Air Gun Home :: View topic - Self-Resetting Practice Field Target

rsterne · Moderator

I thought you might like to see what I whipped up today from my scrap metal box.... It doesn't have the face plate fitted so that you can see the guts and how it works.... The steel face plate will be 3" tall and 7" wide, with two holes, of whatever size you wish up to 1.5", about 4 1/2" apart.... It will bolt on (with the two 1/4" bolts shown) so that you can have several, with different size holes.... Shocked

The basis of the design is an over-center rocker arrangement, preloaded by a spring so that it sits either left or right....

The paddle holder is a 4" corner bracket from a hardware store, welded to a cut down 4" strap hinge.... all framing pieces are 1" x 1" x 1/8" angle.... The paddles are cut from 1/8" steel plate.... and the mount for the face plate is 1" x 2" x 1/4" plate, drilled and tapped 1/4-20 NC.... The front of the spring rides on an 3/4" long 8-32 bolt and the rear sits on a 2" long 1/4" bolt.... Cool

I found the target to be a bit fussy as to spring tension.... If you set it up so that it will flip at 4 FPE, when you shoot it with 12 FPE it will sometimes cycle completely (left-right-left) because it bounces.... I found that for my purposes, if I set it so that it works reliably at 6 FPE then it still works perfectly at 14 FPE (I haven't tried it with anything more powerful yet).... This could easily be solved by making an adjustable spring tensioner.... or by simply changing springs.... Two springs would probably cover most shooting situations.... Twisted Evil

The base can be either pegged to the ground through the three holes in the ends of the legs, or it could be bolted to a piece of plywood and then weighted down.... I think the functioning could be improved by attaching the paddles further out, so that the center of the holes (and paddles) were 2 1/2" to 3" from the pivot point.... I found that lightening the paddles (they were originally square), and striking them further out, both improved the functioning at lower energy levels.... less mass to accelerate from the pellet impact, and a longer lever arm for the force to act through.... Wink

I know that this target doesn't have the satisfaction of having the target fall down when hit.... but there is no string required to reset it either.... you just keep shooting, alternating from side to side.... Mr. Green

Bob

AirGunEric · Site Admin

Nifty. I think you're right about the lack of a "thrill" in something not falling down- but sometimes I'm lazy and don't want to pull a string, just shoot, so that would work great for me!

What are the targets going to be? Clown faces or maybe an ex-wife's mugshot? Wink

rsterne · Moderator

ummmmmmmmm.... a rectagular plate with two holes in it?.... Shocked

I'm too lazy to keep repainting the faceplate when I miss.... Evil or Very Mad

Bob

Alstone · Moderator & Site Supporter

Nice design rsterne and heavy duty, I made something like it last year out of 10g aluminium, but it was shot to pieces within an hour.

I can see I'll have to dig the welder out and have a go at your design, I'm also to lazy to be bothered to pull strings. Smile

Al

Bean · Veteran Member

I like it. I have no real metal working tools but I do like self resetting targets. I use one of these (see first item listed in link below) works very well once you get the balance point right but not really a FT practice aid...

edit to remove pointless link, AirGunEric fixed it for me in the next post Embarassed

AirGunEric · Site Admin

The Birchwood Casey website is lousy for linking- but I believe you are referring to the Airgun/.22 rotating target. I can't find a picture on their site for the AirGun version, so here's the .22 unit:

Bean · Veteran Member

Thank you!! and yes I use the .22 (rimfire) unit. I had a a different brand airgun grade unit years ago and bent the crap out of it over time. I've actually managed to put a few divets in this one too.

Actually - if you look closely, I think the one on the right is the 'airgun' version, looks wimpier.

AirGunEric · Site Admin

Bean · Veteran Member

rsterne · Moderator

I made some 1/8" faceplates today.... I couldn't get any 3/16" material.... lucky to even find anything in Princeton.... Shocked

I made four plates, the one installed in the picture has 1" holes in it.... the other ones are 1 1/2", 3/4", and 1/2".... I also made a sliding adjuster for the spring tension (white slotted gizmo in the photo).... with an added benefit that by rotating it a bit from side to side you can also adjust it so that both paddles take the same energy to flip.... Cool

During testing, I found out that FPE is not the only thing that makes a difference.... Surprise, surprise, a .22 pellet will activate it reliably with significantly less energy than a .177 pellet.... It took only 4 FPE to make it flip reliably with a 14.3 gr. pellet, while it took 6 FPE to make it function properly with a 7.9 gr. pellet.... Rolling Eyes

If you have ever used ChairGun2, you will notice that it will calculate the "Momentum" (the basis of the old Taylor "Knockdown Numbers" for hunting big game).... If I remember my Physics, Energy is Mass times Velocity squared, whereas Momentum is just Mass times Velocity.... The idea is that a heavier bullet (pellet) with the same energy will have more "knockdown power".... ie the old argument about why the RCMP carry a .45 not a .38, etc. etc.... It turns out a 14.3 gr. pellet at 4 FPE actually has MORE momentum than a 7.9 gr. pellet at 6 FPE.... Twisted Evil

In any case, in .22 cal, the target will function perfectly with only 4 FPE, and it will easily handle 14 FPE without bouncing (and I think a fair bit more).... I did confirm that hitting the paddle further out from the pivot does make it flip easier.... but with my adjustable spring tension I can now custom taylor it if I want to shoot a low powered .177 at the longer ranges.... Wink

I'm very pleased with the results and can't wait until the Spring when I can take it outside and use it at longer ranges.... Mr. Green

Bob

Slavia · Moderator

Very nice. I've got several of the Gamo rat/squirrel targets out in the woods at our gun club, but critters keep messing up the strings.

Your design would also lend itself to games in the manner of the Do-All "Dueling Trees:"
http://www.gunaccessories.com/DoAllTargets/SteelRoundUpDuelingTrees.asp
You could have two shooters, unlimited rounds, and a time limit - say 5 minutes. The loser is the one with the target visible on his/her side.

vAgRaNt · Member