building a frame...well thinking about it

[YuriSouder]

I have a class for college called "How to build almost anything". I asked if i could build a frame for my jeep and the teacher said yes. i have a 1994 Sahara with a patched, cracked and practically malleable frame.

What are your first thought about this idea?

i have around 40 hours in class to work on this and all the tools i would ever need. What is the best way to begin going about this?


this is how far i got but...

 

[SteelHeadz]

To build a frame correctly, i don't think 40hrs is enough. The correct way to build a frame is to build a jig first, only then that you can build it according to the spec. sheet you have at hand. Now, you can take a similar frame you have on your Jeep and Re-build it to the way you need to and come out ahead on that time given. IMO.

 

[Saddle Tramp]

I'm with Steelheadz, I think it will take you the best part of your 40 hours just to build the jig let alone the new frame. However rebuilding the frame you have might work. If the jeep is still together you might want to take it to a frame shop and get it tugged into spec first, that way you will know you have it right when you start. (The frame shop has to have the springs, axels, and tires on the jeep to do this work.)

 

[YuriSouder]

my friend and i made a tub bender and i really want something strong to build an XO with. I feel like if i am going to put the time into a full XO i should have a good strong frame. maybe i should look for used then just plate the **** out of it.
I feel like something ran into this problem 6 years ago and patched everything but now the stuff they did not path needs it. So i really dont have a frame...all i have left is the patches haha. so i think i need to make one or by used or get a great deal on a new one

 

[SteelHeadz]

Now there's a thought!! if you can find a frame that you can borrow as a Jig, that will save you time in building a new tubular frame. Just make sure the frame is straight and within specs.

 

[coasty]

I will have to disagree about needing a jig but will agree it will take more than 40 hours to build a frame. I built a 60 foot lattis boom for a crane with out a jig. We did the layout in the concrete floor two sides and then used the lay out to add cross members. The end result it slid right on the pivot and the king pin slid right in.

The biggest thing you need to do is think things through and develope a plan for each step of the build.

I have also built many motorcycle frames with a home made dead table, bending the tubind with a hydarulic bender. When done the frame was less than 128 of an inch out of square as most factory MC fra,mes are as much as one eigth of an inch out.

 

[SteelHeadz]

I will have to disagree about needing a jig but will agree it will take more than 40 hours to build a frame. I built a 60 foot lattis boom for a crane with out a jig. We did the layout in the concrete floor two sides and then used the lay out to add cross members. The end result it slid right on the pivot and the king pin slid right in.

The biggest thing you need to do is think things through and develope a plan for each step of the build.

I have also built many motorcycle frames with a home made dead table, bending the tubind with a hydarulic bender. When done the frame was less than 128 of an inch out of square as most factory MC fra,mes are as much as one eigth of an inch out.

Ever heard of the term "Net Build"?. It's a stacked tolerance of specifications from start to end of an automotive build. If the discrepancy starts on the frame and the components that followed also has a wide tolerance or variation, the final rolling chassis is posibbly going to be rolling down the road sideways or pulls to one side. A good example is the first production Chrysler300C. A mis-communication between the Engineers and the sub-suppliers of the suspension components led to a bad net build and was causing the front end to pull to the right. The correction was to move the engine cradle and install a correction bolt to compensate for this discrepancy. It's since been corrected from the plant and is no longer an issue. To think that a Jeep frame is more Rigid than that of a 300C , the final placements of your weld could mean a disaster on how your going to get that rig rolling down the street in a straight line and equally leveled on all 4 corners. Far more different from building a crane boom or a frame with 2 wheels. I've built Motorcycle frames as well but sorry, i dis-agree with your opinion.

 

[coasty]

Ever heard of the term "Net Build"?. It's a stacked tolerance of specifications from start to end of an automotive build. If the discrepancy starts on the frame and the components that followed also has a wide tolerance or variation, the final rolling chassis is posibbly going to be rolling down the road sideways or pulls to one side. A good example is the first production Chrysler300C. A mis-communication between the Engineers and the sub-suppliers of the suspension components led to a bad net build and was causing the front end to pull to the right. The correction was to move the engine cradle and install a correction bolt to compensate for this discrepancy. It's since been corrected from the plant and is no longer an issue. To think that a Jeep frame is more Rigid than that of a 300C , the final placements of your weld could mean a disaster on how your going to get that rig rolling down the street in a straight line and equally leveled on all 4 corners. Far more different from building a crane boom or a frame with 2 wheels. I've built Motorcycle frames as well but sorry, i dis-agree with your opinion.

A 300C is a poor example since it is mainily unibody. The end result, if the frame is square the ride will be true. There are many ways to accomplish this without a jig, a one to one lay out with bracing and stiffiners to hold things in place is just one. Also, if you have not ridden a motorcycle and do not know the dynamics of turing, rake ot trail and the results of an out of square MC frame then I would not say it is far more differnt. All the same principals apply and due to the uniqueness of a MC frame it is even more critical to get it right. As far as a boom crane if it is out of square someone will die it is more critical to get it right. Weight testing an out of square crane will have devistaing results especially when it is tested at 100 tons. Both the crane and MC frames are examples how someting critical can be made with out jigs. The plan of attack and a well thought through process is all that is neded.

 

[phall92139]

I hear what both SteelHeadz and coasty are saying here and think they both have very valid points. Jig or no jig. Maybe the question isn't can you build a frame without one but do you have the knowledge, skills and abilities to build a frame without a jig?

Now, no offense intended at all to YuriSouder but due to the opportunity of this college class this will be your first frame build? And you are talking about hand bending a tube frame? Hmmm? Could you do it without the jig? Probably, maybe but I'd think you'd be far better off using one. Like SteelHeadz said, if you are off here, the whole build is going to suffer. That would be a disappointing bummer, not to mention the waste of money.

 

[YuriSouder]

YAAAAAAAAAA there is no way i could ever do this in 40 hours

 

[YuriSouder]

thanks for the help guys

 

[Saddle Tramp]

I I built a 60 foot lattis boom for a crane with out a jig. We did the layout in the concrete floor two sides and then used the lay out to add cross members. The end result it slid right on the pivot and the king pin slid right in.

Coasty-

I know I may be splitting hairs here with the semantics but if you do a layout on a concrete floor and then proceed to construct something with it you have in essences "built a jig". I know it doesn’t have raised angles on it but the floor layout is what allows you to make your item "square" and/or "true" and locate the various angles from square that may be needed.

I have built countless walls for concrete tilt up buildings doing just that as well as wood walls for apartment buildings, all of which were lifted into place when finished with a crane like the one you built the boom for. The one thing done in these instances that you may not have done for your crane boom layout is blocks and, in the case of a tilt up, forms are typically temporarily attached to the concrete surface to aid in the construction.

If you look at a modern day truss plant, whether it be floors or roof trusses, their "jig" is primarily a flat surface made out of rollers but rather than a layout marked on the flat surface below the truss layout is projected down from above using lasers so the operator knows where to place the members. It is still called a jig and is a great improved from the old days of building them on a concrete floor.

So, what is a jig? Anything that aids in layout and construction.

 

[jps4jeep]

I think 40 hours is plenty of time to design a frame. I could probably get a quick drawing out in about 10 minutes, my guess is another hour or so getting rough measurements for the frame rails. design is done. I would not copy the original, I would make a number of improvements. I understand what everyone is saying about the Net Build, but the jeep has one huge benefit for frame building, the entire body is built off the tub and pretty much everything is a right angle. The actual building of a frame, 40 hours might be about right maybe a more if it is your first frame.

 

[YuriSouder]

So you are saying that if i just made something like this my yj would still be functional??? i have veteran mechanist that would be helping me with the build...If i can make a simple design this project is Doable!!!

 

[jps4jeep]

I see no problems with that, some fish plates on teh seams would be a smart move though, and no reason for so much frame behind the rear spings unless that is just a pic you took from someone else and it is for a cj8.