glafond

I have resumed building my trainer and I am at a point where I start connecting the pushrods onto the servo horns. My question is this, I found that my TT Trainer came with 2 ez connectors, one to use on the throttle. The futaba servo horn I am using, a small disk, is too small for the ez connector. In other words, the hole on the horn wont' quite fit the threaded portion of the ez connector and the horn itself is a little too thick. I assume that the EZ connector should be able to rotate freely in the hole so that the push rod does not bend and I don't think forcing it is a good idea. Were the servo horns meant to be drilled out to accomodate the connectors? If I have to do this, I not only have to bore out the hole (only slightly) as well as drill an indent in the bottom so that the hex nut doesn't pinch the horn and inhibit movement. Could someone give me an idea of the best course of action here? I don't think the integrity of the horn would be compromised by the slight enlargement of the hole, nor the indent I would have to drill, but then again I am guessing here since this is the first time ive ever connected a pushrod to a servo horn lol. Thanks for any help, I tried to be specific enough but if more clarification is necessary let me know. The plane and servo's I'm using are in my profile. This is a Thunder Tiger Trainer 60.

MinnFlyer

My Feedback: (4)

It's not uncommon to have to drill the servo arm hole to open it up a little

Gray Beard

My Feedback: (-1)

I don't recall ever not having to drill out a servo arm to use one. They should have Resistance but still be able to turn. The bad thing about them is they will all loosen up with use. Not fall off but get a lot of wobble as the keepers slide down the shaft That will change trims.

glafond

Oh good, then I can keep working on it tonight and not worry about having to find some other tiny part lol. Thank you very much. Do you all have any tips on how to thin out the horn (its circular) to make it thin enough so the ez connector rotates correctly in the hole? I am just thinking of using a drill bit that is as wide as the hex nut that goes underneath it to shave a little off.

combatpigg

My Feedback: (3)

It is really handy to have a numbered drill index to make perfectly sized holes.
Harbor Freight has them, last set I bought was about $10.
A cheap dial caliper [$20 or less] completes the package.
I will use an EZ connector on .15 [and under ] powered planes or for any throttle, but would rather use a Z bend at one end and a clevis at the other.

glafond

That isnt a bad idea, thank you as well. Do you have any sugestions on how to thin out the horn so that the ez connector fits snug but still rotates? There is a thread on the end to a point and then the connector is smooth. I want to be able to tighten the nut on the connector and drop some lock tite on it but still have the ex connector rotate in the horn. In order to do that I have to thin the horn out by a little less than a mm. I was thinking of using a regular drill bit but I don't know if the cone shape the drill bit head has will cause more slop or if I should go another route.

jester_s1

If you have to do all of that it'll be less work to just use a Z bend. If your pushrod is not threaded on one end, replace it with one that is and put a Z bend in one end and a clevis on the other. It doesn't matter which end is which as long as you have full range of motion on your throttle when you're done. But if you're determined to use the EZ connector, heating up the head of a nail and pressing it into the horn should give you the dent you need.

glafond

That is a great idea! Thank you. I am just trying to use what I have at the moment, I may make some modifications later to the rods and connections. This is all a learning experience for me. Again, thanks everyone for your input!

JohnBuckner

My Feedback: (1)

The majority of my aircraft I use Z bends on one end of all the flight surfaces and never an EZ connector but most of the time I prefer to use the EZ connector at the servo for throttles.

All of the servo arm holes will be to small for the standand duty EZ connectors and this is by design.

The technique is not to drill at all and very easy taking only seconds. You simply use a standard hobby knife with a #11 blade (the most commonly used blade) and insert it in one side and turn in the hole just lightly then rotate and do the other side. Do this several times test fitting your clevis, Z bend, EZ connector or ninety degree keeper type. All of these will require a slightly different size of hole.

All are very quickly done and you will get the perfect fit every time by using the blade technique.

John

Norain

To answer your question about thickness, sand paper is your friend.

Gray Beard

My Feedback: (-1)

I use an assortment of dental burrs or drill bits to open the holes. The holes I cut are just enough to give the EZ shaft just a bit of snug. The screw on EZs you mentioned are usually found in ARFs. I like them but can't locate them in any of my LHS. To thin the horn or arm sand paper or the side of a grinder wheel works well. The Z bend is very easy and works quite well. Like all things metal going through plastic time will wear out the hole in the plastic. The Z bend tends to get less slop even over time. It works so well modelers have been using the Z bend sense time began. Like John I us an EZ on most of my throttle set ups on the servo arm. When it starts to loosen up you will notice a bit of trim change at idle.

glafond

Thanks again everyone, these are great ideas that I will utilize going forward. I'm glad I have my dremmel! I'm learning that there is a lot of leeway in a build even as simple as an ARF. Knowledge is power right?

Gray Beard

My Feedback: (-1)

Trick, you can buy a smaller chuck for your dremmel tool and it makes it a lot more versatile. I think the stock one is only for 1/8 shanks. The smaller one I bought for mine can take 1/16 bits. Having the shaft drive for your moto tool is a must.