Feyd - 15-12-2015 at 08:13 AM
As we all know the spars on Arcs can be problematic. It's not unusual to have a spar punch through a spar pocket in a crash. Especially over time,
just light crashing will give you that nice "cookie cutter" affect on the spar caps which render them useless and opens the way for the spar to punch
through the spar pocket stitching or even fabric. There are various solutions. New custom alloy caps. Reinforced pockets etc. I've been playing
with ideas that are intended to dampen the impact. Even went as far as placing oil dampening units (used on certain ski binding systems) in the tips.
Of course this added weight. Not a lot but if we can avoid adding weight we should right? Following the K.I.S.S. method I've been playing with
simple rubber bumpers. They are not temperature sensitive, light weight and do a good job of keeping the spar from even getting close to cutting
anything.
As you see in the pic the bumper is inserted into the spar. It is then pinched in the tube and secured. Obviously the bumper is a smaller diameter.
But when impacted, it deforms over the edge of the spar. How much I have no idea but in a vice it expands to about 12-13mm. Much wider than the spar
and seems pretty good and offering punch through resistance. And as it isn't ridged it offers some level of impact absorption I would imagine.
Anyway, just tinkering.
ssayre - 15-12-2015 at 08:27 AM
Should work well. Along that same theory, my local hardware store sells corks of all different sizes. Probably lighter 
On second thought the cork material probably wouldn't withstand the abuse as well.
I thought you used snow plow markers?
Feyd - 15-12-2015 at 09:23 AM
Plow markers make good replacement spars. Dirt cheap and really nice reflex!
But they still suffer to some extent the same ability to punch through and obviously don't pack down. This is a way to deal with stock compact sticks
that cut through. It was a little tricky getting the right length dialed in. As these bumpers add a little length. It makes for a pretty tight fit
but usable.
bigE123 - 15-12-2015 at 09:40 AM
Nice work, I'm all for making things last longer and be more tolerant to impact.
Bladerunner - 15-12-2015 at 11:00 AM
Just not losing the stock caps in the sleeve will be the end of one of my peeves.
KISS and light seem the order. The corks are an interesting thought but I wonder how they would stand up?
volock - 15-12-2015 at 11:06 AM
ATM I'm experimenting with some rectangular ended (last 2-3" on each side) windsurfing batons as my spars. Mostly because I broke both of my
collapsible spars, and someone in town had a pile of old/extra batons... Original plan was to cut two to size for temporary replacements, but when he
happened to have two within 1/4" of what I needed, I went with them. I've often wondered why they don't integrate a solid cup (plastic/rubber) or
kevlar piece into the far end of the baton spot. I've debated sewing a kevlar piece under the velcro on the closing end.
carltb - 15-12-2015 at 11:17 AM
I put a washer in the end cap.
pbc - 17-12-2015 at 08:21 PM
I like this solution. I tried epoxying rounded wooden plugs into the spar ends, but the epoxy separated from the aluminum. I think I'll try a rubber
bottle stopper next.