Thursday, May 7, 2015

R&D: BoomCo Dart Tip Antifriction Coating

Back a while, I had started messing with the .40 caliber plastic body projectile from Mattel's new BoomCo line. I was discouraged, feeling loyal to .50 cal foam, and ready to write them off, but yesterday's redditing led me to a revisit, and I may have got somewhere.

So, as we all know, the rubber tips of the BoomCo dart are known as an obstacle to long barrels.

My first attempt today at addressing that issue: Wrap tip with 33 tape.

Problems: Consistent bore size of the finished dart is difficult to maintain. The tape tends to slip under tension, become unstuck from the smaller diameter features as it un-stretches, and leave sticky residue over time that collects junk. Finally, the tape stiffens the rubber tip and may hurt on impact with the edge, and this may be considered a stefan or a DIY dart.

Attempt 2: Use an old HvZ trick I came up with, cyanoacrylate (superglue) as a low-friction surface coating for rubber.

I wasn't sure what would happen here. Would it bond to the mysterious and proprietary "Smart Stick" compound?

It turns out the answer is yes.

As usual, the first time the coating is flexed, it crazes. Thus the tips look kind of ugly, scaly or volcanic after coating and initial flexure. However, they are smooth and low-friction, and have lost absolutely none of their bounce. The coating is not stiff or sharp at this thickness.

I have a video showing these being bounced and squished to put up later.

This is potentially a very big deal. While others have tested them in long barrels with sufficient overbore and found them to function with uncoated tips, I suspect that in Florida and other challenging environments, consistency and reliability would go to hell - as it does with micro darts in PVC. This coating process will remove this issue as well as making for a much easier time designing magazines and breeches and feeding them in repeating or automatic fire.

Another test that this tip development begged for was this:

The double-stack magazine, holy grail of the hobby. Doing it with foam is considered impossible, as foam tends to self-lock. Slick plastic tubing does not have that problem.

Of course, this test has all the wrong geometry. This mag body is too narrow, and thus does not permit the ideal contact angle, and each round is not in contact with the adjacent ones in the same column, but is rather supported entirely by its neighbor in the next column. As a result, the friction is higher than it should be, and the capacity less for the given length (there are 10 rounds in here, BTW). Also, the feed lip geometry is wrong as well and makes not the slightest sense.

However, with the coated tips, this thing fed. It fed well, too. The strong spring of the 6-round Nerf mag did not phase the BoomCo dart bodies even in such a configuration. The coated tips worked amazingly well.

Pending is a full high-velocity, long barrel, coated tip BoomCo test. First I have to go get some barrel stock. In addition, I am going to test out shortening the body of the BoomCo dart.

1 comment:

  1. Well this is exciting news.

    I think I'm going to have to pick up some super glue and find a good barrel. I've been wanting to make a BOOMco range blaster to accompany the Rapid Madness.

    I eagerly await the next update on this project.