Plaction wheel shooter?

[Cal578]

Thanks for the answer, Alex. Our shooter has a top speed of 6000 rpm. [Not sure we need to go quite that fast, but if the motors can, we'd better make sure it's safe.] If we change to plaction and use your riveting method, we'll make sure to carefully test up to full speed. I'd be worried about the centrifugal force focused on the relatively small area of rivets.

Has anyone tried some kind of glue for holding the tread on the wheel at high speeds? Then all the centrifugal force is spread along the entire circumference of the wheel. Repair and replacement might be difficult, and I'd still be a little concerned about the disc contacting the ends of the tread (that may focus a little more shear force there). If anyone has experience (good or bad) with that, I'd like to hear about it and learn from you.

[commodoredl]

Originally Posted by Cal578

Has anyone tried some kind of glue for holding the tread on the wheel at high speeds? Then all the centrifugal force is spread along the entire circumference of the wheel. Repair and replacement might be difficult, and I'd still be a little concerned about the disc contacting the ends of the tread (that may focus a little more shear force there). If anyone has experience (good or bad) with that, I'd like to hear about it and learn from you.

Be careful with some adhesives on the plaction wheels as they could break the wheels with the wrong chemical combination. In particular, Loctite will crack plactions fairly quickly.

[yarb65]

Our team has always used double stick tape, instead of adhesive and then revit the tread to the wheel. Have never lost a tread, even when all the side wall of the plaction was all broke off.

[ksafin]

Originally Posted by jkessler_22

Our team was using a Plaction wheel until the tread separated at the stapled connection and gave one of the mentors a pretty nasty "rug burn". We went to the pneumatic wheels and balanced them initially by adding 0.75 oz of automotive stick-on weights (Harbor Freight has them) to the opening in the hub directly across from the valve. That seemed to work much more smoothly, but we will probably try to fine tune the balance before competition.

Where exactly did you add the weights?

When you say opening across from the valve stem, does that mean on top of the hub, or in between the spokes?

[Jay O'Donnell]

My team made our prototype shooter with plaction wheels, and then switched over to the AM pneumatic wheels. The plactions work fine for short to mid range shooting, depending on how you use them.

[jkessler_22]

Originally Posted by ksafin

Where exactly did you add the weights?

When you say opening across from the valve stem, does that mean on top of the hub, or in between the spokes?

We placed them between the plastic spokes. The opening was fairly generous for the size of the weights. The weights I had were about 0.75" x 1.0 " and weighed 0.5 oz each. I cut one in half, stuck it to the top of another full 0.5 oz weight, then put them between the spokes.

To determine how far out of balance they were initially, we put an 8 mm shaft through our hub and supported it with two metal 12 inch rulers on edge. If we rotated the tire so that the valve was 'up', it quickly spun so that the valve was 'down'. We added one 0.5 oz weight, which made it spin much more slowly, but still settled into a valve 'down' position. We played with the amount of weight to find a point where the wheel could be placed in virtually any rotational position and it would stay there. That weight came out to be a total of 0.75 oz in our case, but could differ depending on what wheel/tire combination you are using.

The decrease in vibration was dramatic when we were done.