HS-710 Countersink Depth

[Golf Echo]

Another day, another "oops"...

Because of insufficiently squeezed dimples, I've managed to countersink my HS-710 too deep by guessing and testing a few too many times . I re-squeezed the dimples and it fits better, but it's definitely too deep. Since Van's support isn't open on the weekend, I figured I'd ask the question(s) here first. How deep is too deep? Do I need a new HS-710?

Here's a picture of the rivet sitting directly in the countersink. The rivet head sits 0.025" below the surface. According to my [possibly incorrect] math and assumptions here, I think it should only sit 0.010" below the surface. So, I think I'm 0.015" too deep.

Thoughts?

 

[rapid_ascent]

I can't say how deep is too deep, but personally I would just order a replacement and chalk it up to part of the learning experience.

There will be many times in your build when you have to make a decision on what is good enough. This one can be easily fixed. Some of the later ones may not be so easy.

My method of ordering parts from Van's is to keep going on other parts that I'm not being held up on in case I need to order other bits and pieces. This keeps down on the shipping charges. Most of the parts are pretty cheap you end up paying mostly for shipping.

 

[wjb]

Welcome to the RV club! I'm just a bit ahead of you on my empennage -- I just finished dimpling the rudder skins!

This dimple-fit issue has bugged me from the start, esp when you use a die on both sides of the joint ... for example on the the 0.032 HS skins and the 0.040 spars or 0.032 ribs. It seems like the inside dimple should be bigger to properly nest the outside dimple. It's clear that the skin stretches a bit when you dimple (maybe more when you whack it the c-frame), and they do seem to fit well when the rivet is driven.

I did a similar set of calculations - the "as riveted" results are a bit different from theory (both sides deform a bit as the rivet is driven) It sounds like some "lab" tests are in order to find the best depth.

 

[Golf Echo]

Welcome to the RV club! I'm just a bit ahead of you on my empennage -- I just finished dimpling the rudder skins!

This dimple-fit issue has bugged me from the start, esp when you use a die on both sides of the joint ... for example on the the 0.032 HS skins and the 0.040 spars or 0.032 ribs. It seems like the inside dimple should be bigger to properly nest the outside dimple. It's clear that the skin stretches a bit when you dimple (maybe more when you whack it the c-frame), and they do seem to fit well when the rivet is driven.

I did a similar set of calculations - the "as riveted" results are a bit different from theory (both sides deform a bit as the rivet is driven) It sounds like some "lab" tests are in order to find the best depth.

I agree with you on the "dimpled skin to dimpled skin" fit. I ordered a set of 3/32" sub-structure dimple dies from Cleaveland Tools for this. The sub-structure dies are a bit deeper to allow a perfect nesting of parts. I plan on using them everywhere dimpled skins nest into dimpled ribs/spars/etc. Give them a try... I'm happy with the results.

Mike at Cleaveland also custom made a small-diameter 3/32" female die for me to use on the stiffeners.

As a side note, I countersunk the other 3 holes in HS-710 and HS-714 to a depth of 0.010" below the surface (as calculated). I'm very happy with how that goes together.

 

[Golf Echo]

As a follow-up to my original question in case anybody comes across this in the future...

I received word back from Van's that replacement of HS-710 is not necessary. "Build on."