, right?
The 1x1 sides will be welded to the 2x2 framerail. The bolts will be welded to the 1x1 tocreate studs, thereby making the rest of the frame removable for trans service, etc.
With what i have, theres really no room to go up towards the floor of the car and still have things like a driveshaft or exhaust. Not enough real estate.
Dimensions are 32 inches long and 25 wide. So we'r not talking about a large span here.
Gussets can definitely happen, and if im understanding y'al right, any corner of a triangle that i can gusset should be.
As far as using this for aero: i hadn't planned to. But....
I have some .30 cents a sheet aluminium thats about the thickness of 2 sheets of paper. I could pop rivet it to the butterfly brace, but im unsure of its effects on heat from exhaust/torsional stiffness/aero benifit. To be honest, aero hasn't been though about yet. At all.
"Gussets can definitely happen, and if im understanding y'al right, any corner of a triangle that i can gusset should be." No.......just those i mentioned should give you the rigidity yu seek grasshoppper. And if weight is a concern your gussets could sport lightenin' holes too. Happy New Year btw....
I guess the opposite small triangles is confusing me.
Which ones? Cause now i wanna make gussets.....
Oh, dad got the 2x2 fitted already. Going over afyer work to help square up the car and get him ready to weld.
In reply to 759NRNG :
And happy New Year to you as well
If you want to play around with this before committing to metal.. you could mock up some of these with balsa pretty quick.
with no budget hit... and mightcould crossover to teaching kids.
Think of this like how an ikea bookshelf stops being wobbly when you attach the skimpy back panel.
Oooooo
Good way of thinking!
But would paper thin aluminium and pop rivet add the same stability? I could do both top and bottom of the butterfly brace for about 2 bucks.
Dbd13 where the big X touches the frame at the corners ......put the gussets there in the trapezoidal shaped area of the bfly brace at the perimeter angle.....opposite of the smaller triangles
ate three two 4 six five 1 twotwo 6
I'll get her to sketch something up.
I laugh, I'm a Piping Engineer, Give me support spans and thermal growth anyday...
Mad_Ratel said:I'll get her to sketch something up.
I laugh, I'm a Piping Engineer, Give me support spans and thermal growth anyday...
And I'll throw the expansion loops just where you thought they should go......within a bay or two
thinnest aircraft skin I'm finding (for ballpark purposes) is 0.016", 0.020" would probably be better... this kinda depends on the variety of AL, etc etc ad nauseum, where's my structures books?
In reply to sleepyhead :
I'll have to Mike mine when it warms up enough to get it out of the shed. I got it from stampie last year at the challenge and it's used in printing somehow. Super thin stuff.
Mad and 797: thanks guys. Im just making it up as i go along. Regardless of the absolute torsional regidity, its bolted with 5/16 bolts to 1x1x1/8 angle iron welded to the 2x2 framerail. So, keep that in mind. It'll only be as strong as its weakest link, and i have no freaking clue where that is.
Probably the welds.
Aircraft skin is held on with a ton of rivets. I would think that having more widely spaced fasteners is going to reduce the amount of strength that it will add. And do we need to think about galvanic corrosion? This isn't my project so take this next bit with a large grain of salt; welding thin sheet steel to this brace/framework, and then welding that to the car, would probably make for a stronger setup overall. And would make servicing basically impossible. So maybe there's a limit to the usefulness and things might be already a bit out of hand.
Love these project threads and following along.
Dude, it's good. Move on. Perfection is the enemy of good enough.
If ya wanna see if it's good enough, paint it or something and see if you have witness marks after driving aggressively...
Move along to something more important.
In reply to wvumtnbkr :
Part of me definitely agrees with you. The really competitive part of me has this thought: "if i know what perfect/optimal is, i can get as close as humanly possible as my current skill/equipment/budget allows, thereby making the rest of the system better"
You'r probably right, but im definitely learning a hell of a lot through this discussion that should be applicable to the butterfly brace and the rest of the build/future projects.
pres589 said:Aircraft skin is held on with a ton of rivets. I would think that having more widely spaced fasteners is going to reduce the amount of strength that it will add. And do we need to think about galvanic corrosion? This isn't my project so take this next bit with a large grain of salt; welding thin sheet steel to this brace/framework, and then welding that to the car, would probably make for a stronger setup overall. And would make servicing basically impossible. So maybe there's a limit to the usefulness and things might be already a bit out of hand.
Love these project threads and following along.
Hmm.....
That may actually be feasible. As it sits, any service or the or anything in the tunnel will require dropping out the butterfly brace. Which is 9 nuts at this point in time. Overall regidity could be improved by welding it straight to the rails, but service would be impossible. Or assembly for that matter. A stressed sheetmetal skin shouldn't hamper other things, but again, were probably at the practical limit of the attaching hardware as it is i think.
In reply to 759NRNG :
This had me laughing hard enough for people to stand up...
Mad_Ratel said:In reply to 759NRNG :
This had me laughing hard enough for people to stand up...
Y'all hirin'? Can start next week.......
Not really,
Hitting a lull/slow period right now. Mostly Pulp and Paper and our rates are substantially less than petro...
Mad_Ratel said:Not really,
Hitting a lull/slow period right now. Mostly Pulp and Paper and our rates are substantially less than petro...
Work is work the last PnP i worked on was the Weyerhauser in Columbus Miss
Flickr from phone, but thats dad welding in the 2x2 subframe connectors.
Im gonna try to get down there this weekend to flap wheel the welds on the underside and get the butterfly brace and trans mount finished and installed. Depending on how that goes, start making roll bar fit will be next. Or the cowl braces.
Challenge budget so far:
previous challenge budget: 868.78
recoup total: 800
new money:
added core charges back in per the new challenge rules
given 4 unknown rate red coilover springs
purchased coilover sleeve kit for honda civic: 43.99
sold 2 red and 2 civic springs: 22
purchased 4 used bilstein: 40
purchased entire drivers rear suspension 40
purchased passengers fender: 40
purchased inner fenders: 20
purchased 3/16 plate: 10.95
255lph fuel pump from ebay 13.99
2x2 angle 6 feet 5
new total: 1135.71
recoup: 822
to start with, I figure well talk about parts acquisition.
Was told by the spec miata shop that they were unable to locate the stick of cage tubing that I got with my rollbar. He told me to buy a stick and he would reimburse me, which he did. So I went to stock car steel over in moresville and picked that up, as well as some 3/16 plate, as that is the SCCA requirement for a bolt in roll bar. Also got a sheet of plastic for another project while I was there. No picture, because it looks like a piece of steel plate.
20180109_182527 by Michael Crawford, on Flickr
got the spec miata slicks mounted up and balanced on the NB 15s so they'd take up less room. 15X6 wheels, and yes, the slicks are somewhat pinched. Unless someone wants to trade 15x8/9/10 for stock wheels, this will have to do. Toby at freemans tire charged me 40 bucks. 10 bucks each is a pretty good deal.
20180114_114852 by Michael Crawford, on Flickr
20180109_082520 by Michael Crawford, on Flickr
20180109_082530 by Michael Crawford, on Flickr
responded to a facebook marketplace ad for miata parts, asking about struts. I had seen what looked like konis in a picture of the parts stash. After coordinating schedules, dad and I drove to outside of greenville, SC and met a guy named Alex, who parts out miatas for a good portion of his living. Name of the business is SNS Mazda parts. We spent some money.....
20 struts at 10 ea, full drivers side rear suspension to replace our bent stuff, front fender, and inner fenders. Still need to source and NB subframe to replace that bent part. In the struts were a full set of SGX with a spare front and rear, 2 full sets of tokiko Hps, b&g lowering springs for an NA, a full set of speck miata bilstiens, and a bunch of NA tophats. Need to go through them all, then ill start selling off spare crap. A set of the tokikos and stock NA springs may go on my daily NB with NB tophats, as that should lower it 1.5 all the way around.
20180113_101439 by Michael Crawford, on Flickr
20180113_123917 by Michael Crawford, on Flickr
20180113_154457 by Michael Crawford, on Flickr
no pictures of coilover stuff or fuel pump as its still in shipping. Next time...
lastly, an example of how the challenge makes a man resourceful. Were always looking for materials and supplies. I went to an early dinner with brother Dustin and Dallas last night. On the way to dinner, we had to drop off a redbox movie at Walgreen. Coming through their parking lot, we noticed an overflowing dumpster out back where the store is being renovated. A quick peak inside resulted in a “hold my beer and watch this!” moment.
Walgreens dumpster by Michael Crawford, on Flickr
I dug out some quite heavy gauge blue tube and flat stock, 3 seriously heavy duty rolling platforms, and some store fixtures with 1/8 wall 1x1 tubing on ¼ plate bases. All most of the way to the bottom of the dumpster. The manager was cool with it, and we did ask. I ain't going back to jail for free steel.
20180113_182313 by Michael Crawford, on Flickr
anyway, on to the car.
Dad worked on getting the 2x2 subframe connectors welded in, and then ground down in preparation of mounting the butterfly brace.
20180113_161248 by Michael Crawford, on Flickr
20180113_161109 by Michael Crawford, on Flickr
20180103_183357 by Michael Crawford, on Flickr
20180113_161244 by Michael Crawford, on Flickr
something I did NOT anticipate was the fact that 2x2 is actually narrower than what mazda used, as mazdas rails were not actually square. Which meant that my butterfly brace no longer fit. By about an inch. And not enough room on the 1x1 angle to re-drill the holes. Instead of scrapping the whole thing and starting over, I picked up some 2x2 x3/16 angle, lopped an inch off the vertical side and cut it to length. I still need to get them fitted, drilled, and studded, but were close. With plenty pf extra meat left over.
I also used some of the 1x1 tube and leftover angle to make frog arms. These are ugly in pictures and person, but thankfully will be hidden by fenders. Strong though, and I feel a benefit in addition to the seam welding and subframe connectors. Ive never had a car that I felt was too stiff, and the AMC is my benchmark for stiff enough.
20180106_121253 by Michael Crawford, on Flickr
20180107_163942 by Michael Crawford, on Flickr
made an extra pair for the daily while I was at it
20180106_181351 by Michael Crawford, on Flickr
I then moved on to fitting the roll bar and making the rest of it. Because, really, its cool. It doesn't get us any closer to a running, testable car, but it makes me feel good. So ive got that going for me.
First up was making the bar fit exactly where I wanted it. That required some surgery to the drivers side seatbelt tower. The cutting is done, and ill re-weld it shortly, and then box in the rest to strengthen it back up, but the bar is now perfectly situated. I then obsessed mightily over how to do feet and make it a bolt in. the thing I don't like about my hard dog is how you need 2 people and 7 hands to get the reinforcing plates, nuts, bolts, and bar all assembled. Its a pain in the ass. So my idea is to weld nuts to the backer plates, and pop rivet the plates to the floor pans for location purposes. Genius!
Still have to make the plates and feet though. So I went to google, where every idea someone has ever had has a picture taken of it. I found my inspiration in an article of a blackbird fabworx gt3 install. Pretty much did what I thought I wanted to do, but it was good to see confirmation that I was on the right path.
20180113_161114 by Michael Crawford, on Flickr
20180112_182238 by Michael Crawford, on Flickr
Took my portaband to the 3/16 plate, and after a significant amount of cutting, grinding, and shaping, had the different pieces I wanted. I measured for my holes, and too them home with me for drilling.
20180114_135127 by Michael Crawford, on Flickr
Pictures of my shop and drilling setup:
20180114_114022 by Michael Crawford, on Flickr
20180114_114053 by Michael Crawford, on Flickr
then took it all over to dads this morning and did some welding and final fitting.
20180114_155518 by Michael Crawford, on Flickr
should tack the hoop to the new plates tomorrow, and finish the backing plates.
While ive been doing that, dads been working on finishing seam welding. We have gone much, much further than flyin miata recommends, and much much further than we planned on. Seam welding is addictive, as I learned on the AMC. Dads learning it on a mazda. Its hard to know when to stop, to be honest.
20180114_162144 by Michael Crawford, on Flickr
our goal for tomorrow is finish the main hoop feet/attach the hoop to new feet, finish the butterfly brace, make a trans mount, and maybe finish the welding of the 2x2 subframe connectors.
Tell your dad he's doing good work. Well, you probably already tell him that, but tell him that the internet thinks he's doing good work.
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