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First step in and having trouble
I am trying to countersink the VS-702 for the VS-01401 doubler. The problem I am having is I cannot get the sink deep enough before the hole enlarges. What am I doing wrong? I have already reordered the VS-702 as the first countersink enlarged the pilot hole and then wobbled badly. I then tried countersinking with the deburring tool. With the rivet still sitting just proud of the surface the hole is already starting to enlarge.
Not a fantastic start to the project. |
How thick is the part you are trying to CS ?
Can you not dimple it ? If you put a scrap part on the back to act like a guide for the CS tip then you can CS the part with no "wobble" .. assuming CS is what you have to do ... |
The vinyl didn't have a thickness on it and I haven't built enough to know the thickness. I also don't have a caliper. It says specifically in the instructions to CS so that is why I was attempting that.
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Edit add: The plans and parts lists will usually tell you what the part thicknesses are. If it's 0.032" thick, you can just barely countersink it for a #3 (3/32") rivet, but it's much safer to dimple it. Any thicker and you should be able to safely countersink #3. Any thinner and you have to dimple for #3. Unless you have a well-developed eye for material thicknesses (which you will have by the time you finish), I suggest you buy a cheap digital caliper (usually $15 at VXB) and get a drawer full of batteries for it for $10 on eBay. Thanks, Bob K. |
Plans don't list the thickness and it isn't in the parts list in the manual. There were only two VS- numbers. I'll definitely have to go pick up a caliper. I figured if Van's specifically said to CS it should be CS. I guess I figured wrong. The microstop is set perfectly as far as I can tell. The rivet sits flush on my scrap piece I used to set the depth but the scrap piece is also thicker. I will plan on dimpling it and the doubler plate when the new piece arrives.
As for having the correct spot. I quadruple checked and they want you to CS the back side of the vertical spar on the opposite side of the doubler. I assume this has to do with clearance for when it is attached to the fuselage. |
I always test the setting of the cage on scrap pieces of the same thickness. Keep playing with the cage until it is absolutely perfect. Another trick is to CS on a piece of wood with a matching hole in it. If your piece has multiple holes in it, Cleco it down to the board and match drill the board so the rest of the holes line up. Helps hold the die in place and prevents wobble!
What Bob K said and you really need calipers! |
What Paul said - clamp some scrap behind the piece and match drill into or thru it, to give the countersink guide more stuff to pilot off of.
Also, are you using a high speed air drill? I've found low speed drills tend to wander more (in aluminum), although this could just be my poor technique. |
I did something similar to Paul's suggestion for counter sinking all the holes in the spar flange. I used a 1/8" thick 1" wide 36" long piece of aluminum. I clamped it to the flange and then match drilled it along the entire 36" length. I match drilled part way through, then finished on drill press. I then clecoed the support metal to the flange and then counter sunk. This solved my wandering bit when counter sinking. No more enlarged holes.
I can post a picture of what I did if this description does not make sense. |
One other thing, make sure you're working with the right size rivets. If you're drilling and countersinking for #4 rivets where you should be using #3, you can pretty quickly knife-edge the hole. For a #4 rivet, I think that you can almost-but-not-quite countersink 0.040", and the thinnest stock you can countersink properly is 0.050".
Bob K. |
I triple checked I was using the #40 CS. I think tolerance is just too close. Going one turn at a time I used just a deburring tool and even with the head still just proud of the surface the hole was starting to enlarge. I had to do this because two of the holes were too close to the flange to use the microstop. I am going to dimple it. Thanks for the suggestions on CS in the future though. I will definitely remember them.
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