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10-31-2013, 07:01 PM
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Join Date: Dec 2006
Location: New Orleans, LA
Posts: 474
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Quote:
Originally Posted by HeliCooper
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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I would give Van's a call just to verify.
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Stoney
First RV-14 Flight 04/17/2016
Serial #140087, N214SW - Sold
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10-31-2013, 07:32 PM
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Join Date: Sep 2006
Location: Douglas Flat, CA
Posts: 589
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Quote:
Originally Posted by HeliCooper
...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...
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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.
__________________
Bob Kuykendall
HP-24 kit sailplane
EAA Technical Counselor
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10-31-2013, 08:30 PM
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Join Date: Jun 2013
Location: Des Moines, IA
Posts: 255
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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
Last edited by HeliCooper : 10-31-2013 at 08:37 PM.
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11-01-2013, 06:34 AM
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Join Date: Jul 2009
Location: England
Posts: 470
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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 ?? !!
__________________
Jan
Slooow RV6, no hole, builder in UK
Paid up for 2015 ...
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11-01-2013, 07:15 AM
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Join Date: Dec 2012
Location: Greenback, TN
Posts: 534
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Quote:
Originally Posted by HeliCooper
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.
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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.
__________________
Marvin McGraw, 5TN4
RV-14. #140039 Complete
Flight hours: 500+
2020 Dues Paid
The Dues Paid note is a reminder for me
Last edited by M McGraw : 11-01-2013 at 11:34 AM.
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11-01-2013, 09:41 AM
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Join Date: Jun 2013
Location: Des Moines, IA
Posts: 255
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Quote:
Originally Posted by JanRV6UK
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 ?? !!
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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.
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11-01-2013, 09:49 AM
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Join Date: Dec 2007
Location: Flagstaff, AZ
Posts: 2,653
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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.
__________________
Patrick Kelley - Flagstaff, AZ
RV-6A N156PK - Flying too much to paint
RV-10 14MX(reserved) - Fuselage on gear
http://www.mykitlog.com/flion/
EAA Technical Counselor #5357
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11-01-2013, 12:01 PM
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Join Date: Sep 2006
Location: Douglas Flat, CA
Posts: 589
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Quote:
Originally Posted by HeliCooper
...I assume the rivet hole needs to remain tight around the rivet...
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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.
__________________
Bob Kuykendall
HP-24 kit sailplane
EAA Technical Counselor
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11-01-2013, 03:23 PM
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Join Date: Feb 2008
Location: Pensacola, FL
Posts: 374
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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.
__________________
RV-? in planning stages.
RV-14 #140050 SOLD
Permanently willing to contribute fuel for RV rides
Helicopter ATP/CFI(I)
ASEL/AMEL Commercial/Inst/CFI(I)
Aerobatic Instruction available
Atlanta based.
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11-01-2013, 04:35 PM
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Join Date: Jul 2009
Location: England
Posts: 470
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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 ...
__________________
Jan
Slooow RV6, no hole, builder in UK
Paid up for 2015 ...
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