Rivet removal holes - Look ok to keep going?

I had a problem yesterday with riveting the HS-714 spar piece. I was using the pnuematic squeezer and must have had a problem with the lip sticking up and rivets didn't seat very well. I tried to remove them and had a bunch of problems.
I practiced with about 10 rivets and scrap metal and figured out that I was doing the following wrong:
- Didn't drill deep enough
- When the drill goes in crooked, simply aim toward the center
- Drill SLOW
- Start with small bit, then go bigger.
- Don't be afraid to give it some firm whacks to pop out rivet - with good support underneath!

I do learn from my mistakes, and spend a few hours last night cussing at it. After practice, I had each of them out (from the shop end) in just a few minutes!
So, I have three holes that are kind of ugly right now, and wanted some opinions if this seems ok to build on with these.

You can see that I missed the center of thee rivet (and lack of practice) and dinged the edge of the holes. I cleaned up the rough edges with a little deburring and scotch-bright. I'd like to spray a coat of primer on again and move ahead. Just wanted to see what you guys think of my mess if there are any suggestions. The holes other than the outer part are still round, and the rivets have a good fit still.

Thanks again for the help, this forum has been excellent!

Tom
RNT, WA

I am not sure what we am seeing here. It appears, appears, that part of a rivet is still in the hole. Surely is is optical, as a crescent shaped residual would have fallen out.

You clearly have the removal process down. I have to relearn it periodically.

If it is just a mark, the fine sanding and and building on would be my 2 cents.

The rivets are completely removed. The part you see is a crescent of where I miss drilled the rivet head and hit the edge of the hole. The mis-drilled areas are not very deep and it is thick material at that point. I'm pretty sure it's okay to send it down or polish with Scotch-Brite and build on. As you see in the photos I already smoothed it down with Scotch-Brite. I will re-prime the area and try again!
I feel I definitely learned from this mistake. After experimenting and practicing on about 10 rivets and scrap metal, I think I have the procedure down a lot better now!

rivet help

I'm no expert but they look ok to me. I would suggest a few things.
If you don't have a spring loaded center punch it really helps to get a punch mark on the rivet head for the drill. I know they have that little dimple but they never seem deep enough to keep the bit from wandering.
I usually drill with the same size as the hole but stop before getting that deep. Usually just deep enough to use the wrong end of an old bit to pop the head off.
I would also recommend a longeron yoke for your squeezer. It helps get around flanges. Disregard any of this advise if it's old news.

All good advice Larry!
Yes, I think a spring loaded punch would be good. Seems that even a few good smacks with a hammer still isn't enough. They still wander a little bit.
Someone else told me that if it wanders just angle the bit and keep aiming for the middle. Once there go vertical again and drill down. I did that on a practice rivet today and was still able to remove it without screwing up the hole.
I learned a lot, probably a few hundred more to remove over the next year or so.

Tom

tegwilym said:

Someone else told me that if it wanders just angle the bit and keep aiming for the middle. Once there go vertical again and drill down.
Tom

Click to expand...

Yes. I do that. It seems to work.
Did you get an adjustable ram and quick remove pins with your squeezer? Best things since sliced bread.

I had a problem with the drill bit wandering off-center also, which was especially bad with flush -3 rivets. So much so, that when I realized that I had to drill out about a dozen of them the other night I was really bummed.

BUT... my new drill has incredibly good trigger speed control. I have found that I can get the bit where I want it and start the hole by turning the bit verrrry slowly, maybe a revolution every few seconds to start out. That gets the tip of the bit to dig in and the bit stays where I want it to. All of them came out perfectly.

So, if you're like me and have an old cordless drill (or worse), get one that will let you run it at speeds that seem to slow to be useful. Mine is a Ryobi 18V Lithium I got for Fathers Day, and it's simply wonderful compared to my 10+ year old NiCD-powered B&D.

Oops rivets for the top and bottom holes

If this was a flat head rivet or a size -3, I think I would go to oops or larger rivets for at least two of those holes - the top and bottom ones. However, it is more likely that these are AN470 AD4 and you probably don't have AD5s hanging around. In that case, I think you are okayto try again with the same rivet. The factory head will be fine. If you are still concerned you could use a doubler under the shop head.

As regards technique for drilling out rivets, it may be stating the obvious but I find that it is worth being really careful about set up. Make sure you are well positioned with regard to the work (seated if possible) and comfortable with a straight shot to the hole and really good lighting.

As it happens, I don't have an acceptable air drill on my project so I use two Makita two-speed cordless drills for everything. The high-revs setting gets up to about 1300rpm which is just about okay for aluminium but I always use the slow setting for drilling out rivets and even then I trickle in the revs until the hole is established.

As others suggest, a centre punch helps to position the drill hole, especially on universal heads. I also stop and lift the drill bit at the 'countersink' stage, before a cylindrical hole becomes established, to check that I am centred on the rivet head. If not, I can still angle the bit a little or 'walk' the hole back at that stage. However, once the cylinder of the hole becomes established, it is important to drill straight. Otherwise the hole doesn't match the punch and it won't grip properly so you then have to go much deeper before you can pop that head off.

I also use an undersized bit first and then go up to the rivet shank diameter once I am satisfied with the smaller hole.

I find that if the hole is enlarged after rivet removal, a second rivet of the same size often fails also. Then it is definitely time to go to the next rivet size or an oops rivet. The chances of a third rivet of the same size being better than the first one are somewhere between 1 and 5 percent - at best!