V

vernhendershott

Well Known Member
I have just noticed that the screw holes that are dimpled for number 8 countersunk screws are starting to crack, The most forward and most right hole is cracked from the hole through all the skin to the lower edge and another has a crack that has progressed from the hole to the edge of the dimple.

It would seem that these holes and dimples are just to large for this thin material. You may wish to inspect yours, particularly after the skin has been screwed on.

I will ask Van's some day but for now they are not able to address older problems so there is little point in new problems.

Best regards,
Vern
 
Cracked #8 holes

Old topic but I found it via the search button.

I also have the same problem now with the #8 dimpled holes in the F-1204 top cover. I didn't notice it when the holes were dimpled, but it became visible today when I was priming the parts. The (small) cracks are till halfway the dimple starting in the hole. I did debur the hole and the dimple #8 did fit well in the prepunched hole.
Also the compressor went up in smoke, what a fun today :(

Vern what was Van's reaction?
Enlarging the holes will stop the cracks but that doesn't seem a good solution to me. Ordering new parts will do better with the risk that I have the same problem with the next skin.
 
Gagarin737 said:
Old topic but I found it via the search button.

Vern what was Van's reaction?
Enlarging the holes will stop the cracks but that doesn't seem a good solution to me. Ordering new parts will do better with the risk that I have the same problem with the next skin.
Click to expand...

They did not have anything to suggest and indicated it is just poor workmanship on our part.

Best regards,
Vern
 
Great, The only thing I can think off is that the temperature was low (50F) during dimpling. 20$ to replace the part, 100$+ shipping (Europe and my finish kit is just sent to me).
There are a lot off topics about cracking when dimpling #8 screw holes, guess we are not the only one.

What did you do different on the replacement part to avoid cracking?
 
If I remember correctly, there was a post a few years ago about cracks in fuel tank skins caused by #8 dimple dies. One proposed solution was to use the next size larger drill bit to enlarge the holes before dimpling. I couldn't find the post in the archives, but perhaps someone else will know if this idea actually solved the problem. If you're ordering a new skin, you could drill some test holes in the old skin to see if this works.
 
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As the holes are punched by Van's at the factory drilling new holes as a test may not provide valid data. Using the next numbered size reamer to clean up the stress risers from the punch may help but it will not change the hole being to large to near the edge of the material.

Best regards,
Vern
 
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