# PVC Roller Dilemma

We have run into quite a bump in the road… our original plan was to epoxy a 3 Inch ID piece of PVC (OD 1/8-1/4 inch) to the KOP Keyang Hub, thus being able to drive the roller with a keyang.
Unfortunately, the epoxy did not hold up at all.
We have resorted to attaching a wooden cylinder to the hub using screws, and now intend the attach the PVC to the wood using more screws.
Do you think this will hold, if not, do you have any other ideas for quick fix solutions?
Also, would a keyang turning at 80 RPM free speed be fast enough to expel orbit balls out of a hopper into a trailer from a very short distance?

if a keyang isn’t fast enough, should we use a CIM? If so, do you think driving a keyed shaft connected to a hub with a piece of PVC (that conforms to the size of the shaft) set screwed to the shaft be adequate and sturdy?
Hmm, mounting an ID 3" PVC roller to a CIM would be difficult right? Any suggestions…

Thanks

Sincerely,

My Team Procrastinates and Changes Our Minds Frequently

I’ll answer the second question first…

I don’t think running direct off of the keyang will give you enough velocity. Assume it runs pretty close to no-load speed (probably a pretty good assumption for what you’re doing). Then the maximum velocity you can impart to the ball from the PVC is 80 rev/min * (pi*3.25) in/rev * 1min/60 sec = 13.6 in/sec. The rest is a projectile problem; horizontal distance traveled (X) is 13.6 * t, and vertical drop (Y) is (1/2)gt^2, so your vertical drop is (1/2)386.4 in/sec^2(X/13.6 sec)^2. That makes your vertical drop roughly equal to the horizontal distance squared, so if you are 6 inches away the ball will drop 36 inches. Note that just by changing the gear reduction to 2:1your drop will be only 9 inches.

As far as mounting the to keyang coupler, if you are using PVC you could use a PVC Cap and use the 4 existing holes to bolt through. Otherwise I think the wooden plug should work OK as long as there isn’t too much slop in it; wood tends to tear up with cyclic loading.

Some ABS and PVC caps are flat, most are rounded. We found one store in town that sells the flat type, we’re using them for all our rollers.

So you are epoxying the hub to the flat piece of PVC? or just putting in some screws through the hub into the flat piece of PVC?

Also, did you PVC cement the flat piece to your roller?

Thank you

Do you have a globe of FP motor left to use? Both can be sped up by removing stages of the gearboxes.

Or you can increase the speed with sprockets & chain.

We didn’t use the window motors, we used chain to drive the rollers, so we bolted a sprocket to the ABS end cap. You could bolt the window motor coupler to the flat end cap.

Also, did you PVC cement the flat piece to your roller?

We used small wood screws to attach the end caps to the roller, so it could be taken apart later if needed.

We’re using 3 and 6 inch pvc pipe rollers. The 6 inch has wooden plugs with the adapters driven by the keyang window motors. It woorks fine. On the 3 inch we use pressure test plugs and replace the 3/8 inch bolts with threaded rod as an axle. One of the Gates pulleys is then attached to the 3/8 axle and driven by a Globe motor using another pulley and belt. We’re using this roller for ball pickup and it’s working great.