pic: 1726 week 4

[MrForbes]

or, the short answer: we had the pultruded fiberglass channel for the frame already, but no thin angle, so we went with aluminum. Also the aluminum is available at Ace hardware, and easy to replace if it we have problems with it in competition.

[CCCP]

our bot is so cool

[BHS_STopping]

Originally Posted by CCCP

our bot is so cool

I'm sure the rest of the team is proud of it too, Stan.

[Amir]

Is the tensioner an off the shelf item or machined from a piece of round stock? If it is off the shelf where did you get it? If not what material is it, HMWPE or Nylon? We are looking for a new/easier tensioning system and we have been leaning toward the off-center circle. I would also like to know what materials work best for this method.

Thanks,

Amir

[MrForbes]

We made the green tensioners with oil impregnated nylon rod (2" diameter), turned on the lathe.

The white material (UHMW Polyethylene) that the chain guide is made of would work well too, I suppose...we had the nylon rod left over from last year, so we made the tensioners with it.

Also we added an internal/external tooth lockwasher between the tensioner and frame rail to make sure it would not slip.

[GUI]

Nevermind, Mr. Forbes beat me to it!

[Matt H.]

The tensioner is nylon because it tends to self lubricate as it wears away. The piece was machined on a lathe--it was simply a matter of cutting away a little from each side of a thin piece leaving a small runner to guide the chain (you could also cut a groove)--I'll see if I can get some more detailed picture later.

We have been using nylon for tensioners since last year and have little visible wear on it even after two regionals.

[Amir]

We have used the nylon spring-loaded ones from McMaster and it is kind of clunky and hard to incorporate into the chassis.

Can you tell me which nylon round stock you used? I don't need a picture but others may benefit from one.

Thanks

Amir

[GUI]

I believe it was McMaster part # 8664K15

[Matt H.]

Do a mcmaster search for oil-filled nylon rods I believe we used either the 1 1/2in or the 2 in rod.

[Amir]

Do you know if the oil-filled nylon is better than the oil-filled UHMWPE, part number 5243T23? The reason I ask is that the chain guides you are using are made from UHMWPE not nylon.

[GUI]

Originally Posted by Amir

Do you know if the oil-filled nylon is better than the oil-filled UHMWPE, part number 5243T23? The reason I ask is that the chain guides you are using are made from UHMWPE not nylon.

When playing with the chain, the UHMWPE seemed to be a little more slippery. We used the nylon because we already had it, if I was ordering material for the tensioners i would go for the UHMWPE.

[MrForbes]

McMaster part number 8664K15 is enough to last for a few years

[Aren_Hill]

i have to say i do like the pulltrusion shape that easily makes what would've taken multiple pieces of other materials to make. And it would've most likely ended up heavier.

looks like a great drive base, how much did you lower the center wheel?

[GUI]

Center wheel is lowered 1/8"