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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Ken Culbertson on April 16, 2019, 09:39:54 AM
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I recently had my Cobra 3520 bounce off of the pavement on it's way to hiding in the weeds and it appears that the shaft has been pushed in a bit. ~^ Having never done this on one of these motors, is there any precautions I need to take before seating it on it's front bearings and "pounding" it back into it's proper position. ??? I assume that you don't heat the case like it was IC. LL~ The motor runs OK and the shaft is not bent.
Also, does anybody know where to get a 4 hole prop adapter for the 3520? I find it really strange that they use a 4 hole can and give you a 3 hole adapter. Maybe they are subtly encouraging you to use a front mount? I understand that they were originally 3 hole but...damn. HB~>
Ken
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Ken,
Use an arbor press or a drill press to press it back to position. Is the clip still in the front? Also don’t forget to put locktite on the set screws.
The early version had 3 hole and the newer version went to 4. You can get them from Cobra. If not I have one I can send you.
Thanks
Joe
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Ken,
Use an arbor press or a drill press to press it back to position. Is the clip still in the front? Also don’t forget to put locktite on the set screws.
The early version had 3 hole and the newer version went to 4. You can get them from Cobra. If not I have one I can send you.
Thanks
Joe
Thanks - that is what I was hoping to hear. I have a message in to Cobra so I doubt that I will need yours but thanks for the offer. The clip is still there. You mentioned the set "screws" The only place I have for a set screw is on the rear exposure of the shaft. Is there another one I am missing? Have you ever added a support for the rear bearing? I want to try. I have a rather slim nose and I really worry about ramp up torque over time. I think a "sway bar" in the rear would really help. I see two ways that can be done. I could remove the set screw from the keeper and let it be the race or build a race around the keeper or just leave it alone because that is a bad idea. Unbelievable power in these tiny motors!
Thanks Again - Ken
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Helpful videos here from Lucien at Innov8tive RC. He shows Scorpian motors in some of the videos, but similar to Cobra. The press needed is 1 ton, not the half ton, and available from HF. I would be concerned about the magnets getting loose, and case deformity.
https://www.youtube.com/user/Innov8tive8
https://www.youtube.com/watch?v=Oha3DuLWAkc
Shafts and bearing are fairly inexpensive from Innov8tive RC or from RC Dude. Adapters should be available as well?
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Ken,
The set screws are on the back of the motor if you front mount them. (the black end!, not the green end!) there should be 2 90 degrees apart. The shaft has machined flats on it that line up with the holes.
Hope that helps
Joe
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Ken,
The set screws are on the back of the motor if you front mount them. (the black end!, not the green end!) there should be 2 90 degrees apart. The shaft has machined flats on it that line up with the holes.
Hope that helps
Joe
Outside of the Can? The black ring that I have only has one set screw hole and it came w/o a screw but whet the hell, the prop adapter is short one hole. Maybe the accessory bag at Cobra was filled by someone trying to get out the door at 5:00!
Ken
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Ken,
You are right, I had to go downstairs and look. The newer version has only one set screw. The older version has two. See pictures.
PS there should be a screw in there or the shaft will come out! Don’t ask how I know.
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Ken,
You are right, I had to go downstairs and look. The newer version has only one set screw. The older version has two. See pictures.
PS there should be a screw in there or the shaft will come out! Don’t ask how I know.
Does the Prop Adapter then also have a set screw even though it bolts on? Technically, since there is no pulling pressure on the shaft it may not need one but I am planning on using the adapter to slide into a rear bearing. Maybe I want to get a larger one that will fit over the keeper ring. Any clue what the diameter of that ring is? Is all of that perhaps a bad idea?
Ken
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No the prop adapter doesn’t have a set screw. You still need to have a set screw in the houseing to hold the shaft to the housing or it will certainly come apart. I use mostly front mounted. So I really do not have a lot of experience with them. I do have a few rear mounted ones and didn’t use additional bearings and have not had issues. I prefer front mounted. I have had really good luck with it. In fact I have not had many motor issues either way I mounted them. There are many ways to skin this cat!
Hope that helps
Joe