Robert M

Robert M

Well Known Member
The instructructions say "Disassemble the aileron. Deburr all of the aileron parts. Machine countersink the A-903 spar flanges (this will prevent bowing the spar that can be caused when dimpling since it is .040 “thick),...."

Well, I followed the plan and using the scrap template as a guide allowed me to countersink too much. I've ordered another pair and I'm going to dimple them using a narrow female dimple. Then take a bit more with a deburring countersink. This is the same process I used for the wing rear spars - I think Van's recommends this method.
 
me too

I've posted this before, but I too followed the instructions and trashed my ailerons - I ended up trying to save them and made it worse. Finally gave up and ordered a new set. The plus side was I got a really cool wooden crate :D

As a rule, I now dimple anything 0.040 or less. Works perfectly fine with cleaveland narrow dimple dies and pneumatic dimpler. The skin dimples nestiperfectly without any additional countersinking or deburring. I think this is stronger than machine countersinking such "thin" parts. I did this for rear wing spar, aileron spar, flap spar.

Good luck!
 
Thanks for the tips. I just started deburring airleon and flap parts and this would be ahead soon if weather will not allow priming for a while...
 
Don't use a dimpled scrap for a gage.

In the manual, section 5, page 4, it states:

"Use the appropriate rivet or screw as a gage when you machine countersink. When the rivet/screw is flush, you are done. If there is going to be a dimpled skin riveted onto the machine countersunk surface, adjust the machine countersink tool a few ?clicks? deeper than flush. This will make the rivet/screw sit about .005? below flush when dropped into the hole."

If you use a dimpled piece of scrap material, the dimple (and the hole) will most always come out oversize.

Bruce Reynolds
Rv-6A
 
Bruce Reynolds said:
In the manual, section 5, page 4, it states:

"Use the appropriate rivet or screw as a gage when you machine countersink. When the rivet/screw is flush, you are done. If there is going to be a dimpled skin riveted onto the machine countersunk surface, adjust the machine countersink tool a few “clicks” deeper than flush. This will make the rivet/screw sit about .005” below flush when dropped into the hole."

If you use a dimpled piece of scrap material, the dimple (and the hole) will most always come out oversize.

Bruce Reynolds
Rv-6A
Click to expand...


Thanks Bruce

I’m sure it says that, however on page 7-12 of the instruction manual it also says, (somewhere about the middle of the page) …….

“Disassemble the Aileron. Deburr all of the aileron parts. Machine countersink the A-903 spar flanges (this will prevent bowing the spar that can be caused when dimpling since it is .040” thick), the 3/32” rivet holes in the A-908’s, and the A-911. Use your dimple test patch to adjust the countersink tool for the A-903 and A-911."

The “dimple test patch” was something I created back during the tail section build from the scrap pieces provided. I, as did others, followed the instructions and countersunk too deep because they recommended using the dimple test patch. There should be a little warning or reminder added to the instructions. They put in reminders for less critical items!

A little later in the instructions (page 7-13, above the word FLAPS) Van’s put in a reminder to scuff the powder coated parts (if they are to be painted) and yet no reminder about the possibility of over countersinking. This is gonna sound cynical but, Van’s has given a reminder to do something that, if not done correctly, will in no way generate further income for them. However, they have no reminder about possibly screwing up a part or two that you must replace if not done correctly. And who do you have to go to for replacements? Yup, that sure sounds cynical!

Now please don’t go yellin’ at me ‘cause I did a little Van’s bashing, I’m just being me and me is opinionated. Besides, lesson learned and the cost was minimal. Having never built a plane before - I gotta go by the instructions.

But thanks again. I'll go back and review all that information to refresh my memory.
 
Vans method is fine

The trick here is not using a gage to determine the depth of the countersink but support for the pilot of the cutter. What I did and YMMV was take a small piece of 1/8 " thick aluminium angle, about 3" long, and locate a #40 hole near the edge of the vertex of the angle deep enough for the pilot so it can be lined up underneath the hole in the spar flange that is to be countersunk. This supports the spar from flexing and guides the cutter so it cannot wander and cause the hole to become enlarged. Then I clamped it in place and countersunk the hole and used a rivet as my depth gage. Set depth of microstop to 1 click below flush of rivet head. Used hand drill in place of drill press. Dimpled leading edge and trailing edge skins on both ailerons and flaps. Really not that much different from countersinking holes in tank skins where it is riveted to the rear baffle plate except the baffle was my guide.

Another method I've heard of but chose not to use in this application was to countersink the spar with the trailing edge skin clecoed in place but not the leading edge. Here the trailing edge skin adds thickness and even though the hole in the trailing edge skin is opened up, it would be firmly held in place by the dimple of the leading edge skin.
 
Rivet Length Change

Should anyone out there decide to follow the same procedure that I did (and I'm not recommending you do), just dimpling the material will require the use of a longer rivet. Since no material was removed when I dimpled, I had to go with a longer rivet to ensure proper shop head size and depth.

FWI
 
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