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HelicopterScale Model RC Helicopters › Universal Joints
02-23-2014 11:57 PM  3 years agoPost 1
helicrunch

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Rock Hill sc

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small universal joints that have ball bearings cost over $250.00 each so i decided to try and make my own, after 3 days work here is what i came up with.
$250 now doesn't seem all that bad,
22mm outer diameter 8mm shaft and weight 1.3 oz zero slop i also made a dual joint for 60 degree angle.
Going to put them in the raised tail of the Apache tired of noisy gears in the tail drive.

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02-24-2014 12:06 PM  3 years agoPost 2
doorman

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Sherwood, Arkansas

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Looking Good

Had heard you were working on these!!
Look really good..
Will be waiting to hear how they work out...they sure look as if they will be up to the job!! Nice going....
$250.00 vs 3 days on a project for something you have created.. I think "priceless" comes to mind....

Stan

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

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02-24-2014 02:28 PM  3 years agoPost 3
Mojave

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Palos Verdes, Ca. USA

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Very cool. It will be interesting to see how they handle the high RPM demands of the TR. Keep us posted.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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02-24-2014 02:59 PM  3 years agoPost 4
G-Limo

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Europe

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take care!

I have never seen articulated/UJ's work at speed through such an angle of deflection as you need for a high tail. (2 joints at 30 deg each.) CV joints yes.... So take care and good luck.

/DG

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02-24-2014 03:54 PM  3 years agoPost 5
Dr.Tim

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Mojave Desert

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I think Flex Drive would be safer but you might be on to something .. Look forward to hearing your results.

From Simple minds come simple ideas! Approach Engineering

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02-24-2014 04:34 PM  3 years agoPost 6
Mojave

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Palos Verdes, Ca. USA

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I think that I would do extensive bench testing prior to in stalling them in a fuse. Maybe drive it with an air drill motor and see how they act.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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02-24-2014 05:39 PM  3 years agoPost 7
adamsz06

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Geilenkirchen Germany

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Here's an adaptation you could try as well:

http://uberrc.com/product/179/

I'm using them in a 1/5 scale Baja buggy and can attest to the strength and high rpm durability of the design. If you're a machinist, making these in a smaller scale shouldn't be too bad.

R.I.P. Roman

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02-24-2014 06:18 PM  3 years agoPost 8
Copter Doctor

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Enterprise/ft.rucker ,al- home of army aviation

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I think Flex Drive would be safer but you might be on to something .. Look forward to hearing your results
me too

drive a rotary, fly a rotorcraft

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02-24-2014 07:32 PM  3 years agoPost 9
Peter Wales

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Orlando Fl

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I have some UJ's in my Seasprite transmission. The first set I tried were from sdp-si and were a steel pin in the cross going into a bronze bushing.After 2 flights the arm of the UJ were moving out and I had play in the joint.

The speed rating on these was low, around 2000 rpm, but as the loading was about 1/20 of maximum I thought they may work. Nope!

So I went and bought some proper ones with needle bearings in the joint and a speed rating of 5000rpm. Then I re geared my Goblin system to give me a shaft speed of 4600 rpm and set the joints up correctly (you cant just put them on any old way)

Now the vibration is down 90% and the drumming is virtually eliminated.

Just one minor drawback to these joints. They cost $197 each!

Peter Wales
http://scalehelicopters.org

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02-24-2014 08:01 PM  3 years agoPost 10
Mojave

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Palos Verdes, Ca. USA

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X2^^^ They have to be clocked properly, or they will vibrate something fierce...
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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02-24-2014 08:24 PM  3 years agoPost 11
Peter Wales

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Orlando Fl

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A little more to it than that. They have to have the crosses in alignment so that the outside ends have their arms parallel. Also, for minimum vibration, the input and output shafts should be parallel even if offset.

Somehow, I dont see these aluminum ones Russell has made lasting too long at high rpm, and the same size steel ones with needle bearings are only about $50, cheaper than a Vario dogbone.

But the steel ones are heavy and this application is not good for heavy couplers.

Peter Wales
http://scalehelicopters.org

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02-24-2014 10:55 PM  3 years agoPost 12
Mojave

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Palos Verdes, Ca. USA

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Agreed. I was also thinking that it's a lot of weight to have in the tail section of the fuse... It's hard enough to balance out a scale machine without adding extra weight to the tail. Just a thought...
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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02-25-2014 12:37 AM  3 years agoPost 13
helicrunch

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Rock Hill sc

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This is worse than the great clutch debate.
here is the dual joint for the rear at 60 degrees,for those who thought i was using a single joint for the transition.
ran it for 4 hours today in the lathe with a prop on the shaft for load at 3000 rpm to check, cant get any faster with the setup still no play in the joints very smooth and quiet no vibration.
if it fails so be it, no guts no glory no crash.
at least i tried.
As for flex cable drive forget it i had one fail already it broke in the center not at the ends i guess my setup places a lot of load on the drive.

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02-25-2014 02:30 AM  3 years agoPost 14
doorman

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Sherwood, Arkansas

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Sounding Good!!

Sounds as if it is in the right direction.. test results showing it just might work!!
I have to agree with you on the cable drive... I just am not a fan of how they work.. others have had great success with them...just not for me'!
Keep on going Russell..
Stan

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

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02-25-2014 03:45 AM  3 years agoPost 15
Mojave

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Palos Verdes, Ca. USA

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It looks like it could work for you. That double cardan joint set up should run smooth and can take a lot of abuse since it's supported by a bearing at both ends. Looks like you stole the design from my old Toyota truck...
Barry

P.S. This is nowhere near as bad as the great clutch debate

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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02-25-2014 12:37 PM  3 years agoPost 16
Copter Doctor

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Enterprise/ft.rucker ,al- home of army aviation

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after this one runs its course, I will start a debate over the laser light type tail drive

drive a rotary, fly a rotorcraft

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02-25-2014 03:08 PM  3 years agoPost 17
doorman

rrProfessor

Sherwood, Arkansas

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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

^^^^^^^^^^^

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

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02-25-2014 03:41 PM  3 years agoPost 18
coptercptn

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Mesa AZ. USA

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'Sall good!!!

Home of the "Sea Cobra".....

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03-01-2014 11:51 PM  3 years agoPost 19
helicrunch

rrApprentice

Rock Hill sc

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tested in the u joints today for 20 minutes running time,
while running i was loading and unloading the tail rotor to stress test the joints, after the test felt all the joints they remained cool to the touch and had not developed any slop still nice and tight and no deformation.6000 rpm and still together,
will bolt on the mains tomorrow and test fly.

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03-02-2014 12:36 AM  3 years agoPost 20
Mojave

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Palos Verdes, Ca. USA

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It looks like your having success with your static test. Glad to hear that it doesn't vibe. You may have a winner here. It will be interesting to see how it holds up over time.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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