We all know that to make servo mounting holes tougher we should put thin CA into them and let it dry before we insert the screws. I always assumed that you should:
1. Drill the hole
2. Screw in the screw
3.Back out the screw
4. Then put in the thin CA in that order.

My latest ARF kit says to put the thin CA in BEFORE you ever thread the holes with the screws. It seems to me that you want the threads in thereBEFORE you harden up the hole so this seems backwards to me.

Am I correct? Why would this ARF say to do this?

You are correct. I'm not sure why the instruction manual told you to put the screws in and then CA, but that's not a good thing to do. I you do that they screws will more than likely become permenant and you will not be able to remove them later. Follow your own instruction for applying CA to the the screw holes after you cut threads into them. But do not put the screw in until the CA is completely dry, otherwise you will have the problem in talked about above with the screws becoming permenant.

Hope this helps

Ken

I've always done the tap, remove, CA and then reinstall the screw.  I don't know that CA will penetrate the full depth of a servo screw from the surface.

Mine never stick if I ca first.

On the bigger nicer planes I do all the above steps, but on bashers, trainers, etc., I don't worry about it any, and they always come out.

Best to get in the habit of above though.

Thanks for all the advice!!!

RCKen.....just to be clear.....theARF kit I am talking about (Hanger 9 Fokker)does nottell me to CA in the screws. That was not what I was trying to say above. It says to CA the drilledholes and let them dry before I ever tap them with the screws. (You may have a typo in your response but I think we are on the same wavelength here.)

My concern was that every other build thread and manual had you tap first, then CA the hole. <now body="" confirmed="" guys="" you="" correct...and="" sound="" this=""></now>

my concern is that if you hardend the wood before tapping, you'd run the risk of the threads not being able to cut deep enough into the wood and the screws won't hold very good, my 2 cents

If you were actually tapping it probably wouldn't matter. The CA penetrates farther into the wood than the threads do (unless it's hard plywood) so it's a non-issue how you do it. But pressing in the threads with the screw you're actually breaking the hard surface that the CA creates.

I agree completely.

I wonder why the ARF manual has you do it the other way? Oh well....probably lost in translation.

That's why proofreading <u>used</u> to be a career choice.

I would imagine that the CA first advice is a result of observations.

If you install a screw into a small hole first, you are effectively squeezing the wood along the sides and at the same time burnishing it. This would make it more difficult for the CA to penetrate the wood itself or at the least making the penetration more superficial.

The uncompressed wood, might be more prone to soak up thin CA.


Whenever I'm working with screws going into soft balsa ( not ply ) I put CA on FIRST to assure maximum absorption.

With ply I do the exact opposite, putting in the screw first, backing it out then applying CA.

I agree with opjose It depends on what wood you using not everyone uses plywood or hardwood servo bearers.

I use balsa sticks for servo bearers in many installation and I generally will coat the spot with thin CA first to harden the surface then pilot drill and run the screw in.

John

WOW! I love this forum. I never would have guessed this technique.

So to get it straight...

1. Hardwood or Ply: Drill, Tap, Remove, CA (let dry), Install Servo

2. Soft Wood or Balsa: Drill, CA (let dry), TAP &amp; Install Servo

Probably either way would work just fine but I love the thought processes! 

I have often used CA in the drilled hole before I ran a servo screw in and out. Usually by mistake or a brain fart. It isn't really wrong but the problem is by doing it first the screw doesn't want to cut the threads in that hardened wood. I end up doing a lot of grunting and groaning and turn my shop blue with my language. Screw in and out first then CA. Often the screw is still tight going in and out this way too because the wood swells a bit with the CA.

I have always found I got the best results (this is for 4-40, 6-32, 8-32 and 1/4-20 size bolts) by first drilling the proper size hole, run in the tap, remove tap and apply CA, give time to set up CA, retap and then insert bolt.

That's what I do but in this case it is servo screws so the screw is the tap. I also do the same thing as John when using balsa servo mounts.
I was just out taking my gear out of a plane I'm giving to someone and I took note of the servo screw holes I made years ago, everyone one of them was in nice shape and the servos were all nice and tight.
This just proves, even a blind hog finds an acorn once in a while!!