Competition legal alternative to tank-tread paddles

After running out of tank-tread paddles I have been investigating alternatives, these polycarbonate replicas are VEX competition legal, easy to make and above all work very well.

These are really easy to make;

  1. Cut polycarbonate to desired size.
  2. Clamp in vice with 2-3mm out the top.
  3. Run 4 cuts vertically into the plastic.
  4. Bend tabs over with a hammer, alternating sides.
  5. hammer tabs flat to vice to produce clean 90 degree corners.
  6. trim tabs to fit into slots in the tank-tread flap holders.

Use cable ties to prevent the flaps from sliding sideways out of the holder.

Does this mean Massey is building a robot at the moment… I am very VERY scared… No doubt it will be exactly like everyone else’s, except way different, and of course infinitely better =P

Edit: Oh by the way, forgot to mention, cool trick, I might try this sometime soon. Is it difficult to put the polycarb attachments into the chain links? Like, do you have to push really hard or not? Also, wouldnt these be far less grippy than the normal ones? Unless you say… coated them in grip mat? =P

Basically once you have hammered the tabs flat to the vice run a knife down each side to trim them back so that they are a firm fit in the chain links, I just eye-balled it. The tabs are just to keep the paddles vertical, the zip-ties take most of the stress.

This is a great suggestion for teams who don’t want to use the tank-tread flaps. Thanks for sharing…


Great suggestion. Is it valid though?

or if you dont have the paddle kit to begin with (and dont have the slotted tank treads), you can bend the whole bottom piece of lexan like an “L” shape
then just drill two holes and screw them onto the grey tank treads with holes you see in the pic

just an update, we tried using some form of “lexan flaps” and they were wayyy too stiff
the objects/whatever you are trying to do, will just get stuck
the flaps are around 10 times more flexible than the lexan…

we ended up using zipties and anti-slip mats

What thickness polycarbonate were you using?

You can always try thinner plastic & longer flaps.

we used the standard legal thickness
we didnt try to sand them down thinner though
it would be interesting so see if it would bend more or just snap off

I imagine 0.20 polycarb would be MUCH better suited to the flexability that tread flaps require. 1/16 is pretty solid stuff. Fortunatly, 0.20 is sold pretty much anywhere you could get 0.64. I also bet that with some clever use of surgical tubing you could make them quite grippy.

Unlike acrylic, polycarbonate do not snap / shatter (it shouldn’t in most cases).

One test you can do is take a pair of pliers and bend the corner.

Or you can simply throw it on the ground (make sure you wear safety glasses though, even though it shouldn’t shatter).

It was 1mm polycarb, (25.4mm to the inch) they worked fine only slightly less flexable then the rubber flaps, definately not 10X stiffer.

if you were to use polycarbonate as a flap alternative, wouldn’t it count as using up the space under the 12"x24" polycarbonate size rule?

Yes, it would.

Yes it would. Most of the time the inspectors are not very strict on how much you have
(from what i have heard.)

Although some inspectors that you have encountered may not have been very strict on enforcing this rule, that does not change the rule. Teams are not permitted to use more than 12"x24" of polycarbonate as cut from a single sheet. Expecting to get away with breaking this rule because of lax inspectors is both foolhardy and inappropriate.

Oh, I understand that, I was just saying most do not really “check up on it”.

It was weird seeing Karthik post in a thread not posted in the Q&A forum.

We have a print out of the lexan we use in a scaled down 12x24 rectangle. We were sure we would raise lots of questions due to the nature of our usage.

1107B, you never fail to amaze us with your use of polycarbonate.


It’s kind of sad, seeing all the small and medium tread paddle sizes and chain link additions going to waste with this huge trend in side-rollers. Slightly reminiscent of intake rollers from last year.

Anyway, very nice suggestion for teams with a lot of lexan and not wishing to buy extra tread paddles. Like murdomeek said, the mats and zipties also suffice and tend to be more flexible.

and we’ll be seeing you on saturday i assume?
excited for this 63 team, 10+ projectors, full out computer system loop competition :smiley: