Option 1:
Why mess with CAD? There is a time to just build. Since you are doing this yourself, make it out of paper, then turn the paper to steel. That is what everyone I know who does bumpers uses. In the end, fab guys usually build by feel on a rig rather than using fancy stuff in one off applications.

Option 2:
I have not the slightest idea how to use that computer design stuff. I am really jealous that you can. Because I can't, I resort to making little paper dolls of what I want then taking it to the fab people to build it. Though I can cut and piece, I lack the complete skills.

I still farted in your box.

 

Box.

 

Why CAD you ask? like you said - because I can. CAD is first. Cardboard Mockup of the sides/corners is next. Then I'll cut steel and start hanging it. Brackets first, then I'll modify the main beam to get the basic shape, then I'll hang it so that the OEM plastic thingy is usable. After it's tacked up, then I'll work on the sides and then finally the angles on the corners. After that, it will get all the bracing underneath and some testing. Building the Carrier will be last on the list.

How many people have asked Bruce for some measurements of his bumper so they could build one or have one built since he wasn't going to make them available? A BUNCH. Secondly, this week is full for me. I work full time as an engineering project manager currently overseeing about 1/3 of a $72MM expansion project. I also have a home life and a wife and son. My free time is precious and time to play w/ the steel is few and far between. That's why I'm estimating that it will take me the entire month of Nov to get the bumper built. Third, since I don't have time to get started and I want to get some of the details worked out and I have to be on the jobsite, I wanted to figure out some of the geometry of the lines that I want to use. About a month or so ago, I took detailed measurements of the OEM bumper and also took pics w/ the tape measure on the bumper. I'm using those now as go-bys to build the CAD file. The CAD file isn't exact, but it's pretty dang close. I'll work out some stuff around the camfered corners on CAD, plot it out on a 36"x48" sheet of paper and then hang that up in the garage. I can use it for a reference as I build and can make/take notes as I go thru the build process.

My goal isn't to only have a nice bumper for a 3rd gen that compliments the lines of the ARB up front, but I also want to have a CAD file good enough to build them from and have plenty of notes and pics of the buildup in case others are eventually built...

 

I posted that way in part for humor and in part for perspective.

I know a lot of professional fab places that build bumpers for trucks. The vast majority are as CAD clueless as I am. The stuff is built with fancy machines, but ultimately jigs are built because it is by hand.

Most of these places out here would laugh at you if you brought in a CAD file and asked the bumper to be built. If you have the truck and the time, it is SO much easier to build on the rig.

If you match the 100, it will be great. You have the right idea and I am really excited to see what you make. I know there is little time on this, my truck is barely done and I am both single and unprofessional.

Really, good luck. Make something new and different.

 

thanks for the insight. like i said before, critique is welcomed, both good and bad.

i made the cad file cause i could, and to be honest, i'm pretty stoked about the build and want to do SOMETHING on it, and since i'm not going to cut any steel until next week and i've got the time at the desk and the computer, software, and know-how to do it - why not?!?

yeah, taking cad file to a fab shop is overkill, but taking 2 or 3 pics printed off the net or a sketch on a napkin is underkill is some aspects. it will be overdesigned and overbuilt, but that's the idea behind a good bumper, isn't it?

i'll get the cardboard mockup of the sides and corners done by next week and prob spray them w/ some rattle-can so it would be easier to make out the lines.

 

CAD file is updated with a better view of the wireframe. I got rid of the underlying angles so it gives a better "picture" of the shape and feel of what it's going to look like. I also added a profile shot, showing the 1.25"x3/16" angle that is under the rear edge. That also runs (but in a flat profile) under the lower-most part of the wing edges, behind the 3/16" plate. should be VERY stout.

 

Flygt:

can you get me some outer dimensions of the Slee Carrier Hub and Spindle (length and diameter)???

 

The shaft you weld in is 1 3/4" if I remember right, you drill a 1 3/4" hole to mount the spindle shaft in. I used one on the Jeep bumper. That's all I have.

 

i was looking at the pic and used a engineering scale and it appears that the if the spindle truly is 1.75" diameter, then the spindle shaft mounting depth is about 5", the hub diameter appears to be about 3", and about 4" tall.

i'll be trimming the shaft to a total depth of about 3.5-4.0" or so, and welding on the top and bottom....

 

Talk to CDUFF. If anyone can get one he can.


What are the alternatives other than up underneath? (I have grand plans of putting an Econoline tank back there on mine someday)

- Roof - makes rig too top heavy

- Rear - gets caught on ledges, makes it too tail heavy, plus the other issues Steve stated.

- Inside - takes up too much room

- Under - OK if no gas tank in that space and it fits between the frame rails.


So anyway you look at it, there are tradeoffs. What is the least of all the evils?

 

for me (right now) it's to have it hang off the back. i can't give up cargo area, i can't fit it in the garage w/ the spare on top and i don't want it up there anyway, and i want an AUX tank underneath between the frame rails.

 

I wish I had done a CAD file on my bumper, but there will be one made. As soon as I get time, I'll be dropping my bumper off at a manufacturer. They'll make the CAD file, laser cut, bend and weld everything, Since our jobsite got rained out this week, it gave me some time to catch up on a few things around the house. If I'm still off work tomorrow, it goes in to get the measurements done and hopefully by next week I'll have a price for everyone.


bamachem, the box construction of my bumper will have different harmonics, compared to Steve's design and you shouldn't have the highway problems like he did, besides the 3.4L equipped rigs are heavier up front. having the tire hanging out the back does severely change the CG during a steep ascend, especially with the 35's, those things are heavy. That's why I've been slow in making my carrier, I've even thought about building a pull-out rack inside the cargo area to hold the tire upright like the stock H2 carrier.

One of my original design plans was to install a series of urethane bumpstops to prevent contact between the body and bumper. I never did install them, in fact the rubber weather stripping has done an excellent job preventing damage, unlike other designs, where some severe damages has occured. Up travel isn't as much as an issue as the horizontal flex, especially if you have a body lift, this increases the distance sideways. I've experience almost 2" of deflection. If you install stiffer mounts, this will transfer the flexing directly to the body and over time this can cause the joints in the body to crack.

 

good points bruce about the body flex.

i'm updating the CAD now w/ the carrier...

 

CAD file is done.

 

okay, i have been looking for a long time at rear bumper designs and tire carriers, and have been trying to figure out if i which way to go. but like steve says, there is a lot of flex on the rear of the frame and basically some more stress on everything back there. fine. it's only 80 lbs or so but here's my thought...
you are already gonna lose most of your visibility out the rear window, so instead of offsettinng the tire location to the passenger side, center between the two frame rails. this will spread the little extra weight evenly onto both frame rails, rather than putting all of it (or most of it) on the passenger frame rail and nothing on the driver side.

 

I draw everything up in cad because I can and it's also fun and challenging. It also forces you to draw it like you would build it so it can eliminate potention problems you might not have otherwise thought about. It also helps approximate how much steel you need and also the overall weight. Obviously, building in cardboard does a lot of this too. But the main reason I use cad is because I can run finite element analysis backed up with stress calcs done by hand.

What I don't understand is why aren't people who tow a trailer everyday having frame problems? The tongue weight (up to 500lbs per toyota) is much more than the weight of the tire carrier. The fatigue forces from a trailer would be much more too. Toyota had to design for the worst case easily foreseeable scenerio of towing a trailer everyday. If the frames were breaking and the trailers coming loose, toyota would be sued.

Centering the tire could be a solution, but with that comes an increased lever arm on the hinge.

 

I'm more worried about stresses on the spindle and hub than stresses on the frame.

Like Steve said, I'm keeping the moment arm as short as possible - for that reason. I'm not going to center it - the stress on the spindle would increase by an additional 41% if I did.

I did find that I need some more 2x2 tubing and some 1/4" plate now by using CAD. I also was able to effectively design the corners so they look fairly decent. I was planning on using a rounded corner like on Bruce's bumper, but that quickly went out the window once I started CAD-ing the bumper and realized that I'd have a rounded corner directly above a square one - funky looking to say the least.

 

Ever thought about a poison spyder type tire carrier? Keeps it from getting caught up on ledges and deals with a lot of steve's issues. That's the way I'm going to build mine come winter break.

 

like this?



i don't get what's so different...



.

 

They have one that folds down, not across. Looks like a rear stinger.