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First step in and having trouble

HeliCooper

Well Known Member
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.
 
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.

One thing to consider is, are you sure you are countersinking the correct part? There are a lot of parts where you countersink the thicker part and the dimple the thinner one so that it fits into the countersink.

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.
 
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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.
 
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.

I would give Van's a call just to verify.
 
...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...

You might check the angle on that deburring tool. I think that a lot of deburring tools have an included angle of 90 degrees to put a nice chamfer on a hole, while MS20426 countersunk rivets (and the countersinks for them) have an included angle of 100 degrees. If you use a 90-degree tool to countersink for a #3 rivet, I think you'll knife-edge and enlarge the hole in any sheet thinner than 0.038" before the head goes flush. And though you won't see it by looking at the top of the head, the cones of the hole and the rivet won't really fit together right. I don't know what the angle of your deburring tool is, but it would probably be good to check.

Thanks, Bob K.
 
HaKaqk2l.jpg


Here is a picture of the hole with a rivet inserted backwards. This was using the deburring tool and the rivet will still sit proud of the surface. You can see that the hole is already starting to enlarge. It is a 100 degree hex deburring tool in a small low speed electric drill.

Edit for added picture
 
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Ok .. I have gone wrong with the English vs American before … :)

But thinking a bit more about this … “Counter Sink” question .. does not tell you how to do it … Just what you have to do ..

You can Dimple CS OR Machine CS … Does the manual for the 14 make this distinction ?? Or do I make you even more confused ?? !!
 
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.

HeliCooper,

I believe you are referring to Page 06-02 Step 6. Part VS702 and part VS01401 are each 0.032 thick. I clecoed them together to give the countersink pilot more grip. Drilled a 2x4 with the hole pattern and clecoed both parts to the board. Slid two pieces of .032 scrap up to the edge to let the countersink lay flat and performed the countersinking of the four holes (the two outboard holes conflicted with the width of the countersink cage, I did those with a deburring handle and a piloted countersink cutter). The reason that bottom row needs to be countersunk from the backside is so that the front spar will fit over part number VS01402 on page 11-08 Figure 1.

I chose to countersink as per the plans; however, there is no conflict with dimpling as shown in the figure referenced above. I will say, I suspect Van's prefers a countersink because the edge distance for that row is 0.218 rather than the 0.025 to 0.030 edge distances of the rest of the Vertical Stabilizer parts.

Marvin

NOTE: The edge distances as measured are actually from the hole centerline, not the edge of the hole.
 
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Ok .. I have gone wrong with the English vs American before ? :)

But thinking a bit more about this ? ?Counter Sink? question .. does not tell you how to do it ? Just what you have to do ..

You can Dimple CS OR Machine CS ? Does the manual for the 14 make this distinction ?? Or do I make you even more confused ?? !!

The plans actually specify Machine CS. That being said I did contact Van's and they said that it could be dimpled. I re did the CS on my now piece of scrap 702 with the doubler attached. This helped alot. The rivet sits flush, there was no wobble, but when you take the doubler off and insert the rivet backwards again you can see that the hole enlarged. Is this acceptable to some standard. I assume the rivet hole needs to remain tight around the rivet. Additionally there were no score marks on the doubler so the CS did not get to it.
 
You seem to have figured it out already, but always countersink with a guide piece unless the part you are countersinking is very thick. If the part doesn't nest to a doubler, like the part you are discussing, then I drill it to a piece of wood and use that for a countersinking guide. If the countersink is deep enough to let the pilot protrude through the other side, there is a danger that you can tip the countersink, causing an oblong countersink and possibly an enlarged hole. The cage does not fully prevent this, so having a guide hole behind the part will improve your odds.
 
...I assume the rivet hole needs to remain tight around the rivet...

That's kind of true, but not an absolute. When you dig into it (AC43.13 is a good resource for this), you find that there is rather a range of acceptable hole sizes for the various rivet sizes. The key here is that driving a rivet compresses it lengthwise and expands its diameter, so within limits the rivet expands to fill the hole it's in. The "official" hole sizes in AC43.13 are pretty conservative, and I've seen some pretty oversize holes filled acceptably with good riveting technique. Not that I recommend it; I'm just observing that it can be done.

Thanks, Bob K.
 
CS Cage

All mechanical items have SOME tolerance. I purchased two identical cages at the same time from the same supplier and one is fine while the other is not. The bottom bearing has obvious slop in it (this can be felt as a rough feeling when turning the spindle by hand). This was enough to enlarge the bottom of my CS holes just enough to make me move from a -3 to a -4 rivet in my spars (per contact with Vans). I realized too late (after successful practice on scrap) that my cage was to blame.

I would check to be sure this is not the problem or similar...I assume you used a cage first then did it by hand to go a little deeper? If you never used a cage because you couldn't fit it in there, even a few degrees from "normal" to the surface might explain the hole enlargement.
 
If you are not able to get your full cage cutter in a tight corner .. just get a grinder out and 'trim' the cage a bit . you can even buy them with 1/2 cages for close quarter work ... Go on eBay and buy a few second hand ... I bought several of eBay and find it easier to have them set up for each size... Get a US made .. not China clone ... then trim one back to 1/2 cage ... great time saver to have them set up for the right size ...
 
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