So I'm to the radio installation part of my Sig Kadet Mark II. The plans call for a servo tray that came with my radio, problem is I don't have a complete radio system yet. Also it seems not many of them come with a servos anymore more or less a servo tray.. So should I just frame it in with some Pine 1/4" Sq. strips and call it good?

Also the plan calls for 1/4" Sq Balsa push rods.. Do you guys recommend this or should I look into a different type of push rod? Another booklet that came with the Sig kit is called "The Basics of Radio Control" says something about arrowshaft push rods.. Any ideas?

Thanks , Bill<br type="_moz" />

Most folks don't use wood pushrods much anymore. They prefer plastic pushrods like Sullivan or wire in a tube for a pushrod. My last three builds have all used the wood pushrods. They work just fine and cost almost nothing to make. I buy 5/16" dowel at home depot and use it for a pushrod. Its a little stiffer than balsa. I buy the threaded wire rods that are about 12" long and use these for both ends. The threaded end goes to the rudder/elevator and the smooth end to the servo either through a brass keeper with the set screw or a plastic keeper that snaps on a 90* bend through the servo arm. The brass EZ connects are what I use most.

To make the pushrods drill a hole an inch from the end. I like to groove the wood for the wire to sit in. You will have to bevel the hole for the bend in the wire. Now wrap the wire and push rod with strong thread. Coat the thread with epoxy and you are good to go. I have never tried it but supposedly bicycle spokes are 2/56 threads on the end. I have been looking for a junker bike at the curb but we have a scrap metal guy that goes around at daylight and nabs all the junk metal set at the curb. So I haven't tried that yet.

While you are at home depot go by the paint dept. and ask for some paint stir sticks. Get a couple of one gallon and a couple of 5 gallon sticks. These make excellent servo rail material. And they are free unless HD finally figured out I am not stirring paint with them. You can cut these into strips a half inch wide and glue a horizontal to the fuse sides and use these for cross members to mount the servo to. Be sure and leave a little space on the servo. Don't jam the wood up tight. You need to be able to rock the servo to get it in place.

They also sell yard sticks for about .60 cents that are a 1/4" thick. These also work for places where you need a piece of harder wood for bracing and other uses. You don't have to buy all your wood from a hobby store.

Thanks for all the info and tips!

Edit: One more thing, can the store bought ones like the Sullivan be cut for length? I'm totally new to this so Thanks again!
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Bill,

Most Sig kit instructions date from a time when you always got a complete "system" with TX, RX, servos, hardware and a radio tray. I'm sure revising them is on the new owner's "to-do" list. The trays usually were soft mounted to preserve the electronics of the day, mostly through-hole soldered that were prone to vibration damage.

You can make one from some plywood, or use 1/4" basswood as servo bearers. If you really want a tray, send me a PM and I'll mail you one.

The balsa pushrods work fine for what you're building. The only change I make to that design is to add some supports in the tail of the fuse so the 'rods can't flex. I'm not a big fan of the plastic pushrods, they have to be routed carefully to prevent flexing and can change length with temperature. FWIW, my 60 size Platt FW-190D9 has hard balsa pushrods....

Balsa push rods work fine but they may break. That happened to me on a Trainer. The plane went in straight down and engine, servos, and receiver were destroyed in that crash. I have changed to carbon fiber arrow shafts. They are light and do not break.

I much prefer to use hardwood pushrods, or arrow shafts or carbon fiber tubes for pushrods. Balsa was popular for pushrods in the past as with a trainer the pushrod would likely give and break before damaging the servo. Nowadays it can be hard sometimes to choose a good piece of balsa for pushrods as the stores may not have a good piece to use for that purpose. The balsa is hard and heavier than light balsa, almost like it is hardwood. So it is much easier to go with spruce or pine or something for the pushrods.

Servo trays don't usually come with radio systems anymore. The stores may or may not have them anymore in stock either. But it is quite easy to make your own though. I like to take two pieces of 1/8 inch model aircraft plywood and glue it together to make a 1/4 inch thick piece and then use this for the servo trays or servo mounts. The multi-layer plywood doesn't split easily, when you insert the servo screws, and is more stiff than the plastic servo trays. I usually cut out some 3/4 inch wide strips of 1/8 inch plywood and glue them together. Then later I cut them to length and mount the servos on them and glue the servos and wood into place in the fuselage.

Yes, the Sullivan push rods can be cut to length to suit the plane you are building. I would suggest going the Sullivan route until you gain further experience and find something that works best for you. After many years i still use them quite often. You really can't go wrong with the Sullivan push rods. Add some support to keep them from flexing and you are good to go.

Typically i use 1/4 X 3/8 bass wood as rails to mount the servos. Most any way you make the servo mounts is ok as long as you do use a hard wood versus balsa wood.

Trash the push rods and go with pull-pull. More reliable, lighter, no slop and neater installation. Works well on both elevator and rudder.

I usually make my own servo trays, I can customize them and build them the way I want to so that I can mount them a certain way or whatever the situation may be.

I got a trainer from my grandpa (years ago) that he had built, and it still had the old 1/4 balsa square pieces for the elevator and rudder pushrods. He put a coat of just plain fiberglass resin to make them fuel proof and stiffen them up, and they are still the originals today. So, I got balsa pushrods that still work great that are 20 plus years old, so there is nothing wrong with them.

I will agree with everyone else though,  don't use them, use pull pull or a sullivan or great planes pushrod.

Jason

I'm brand new so I'm not sure which pull pull system to use? Are they all about the same? I take it that I would still need two of the pull pull systems right? One for rudder and one for elevator.. How about when the rudder servo also operates the steerable nose gear?

edit: now that I look at the nose gear illustration in the plan again, it looks like it is an flexible cable hook up. I guess that means no to using a pull pull there.<br type="_moz" />