Air cannon aiming issue had an easy fix.

[Winchman]

It was two feet shorter than the Big Shot. That was convenient for carrying it around and storing it, but not so good for aiming. Since I have to use a ramrod for loading the throw bag, I added two short pieces of slightly larger PVC pipe on the barrel to hold the ramrod. I had to do a little lathe work to get the inside diameter just right, and I left a little step, so the extension always fits in the same position. The ramrod stays in the barrel when the cannon isn't being used.

With the extension in place the aiming is just as accurate as with the Big Shot, maybe even better. I've used it several times for shots over 75-feet and hit my mark in one shot each time. What an easy fix to what had been a vexing problem.

I'm already thinking about adding a piece of pipe to the Big Shot so they both look the same when aiming.

 

[Bart_]

On the sling-shot the travel path of the bag isn't dead-on-axis of the pole/tube due to the various methods of hold/trigger release vs the offset of the forks. On my setup I'm fairly axial, but I've got some offset/angle which I'm sure adds up to aim error at distance. But I bet having the extended tube tip to sight by eye would improve aiming.

Correct me, you don't look through the extension tube, you just sight along the outside of it?

Do you shoulder fire or butt-end-on-the-ground fire?

 

[Winchman]

I kneel when using either launcher, put the butt on the ground, and brace it against my knee. It's really easy to aim with the arrow release trigger or the blow gun trigger on my launchers. Both require no significant movement or effort, and I can take my time while aiming. The blow gun takes the place of the solenoid on the modified lawn sprinkler valve. I'd be shooting all over the place without the triggers.

My Big Shot consistently goes just a little to the left, but I've learned to correct for that.

 

[Bucknut]

I actually had a red dot sight mounted to mine. What an idiot. Your solution is simpler and probably more accurate too.

 

[Bart_]

The laser dot aiming made perfect sense except if you're aiming at an empty spot like above a union (?) then what do you do?

missed my Q: do you look through the extension tube

 

[Winchman]

The laser dot aiming made perfect sense except if you're aiming at an empty spot like above a union (?) then what do you do?

missed my Q: do you look through the extension tube

I line the extension up with my desired spot in the tree (left-right position) and then judge how much to lean the cannon forward to get the height I want. If the line ends up above the desired spot, I can usually work it down with another weight. If it's off left-right, I can put a stick on the line and flip it over the limb to move the line where I want. Most times it's just quicker and easier to make another shot.

I made three shots this morning to get a good TIP eighty feet up. The first two bounced off the limb I wanted. The third was several feet out, but I was able to stick-flip it back to the trunk and then use the extra weight to get a straight drop from both sides of the limb. I pulled up a climbing line to make sure there was nothing that would stop it from going over the crotch. Then I left a bookmark line in the tree for when I come back to make the climb. With all the preliminary stuff done, I can concentrate on climbing when I come back.

 

[DSMc]

The laser dot aiming made perfect sense except if you're aiming at an empty spot like above a union (?) then what do you do?

I've been using a green laser on my apta for years and have never found shooting above a union to be a problem. There is almost always something close enough that allows for doing a few sweeping passes. This allows timing the shot to be released into the void. Works well.

 

[Bart_]

aim-jog-shoot lead-angle compensation in your HUD just kidding, sounds good

 

[Winchman]

I've got a birthday coming up, so I just ordered a green laser pointer.

 

[DSMc]

I hope you get a good one. It is unfortunate that there seems to be little control in the quality and brightness of small lasers.

 

[Bart_]

IIRC there used to be grey market kind of too high power units that worked well but may have been chased out of the marketplace. Got to be careful about getting picked up by an airplane if the beam exits the top of the tree - not looked on kindly. Brightness rated by class of laser. Beam divergence may be the other quality factor. besides basic quality eg materials construction and the usual

 

[Reach]

IIRC there used to be grey market kind of too high power units that worked well but may have been chased out of the marketplace. Got to be careful about getting picked up by an airplane if the beam exits the top of the tree - not looked on kindly. Brightness rated by class of laser. Beam divergence may be the other quality factor. besides basic quality eg materials construction and the usual

This is one of those, incredibly bright. I have several floating around, used to keep one in every truck. https://ebay.us/m/ScFHxj

 

[Winchman]

It'll be fun to play with the laser. Meanwhile, the ramrod-as-aiming extension on the air cannon got me an 81-foot TIP in one shot yesterday.

I'm not going to worry about using the PVC with compressed air. The 2" pipe is rated at 280psi at 73 degrees F with a safety factor of two. I don't foresee needing to use more than 50psi and most shots will be less. That's only 18% of the working pressure. Just to be on the safe side I've reinforced the air chamber with two crisscrossing spiral wraps of white Gorilla tape. That'll add a little strength, some UV protection, and some peace of mind. I used white tape because PVC loses strength as its temperature increases. Dark tape in the summer sun wouldn't be a good idea, and I already avoid being out in the sun whenever it's warm.

I just realized that the crisscrossing spiral wraps of tape with no overlaps might have an added safety feature. If the pipe ever breaks the escaping compressed air will inflate the wraps and create lots of vents where the small gaps between wraps cross. That may be just enough to prevent a catastrophic burst with lots of fragments flying around.

 

[Winchman]

Here are the mounts I made for the pointer. I haven't had a chance to try it yet and I haven't decided if I want it on top or below the barrel. The mounts have a pretty tight grip on the barrel and the pointer, but they can be repositioned easily for sighting it in. Then I'll add some spots of glue to lock them in place.