New main frame - RC Groups
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This thread is privately moderated by Chap1012, who may elect to delete unwanted replies.
Apr 22, 2012, 11:34 PM
Epilepsy Awareness
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New main frame

Sometimes we all come to the horrible conclusion that your main frame is gone, FUBAR if you will. Not a big deal. Removing everything from your main frame is simple. First, take some pictures. Next, with some 1/4" hobby tape, mark each wire. Everyone has their own preference of marking, so do what's best for you to remember.

OK, everything is off the old frame, marked and pictures taken.

STOP: This is for instructions on the "stock" V4 main frame.

With the new plastic stock main frame in front of you, you'll now want to clean it up. Sand all the slag (or imperfections) smooth. Pay particular attention to a nice smooth area were the motors and servos will mount and also the underside where the motors will screw into. You may have to use an Xacto blade to the screw holes on the underside to insure they seat flush to the frame, otherwise the screw heads may hit the "B" gear. In addition to the normal preparation, I did my 4in1 (brick) reinforcement mod, that is already documented. Also as an extra, I added some J-B Weld 4 minute epoxy to the two front feet. The weakest and most vulnerable.

Contrary to many, I don't use double sided sticky tape to mount my servos. I use Gorilla Super Glue. Some on the bottom of the main frame were the servo would go,,,...position servo in place (always check for fit before CA'ing). Then another few dabs around the out side edge. Don't worry, they will pop off when the time comes. I use an Xacto blade between the servo and main frame tapping gently until it frees.

Next we'll mount the motors: First we'll test the motors so your hard work is not in vain should one (or both) doesn't spin up (see picture). When your heli is completely broke down it's always easy to mount the "B" motor first because you have a clear view of the motor pinion gear and the "B" gear mesh . The "B" motor drives the outer shaft and is situated at the front of the frame and the motor pinion gear is closest to the motor can. I usually mount my motors with the red wire facing away from the main shaft/mast (it just makes sense and is a good reference when shimming is needed). The picture below shows the different materials I use in the shimming process. As you can tell the same motors will be installed on the new frame. The motor on the right ("B" motor) I used a piece of broken canopy (brown windshield) to raise the whole motor a bit. If this isn't done, there's a good chance the large "A" gear might hit the "B" motor pinion. Lets mount the "B" motor, "B" gear and outer shaft and see how it looks. Refer to the pictures. See the motors I'm holding, the one on the left ("A" motor/rear) has shim material on the right. Remember I said the red wire on the motors should face away from the main shaft/mast? So, looking at my "A" motor (rear) this motor needed to be "kicked in" a little closer to the large "A" gear (see picture). If the mesh was too tight on this same motor, you would put the shim material on the other side of the motor to "kick" the motor away from the large "A" gear.

How do you know when the mesh is right?
By eye. By feel. And in time, through experience. I have read many posts on checking the mesh between the motor pinion gears and the large drive gears. The method I found the easiest? Cut off a 1/4" piece/sliver of 20LB printing paper. This piece of paper should ride through the pinion gear and "A" gear with not too, too much force (see picture). If you can't even get it started, it's way too tight.

Once the motors are mounted and the mesh is to your satisfaction, the 4in1 (brick) can be mounted and the wires plugged up. If you don't have the right material to mount the 4in1 do not skip the step of spinning up the outer shaft to check for wobble. Simply plug up your motors to the 4in1. You will need to hold the 4in1, heli and battery in one hand. Be very careful minding ALL the wires (see picture). When the inner shaft is installed, you want to spin up and check that shaft for wobble as well.
Here is a great "how to" by mnwizard at helifreak for inner and outer shaft replacement. Thank you "mnwizard":

If I missed anything or if you would like to add or comment, please feel free to do so.
Last edited by Chap1012; Aug 05, 2012 at 03:28 PM.
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