Paging Engineers or People Familiar with Aluminum & HDPE

[aepeak]

If you are willing to act as a mentor for a few simple questions regarding the construction of a Remotely Operated Vehicle for my HS Systems Engineering II class, please send a PM or reply via a PM (for any simple suggestions or questions regarding the project, you can reply via email. but i need the email-ish format for my teachers.

Background:
constructing a Remotely Operated Vehicle (ROV)
assigned to construct the vehicle structure
the vehicle structure is mainly being constructed from aluminum and HDPE

Questions:
What welding technique is required for 5052-H32 aluminum sheet (36 inches x 36 inches, 0.05 inches thickness? TIG welding or MIG welding

How can I water/pressure seal the edges of the aluminum? epoxy

How can I cut the aluminum sheet effectively? band saw

How can I bend the aluminum sheet to form edges?

How can I attach the aluminum body to the High Density Polyethlyene (HDPE) skids? fasteners

What type of fasteners (like screws) can be used to attach aluminum to HDPE? Note: the HDPE is ideally 1 inch in thickness, but I can order 1.25 inch thick HDPE?

I have attached a picture of the proposed ROV design.

[The Reverend Floater]

PM Rontele. He builds this shit for NASA or CASA or MASA...can't remember.

[DoWork]

Try to make the aluminum from all one piece and bend on a brake to reduce the amount of weld points.

Can we get another 3D view of the bottom?

Is this thing supposed to hold pressure??? Why and to what degree/threshold are you sealing edges for water and do you have to be able to open it up again??

I used to have to weld deep-drawn aluminum control boxes for helicopter electronics with .040 wall with no burn through in a TIG, but the right MIG will get the job done too.


For attaching to HDPE, you could use rivets, but the oles will weaken the overall structure- not sure if that matters, but there it is. Otherwise, you could make the legs from aluminum too, weld the whole thing and say fuck the plastic, which is what I say all the time, Plastic is for Legos.

Give some more details and I'll do what I can to help you on your way, but just a heads up I won't be back in civilization until monday, maybe tuesday. Just please don't call me a mentor. It makes me sound too distinctive.

[pointemstraight]

If you have a metal shear available to you, that will cut aluminum sheet far better than a bandsaw will (far cleaner edge, etc). A press brake for bending is ideal - if you don't have that available in your shop, call a local sheet metal working shop in your area and see if they might help you out based on your student status.

[splat]

Even sleds have gone hi-tech?

Or is that a hifalootin kegerator that has taken the place of the Saint Bernard?

[aepeak]

more reliable background. (this is the ROV competition website that the school competes in) http://www.materover.org/main/ (its a remotely operated underwater vehicle.)

http://www.seabotix.com/products/vlbv950.htm

i am sort of basing my design off of this company's idea of using skids, because we need to use hydrophones and thermometers to take measurements

basically the class consists of one project - the capstone design project, where we combine our knowledge and experience from 'technology and problem solving' class from 9th grade, 'AutoCAD' from 10th grade, and 'Sys. Engineering I' from 11th grade. however, we are required to use a mentor, so i ask this community for more help beyond my mentor, because i know there are some engineering majors in the group. any suggestions help. really just trying to gather as much advice, because i need to fill out mentor contacts for tuesday.

@ 'The Reverend Floater' thanks.

@ 'DoWork' much appreciated advice. i plan on bending it by creating a net initially. so i will go ahead with bending the aluminum with a brake. sorry but i am not handy at all. my dad does not touch anything, so I am slowly picking up on stuff in school.

http://www.mathsisfun.com/cube.html

unfortunately, i am not at school anymore (where the drawings are). 3rd point - air tight (ballast for buoyancy); the ROV will be at a max of 4 meters underwater (chlorinated indoor pool). and no i don't have to open the aluminum body up once its welded. thanks for the knowledge about the welds holding up and the advice on the rivets. it should not matter, but i truthfully don't know. i was thinking screws but i didn't know what screws would work best with hdpe (i'm afraid of splintering). the HDPE will be made from 1 inch thick HDPE. if i go the screw route, any suggestions on screws that can drill into 1 inch thick HDPE. i would love to make it all aluminum but i need the skids to provide a stable platform.

@ 'pointemstraight' thanks. i will test the aluminum with both approaches at first. and are you referring to snips or actually metal shears. i know we have snips because i had to help a classmate cut slotted aluminum with snips, but i will have to ask the teacher about metal shears. and i'll look into the brake.

lastly, my blog for additional information that includes lead up background, the problem, some more drawings (but basically the same view). maybe the description of the alternate solutions could help.

http://se2aengrov.blogspot.com/

also the competition website might help.

[farmer]

I'd use 2 pieces of al, bent to shape. one for the bottom, front and back. The other for the top and remaining 2 sides. I prefer TIG for al, but like dowork said, MIG will do as well.

and fuck the plastic. Use square pipe instead. It looks and works better.

[aepeak]

@ 'farmer' thanks. and i assume you mean use metal square pipes, because you say fuck plastic. i should look into aluminum square pipes, correct, because it would be easier to weld aluminum to aluminum?

something like this: http://www.mcmaster.com/#aluminum-bars/=akuhmc

[The Reverend Floater]

My work here is done.

[slim]

PM Rontele. He builds this shit for NASA or CASA or MASA...can't remember.

It's NAMBLA.

[aepeak]

update:



ROV Summary

As the ROV is being employed for scientific research, the small platform affords a well-rounded system that provides a combination of performance, maneuverability, and stability. As displayed by the renderings, the platform is achieved by separating the vehicle structure system into two elemental components – the body and the skid.







The aluminum body is a trapezoidal prism that is ten inches wide and five inches high. The two base lengths are fifteen inches and twelve inches. Accordingly, the body’s volume is 675 cubic inches or 0.390 cubic feet that delivers a neutrally buoyant system, which is the body’s fundamental role, as it functions as a ballast tank. The skids, which resemble helicopter skids, extend three inches past the body and are equipped to the body in order to add stability. Additionally, sensors and the manipulator system are placed on the ROV by fastening the instruments to the high density polyethylene (HDPE) skids. Furthermore, an aluminum mounting rack, which is attached to the HDPE skids through rivets, supports the four thruster design. Moreover, the stable platform that stems from the skid enables the ROV to acquire sensor data. Altogether, conscientious attention to design and layout provide a balanced system that should prove effective in the competition.

ROV Specifications
Body
Length: B1 = 15 inches B2 = 12 inches
Width: 10 inches
Height: 5 inches
Skids
Length: 18 inches
Width: 1 inch
Height: 5 inches

at this point, my raw materials are:
Aluminum (Alloy 5052) .050" Thick, 36" X 48"
and
Polyethylene (HDPE) Sheet 1" Thick, 12" X 24"

however, i need verification with supply lists and equipment lists.

currently, my supply lists include:

-sealant for sealing the edges of the aluminum geometric net after welding. the aluminum body needs to be water tight.
recommendations for sealants:
looking at underwater silicone sealant or polyurethane adhesive/sealant for underwater

-mesh abrasive hand pads for deburring the aluminum sheet and HDPE sheet after cutting (Nylon Mesh Abrasive Hand Pad 3M)

is a file needed for deburring the aluminum or HDPE

tool and equipment list:

-snips for cutting the aluminum

-jigsaw for cutting the HDPE

-press brake for bending the aluminum

-TIG welder for welding the aluminum
can i get a breakdown of the necessary supplies or parts to go along with
the TIG welder. currently my list includes tungsten electrode, welding cable,
torch, ground cable, gas regulator and hose, foot-pedal control, power cord,
shielding gas, welding rod.

what diameter electrode do i need to use for 0.05" thick aluminum? what diameter welding rod ...?

-drill for preparing rivets holes

what drill bit is necessary for drilling into 1" thick HDPE? can splintering occur?

-caulk gun for sealing the aluminum body

parts list:

-shank rivet for attaching the aluminum mounting bracket onto the HDPE

-blind rivet for attaching the HDPE skids to the aluminum body

what rivet tool would i use?

is that all? should i reconsider some items? suggestions?

[splat]

Contact Crown Plastics in Harrison, Ohio. They have a division that specializes in bonding HDPE to the hulls of river boats.

[aepeak]

thanks splat. i assume you work with crown plastics because they make the sintered bases for your skis.

[Skipig25]

what drill bit you should use?

dude, this is TGR, just fuckin' giv'r

[DJSapp]

Not to be an idea killer, but if you're going 4 meters down, 0.05" plate AL is going to be CRUSHED by water pressure without building an internal structure to support it. You're talking about building a ROV using sheet metal the thickness of a soda can. I'd suggest upsizing the body and reinforcing it with an HDPE structure on all sides.

Idea #2--fabricate an AL mounting plate with studs on it, mount it to the body, connect via elbow bracket to HDPE skid. Drill & tap HDPE skid, or drill through and bolt.

Idea #3--Can you solder the AL with a good heat gun? If you don't have access to a great welding instructor, or have the experience, you're going to burn holes through all of your stock before you get a good bead on it. My humble experience doing ASCE steel bridge was that anything less that .5" chrome molly steel was best left to the pros. You're 1/10 of that.

Idea #4--The sloped nose isn't doing anything for you, except looking cool and being a pain in the ass. Build a square box, it will be easier and more watertight

Idea #5--If you do go with the box, mount it so your metal bends are on the top, and welds are on the bottom. There will be less risk of leaking, since the air will be trapped.

edit--Crazy idea #6--Don't put a bottom on it whatsoever. Upsize the body slightly to accommodate for water compressing the trapped air at depth to maintain near neutral buoyancy. Think flipping a small garbage can over, mounting skids on the bottom and going for it. COG of the rig will be low, and should resist capsizing. This also solves your mounting issues and internal bracing issues, but creates a variable buoyancy issue. It may not sink below the surface, or it may not come up.

[Marius Titulescu]

thanks splat. i assume you work with crown plastics because they make the sintered bases for your skis.

He does have awesome skills, right?!