Need Help!- Making a hole in aluminum smaller

[flatfnder]

I have a few cast aluminum (A380) parts that have a reamed hole that is .315 in dia with a depth of half inch. The reamer cut a thousandth of an inch large so trying to come up with a way, if possible, to shrink the hole size by .001 inches. Anyone every done this. I tried filling the hole with alodine overnight but it didn't work. Also have tried temperature changes along with some boric acid. Was thinking of anodize but not sure if it is possible to do it just inside a hole. The hole is for a press fit insert of some kind and I don't have access to the insert to manipulate it so I have to fix the casting.

Any ideas would be greatly appreciated!!

Thanks

[Pandinus]

Well I'm assuming its near the finished stage so probably too late for this, but how about putting it on a nice solid backing and us a 5-10lb sledge and "bump" it to size???

[fatal-exception]

There are aluminum brazing rods that you could use to melt a new surface inside the hole then re-machine the hole to the correct size. They are made by Bernzomatic and they work well with a standard propane torch.

Paul

[underthetire]

a ball bearing bigger than the hole, and a hammer. Or call a welder.

[irving2008]

Originally Posted by fatal-exception There are aluminum brazing rods that you could use to melt a new surface inside the hole then re-machine the hole to the correct size. They are made by Bernzomatic and they work well with a standard propane torch. Paul

I'll second that suggestion, its called Alutight here in the UK although there are other trade names. Its an alumnium welding technique (technically its not a braze) which wont stick to steel so you can melt it into the hole, screw in a steel bolt thats smaller than the hole while its still liquid and leave to cool down then re-machine to size.

[bsmiaz86]

Originally Posted by underthetire a ball bearing bigger than the hole, and a hammer. Or call a welder.

I 2nd that

[Nastyzen]

Originally Posted by flatfnder I have a few cast aluminum (A380) parts that have a reamed hole that is .315 in dia with a depth of half inch. The reamer cut a thousandth of an inch large so trying to come up with a way, if possible, to shrink the hole size by .001 inches. Anyone every done this. I tried filling the hole with alodine overnight but it didn't work. Also have tried temperature changes along with some boric acid. Was thinking of anodize but not sure if it is possible to do it just inside a hole. The hole is for a press fit insert of some kind and I don't have access to the insert to manipulate it so I have to fix the casting. Any ideas would be greatly appreciated!! Thanks

If your saying A380 as in the airplane A-380 your part is scrap.I'm a welder and I repair aluminum and magnesium race car castings all the time using tig welding.But that's for racing.If you have an airplane part you will have to put a bigger dia. bush to fix it.If you can get the repair approved first by the plane people.Anything done to a commercial aircraft part must be done by the book and documented by law.And usually they don't like weld repairs.
Good luck

[HuFlungDung]

If there is no liability involved, you might run an 8mm cold forming tap down the hole. This will generate some slight upset 'threads' as it were. Might be enough to tighten up a dowel pin fit quite adequately. Taps are usually a little over nominal size, so it should still bite a little bit in a .315 hole.

[Metalmanti]

Originally Posted by bsmiaz86 I 2nd that

I would agree with this as well. I have used this technique many times.

[Delw]

WOW a ball bearing? you guys are kidding correct? this is a back woods in your tent fix for your own personal stuff right?

Anyone who uses a ball bearing to fix a hole like that is a HACK.
using a ball bearing in a "real shop" would be suicide.

A ball bearing only mushrooms the top edge. everything else would still be over sized and be GARBAGE. the "ball bearing fix" would only work for inspection. any funtionability would wipe it out at assembly.

if you CAN get bought off by who ever your selling the parts to aside from hungflung you can press a 4-6 flute reamer .010-.020 bigger than the .315 into it. this will cause the bore to mushroom the entire length of the bore and recutting it will hold size, and some functionability. having said that it better be a non liability part that doesnt require any major force on that hole.

other ideas are welding a bigger plug like 1/2-5/8" then reboring. but make darn well sure its OK with your customer. other wise your going to loose a customer and have the possibility of being sued.


Delw

[Nastyzen]

An other method that I have used with success is tapping the hole to the next size up and screwing a 6061-T6 threaded rod and then rosette welding both ends.Assuming your alloy is not 2024 witch can't be welded properly because of the high copper content or 7075 that has a high zinc content.Then locktite is the only way to glue it in.
If you weld up the entire hole with 5356 alloy,witch usually works fine but is softer than 6061-T6 it will stay soft forever.It will also not have the same color as the base metal.
To get the hardness up I have used strips of sheet 6061-T6 as a filler.Keep in mind that once you have welded 6061-T6 the immediate area you have heated will be of the T-4 hardness.T-6 hardness will come back with aging a couple of years or so. There are also chemical techniques for artificially aging of witch I don't have the practical experience to help you with.
Just putting a strait plug wont cut it.Especially for an Airbus.
Internal Knurling might work,if it exists.
The ball bearing n hammer trick has gotten me through the race weekend before as the only trackside option available but was properly fixed when back at the shop.
good luck with your problem,let us know how your project turned out.

[CalG]

Can you open up the hole, Insert a plug (locktite!) then redrill/ream?