Lightweight Skid Plate Ideas...

I don't recall the thread, but someone posted ideas for a laminated skid plate last week, and I said I'd beat it around with my Materials & Processes teacher - as well as my return idea about the wriggly tin between the lightweight plates.

It was decided that the laminate/weld idea wasn't going to fly - for the reasons I stated.

My idea wouldn't work - after the first hit. The "column strength" that would be gained from the compressed wriggly tin is fine - until the panel gets deformed. Since the strength element can't recover its original shape, the strength is lost.

The "crux of the biscuit" is that the strength member won't recover its original shape after taking a hit

Alternate Plan #1 - Similar idea, different strength member. Get some of the rubber "drainage" work mat (with all the holes,) and put that between two 1/8" or so steel plates. Use bushings to prevent seriously compressing the strength member, and bolt together (or retain with the mounting bolts, along with others at intervals.) Paint fully prior to assembly.

Alternate Plan #2 - Aluminum. Since aluminum carries about 1/3 the weight of steel, go with an aluminum plate the same thickness or greater. A 1/2" aluminum plate will mass about half that of a 3/8" steel plate, will be easier to fabricate and work, can be bent readily using a torch and some sort of form, and won't rust. Check around for dealers in scrap and rems to find usable sections.

This is, of course, predicated on reducing the weight of the mod - I can understand that, 3/8" steel is heavy! I may do the aluminum myself once I get a few other things done...

I didn't put this in Fab Tech because it just didn't seem worthy... But, it IS a modifications, so I wound up here.

Anyone else care to weigh in - on either plan?

5-90

a lot of comp and trail buggies these days are using high density platics for skid plates, it seems to work real well and slide off the rocks nicely. If weight is the primary concern, you can probably make a skid just as light as platic or aluminum while still using steel if you invest some time in engineering it better.

Yeah - I'm still running on the KISS principle - I can see the idea of using HD plastics or some composites (we talked about it, actually,) but the guiding idea was to make it something that could be done without a plastics shop, or would require a minimum of equipment (hobbyist friendly.)

That, and I don't have enough knowledge of plastics to design a plastic skidplate - gimme about five years (once I've finished my three degrees at De Anza and get through more of my engineering courses...)

5-90

just order some UHMW plastic sheet from McMasterCarr, different thicknesses depending on how much support you have behind it, and bolt it up with countersunk bolts...

How well does UHMW work for hardness? That seems to be the key issue - resistance to penetration by outside objects. Maybe light steel backed with UHMW would work - but it seems to me like it would take about an inch and a half of hte stuff to be really useful - but I could be wrong. I never had much faith in plastic...

5-90

i have no personal expereince, i like 1/4" steel myself, but there has been tons of talk of platics on PBB. everyone using them seems to be real happy, but they do need replacing (from gouges) after a lot of use.

Yeah - it seems to me like a plastic plate would really get, er, "eroded" quickly - another reason to use aluminum (abrasion resistance, related to hardness.)

I'd also prefer to not have to replace the thing every year - but it's still an idea. I think I'd have to figure some relative densities and see what it would take to make it solid.

Still - what would you think about the idea of bonding a steel plate (1/16", probably) to about a half-inch of UHMW?

5-90

If the plastic gets gouged easily,why not put rubber over it(which would probably create friction,not good)........maybe used tire strips riveted to the plastic??Or a little aluminum.Just an idea,though.I still favor steel,but on the other hand people used to favor public drinking fountains untill people started getting deathly ill....then we invented indoor plumbing.

Aluminium gouges just as much as plastic. Now if you want lighter than steel, stronger, and more resilent to gouging, titanium is the way to go. However the cost would be shall we say a tad high.

As for plastic, I make the plastic sheets that everybody is talking about. UHMW is very resistant to gouging. In Fact some of the sheets we make are used for liners in the back of dump trucks. It comes in many colors and even oil filed plastic. We make sheets from 1/4" thick to 4" thick and either 8', 10', 12' lengths. We even make sheets with embedded expanded metal.

Some of the plastics can be welded. The only problem I see with using plastic is the cost. All that can say is that some of the stuff is not cheap. It is much lighter than aluminum or steel a 1x4x10 sheet weighs 232 lbs.

I am going to be using some as rock sliders and maybe a lining over an engine skid. The plastic is tough and slicker than snake snot.

If anybody wants more info on the UHMW let me know and I can get some spec sheets and post or send through email.

One of the editors for Peterson's used cutting board material from a cabinet shop. Seems like this would be pretty resistant to scratching/gouges. This may be the same material you all are reffering to (UHMW), but you may be able to find it pretty easy this way.

Hit the submarine junkyard for cheap titanium. The stuff that was nearest the reactor is the best.......

I have designed a boatload of industrial automation using UHMW and I will attest to it's wear resistance. I prefer it to Aluminum for wear. There are a few problems though...

You cannot bend it.
It is very expensive.
While it works great for a wear material, it isn't very rigid. If you were to cover a large span, like frame rail to rail, it would have to either be ~1" thick or thicker, or be backed with an aluminum/steel backbone.

So are you really gaining anything by using plastic? By the time you go thick enough, you are equivalent weight to steel. And you will spend A LOT more on quality UHMW than you will on steel or aluminum.

It's great stuff, but like everything else it's not perfect.

BTW, UHMW stands for Ultra High Molecular Weight, fyi.

HTH

I have a 1/4" sheet of uhmw that I have been using as a hard flat surface for jacking while in I'm the sand. In the near future it's going to be used on several of my skids. It's supposed to be almost as slick as teflon. If that material can stand up to being a cutting board it should do decent on rocks. Am I worried about it getting scratched? Well not really cause skids are there to protect the vitals. The plastic is a little on the bendable side so it would be a good idea to back it with some steel. I plan on trying it with some steel grating that is used on like campfires/grills (has the diamond shaped holes).

CRASH said:

Hit the submarine junkyard for cheap titanium. The stuff that was nearest the reactor is the best.......

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Ha! I live near Portsmouth Naval Shipyard, maybe I can supply some slightly used titanium. Just think, you wouldn't need trail lights either, your new skid plates would glow enough by themselves.

Has anyone tried a product called "Starboard"? It is sold for boat deck panels, cuts like plywood, never rots, and is very durable. I think it might work, but anything sold in a marina is, by default, expensive.

Why not use a plywood backing with a thin steel skin so that it will slide over things. You should should also build your long arms out of an australian birch. With a nice layer of thompsons weater sealer, those arms will stay beautiful for years to come.


:hang: Sorry, had to suggest it. I've seen that skid done on some redneck mobile back east. No joke.

On a serious note, why does the steel have to be thick? Would a stiff skeleton with say .120 or maybe .188 thick plate still be lighter than just .250 by itself? For me, The only thing I ever touch is the xmember right in the dead center. All I want to make is a skid maybe 12" wide that spans between the frame right where the xmem is and gets under the TC where it's lowest. If I were to get up in there somewhere else, I'd have other problems like grenaded drivelines. I don't like those big belly pans that many have made in the past that are 3' deep. I'm going to stick with steel.

I think some guys are using thinner steel for the skid and then putting the plastic over top of it.Here is a place that sells the material www.cuttingboardfactory.com

TrailHunter said:

On a serious note, why does the steel have to be thick? Would a stiff skeleton with say .120 or maybe .188 thick plate still be lighter than just .250 by itself?

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It doesn't and yes.

A well thought out skid with gussets and braces in the right spots will be stronger and lighter than a thicker plain piece.

The problem is fitting all the gussets and braces where you want them. Plus it's much easier to just use larger material and less thought/work.

ok guys basicly youve all surpassed me by far in knowledge about this stuff, so I had an Idea id like to pass by you all.....

1/8th inch aluminum spanning rail to rail bent at ends bolting to outer side of rails. on top of said aluminum using 3/4 inch square tube to cross the span and provide virtical suppor to body and retain critical area clearances (tc, oil pan, tranny, drive shafts etc) clad the whole thing except attachment points and access holes with 1/8th steel thats riveted to the whole structure.

now my idea on the aluminum is its light and fairly easy to work with for making the bent tabs for attachment and general shaping and not so much for structural strenght.

attaching on frame rails to protect the bolts and keep in a easy to access place if you need to make repairs to underlieing equipment

square tube adds regidity and structural attributes (maybe c-channel would be better but i can get the square tube cheap)

steel skin adds protection from puncture and a replacement without scrapping the whole unit.

total weight should be minimal using basic materials and clearance shouldnt be effected any more than by using a stock tcase skid

Feel free to shoot my idea full of holes ill enjoy the feedback. Im a noob to fabrication but its what ive been able to come up with. maybe some one has done this already and can let me know how thiers turned out

I believe Jon (Kaczman on the board here) is using UHMW for his boatsides. super simple to install and it takes a serious beating. instead of hanging on stuff, it pretty much slide him off of whatever. I have another buddy that used it for his boatsides on his YJ... he spent right around $60 for it and spent the next month beating the living hell out of it (almost daily) trying to tear it off or damage it... 2 years later and he's still running his original set of plastics.

I can't remember what Jon is using but my other buddy is using recessed allen head bolts to hold it into his tapped 3/16" crossbracing.