Priming inside W-716 aileron push tubes

[John Courte]

Apologies if this has been answered already, but my search-fu is weak this morning.

Is it OK to prime the insides of the W-716 push tubes (and any other control tubes for that matter) with a cylindrical brush attached to a dowel? I stopped halfway through designing an odd system of tubing and lawn irrigation parts and realized there must be a better way. I'm using SEM self-etching primer, and I've noticed that if the stuff gets laid on too thick, it tends to flake and detach. The recommended methods for doing the push tubes involve spraying a bunch of paint in each end and rolling the tube around for coverage. Sounds to me like this would have a lot of excess paint in there, leading to the condition described above. I figure with a brush and a slightly thin solution, I can get coverage without making a mess or worrying about the paint flaking off.

Thanks in Advance,
-John

 

[JonJay]

If your primer is "flaking off" something is not right. You either are not getting your part clean before priming or you need to find a different product. I used Sherwin Williams self etch, same stuff Van's uses, and it calls for a 4 mil thick coating. That is really thin. However, if you put it on too thick, it still did not flake or do much of anything bad.
I "fogged" the inside of mine with a paint gun shot right down the tube. It did fine.

 

[John Courte]

I've only had the flaking happen a couple of times, but I assumed it was because of thickness. Not getting the part clean is more likely a culprit.

When you say you fogged it with a paint gun, that means sticking the nozzle of the gun into the tube and pulling the trigger for a while? How did you have your spray pattern set?

 

[JonJay]

I've only had the flaking happen a couple of times, but I assumed it was because of thickness. Not getting the part clean is more likely a culprit.

When you say you fogged it with a paint gun, that means sticking the nozzle of the gun into the tube and pulling the trigger for a while? How did you have your spray pattern set?

Yes - frankly too long ago to remember but I dont think it matters much. For this, I would us a regular gun, not an HVLP. Overspray is what you are after, hence my term "fog". You will be surprised at the amount of "fog" that exits the tube. I did this only on the aluminum tubes like your aileron push tubes. On steel tubes I poured epoxy primer into the tube and sloshed it around. I am not a fanatic about priming and believe that you could not even do the aluminum push rods and be just fine.

 

[jsharkey]

I cleaned the inside of the tubes with acetone pulled through with a rag on a string. I then plugged the end and poured in some Dupont VariPrime, swilled it around and let the excess drain into a cup. Seemed to work well. There is no action that will damage the paint in service - its shut up inside the tube - and in my experience VariPrime is near bullet proof, much better than the grey Marhyde rattle can stuff that I sometimes use for convenience.

 

[John Courte]

Thanks for the info! I'll probably wind up doing the paint gun method, since I've got one laying around.

Would MEK be a suitable substance to clean the inside? And do I need to drag a wad of scotchbrite through there as well?

 

[JonJay]

Thanks for the info! I'll probably wind up doing the paint gun method, since I've got one laying around.

Would MEK be a suitable substance to clean the inside? And do I need to drag a wad of scotchbrite through there as well?

You can use MEK, but it is expensive and pretty much overkill. I use a good Degreaser/Wax remover called PrepAll. You do not need to scotch bright it but you will want to drag a rag through a few times. You will know when it is clean when the rag comes out without any gray matter on it. Soak your rag, wad it up, stuff it in, and blow it out the other side with your airgun.
By the way, many self etching primers offer little corrosion protection. Not sure why I even bothered.

 

[Bruce]

John,

I did the scotchbrite method and used mek. Roll the scotchbrite 1/2 pad up and push it through a couple of times with the broom handle and then clean with mek and then I sealed the ends and poured 1/2 cup in the tube and let it go. Worked great.

 

[IowaRV9Dreamer]

what about use rattle can people?

How can I prime the inside of these tubes using the NAPA rattle cans? Just spray a bunch in and hope for the best?

Thanks!

 

[Ironflight]

trick...

How can I prime the inside of these tubes using the NAPA rattle cans? Just spray a bunch in and hope for the best?

Thanks!

I learned this SOMEWHERE, from someone when I was building - hold the rattle can and your air nozzle up to the open end of the tube, spray primer and air at the same time - watch how much primer comes out the far end with the "air assist"...shoot plenty, and you should get a coating.

Paul

 

[N941WR]

How can I prime the inside of these tubes using the NAPA rattle cans? Just spray a bunch in and hope for the best?

Thanks!

Dave,

This is easy. Buy one of these handles for spray cans. Shake up the can like you would if you were going to use it. Turn the can upside down and rubber band the trigger and leave it upside down. When it is done letting all the pressure out, drill two holes in the top of the can.

I capped one end of the push tube with plastic wrap and a rubber band. Poured the paint in, capped the other end and swished it around. This worked but is a bit messy.

One other thing, make sure the can is completely depressurized. Otherwise it is possible to turn a nice yellow DeWalt drill gray. Just ask me how I know.

 

[rjcthree]

Good ole' rustolium?

I MEK'd with a paper towel and then did the slosh/drain method with a rustoluim enamel cut with acetone(per instructions). Good bond, comes in quarts and spray, the 'satin' finish seems to be the best comprimise of dry time vs toughness. I know it's not a 'aircraft specific' product, but . . . .T6061 is pretty corrosion resistant stuff on it's own. I'll paint the outside with the same, as I did with the inside/visible ahead of my landing light windows. Rick 90432