Mechanical Engineering fab question on my 80 series

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LandCruiserPhil

LandCruiserPhil

Peter Pan Syndrome
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I need to span between the 2nd row grab bars on an 80 series. What shape material offers the most strength considering weight and size.

Im looking to do something along the lines of the picture but Im not limited to round. I can use c-channel, angle iron, square, round, or flat strap mounted on end.

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What kind of weight does it need to hold and what function will it perform? If it's just for hanging some shirts and similar objects I think a 1" .125 wall 6061 aluminum would be more than ample. You're a pretty smart guy Phil, so I'm kinda curious as to why you'd need to ask, are you looking for a materials analysis type response? If so you're going to need to put more information in your post such as length of the span, maximum weight you expect it to hold and function...to say, if it carries some weight it will likely flex while going over bumps and such and fatigue would be a consideration for material.
 
I had a bar like pictured that I carried my uniforms on, and over time it started to bow really bad in the center.
I would think a piece of 1" square or round aluminum would work as long as your not hanging a bunch of full uniforms or suits.
 
I made up a couple of flat bar brackets with an eyelet cut into one end of them.
they sat under one end of the grab handle, and bolted on with the grab handle using 6mm cap screws.
I put a cam lock strap, or ratchet strap been the two and tension it a little, I've done similar in the rear too
I use it to carry a couple of surfboards inside the car, and hang clothes etc on it.

I also hang a little mesh gear hammock in the rear using the same idea

I used a strap because it's easy to remove and fit, and if it breaks, there's no metal pole rattling around in the cab
 
LandCruisinMy93 said:
What kind of weight does it need to hold and what function will it perform? If it's just for hanging some shirts and similar objects I think a 1" .125 wall 6061 aluminum would be more than ample. You're a pretty smart guy Phil, so I'm kinda curious as to why you'd need to ask, are you looking for a materials analysis type response? If so you're going to need to put more information in your post such as length of the span, maximum weight you expect it to hold and function...to say, if it carries some weight it will likely flex while going over bumps and such and fatigue would be a consideration for material.
Click to expand...

Smart guy ....you must be drawing from a small pool:D


Ya more info - I want to run 2 bars? at the top of the ceiling and install/build baskets to hold light dry food goods drivers side, maps in the center, and reading material on the passengers side. I think if I knew would the best horizontal material was I could figure the rest out.
 
If you're looking for flexibility down the road you can fab a bar joist out of two pieces of 1 inch solid aluminum round stock joined together by 1/2 x 1/8 flat stock. The whole joist can be tapered and bracketed at each end. For mounting you can take advantage of the grab bar mounts, and then re-mount the grab bars onto a bracket.

I'm talking a lateral bar joist rather than the typical vertical bar joist you often see used. This would give you multiple points to mount from while maximizing clearance. The sides can be angles up to follow the curve of your roof line. The solid round stock will

Edit: I found plenty of photos of bar joists (I guess engineers call them open web joists), but nothing mounted in the horizontal. I've seen it used on rock bouncers, but can't find an image of it.

If you make this I'll buy it from you. I don't have solid works - I can see it but I can't draw it.
 
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Round will always give you the best overall strength in multiple planes. If you were looking solely at a static load hanging, than yes, vertical strap would work but you will also have some amount of fore and aft load when you brake and accelerate. I would either look at round or square tubing. I think round will look better. Aluminum is light and easy to work with and a 1.25"x0.188" will be plenty for anything you might hang. If you want to go overkill which is pretty normal cruiser fashion go 0.250" wall and never worry about it. You could likely hang from the middle of either.
 
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Basically flat aluminum (hardened to like T6) on a vertical plane would be very strong. From there, structure on the horizontal would support wobble on the horizontal. Not sure what off the shelf shape would be best- angle at the simplest and maybe slotted aluminum extrusion on the fancy end (like the crossbars of a prinsu rack). McMaster Carr has it.
 
What about an overhead roof console?

There's lots of varieties from an overhead centre console, or full width console at the top of the windshield where your sun visors are.
There's a fair bit of room for a console that would fit maps, snacks, glasses, UHF radio etc
 
mudgudgeon said:
What about an overhead roof console?

There's lots of varieties from an overhead centre console, or full width console at the top of the windshield where your sun visors are.
There's a fair bit of room for a console that would fit maps, snacks, glasses, UHF radio etc
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Im too tall for overhead console, hell I take the rear view mirror out everything I own because it blocks my view.;)

The idea started with the need for more food storage. I keep my food inside my passengers door along with my fridge and a small shelf for quick access to food and drink.

I would like to keep the crossbars as small as needed and make them as close to the ceiling as possible. Make the basket removable to keep the second row passenger option open.
 
Can I assume -

Round over square will give the best torsion strength in all directions across the full plane?
Flat strap works well on edge if one can stabilize it front to rear?
The 4 - attachment point of the 2nd row 80 series grab bars should be strong enough?
 
These are all correct.

Not exactly sure I understand what you want but I think it is a shelf suspended above the second row, so using aluminum tubing on the ends with an aluminum sheet between them would net a very strong structure. If you want to get fancy, I would probably use flat aluminum where it bolts to the handles, bend the aluminum so it drops down and gives you a little more room, and use a fairly thick aluminum sheet in the middle to help mitigate the noise of either thin sheet or expanded metal. Weld good solid tie downs on it and you could both hang things from it or strap them on top between the roof and the shelf.

**Edit** saw your post about having a hanging basket that is removable. So forget about the shelf part. Go with a thick wall steel in a thinner diameter.



LandCruiserPhil said:
Can I assume -

Round over square will give the best torsion strength in all directions across the full plane?
Flat strap works well on edge if one can stabilize it front to rear?
The 4 - attachment point of the 2nd row 80 series grab bars should be strong enough?
Click to expand...
 
If you're supporting a full or close to full width basket most of the stress will fall on the basket and outer edges of the supports. Either way, if it's to suspend a basket some 1" OD .125 wall 6061 should be more than sufficient for the job.
 
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With all your input, some weight data and testing I will starting with what I have on the rack and Ill adjusted as needed.:grinpimp:

Weights and measures
Maps 8lbs (Center location)- More weight than I wanted so I will only store the map Im using at the time.:(
Books 7lbs - Im thinking Im OK being on the end but still on the fence if I want that much extra weight.:meh:
Dry food 4lbs estimate - Im OK even if its more because that is the main reason for the mod:)

The total span is ~44" plate to plate using 1.5" x 1.5" alm spacer on ends
Partly because my headliner has more insulation the tubing will only gap <.5" at the center
For the first attempt I will be using 3/4 x .095 tubing. I cut, clamped, and spanned A 48" piece and I think it will be a great starting point.

Total estimated weight

Piping and mounts 7lbs
Baskets 4lbs
Food 5lbs
Map 1lb
Books 3lbs

Estimate total 20lbs - Gross 80 weight will stay the same Im just relocating 20lbs to the roof line:eek:

How much will the relocation of the 20lbs impact my past salmon times?
 
An I-Beam is the best strength to weight for spanning, but has very little torsional stability. This is why the shape is used for bridges.

Round tube gives the best torsional and multi-axis loading stability.

Rectangular tube with the wide flats at the sides would suit your needs pretty well. 0.95" (2.4mm) in a 1"x2"(25mmx50mm) should hold a bit of load. To add strength, add material to the top and bottom.
 
Get a used stripper pole. Functional and aromatic.
 
reconranger said:
Get a used stripper pole. Functional and aromatic.
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Inside naw not into midgets. Now on top of the CampTeq you might have something there, is a fold down version available? Probably the ONLY RTT that could handle a pole and a few strippers with no problem, Ha! What are my height limits for the highway, the top of my 80 is 84" exactly.
 
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