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Author Topic: Servo wheels for JR and carbon arms.  (Read 3312 times)

Offline Anthony Oxlade

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Servo wheels for JR and carbon arms.
« on: June 18, 2012, 01:12:52 PM »
Hi Guys,

How are you all fitting the carbon servo arms to your JR servos? Can anyone help me find servo wheels to fit the synergy carbon arms to my JR DS8917 servos?

I ordered the standard small servo wheels but they are not suitable (part JRPA217). The holes in the small wheels only fit two of the four locations on the carbon arms. Drilling would be difficult because the clearance on the remaining holes is so small. I suppose i could drill and turn down the much larger JR servo wheels but i'm looking for a simpler solution.

When i bought this e7 it came with servo wheels that fit the carbon arms perfectly and seemed to fit on the JR servos. However i think they must have incompatible splines because they strip very easily. They did hold up in normal flight so I would try these again but i don't know who makes them!
Synergy E7 - 4525 Ultimate, 8917HV, HBL980, Vbar Silverline, HW 120HV, Quasar 7075 BEC, Edge 693/115
Synergy E7 - 4525 Ultimate, 8717HV, HBL980, Vbar Silverline, Scorpion 130A, HV2 BEC, Rail 696/116

Offline RyanW

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Re: Servo wheels for JR and carbon arms.
« Reply #1 on: June 18, 2012, 05:07:25 PM »
Let me look through my photos, I have some detailed info on this...
-Ryan

Offline RyanW

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-Ryan

Offline Anthony Oxlade

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Re: Servo wheels for JR and carbon arms.
« Reply #3 on: June 19, 2012, 02:26:31 AM »
Hi Ryan,

Thank you for the link. I'm looking at the picture you posted of a small white servo wheel mounted on a carbon arm. Can you tell me which wheel this is? It is smaller than the 'small' JRPA217 wheels i bought, which have a larger diameter than the carbon arm.

I might give the JR four star arms a try. Do these fit the carbon arms or do you just use them alone?

thanks

Anthony
Synergy E7 - 4525 Ultimate, 8917HV, HBL980, Vbar Silverline, HW 120HV, Quasar 7075 BEC, Edge 693/115
Synergy E7 - 4525 Ultimate, 8717HV, HBL980, Vbar Silverline, Scorpion 130A, HV2 BEC, Rail 696/116

Offline Anthony Oxlade

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Re: Servo wheels for JR and carbon arms.
« Reply #4 on: June 19, 2012, 03:01:03 AM »
Sorry i've just been inspecting your picture more closely and it looks like this is the four star horn with the arms cut down. I can see the reinforced metallic shoulder poking through the carbon arm.

Are these horns weak enough to strip in a crash? I would prefer to strip the horns instead of the servo gears.
Synergy E7 - 4525 Ultimate, 8917HV, HBL980, Vbar Silverline, HW 120HV, Quasar 7075 BEC, Edge 693/115
Synergy E7 - 4525 Ultimate, 8717HV, HBL980, Vbar Silverline, Scorpion 130A, HV2 BEC, Rail 696/116

Offline RyanW

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Re: Servo wheels for JR and carbon arms.
« Reply #5 on: June 19, 2012, 09:42:29 AM »
Yes, they are the four star horns cut down. Two of the arms have holes that line up perfectly with the holes in the carbon arms, the other two need to be drilled and tapped. (You can thru-drill, but I prefer to tap them)

The key is to find the super flat head screws. I had some around, but have no idea what kit they came from. If I find them online, I will definitely post the link!

Crash wise...  I wish I didn't have data to support this, but I do! If you asked me if these would ever strip in a crash, I would have bet you $100 they wouldn't. They are so hard to get on and off the spline with the outer metal reinforcement band (almost takes a gear puller to remove), I would have thought it would be near impossible to strip.

When my E7 went in full bore, I checked all of the servos and they all worked fine, nothing was rough, all of the servo sweeps were normal and no unusual amperage draw through the travel. I rebuilt the machine and during set up I couldn't figure out why the swash was off so much when everything was centered. When I checked out the elevator servo, I found the arm to be off a click. I just shook my head on how that could be. The arm was super tight, the settings in the radio and V-Bar hadn't changed. I finally pulled the servo arm off- (with the said gear puller) and sure enough the inside looked like it had been forcefully "mushed" a few degrees. It was so tight that I could hold it and try to torque it and there is no way it would move. I honestly think you could have flown it the rest of the servo life in that position and never know it had damage. I replaced that horn and all is good.

Long story short- I am very surprised, but glad to see they will strip and I think it dang near will take a direct hit to the swash to make this happen (note: my swash was completely lunched and the mainshaft was bent over so hard it pulled the entire upper bearing apart... as in the balls and ball race were all over the top of the frame!!!).
-Ryan

Offline Anthony Oxlade

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Re: Servo wheels for JR and carbon arms.
« Reply #6 on: June 20, 2012, 10:13:42 AM »
Thanks for the help ryan. I have since discovered that spektrum servo horns are JR compatible, so the wheels my kit came with must have been from spectrum. I will try these again since they need no modification, but if they keep stripping i will switch to the four star arms you recommended.
Synergy E7 - 4525 Ultimate, 8917HV, HBL980, Vbar Silverline, HW 120HV, Quasar 7075 BEC, Edge 693/115
Synergy E7 - 4525 Ultimate, 8717HV, HBL980, Vbar Silverline, Scorpion 130A, HV2 BEC, Rail 696/116

Offline RyanW

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Re: Servo wheels for JR and carbon arms.
« Reply #7 on: June 20, 2012, 12:55:28 PM »
I have not personally checked out the Spektrum servos, but if the wheels are the same as the stock JR servo wheels, I would caution against using those. They have been known to strip pretty easy with the high torque servos and direct to swash FBL set ups. I can't recall if there have been actual in-flight instances of stripping, but I would check them regularly if you use them.

Here are the ones I purchased for the JR servos. http://www.readyheli.com/JRPSH8711HV-JR-Super-HD-Servo-Arms--Standard-JR-Spline_p_38235.html
-Ryan