Dave Bernard

Dave Bernard

Active Member
Using the Vans method of #30 Countersink using a platenut as a guide, it sure didn't come out too pretty:

photo2_zpsceba649e.jpg


Pretty disappointed as from here on the mistakes start getting expensive! Anticipating me screwing this up, I only riveted one platenut on to try this method. Did about 5 hours of research about this hole prior to cutting it- High anxiety!

Since this is just a hole for a dimple, should I switch to the other method (backing bar w rivets and #30 guide hole) or do the hole just come out like this sometimes?
 
Dave it does happen some times, but technique is a big factor.

Do not use an air drill.
Do not turn the cutter fast.

Use a good cordless drill with good torque.
Make sure the countersink cage is set up properly by testing on scrap and to practice your technique.

Use a lot of pressure and slow speed (not ultra slow... you will learn with practice). If the drill has selectable speeds, use one of the slower ranges so that you can run the motor at full.

The slower speed with a lot of pressure will minimize the likelihood of cutter chatter.
 
Heck with the nutplate method... grab a piece of .060 or heck even 1/8" bar stock and drill it up with the correct drill size. Use the rivet holes for a neighboring nutplate to drill and cleco the piece on the back side and then Countersink the spar. You will have a few different patterns... Check and set the plate up for each hole. The countersink will be clean and smooth... oh and very hard to make the countersink chatter. You will be extremely pleased. :)
 
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What Riley said. A good thick piece of metal on the back side to hole the guide in the countersink will prevent this from happening. If you look at the hole in your countersink, the hole is enlarged so nothing holds the guide point anymore.
 
As always, there are a lot of different ways to complete a process... some take a lot more time and effort than the one described in the manual, which does work well, if the proper technique is used (and some lubricant that I forgot to mention... thanks Walt).
 
CharlieWaffles said:
What Riley said. A good thick piece of metal on the back side to hole the guide in the countersink will prevent this from happening. If you look at the hole in your countersink, the hole is enlarged so nothing holds the guide point anymore.
Click to expand...

Mark is correct, using the nutplate method your nice facory hole will end up way oversized. For me it is all about quality and sometimes it can take a little more time but the end product is well worth it. :)
 
LifeofReiley said:
Mark is correct, using the nutplate method your nice facory hole will end up way oversized. For me it is all about quality and sometimes it can take a little more time but the end product is well worth it. :)
Click to expand...

I disagree...
I have at least 10 sets of wings using the described method (install the nut plate first, and use the proper size pilot, and turn it slow).
 
If you're using a 3flute cutter for your regular rivet countersinks, don't look at a magnified pic of the countersunk holes....

Charlie
 
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LifeofReiley said:
Heck with the nutplate method... grab a piece of .060 or heck even 1/8" bar stock and drill it up with the correct drill size. Use the rivet holes for a neighboring nutplate to drill and cleco the piece on the back side and then Countersink the spar. You will have a few different patterns... Check and set the plate up for each hole. The countersink will be clean and smooth... oh and very hard to make the countersink chatter. You will be extremely pleased. :)
Click to expand...

Here's my take on LifeofReiley's technique, except that I used cleco clamps instead of adjacent nutplate holes to secure the 0.125 pilot plate. I used shortened rivets taped into countersunk holes in the plate to locate the pilot hole accurately. The photo shows the setup for the #6 holes for inspection covers on the aft edge of the flange. I also had one end of the plate set up for #8 tank screw holes (results shown on the forward edge of the flange).
FP28042012A0007G.jpg
 
longranger said:
Here's my take on LifeofReiley's technique, except that I used cleco clamps instead of adjacent nutplate holes to secure the 0.125 pilot plate. I used shortened rivets taped into countersunk holes in the plate to locate the pilot hole accurately. The photo shows the setup for the #6 holes for inspection covers on the aft edge of the flange. I also had one end of the plate set up for #8 tank screw holes (results shown on the forward edge of the flange).
FP28042012A0007G.jpg
Click to expand...

Miles,

Your system should work great! I just elected to have a cleco on the holes for any possible movement. (Slip) I also ream fit my template hole for a tight fit and a beautiful finished sized hole in the countersink finished product. :)
 
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