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Old Dec 10, 2011, 02:20 AM
Knife Liddle is online now
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Lee Liddle
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Mini-HowTo

Bringing weak E-tracts up to snuff for 25 cents


I know this isn`t strictly EDF related, but I just wanted to share this with my EDF brothers.

I love my cheap E-tracts from HK. The larger size can work up to about 10lbs if you operate off pavement, and if the micro switch fails, just throw it in the spare parts bin and grab a new one. I`ve only used the cheapies from HK, but my guess is that many of the other brands have the same problem.

The main draw-back they have is that when you tighten the set screw for the strut, it can easily break the rotating pin and leave the strut to spin. That makes the retract vertualy worthless.

After giving it some thought and trying various methods of securing the strut or using the retract with the broken pin, I`ve got a fix that is pretty easy to do with simple tools, and once the part is made, it can be swapped from unit to unit if something else breaks or wears out.

The rotating pin design is the problem. The hole for the strut is very large which weakens the pin, and then the diamond pattern that is designed to hold the pin in the truion gear further weakens the pin, making it easy to break.

The pin is 8mm in dia, which is equivilant to 5/16". So I picked up a 12" piece to aluminum rod from the LHS for about $2.50. This will make at least 10 new pins, which brings my material cost to about $.25 per pin.

The pics pretty much explain the process, but a couple of notes.

1) When drilling the holes, start with a small hole (1/16"), make sure it goes in straignt, then open it up in steps to the 3/16" strut size. If you only want 5/32" struts or 1/8" struts, you can use brass tubing to take up the slack in the plastic truion gear and keep the hole in the rotating pin smaller.

2) Same goes for the threaded hole for the set screw. Start with 1/16" and then use the size needed to match the tap to be used.

3) Use a little lube like WD-40 when drilling and tapping, or you`ll break stuff.

4) When removing the original brass pin, press it out with a vice or a drill press. You can`t just knock it out unless it has already broken in half like the one in the pic.

5) The strut itself holds the new pin in place, so there is no need for any other method to hold the pin in place.

6) I chose to counter sink the set screw and use a regular 3mm bolt. The regular bolt uses a larger alan wrench and doesn`t strip as easily as a grub screw. You don`t have to counter sink the head of the bolt, it just makes it easier to fit into the mounting beams if you do.

7) I used a 3mm bolt for the set screw, but a 4-40 bolt should work just as well. Even a 4mm or a 6-32
would fit.

Anything else, feel free to ask.
Last edited by Knife Liddle; Mar 10, 2012 at 08:57 AM.
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Old Dec 10, 2011, 11:06 AM
SCALEFAN is offline
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Done it all
Thanks Lee, we need more of this type of info posted here.

Not many people talk about the 25-46 retracts having worthless trunions made out of soft aluminum.

These things are such an easy upgrade I'm surprised HK and E-Flight haven't picked up on the defects and fixed them.
Old Dec 10, 2011, 11:30 AM
zaskarkid is offline
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what it do everybody?
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good stuff. hopefully hk will see this and offer some hardened parts. I know they did so in their offroad bike which had a soft metal suspension link.
Old Dec 10, 2011, 01:44 PM
Glacier Girl is offline
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Very nice fix Lee!!!

Hmm, wonder would mild steel or even stainless work even better? Thoughts?
Old Dec 10, 2011, 04:35 PM
Steve Haynes is offline
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There was a crease in the plan
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Don't have the retracts but love the 'Liddlefying' fixes you come up with. Perhaps we need to put this forward to Collins modern dictionaries as a new entry?

Sic: To Liddlefy : to get seemingly average items, mess them about with some basic tools and a budget less than $1 in order to make something quite remarkable as a result.
Old Dec 10, 2011, 05:07 PM
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Lee Liddle
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LOL

We could also add Liddlefry just above it...

Liddlefry.......the action of taking perfectly good electric power systems and destroying them for no good reason.........
Old Dec 10, 2011, 05:10 PM
Knife Liddle is online now
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Lee Liddle
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What would make this fix super easy would be to find 8mm or 5/16" rod with a threaded hole already in the middle. Then it would just be a matter of cutting to length and drilling a hole for the strut. If someone knows a source for something like that, please let us know.

Thanks guys, I hope this helps more guys enjoy the budget e-tracts.
Old Dec 10, 2011, 05:16 PM
CoolerByTheLake is offline
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Do it Right, the first time!
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I always like a challenge to find something. But, you might look at this.


http://www.mcmaster.com/#standard-th...ndoffs/=fb1tg5
Old Dec 10, 2011, 05:41 PM
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Lee Liddle
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Yes, I looked through their stuff, but they don`t have anything the right diameter and length.
Old Dec 10, 2011, 05:44 PM
CoolerByTheLake is offline
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Lee, what exact size is it you need. I'll keep looking.

http://www.grainger.com/Grainger/Round-Spacer-6MYU4 No thread inside.
Old Dec 10, 2011, 05:50 PM
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Lee Liddle
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5/16" OD, or 8mm OD, they are the same. The threaded hole in the center can be 4-40, 6-32, 3mm or 4mm.Or the center hole could be 1/8" or 3mm and not threaded. Minimum length is 7/8". Happy hunting.
Old Dec 10, 2011, 05:56 PM
AceMigKiller is online now
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Team EJF >>>WHOOSH>>>
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This is great!
Very informative, thanks for posting.

Vic
Old Dec 10, 2011, 06:19 PM
CoolerByTheLake is offline
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Do it Right, the first time!
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Try this one. http://www.grainger.com/Grainger/Rou...B16?Pid=search


Here's all round spacers 5/16 x 1" http://www.grainger.com/Grainger/rou...omViewAll=true
Last edited by CoolerByTheLake; Dec 10, 2011 at 06:27 PM.
Old Dec 11, 2011, 12:44 AM
Eddie P is offline
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Official Boat Bum
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Great post! I like your fix.
Old Mar 10, 2012, 08:56 AM
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Lee Liddle
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I just thought I`d bump this thread for those who might have missed it. It really works well.


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