HDPE compared to UHMW for ramping

What do you guys think would make better material for ramps and skirting....

HDPE or UHMW Plastic???

My guess would be HDPE because of the tougher surface but how is the elongation factor compared to UHMW??

What would you use???

While I don't know what you mean by 'skirting' I'm assuming you're talking about a wedge bot and are interested in some materials for the wedge. Personally I would never use plastics in battlebots. Lexan is alright for some not structural or stress free part, but overall plastics are usually a no no.

That being said, in a wedge bot, most would like a strong, light and somewhat slick material to ram their opponents. E2V2 (link below) used a chrome finish on their robot and it was one of the best wedges winning at BotsIQ in 06.

http://www.buildersdb.com/botpics/6429.jpg

Maybe a Ti wedge with a chrome finish might do the trick.

by saying UHMW plastic it kinda throws people who dont know much about it off. As "plastic" its nothing like lexan at all. There have bee several 12/15lb robots that have had UHMW frames sometimes with a thin aluminum to protect with much sucess. It is actually a great material that while very strong and rigid, it can also allow flex and takes hits very well
As for HDPE and its comparison i have no clue :/ I've never even seen any applications of it

SenaiERI wrote:

While I don't know what you mean by 'skirting' I'm assuming you're talking about a wedge bot and are interested in some materials for the wedge. Personally I would never use plastics in battlebots. Lexan is alright for some not structural or stress free part, but overall plastics are usually a no no.

That being said, in a wedge bot, most would like a strong, light and somewhat slick material to ram their opponents. E2V2 (link below) used a chrome finish on their robot and it was one of the best wedges winning at BotsIQ in 06.

http://www.buildersdb.com/botpics/6429.jpg

Maybe a Ti wedge with a chrome finish might do the trick.

e2v2 used stainless steel, not ti for the wedge thats why it was so shiny

Cody Harris wrote:

by saying UHMW plastic it kinda throws people who dont know much about it off. As "plastic" its nothing like lexan at all. There have bee several 12/15lb robots that have had UHMW frames sometimes with a thin aluminum to protect with much sucess. It is actually a great material that while very strong and rigid, it can also allow flex and takes hits very well
As for HDPE and its comparison i have no clue :/ I've never even seen any applications of it

I'd like to see Sting and/or It Stings get some hits in on a uhmw bot clad with alu...and see how well it holds up.....

I predict BIG teeth marks....lol maybe we need a small nozzle spraying cutting oil to keep the teeth sharp..where's Josh when you need him???

but i could be wrong...I mostly am...

your in luck.... scurrie

donsun wrote:

e2v2 used stainless steel, not ti for the wedge thats why it was so shiny

It might have been stainless but I'm pretty sure it had a chrome finish on it. All the polish in the world couldn't make stainless that shiny.

Cody Harris wrote:

your in luck.... scurrie

Maybe Josh is in luck...I'll be playing ground and pound and hit the ceiling with the wedge bots

SenaiERI wrote:

donsun wrote:

e2v2 used stainless steel, not ti for the wedge thats why it was so shiny

It might have been stainless but I'm pretty sure it had a chrome finish on it. All the polish in the world couldn't make stainless that shiny.

we have some stainless pieces that buffed to a mirror easily...but we don't use them anymore...lol

he went to bergen. theres enough polish for anything anymore
Shelby GR-1

Cody Harris wrote:

he went to bergen. theres enough polish for anything anymore
Shelby GR-1

You Ford guys are killing me...

you have a mazda!!!!!! lol

Cody Harris wrote:

you have a mazda!!!!!! lol

that's true....lol

Sold both vettes.....

Holy shiznit...does that mean I'm a ford guy now? ouch.....

Stainless will polish, if you put a lot of time into it. Basically you have to do the whole wet-sanding deal, then the multiple passes of super-fine polish. It would probably take two or three days of solid work to get a single plate on E2V2 polished to the point of being a mirror, but it's doable.

Jeff L wrote:

Stainless will polish, if you put a lot of time into it. Basically you have to do the whole wet-sanding deal, then the multiple passes of super-fine polish. It would probably take two or three days of solid work to get a single plate on E2V2 polished to the point of being a mirror, but it's doable.

I buffed a rattler shovel ...no sanding, just a bit of compound, and it turned into a miorror in under 5 minutes....Isaw it today , lying around at mlec...I'll try to remember to take a picture....but the buffing won;t stop the stainless from bending like a pretzel...first hit...lol

Anyone ever see UMHW clad with something tougher than Al? Like spring steel maybe?

Just wondering, 'cuz we had a bot with a Al frame, a layer of soft rubber, and a thin layer of spring steel. (It's all rusty now) that could REALLY take a hit. It was a 15lber, but it got hit by Blender and there were no marks. It got hits from Woodynator that did almost nothing to the armor/frame. One of MLEC/Team Jag/rjw's group's drums did manage to split a bit of the spring steel where it was cantilevered and unsupported, but really that's all. I've hit it HARD with a 20oz hammer and nothing showed.

Kinda like the chrome, the spring steel has a hard 'slick' surface, but it also can be flexed like crazy without bending or breaking (high elastic deformation, low plastic deformation). If this could be coupled with a lightweight but also 'energy absorbing' material for the frame it might be well nigh indestructible, but very lightweight and relatively cheap. (but a pain in the butt to machine--you gotta grind spring steel)

Hdpe is structurally more rigid and holds its shape better after machining than uhmw. Its not as impact resistant or as slippery as uhmw. On the other hand uhmw is the most impact resistant thermo plastic which also makes it hard to machine cleanly. You usually end up with whiskers and fuzzies on the edges. Screw heads dent into or pull through uhmw more easily than in hdpe.

My dad uses hdpe for deck plates and work surfaces on machines and sometimes chunky brackets or braces, and use uhmw for skids, wear pads, chutes, guides, diverters, etc.

We've been talking about using uhmw clad with stainless or spring steel, because you get the toughness of uhmw with the hardness of its coating. try as you might, you WILL NOT BREAK something made out of uhmw. It will deform and bend, but it won't break. Couple that with an outer skin that's so hard nothing's gonna get a bite on it, and you've got the best of both worlds. It's not done all that often though, and I don't know why...

What was the thickness of the spring steel on trianglebot? 1/16"?

Yes, Jeff, I believe it was 1/16, or some decimal value close to. Will Bales was the one who ordered it from Mead Metals, I think.

I probably should also mention that in addition to being difficult to cut, and impossible to shape, it can also cut the crap out of you.

rjw wrote:

Jeff L wrote:

Stainless will polish, if you put a lot of time into it. Basically you have to do the whole wet-sanding deal, then the multiple passes of super-fine polish. It would probably take two or three days of solid work to get a single plate on E2V2 polished to the point of being a mirror, but it's doable.

I buffed a rattler shovel ...no sanding, just a bit of compound, and it turned into a miorror in under 5 minutes....Isaw it today , lying around at mlec...I'll try to remember to take a picture....but the buffing won;t stop the stainless from bending like a pretzel...first hit...lol

yea, all it took was buffing the exterior of the bot for like half an hour and it got pretty shiny. sorry for jacking the thread with all this shiny metal talk

Dan Curhan wrote:

Hdpe is structurally more rigid and holds its shape better after machining than uhmw. Its not as impact resistant or as slippery as uhmw. On the other hand uhmw is the most impact resistant thermo plastic which also makes it hard to machine cleanly. You usually end up with whiskers and fuzzies on the edges. Screw heads dent into or pull through uhmw more easily than in hdpe.

My dad uses hdpe for deck plates and work surfaces on machines and sometimes chunky brackets or braces, and use uhmw for skids, wear pads, chutes, guides, diverters, etc.

We've been talking about using uhmw clad with stainless or spring steel, because you get the toughness of uhmw with the hardness of its coating. try as you might, you WILL NOT BREAK something made out of uhmw. It will deform and bend, but it won't break. Couple that with an outer skin that's so hard nothing's gonna get a bite on it, and you've got the best of both worlds. It's not done all that often though, and I don't know why...

Sooon.