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Building a frame "from scratch"......?

Discussion in 'Center Of Gravity' started by Greg72, Nov 21, 2003.

  1. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Building a frame \"from scratch\"......?

    I didn't want to even consider it.....but I blame all of YOU for these new ideas! /forums/images/graemlins/grin.gif I feel invincible now that C.O.G. exists!!

    So here's the basic scenario, I'm still in the research/feasibility phase of this project:

    Existing "stock" frame -

    Basically can be described in three major parts, each is roughly 6 feet long.

    Metal thickness = .145"
    C-Channel stamped construction
    Rear section = 3.0"W x 4.5"H
    Center section = 2.5"W x 6.0"H
    Front section = 2.5"W x 5.25"H

    I'm looking at it as basically a center section that could be replaced with rectangular tubing (3.0" x 6.0" x .188") and then graft the rear and front sections to it (3.0" x 5.0" x .188")

    This would effectively give me a "boxed" frame from the get-go, with a slightly thicker metal than stock....since I'm designing custom links for the front & rear suspension ANYWAY...preserving the hangers and bracketry is irrelevant. About the only thing I need to preserve are the 12 body mount points, and motor mounts....everything else would have been custom-built anyway.


    So, a couple of questions:

    1. How do I graft these sections together? I can't imagine that a standard "butt-welded" connection is going to do the trick. Some kind of extra metal plates on either side to create a "sandwich" effect, perhaps??

    2. Since the sections are of the same thickness, but different heights, how should I accomdate the difference in height? I was thinking of a "fishmouth" cut on the center section, that would create a slight lip for the front and rear sections to dovetail into....but again, the particular welding technique is unclear.



    I have no idea if this will be worth the tremendous headaches or not. I do like the fact the my suspension links will be able to tie into areas that should now be a LOT stronger than a stock C-channel...and building crossmembers that can connect to square framerails should be quite a bit easier to design and build too.



    /forums/images/graemlins/thinking.gif
     
  2. Muddytazz

    Muddytazz 1 ton status

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    Re: Building a frame \"from scratch\"......?

    Why not do it. Few yrs back, my dad complete built a new frame for his 1929 Ford Model A 5 window coupe. Don't remember exactly what he used, but it was all boxed in, extra and beefier crossmembers. He did this cause it was holding a blown 440 interceptor/torqueflight tranny /forums/images/graemlins/eek.gif
     
  3. blk87K5

    blk87K5 1/2 ton status

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    Re: Building a frame \"from scratch\"......?

    I wouldn't waste my time grafting stock portions of the frame on to the rect. tubing. I would suggest using the rect. tubing the entire length of the truck. With as much as the stock K5 frames flex, I would bet that the C channel would flex many times more than the rect. tubing putting a load of stress on the joint between the two. I think the two options would be to either using cut steel plates to box in the current frmae for increased strength and more ridgedness, or to just completely build a new frame.

    You might consider building a new complete rect. frame for the portion from the front bumper to the t-case, then tube from the t-case back tied into your roll cage. That might help make up for the incresed wieght of the full rect. frame.

    My $.04
     
  4. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Building a frame \"from scratch\"......?

    LOL, seems I remember someone saying something about building your own frame when you first started this... /forums/images/graemlins/thinking.gif /forums/images/graemlins/rotfl.gif

    And I agree, ditch the factory frame all together and build what you need. To make your life easier, you can reuse most of the factory mount points by cutting the rivets and bolting/welding them on the new frame.

    [Edit] And BTW, if it were me, I would probably go with 2 x 4 x 0.188 box which is probably still over kill...
     
  5. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Re: Building a frame \"from scratch\"......?

    Rock Whore,

    I wasn't intending to graft any part of the stock frame back onto the new setup....just to clarify.

    The confusion is that I have two different sizes of rectangular tube to attach to each other, and the front and rear sections are both going to be coming in at an angle to the mid-section (which sits basically parallel to the ground).

    The front and rear sections are swept up and away from the middle part, so I' just trying to visualize how to weld it all together in a way that won't tear itself apart under load....


    /forums/images/graemlins/thinking.gif
     
  6. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Building a frame \"from scratch\"......?

    Check this out from the Garage!
    http://www.gradysoffroad.com/special/blazer/blazer.html
    Your too late, already done… LOL!

    I would miter the joints and but weld followed by grinding smooth and fully welding a circle over the joint at the high stress points. Alternately, you could tack a backing strip inside with fully beveled edges and weld it up solid, giving a smooth outer surface with no loss in strength. I wouldn't sweat it at all...

    Also remember that the front needs to taper in to clear the front tires when turned.
     
  7. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Building a frame \"from scratch\"......?

    Oh, and on different sizes. Notching for a "dove tail" type fit would be good. You could also just notch the wide piece on the out side and bend in the wall to close up the gap. That's how my front bumper/mount/cross member fits into the taller frame rails.
     
  8. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Building a frame \"from scratch\"......?

    Here is what I'm thinking
    [​IMG]
     
  9. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Re: Building a frame \"from scratch\"......?

    [ QUOTE ]
    Check this out from the Garage!
    http://www.gradysoffroad.com/special/blazer/blazer.html
    Your too late, already done… LOL!

    I would miter the joints and but weld followed by grinding smooth and fully welding a circle over the joint at the high stress points. Alternately, you could tack a backing strip inside with fully beveled edges and weld it up solid, giving a smooth outer surface with no loss in strength. I wouldn't sweat it at all...

    Also remember that the front needs to taper in to clear the front tires when turned.

    [/ QUOTE ]


    Russ,

    That link has me "aroused"....!!! /forums/images/graemlins/shocked.gif

    Certainly, that's further off the deep end, than I'm interested in going, but conceptually there's a LOT to learn by studying those pics.

    Pardon me for a few moments .......Right-click, Save-As..... /forums/images/graemlins/thumb.gif



    /forums/images/graemlins/thumb.gif
     
  10. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: Building a frame \"from scratch\"......?

    I'd use .125" wall if you're gonna build it from box tube. Factory is .145" wall channel but it's an inherently weaker 'shape'. The box tubing has 4 sides obviously and is a much stronger shape. No reason to add an extra 33% to the weight of the frame.

    I would mitre the joints, use internal backing and prep the edges. You're not going to need more than 100% penetration, but if you're worried about the joint areas the circle over the joint would certainly alleviate that concern.

    Rene
     
  11. Butch

    Butch 1/2 ton status

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    Re: Building a frame \"from scratch\"......?

    OK, first the pet peeve. It is 6 x 3 x .188. The large # always comes first when sizing tube. If you call to price it and call it 3 x 6 the price they quote will have a "rookie" upcharge to it.
    Rant Off /forums/images/graemlins/grin.gif

    As far as the 6 x 3 x .188 Rene hit it on the head. That is way way overkill, plus it weighs 10.7lbs to the foot.

    I think 4 x 3 would be plenty, but might not look porportionant(sp?). To get down to .120 wall you would have to go to 6 x 2 as 6 x 3 is not offered in .120 wall.

    Oddly enough 6x4 is as well as 5 x 3. They are both available in 2" width at .120 or 11 gauge.

    6 x 2 x .120 is 6.45lb per foot while 5 x 2 x .120 is 5.6lb per foot. That is still heavy, but way better.

    As for how to connect them. If you are going level with the 6 and angling with the 5 then only miter the 5" side. A 20 degree angle on 5" will make it measure 6". If that is not feesible then Baddog has a good approach. I would use an elipse instead of a circle though.

    I think it is a Kick Ass idea. I have given it some consideration on mine to ditch the frame and have control over drivetrain elevation in relation to body for CG control.

    Another thing that I think would be awesome would the to drill large diameter holes through the tube on the verticle plane and "let in" DOM that would be welded and ground smooth. You might loose a little weight, but the main thing would be to have a hole through the framing for looks and the DOM would just keep the mud from getting inside the tube. Does that make sense??

    So depending on how it turns out for you maybe I will try it also /forums/images/graemlins/thinking.gif
     
  12. Muddytazz

    Muddytazz 1 ton status

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    Re: Building a frame \"from scratch\"......?

    Hey Butch,

    6 x 3 x .120 = 7.15lb per foot /forums/images/graemlins/thumb.gif
     
  13. Triaged

    Triaged 1/2 ton status

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    Re: Building a frame \"from scratch\"......?

    Greg,
    Why even have frame rails? They might make things easier to mount in the way of drivetrain but I can't see much other need for them. Design your suspension first and then connect the dots. Make sure it is well triangulated and use 1.75" tube for the whole thing. Only area that would get "interesting" is the steering box but it has been done many times befor. Now you don't have to worry about welding joints in because you could just use your bender. If you don't feal that adventurous I would see nothing wrong with only using rectangular tube for the portions between the link mounts. It could be just 2 straight pieces. Just remember NASCAR only runs the rectangular tube because they "have to".
     
  14. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Re: Building a frame \"from scratch\"......?

    Geez Tim.....I guess you really ARE a professional smart ass!! /forums/images/graemlins/wink.gif


    I took the numbers directly out of the catalog of my local tubing companies catalog.....so maybe your "peeve" is misplaced?

    For the record, their catalog shows the following:



    2 x 5 OD

    .120" 5.515 Lb/ft
    .188" 8.300 Lb/ft
    .250" 10.810 Lb/ft


    2 x 6 OD

    .120" 6.332 Lb/ft
    .188" 9.590 Lb/ft
    .250" 12.510 Lb/Ft


    3 x 5 OD

    .188" 9.590 Lb/Ft
    .250" 12.510 Lb/Ft
    .375" 18.020 Lb/Ft


    3 x 6 OD

    .120" 7.148 Lb/Ft
    .188" 10.840 Lb/Ft
    .250" 14.210 Lb/Ft
    .375" 21.038 Lb/Ft


    Looks like you'd better call up Tube Service Co. and tell them what a bunch of "rookies" they are for spec'ing their dimensions BACKWARDS!!!! /forums/images/graemlins/eek.gif /forums/images/graemlins/thumb.gif
     
  15. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: Building a frame \"from scratch\"......?

    I've always heard it referred to the other way, just as it's listed in the catalog. 3x6, 2x6, etc etc. Kinda like lumber I guess. Ever go to Home Depot and ask where the 4x2's are? /forums/images/graemlins/grin.gif

    Sorry Tim, maybe Colorado is different somehow...or maybe us dim wit Canucks have it backwards? /forums/images/graemlins/rotfl.gif At any rate I've never gotten the 'rookie' price for speccing it the 'wrong' way before.

    Rene
     
  16. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Building a frame \"from scratch\"......?

    So, from the other posts it looks like you guys think the 2x4 0.188 wall is not a good choice (since I'm the only one who mentioned it). Seems to me even 0.120 would likely do fine in 2x4, as I mentioned earlier, 0.188 is probably over kill in my mind. With an integral cage I just can't see how 2x6 and larger would be justified...

    As for circle or other miter plates, I’ve seen circles, ellipses, diamonds and other shapes. I kind of liked the looks of the circles, plus you can get them mail order cheap in 0.120 plate of various diameters. I think probably the only place I would want to use them are on the kick ups off the lower horizontal, but even that’s not needed once you get 100% penetration with a backing plate.

    Building a complete tube structure seems to me quite a bit of a jump in complexity from a frame + cage, at least based on my level of knowledge and experience.
     
  17. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    Re: Building a frame \"from scratch\"......?

    it is a bit of a debate of me posting up in this forum as i dont fab much for the time being. and the majority of fab i do do is al sheet metal with no welds. just rivets.

    please keep in mind that im an overkill person as well. i do however bring up great ideas from time to time

    [ QUOTE ]
    I need to preserve are the 12 body mount points, and motor mounts....everything else would have been custom-built anyway.

    [/ QUOTE ]
    the only thing you would NEED to keep from the factory frame is the dimensions of the body mounts. as for the engine most people want to shift id won and back a bit. for obvious reasons. CG. if you make your frame the size of a 1 ton frame(5 inches in the center i think) then you would have plenty of room to do this.

    as for x-members, and motor mounts being made you are 100% correct. they would be a lot easier to make and mount on a boxed frame. you can use urethane or rubber suspension bushings for them. then make some nice tabs for the x-members to slide into on the frame. this would simplify tranny and t-case installs BIG TIME.

    as for joining the different size sections together, i think you have a good idea with fishmouthing them up and what not. and i agree on the but weld question. why not build them to be bolted together? nice Grade 8 bolts on top, bottom and one side with a pocket to access the bolt heads or nuts on the inside. a pain, but only have to be done once. this way if something happens or you decide on a design change it can be fixed or made new fairly easily.

    another option is continue with your fishmouth and dove tail idea then but weld it. then plate ofer it with a slightly thinner plate with a few inches on each side. thinner as to not creat an area to much stronger than the rest of the frame.

    i have thought about building a frame a few times. personaly if i do it im going to run a straght rail frame for the front 2/3rds of it and run the motor in the back. this is a whole other can of beans, seeing as i am thinking you want to keep your nice new rust free first gen.
    good luck with it and i am very interested in this.
    hope i could help.
    Grant
     
  18. Butch

    Butch 1/2 ton status

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    Re: Building a frame \"from scratch\"......?

    Maybe. Just working in estimating for structural fab shops, all of our estimating programs, IE: Fabtrol and all of our ASD books and what not make a point of going the way I said before. If you tried to enter it as 3 x 6 it would give you unknown shape. Doesn't really matter. Hope you did not take it the wrong way, I was jabbing you a bit. /forums/images/graemlins/thumb.gif

    Does anybody like the idea of holes in the frame from an Architectural standpoint?

    In Colorado, Tube Service SUCKS. They are hard to deal with and do not deliver on time. I would not buy anything from those Assholes /forums/images/graemlins/angryfire.gif. The want more for HREW than I can buy DOM for. R & S Steel $0.92 for 2" x .120 Tube Service $2.23 Marmon $2.35 for 2" x .120 DOM.

    That K-5 that is linked to. I would love to see that thing put on a scale.
     
  19. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Re: Building a frame \"from scratch\"......?

    OK, I'll post up my consolidated responses in one shot:


    Tim - No problemo on the jabs...I know you were just venting at "rookies" everywhere, and not just THIS one! /forums/images/graemlins/wink.gif I agree that Tube Service isn't exactly the "price leader", but they deliver right to my door and are willing to sell me small(ish) quantities.....I'd like to get your kind of pricing on DOM, though

    Grant - I like the idea of a lower CG, and I know I'll get some crap about mentioning this, but my drivetrain is actually going to be going FORWARD and UP relative to the frame. It's a really sucky situation to be in, but my the time I bolted the entire drivetrain mock-up into the frame and starting looking at driveshafts, the rear shaft was something like 15" shorter than the front, and the front was ludicrously long (like 2-piece driveshaft long! /forums/images/graemlins/eek.gif) I figure I'll be moving the entire assembly forward about 5" over stock (relative to the motor mounts) and UP another couple inches to meet my other objective of a completely FLAT bellypan.... Hmmmmm? Now that I've typed the words, I realize that building a "from scratch" frame means that I can drop the center section of the frame to accomplish the same thing!!! /forums/images/graemlins/thinking.gif Maybe the drivetrain DOESN'T have to come up anymore..... I still plan to build an all aluminum motor to keep the CG penalty to a minumum, but it does mean that the project will take longer to finish (due to the $$$ involved)

    Russ - I pretty much like ALL your ideas! /forums/images/graemlins/thumb.gif Sometimes, I don't fully appreciate the REASONS why you suggest certain things....and it takes me a little time to re-read and digest the information before it all sinks in. I am not opposed to using non-standard size tubing to replace the stock frame, but my initial fear is that it will somehow look "odd" with a big gap of daylight underneath......I am "aesthetically obsessed" about these types of issues, but maybe a little time with some graphpaper or SolidWorks (thanks Dan! /forums/images/graemlins/thumb.gif) will allow me to "see" what you are talking about better????
     
  20. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: Building a frame \"from scratch\"......?

    Tim,

    I'm running into the same problem here as far as pricing and even availbility. I'm going to start telling them I'm building railings or something...as soon as I mention roll cage they all want to sell me 1.75" x .134" DOM for $5.00 a foot /forums/images/graemlins/angryfire.gif. Either that or they want to sell me pipe.../forums/images/graemlins/rolleyes.gif

    Best I've found price wise was 1.75" x .120 HREW for $2.40 a foot so far. /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif

    Rene
     

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