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07-07-2013, 10:25 PM | #1 (permalink) |
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Join Date: Aug 2010
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Mounting Blade ball studs on non-blade servo arms
I have an expense pile of parts to replace extensive damage caused by failed DS76 servos, including replacement servos (Savox SH-0263MG/SH-0264MG).
I started to install the new Savox servos, but had serious problem. How to mount Blade ball link studs on non-Blade servo arms. Blades arms don't fit Savox servo output shafts. Most of the arms included with Savox servos are too short to match the required servo shaft to ball distance. All of the arms are thin, narrow and appear to be fragile. Screwing these studs in to the arm doesn't look look strong enough. The only stock servo using a nut to retain these studs is the tail servo. What size and thread are these nuts? Where do you get thin nuts to fit these tiny metric studs? I spent two hours today driving from hardware store to hardware store. None had nuts this size. I'd prefer to place very thin washers between nut and arm for extra strength, if possible. How did you attach Blade ball link studs to non-Blade servo arms? What size are threads on Blade 450X ball studs? What size drill bit did you use to slightly enlarge the servo arm holes to fit the studs without become loose and sloppy? The smallest bits at hardware stores were 1/16 inch. Did you add very thin metal washers between the nut and arm to help reduce the chance of snapping thin weak looking servo arms? It would be so much easier if the Blade arm fit Savox servo shafts. |
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07-08-2013, 02:00 AM | #2 (permalink) |
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Join Date: Aug 2010
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Someone must know what size these damn ball link studs and nuts are. Once I know the size I can locate/order them without driving to dozens of hardware stores with a ball stud in my hand. I tried that, it didn't work. That process wasted a couple hours and a half a tank of gas.
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07-08-2013, 06:58 AM | #3 (permalink) |
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For my A3020's.
I used a #53 (.059) bit, hand drilled out the hole on the arm bigger but slightly undersized. (using fingers or ball link pliers to hold the bit) Then I thread my balls onto the arm. Careful to run up flat on arm snug but not torque it. I use a nut from the Jesus bolt or Tail drive gear on back side and some blue LocTite. This I will snug up tight. Works great and not like I don't have any of them nuts around. |
07-08-2013, 08:20 PM | #4 (permalink) |
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Join Date: Aug 2010
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I went to an industrial supply house today.
They didn't have much to choose from in these sizes. The threads on Blade 450 ball link studs are M2. After a long time test fitting what they had I left with 100 stainless steel M2 nuts and washers. Plus a range of wire gauge drill bits in sizes smaller than their charts indicated were correct for M2 threads. I purchased the following drill bit sizes: 52 53 55 56 They didn't have 54. Should anyone else need these nuts and washers they're available at www.olander.com. The nuts are M2-.4 Hex Nuts SST (Part number .2CHNTS) The washers are M2 F/W SST (Part number .2NFLWS) 100 nuts was $1.69 100 washers was $1.14 Drill bits were $1.40 each Gas expended finding them was many times higher. Now I can replace all DS76 servos in both 450X and repair them without expecting a DS76 to destroy 10x its value in other parts. |
07-09-2013, 08:08 AM | #5 (permalink) |
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Join Date: Apr 2013
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LizardMan,
Thanks for figuring this stuff out! I'm attempting to replace my stock servos with Savox 0257/0262. |
07-09-2013, 12:13 PM | #6 (permalink) |
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Join Date: Apr 2013
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LizardMan,
Did you figure out which of those drill bits works best? |
07-09-2013, 12:21 PM | #7 (permalink) |
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Join Date: May 2006
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I usually stick the point of an exacto knife in the hole and spin it. Then from the other side. Once the hole is close I thread the ball into it. Once the ball is snug against the arm I put some loctite on the threads that protrude from the back of the arm. I then hold the nut with some pliers while threading the ball into it. I allow the arm to spin freely as I tighten the ball into the nut. You don't need he-man torque on any of this, but do allow the loctite to set before flying.
-J |
07-09-2013, 12:33 PM | #8 (permalink) |
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Join Date: Feb 2012
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I have upgraded the servos on my 450x using Savox as well. I just used the hole that closest matches the stock length and just so slightly used my xacto knife to enlarge the hole a bit and just threaded them in using some ca to lock them in place. I dont think the small difference in arm length has made any difference at all. when I redid the ar7200bx setup it all works good. no nuts no washers just ca glue.
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07-09-2013, 08:51 PM | #9 (permalink) | |
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Join Date: Aug 2010
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Quote:
I'm thinking about using CA to avoid loctite damaging these thin brittle looking servo arms. I'd hoped to have the stud's thread cut in the plastic arm to reduce the chance of it twisting or tilting away from square to the arm. OTOH, if there's enough thread to use a washer on each side and a nut it's not going to move much. |
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07-09-2013, 08:54 PM | #10 (permalink) | |
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Join Date: Aug 2010
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Quote:
CA vs loctite seems to be the real question. |
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07-09-2013, 09:17 PM | #11 (permalink) | |
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Thread Starter
Join Date: Aug 2010
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Quote:
Replacing the DS76 servos is the first real modification to my 450X helis. Both 440H motors were replaced after lower bearing failures. I replaced them with loctite 680 mod 440H motors. Removing slop with loctite seems to make any imbalance in 440H motors more obvious. Maybe HH depends on loose bearings to hide motor bell imbalance. I have EF 450 motors w/12 tooth pinions waiting to replace both 440H motors when the motor bearings fail again. I don't have an issue with 440H power output, only bearing failures. I ordered a pair of CC Edge 50 Lite ESCs. July 4th sale, couldn't resist. I'm looking forward to CC ESC data logging. They support upgrading to 6S power should I feel the need in the future. Will a CC Edge 50 Lite ESC BEC support four Savox servos? |
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07-09-2013, 09:35 PM | #12 (permalink) | |
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Join Date: May 2006
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Quote:
-J |
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07-09-2013, 11:33 PM | #13 (permalink) | |
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Thread Starter
Join Date: Aug 2010
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Quote:
The arms I received with SH-0263MG/SH-0264MG servos don't feel beefy. The holes are smaller than M2, but there's not much plastic around them. These arms don't have ribs or other stiffening features, just thin flat white plastic. Maybe I'm expecting too much from micro servo arms. I'm used to servos with larger thicker arms with more material around all holes. If it's going to crash it should be because I flew it in the ground, rather than a 2 cent part failed. |
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07-10-2013, 04:14 AM | #14 (permalink) | |
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Join Date: May 2006
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Quote:
-J |
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07-11-2013, 04:39 AM | #15 (permalink) |
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Thread Starter
Join Date: Aug 2010
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I found my pin vise, and calipers. Starting with smallest wire gauge drill bits I tried bits until finding #53 (0.059) to be the best choice. The shop didn't have #54 bits. If I had one I'd try it.
A #53 bit works. Thanks Rich. Ball link stud thread found some bite at this size, but don't create much stress on the plastic. Rudder hole offset seems to be 8mm. I didn't find a great match on Savox wheel arm. Cyclic holes are between 12 and 13mm. The larger double arms matches well, without using the outer most holes. The larger arms may require a bit of trimming to avoid contact. A washer fits under the stud. I feel a washer on stud side adds more strength than behind the nut. The nuts have 4mm faces, almost as large as the washers. I could place a washer under the nut too, but prefer more thread engaged with the nut. A touch of loctite or CA should prevent nuts from becoming loose. I may be over estimating forces on flybarless cyclic servo linkages. So many DS76 failures have made me a bit plastic shy. I'll avoid using the outer hole of Savox arms on cyclic servos. |
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