PVC Rollers?
 

I've asked this before on the forum last build season, and absolutely no one replied :(

So I've come to ask it again.

Can anyone link me or show me where to get PVC rollers for conveyor systems utilizing polycord?

Last year we were so misguided we ended up buying those foam rollers (the ones used for exercise).

Thanks in advance.

Re: PVC Rollers?
 

I'm not sure what foam rollers you speak of, but a lot of teams just purchase PVC from Home Depot or a similar store for their rollers. It is just pvc tubing that teams can machine grooves into or put rings around the PVC pipe to capture the polycord in place, but it is nothing special.

Other teams use other materials for their tubing: aluminum, acetal, polycarbonate, etc.

Re: PVC Rollers?
 

I don't have a picture on me, but for some of the bots I saw, the grooves were HUGE and DEEP.

Like, anywhere from 1/4" to 1/2" deep. I haven't seen PVC with a wall that thick, unless they were using a bunch of small segments of PVC connected by some sort of fittings to simulate grooves.

Re: PVC Rollers?
 

I've seen more ABS rollers than PVC. ABS plastic is more appropriate for this type of application (less shatter-y, rougher surface finish), and generally comes in thicker walls, which can be machined. However, it can be much easier to add grooves onto the surface of a roller than cut them into it. The solution can be as simple as a couple of donuts cut from plate stock and epoxied to the surface of the roller.

Re: PVC Rollers?
 

McMaster catalog page

There are a variety of sizes and material options. Take a look around McMaster or Grainger searching for 'Conveyor rollers' and you'll turn up some more.

For what it's worth, 95 used some rollers from McMaster last season and they worked out alright. We ran actual conveyor belting around them. Our early tests using polycord was suggesting it was going to be more trouble keeping them on track then it was worth in weight savings.

Re: PVC Rollers?
 

On 330 we just cut thin sections of PVC pipe and then make a slit in the resulting ring. The sections are then glued to the main roller on either side of the spot where you want the belt to be using PVC cement. Simple, effective, and cheap

Re: PVC Rollers?
 

We prototype using PVC with wood plugs in the ends and 1/4 20 bolts sticking out long enough to put electric hand-drills on for proto-power...

On production, we use hollow aluminum tube with Nylon plugs in the ends and we press aluminum shafts in, spinning on lubricant-infused bushings.. I think going forward we'll skip the bushings and use sealed-bearings if weight/cost isn't an issue.

As for keeping Polycords in-place... we abide by the 148 Robowranglers credo... "IF gum-rubber isn't the answer, THEN you're asking the wrong question..."

LOL

SERIOUSLY, the black gum-rubber works _great_ creating channels and looks _awesome_!! < some scrolling pictures www.broncbotz.com > You need to apply at least TWO layers and super-glue each layer...

From McMaster:

4568T18 Architectural Anodized Aluminum (alloy 6063), Tube, .065" Wall Thk, 1-1/2" Od, 1.370" Id, 6' L
93625K58 Natural Gum Foam, Adhesive-backed, 1/8" Thick, 1-1/2" Width, 50' L
8541K56 3 Ft. Wear-resistant Black Nylon Rod, 1-3/8" Diameter

Re: PVC Rollers?
 

We machined them from 2" delrin round stock. Very simple to do.

Re: PVC Rollers?
 

We did the same.. expect out of 1.25 billet 6061.

Re: PVC Rollers?
 

This is exactly what we did as well, but with Polycarb tubing. It requires no machining time other than a bandsaw and provides the same function.

Re: PVC Rollers?
 

Do you do anything to fill the gap that spreading the ring makes? We did this method one year, and it worked, but looks left more than a bit to be desired.

Re: PVC Rollers?
 

'Tis just standard PVC and end caps (obviously drilled into them for the axle) purchased at the local home depot. The rings around the PVC that keep the polycord in place are just strips of another pipe of a slightly wider diameter (It may even be a end cap that we chopped up and slid on, I don't remember exactly).

Re: PVC Rollers?
 

It's great to mention and bring up in this topic regarding what materials you should use for your rollers. Everyone knows a combination of ABS, Delrin, Aluminum, PVC, ect. Another one to throw in there is wood and 1114 used it effectively this year on their intake. It's just a great thing to remember that some of the most "effective" components of a system may just be in a scrap pile in your high schools woodshop. :)

Re: PVC Rollers?
 

If you're specifically interested to machine a roller from PVC then you might try schedule 80. It's thicker than Schedule 40 and usually dark grey.

McMaster sells it.

We have used it in the past with polycord. It worked well.

Re: PVC Rollers?
 

I ADDED to my above post the materials we use purchased from McMaster.com

Hope this is helpful...