AceBird
Elite Veteran
Location: Utica, NY USA
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You are spinning your wheels Jack … That bronze spacer will not change the mesh in your miter gears. All it will do is raise or lower the main gear on the autorotation hub. If you thin it down too much you will just create more slop up and down or bottom out the main gear on the frame. That is not what you want to do.
The crown gear is pinned to the main mast and the main mast is located vertically by the stop collars, one on the bottom and one on the top. You basically set the mesh of the crown gear by the top collar. Then if the bottom collar is a clamp collar you slip it up on the mast to take out any play and lock it down. Pretty simple it only gets complicated for two reasons. The fixed collar at the bottom is fixed so it may require some careful shimming or shaving off to make it fit right. The easy way is to use a clamp collar on the bottom just like the top. The second issue is if the crown gear housing bottoms out on the main gear because the bronze sleeve is just too long. So you have to take a little off to let the crown come down a little but bear in mind that the bronze sleeve is positioning the main gear on the mast not the crown gear.
Reference my gallery under the heading “Doing Alignments”.
The lower housing of the Zenoah motor is a casting. The two screws, one on each side, are on a surface that has a draft angle. That can’t be helped. I use a #10 washer (about .040 thick) between the frames and the housing to make up for that angle. With a metal frame it is better to bow the side frame out than bend the frame in so it is easier to remove the engine without loosening up the side frames.
The manual tells you to assemble the motor to the motor plate first. I suggest you do it last. If you assemble the side frames to the motor plate first you can use a flat surface to get them square before you lock up the screws. This will put the holes in the top of the side frames all at the same elevation which will insure that the clutch and the bell will be assembled parallel to each other. One note here; the whole top section of the helicopter and the whole bottom section of the helicopter should be assembled as two separate sub assemblies and as a last step assembled together. The mesh of the main gear and the pinion gear should be set as shown by my photos using rubber bands prior to this marriage. The screws in the side of the motor should not affect alignment of the clutch because these screws should be already tightened before you marry the upper section to the lower section.
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| required lash …
The problem is to find out what that means. It is very empirical
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There is nothing empirical about it. For these size gears the backlash or clearance should be set between .0015 to .0020. Some say use paper as a shim between the gears. Paper is .004-.005 thick and as hard as a brick that can support 1000psi before it crushes. Use what I show in the photos, cellophane or syran wrap. Twist the rubber bands so you will have near equal pressure across the face of the gears so they will align perfect before locking up all the bearing block screws.
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| I will try to move the pinion a little further back to see if that solves it.
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No, that’s where you will create another problem. Moving the pinion in and out to change the mesh of a miter gear set is wrong, nothing empirical about that. The outside edge of the pinion must, MUST, be lined up to the outside edge of the crown otherwise the gears are toast. They will destroy each other.
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| I think this is quickly becoming too much for me... Not sure if this bird will ever last if doing hard 3D
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I don’t think it is too much for you at all. I think there are a lot of bad habits that you can get away with on a small machine that you can’t get away with on a larger one because of the horsepower and forces involved. You learn the right way, you do it once, you learn the wrong way and you will never stop doing it.
Ace
What could be more fun? |
Very clear now! What was I thinking?
