BrokenChild
01-07-2002, 09:20 AM
I have seen several ways to set up a bomb hatch but the way I always do it is with an electric magnet. I build my hatch, hindge the door with a slight spring load to close itself back after the magnet's connection is broke, then make the magnet. To make an electric magnet I take 2 large bottons like what grandpa would have used on an old vest, or make coil caps out of 1/16" ply wood, and a bolt about 2" long... I got the idea from building magnetic tattooing machines... This description is short, but here we go:
The bottons act as coil caps on a tattoo machine... Take the desired botton size (most of the time around an inch) and the desired botton (with the 1" diameter coil caps, use 1/4"-3/8" iron bolt, and drill out the center of the botton or coil cap to the size of the bolt diameter. I use a 3/8"X2" bolt and 1"diameter caps, along with 22 G. enameled wire. After I get the holes drilled out, I put both caps on the bolt and stick the bolt in a drill. I leave about an inch of bolt outside of the chuck so that I end up with a coil thats 1" tall. Then I tack the caps in place with a drop of CA, and file a very small notch for the enameled wire to fit in in the BOTTOM cap. I wrap about 4 to 6 inches of the wire around the chuch to allow the end of the wire to be safe and out of the way, then slide the wire over the notch in the bottom cap, then set the dril to wind forward, and start winding. Start off slow, and then after you get about half of the first wrap done, then you can speed up to how ever fast you feel comfortable working at. Start at the botton and wind up clockwise. With the 1 inch coil caps, and 22G wire you will have about 8-12 wraps. When your winding and you get from the bottom cap to the top cap, then start back towards the bottom... just like if you were trying to wind fishing line back on the spool. When your wire is flush with the coil caps you stop winding, and then tie your end wire to the start wire with a piece of thread. Take out of the drill, and coat the whole coil in epoxy, let dry. When you are finished, you can take a 6V1200MH camera battery and stick to this coil.. A 1.5" coil with 22G enameled wire will weigh about 2.5-3 ounces and with this voltage will pick up a 3 pound monkey wrench! I always make me a simple base out of 1/4"ply and glue it to the inside of my hatch, then drill a hole for the bolt to go through and bolt it to the base. I always make mind adjustable for future ease. I then take a strip pf alum. thats 1/8" thick and drill a hole through the end of the plate and run a short cut off section of the bolt through this hole and place a nut on each end for the magnet to work off of. You can shape this plate and then screw/bolt it to the hatch and presto! You have addes about 4 ounces to the plane, so I wouldnt try this on anything small. I was really supprized at how well this design worked, and a few of the guys fromt he feild a few years ago had me make a coil for them. You can set this up to your radio how ever you wish, thats the beauty to it all, you dont have to follow directions to closely...just remember what size bolt to use with which coil, and what size enameled wire to use, and use a light weight, high amp batt. I always made a contact on my throttle servo, so I could set my idel at half trim, and full down trim wouldnt cut the ending off...just a really low idel. I made some contacts on a piece of 1/16" balsa and the other contact on the end of the servo arm, so that full down stick and throtle trim would make the contact... Works well.....
I know this is kinda hard to understand, I just cant get the right words out.. If you look at a professionals tattoo machines, you might better understand. I first did this in a CGM Eaglet 50, which is a 20 size trainer, and i didnt notice any extra lugg after I added the weight. Have fun with this one!
cheers,
broken
The bottons act as coil caps on a tattoo machine... Take the desired botton size (most of the time around an inch) and the desired botton (with the 1" diameter coil caps, use 1/4"-3/8" iron bolt, and drill out the center of the botton or coil cap to the size of the bolt diameter. I use a 3/8"X2" bolt and 1"diameter caps, along with 22 G. enameled wire. After I get the holes drilled out, I put both caps on the bolt and stick the bolt in a drill. I leave about an inch of bolt outside of the chuck so that I end up with a coil thats 1" tall. Then I tack the caps in place with a drop of CA, and file a very small notch for the enameled wire to fit in in the BOTTOM cap. I wrap about 4 to 6 inches of the wire around the chuch to allow the end of the wire to be safe and out of the way, then slide the wire over the notch in the bottom cap, then set the dril to wind forward, and start winding. Start off slow, and then after you get about half of the first wrap done, then you can speed up to how ever fast you feel comfortable working at. Start at the botton and wind up clockwise. With the 1 inch coil caps, and 22G wire you will have about 8-12 wraps. When your winding and you get from the bottom cap to the top cap, then start back towards the bottom... just like if you were trying to wind fishing line back on the spool. When your wire is flush with the coil caps you stop winding, and then tie your end wire to the start wire with a piece of thread. Take out of the drill, and coat the whole coil in epoxy, let dry. When you are finished, you can take a 6V1200MH camera battery and stick to this coil.. A 1.5" coil with 22G enameled wire will weigh about 2.5-3 ounces and with this voltage will pick up a 3 pound monkey wrench! I always make me a simple base out of 1/4"ply and glue it to the inside of my hatch, then drill a hole for the bolt to go through and bolt it to the base. I always make mind adjustable for future ease. I then take a strip pf alum. thats 1/8" thick and drill a hole through the end of the plate and run a short cut off section of the bolt through this hole and place a nut on each end for the magnet to work off of. You can shape this plate and then screw/bolt it to the hatch and presto! You have addes about 4 ounces to the plane, so I wouldnt try this on anything small. I was really supprized at how well this design worked, and a few of the guys fromt he feild a few years ago had me make a coil for them. You can set this up to your radio how ever you wish, thats the beauty to it all, you dont have to follow directions to closely...just remember what size bolt to use with which coil, and what size enameled wire to use, and use a light weight, high amp batt. I always made a contact on my throttle servo, so I could set my idel at half trim, and full down trim wouldnt cut the ending off...just a really low idel. I made some contacts on a piece of 1/16" balsa and the other contact on the end of the servo arm, so that full down stick and throtle trim would make the contact... Works well.....
I know this is kinda hard to understand, I just cant get the right words out.. If you look at a professionals tattoo machines, you might better understand. I first did this in a CGM Eaglet 50, which is a 20 size trainer, and i didnt notice any extra lugg after I added the weight. Have fun with this one!
cheers,
broken