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Old Oct 10, 2012, 11:14 PM
sam51401 is offline
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Request to any machinist


I have special request in that i need a trunnion for a Eflite 120 size electric NOSE retract made of steel. My 18lb A-10 is taking a toll on this part in the retracts when my landings are ANYTHING less than perfect. Crosswind landings with the A-10 are a monster so im not as smooth as i wish to be.
The mains are doing ok so no issues with these at this time and i did a thread on "converting" the way these are mounted compared to the original in that i changed the side plates on each unit by using the NOSE side plates on the mains and the main side plates on the nose. No moding was needed to facilitate this mounting.
I also still use the stock size 4mm nose and 5mm main mold pins i ordered from a supplier online.
Bottom line, the aluminum trunnion cant take the extra weight AND BEFORE anyone chimes in, yes i know these are being used over the stated max usable weight as listed by E-Flite but they were a drop in replacement for the original kit SpringAires that they replaced.
Anyone to the rescue???

FYI, even though Tam at TamJets makes the smaller upgrade trunnion, he has declined to make the larger size due "to slow sales" as per the response to my request.
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Old Oct 10, 2012, 11:25 PM
unclecrash is offline
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Im grinning from ear to ear. But my lips are sealed!!
Old Oct 11, 2012, 12:24 AM
Jayray123 is offline
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Sam, give it a few weeks or so, eflite themselves may have something in the works. One of the horizon guys at seff hinted as much when I aked him why their retracts won't accept scale struts. Sometimes those boneheads just don't seem to have a clue lol.....

Jay
Old Oct 11, 2012, 12:48 AM
racer1 is offline
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Being involed with machinist every day. Making a one off out of steel is hardef that it looks.

That is why I make most of my own parts due to what they want to charge.

Maybe you can find a retired person who wants to help, if not it may cost you more that a quailty gear set that can withstand the loads.

Clay
Old Oct 11, 2012, 08:49 AM
stoneenforcer is offline
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why not use a different retract? dreamworks rc has some nice electric tracts for heavy planes, up to 44lbs. I checked them out in person and they werent much bigger then the 120's but built much stronger. sell the 120's or whatever and buy a set thats already designed for the correct application. ???? for what it costs and the PITA efforts to get a custom trunnion... ect..ect...
Old Oct 11, 2012, 11:35 AM
SCALECRAFT is offline
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You can buy a mill and lathe for what a single piece may cost. Harbor freight.

Steve
Old Oct 11, 2012, 11:50 AM
SCALEFAN is offline
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Done it all
Two hundred bucks might get you the new part, aluminum. If Interested at that price, I will ask Walter, my buddy. Turn around time will be two weeks including mailing time,

If you are looking for a donation, forget it and fly the plane with the wobbly gear.
Old Oct 11, 2012, 03:30 PM
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Freebies and donations , im not asking for. I understand the effort in making one of parts and and somewhat the milling and machining that would be required. I could buy a mill/lathe but i dont have the time to actually justify doing that and making the part myself, i would love to have the ablilty.
I look foprward to what Jay said and unclecrash, please do tell! PM me but please.........the suspense!
Old Oct 11, 2012, 06:23 PM
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I just went to look at the Electron gear at Dreamworks and those look great but very very pricey. Need to find out the measurements on the nose unit and see how close they are
to the Eflites.
Old Oct 12, 2012, 01:40 AM
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Making a stronger trunion will probably make a different failure point.

Since you are exceeding the weight limits of your gear.

Even Robarts that handle that kind of weight are not that expensive.
Old Oct 12, 2012, 02:15 AM
Arngeir Blakseth is offline
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Quote:
Originally Posted by sam51401 View Post
I just went to look at the Electron gear at Dreamworks and those look great but very very pricey. Need to find out the measurements on the nose unit and see how close they are
to the Eflites.
I went from broken Eflites to Electrons in my Falcon 120 and they are very nice and definately worth the cost. The nose unit is bottom mount the same way as the mains are so adapting your airframe to fit will be some work. The units are close in size but they are wider than the Eflites so that may be an issue depending on the way your retract mounts are designed.
Old Oct 12, 2012, 10:43 AM
SCALEFAN is offline
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Done it all
Racer (Clay) hit the nail right on the head.

The real weakness with EFlight retracts is not the trunion, it is where the shaft connects with a small gear inside the transmission. If you unscrew the two screws holding the silver cover you will expose the transmission.

Here is what happens:

On the stock EFlight, a hard landing will bend the arms of the trunion and then the gear will wobble. When you strenghten the trunion, the stress is completely passed on to the connection of the shaft and transmission, the shaft will easily snap off the tiny gear. This cannot be fixed and the whole retract will be trash.

I have experimented with this, have modified both sizes of EFlight retracts with Tam's upgrade, all with the same end result. All the EFlight retracts are made the same.

The fix is not a stronger trunion, but nobody believed me when I said this before and Tam wasted his time with the upgrade.Only the best pilots will realize the benefit of the trunion improvement. (pays your money and takes your chances)

PS: You also can cause the shaft failure by jamming up the retract, or trying to free a jam up with your hand.

PPS: Before splitting the aluminum case for an EFlight retract mark the exact position of the curcut board, on the bottom, held between both sides. Sometimes the factory glue doesn't hold and the board can slide forward and back. This will render the retract useless until you keep loosening the sides of the retract while trying to find the exact position of the board. This board has contacts that determine the lock to lock position of the mechanism. The retract will act dead if this board is installed in the wrong position. This usually happens when installing the Tamjets upgraded trunion.


Quote:
Originally Posted by racer1 View Post
Making a stronger trunion will probably make a different failure point.

Since you are exceeding the weight limits of your gear.

Even Robarts that handle that kind of weight are not that expensive.
Last edited by SCALEFAN; Oct 12, 2012 at 12:57 PM.
Old Oct 12, 2012, 06:46 PM
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Here are the measurements of the Electron-Retracts. I have a pair and I can tell you there's nothing better out there (I also have Lado Retracts). They might look pricey but they are worth every penny and customer support is top notch. You can get them from Dreamworks Rc or direct from Electron.

http://electron-retracts.com/product...cts/er-40.html
Old Oct 12, 2012, 09:21 PM
sam51401 is offline
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I will post pics this weekend but i changed the side plates of each retract for the opposite mounting arrangement from the stock units.
The "nose" retract uses the side plates from the MAIN units and vise versa on the mains having a TOP rail mounting which is attached to a ply plate on the bottom of wing.
The nose unit uses RAIL type mounting with the unit rotateting forward and the retract mechanism above the rails.
I hope this isnt hard to visualize but i will post some pics later this weekend and hence the reason for wanting to mod the units without installing completely new units with the opposite mounting requirements.
Sam
Old Oct 12, 2012, 09:44 PM
jefffassbinder is offline
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Al


I'll goind to stay old school, it involves a pump. And even if you hit the ground at high speed I don't have to worry about a gear. I saw a lot of people jump onto the electric gear and yes simple. But I like the tight positive feel of pneumatic operation. And if your creative, you can operate brakes, doors with one servo. Just like Tam does.

Only time I need a trunion is when I hit the ground at 100mph with my gear down.


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