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-   -   How to countersink these holes? (https://vansairforce.net/community/showthread.php?t=199906)

ravenstar 10-07-2021 05:09 PM

How to countersink these holes?
 
2 Attachment(s)
Well, I promised lots of questions a few months back and my first RV-12 kit finally arrived and it hasn't taken long for me to run into my first puzzle: I can't figure out how to do countersink a hole in tight quarters. On page 06-04, step 3 the instructions innocently say to countersink four holes, but two of the holes are next to a flange and my 1" diameter countersink cage doesn't come close to fitting. I don't see any narrower cages online, and I haven't found anyone else mentioning this problem. So how did you all manage to accomplish this step? I've attached the plan diagram and a photo of the actual part. The holes in question are 1/4" away from the flange.

Am I missing something obvious?

Thanks!

TX7A 10-07-2021 05:15 PM

You could use one of these. (without the cage)
https://www.browntool.com/Listview/t...1/Default.aspx
Get a threaded extension for your drill. Go slow & use Boelube.

wirejock 10-07-2021 05:57 PM

Threaded drill bit adapter
 
This little adapter is very handy. Same thread as all the other tools. 1/4-28
https://www.yardstore.com/1-4-thread...-drill-adapter
Chuck it in the drill press. Thread the countersink cutter and very carefully cut the countersink.

ravenstar 10-07-2021 06:31 PM

I knew it was something obvious. (What do you mean a tool can be used for two different purposes?)

Thank you all!

wirejock 10-07-2021 07:29 PM

Adapter
 
Quote:

Originally Posted by ravenstar (Post 1560510)
I knew it was something obvious. (What do you mean a tool can be used for two different purposes?)

Thank you all!

Well. Any 1/4-28 threaded tool can be used in a drill. Imagination.
I also threaded the shaft on my 90 degree adapter. Now it can be jsed as a 90 degree deburring tool by threading it onto the speed deburring handle. Very handy for deburring rib holes.
https://drive.google.com/file/d/0B7h...CjF_k4OrKfi3kA

rv9builder 10-08-2021 01:42 AM

If I remember correctly, I did this step by hand using this speed deburring tool.

https://www.aircraftspruce.com/catal...s/speeddeb.php

Instead of using the hole deburring bit that comes with the tool, I used the same countersink cutter that I normally use with a countersink cage. It takes about a minute to countersink each hole, and you can stop turning the handle for a few seconds to check your progress. Practice on some scrap to get the hang of it, but itís really pretty easy.

ravenstar 10-08-2021 06:32 AM

Quote:

Originally Posted by rv9builder (Post 1560591)
If I remember correctly, I did this step by hand using this speed deburring tool.... Practice on some scrap to get the hang of it, but itís really pretty easy.

I have a similar tool so I popped in the countersink bit and drilled those holes in no time. Thanks! I think I prefer the hand countersinking for the control it gives me. I feel silly for not thinking of this myself.

rapid_ascent 10-08-2021 09:47 AM

I think most people would drill this countersink by hand in some way without a microstop countersink. However, just to put out all the options there are microstop cages available that don't have the full 360 degrees enclosed. There are a few different configurations. The one I'm thinking about only has half a cage so it might work in your situation. BTW I don't have one of these.

RFSchaller 10-08-2021 09:47 PM

I canít remember this part. Itís been almost 9 years since I finished my build, but hereís a stupid question: which way is the angle pointing, toward or away from the viewer? Isometric drawings can be confusing. Check the context in which the part is to be used to be sure ou have the correct side to countersink.

tyconnell 10-08-2021 10:40 PM

with an adapter, countersink bit in a drill press (no cage). the drill press has it’s own depth stop mechanism. a little fiddling with depth using scrap, but worked well for me.


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