Whoo hoo! It's not bulls*** - removing broken taps

[dirty old man]

Here in Ga is Fort Benning, just across the Chattahoochee river is Phenix City, AL, which was one grear big gambling and red light district for the Ft B. soldiers until the mid 50s.
Joke of those days was that a General in a tank drove in the river and because of all the alum in the water from the ladies of the night, came out on the other side a Private in a jeep!

[Wirecutter]

Aaaand so, while putting the leaf blower/vac away this past weekend, I come across an item in the garage. It's a yellow and white plastic bag with Aluminum Sulfate printed on the front. 4 lbs, it says. $7.99. Arrrgh!

Turns out that SWMBO purchased the stuff a couple of years ago - someone at the garden center suggested it for raising the acidity of the soil in the yard so stuff would grow better. So it was there all the time. Yeesh.

[MikeyR]

New guy here, but I've been buying alum for many years in the "spice" section of most all of the groceries in town. It will eat taps out of any non-ferrous metal I know of, but will will eat anything with iron in it at the same rate as the tap.

[Davis In SC]

<font face="Verdana, Arial" size="2">Originally posted by dirty old man:
Here in Ga is Fort Benning, just across the Chattahoochee river is Phenix City, AL, which was one grear big gambling and red light district for the Ft B. soldiers until the mid 50s.
Joke of those days was that a General in a tank drove in the river and because of all the alum in the water from the ladies of the night, came out on the other side a Private in a jeep!</font>

My 88 year old Uncle told me that same thing,recently, He was at Benning , before he got shipped out...

[andy_b]

<font face="Verdana, Arial" size="2">Originally posted by Davis In SC:

My 88 year old Uncle told me that same thing,recently, He was at Benning , before he got shipped out...

</font>

isn't he a little old to be shipping out?

andy b.

[Mcostello]

Wonder if you could get the steel part dirty or greasy enough to stop alum from attacking it? Leaving the center of the tap as clean as possible.

[Frank T]

I have a bronze cast cannor with a SS pipe cast in the center with 1/4 wall thickness.

I was trying to enlarge the touch hole and broke the drill in the hole. The hole diameter is ~ 1/8".

Will this process work to erode the drill? Will there be any effect on the bronze or SS?

The final hole would be in the 1/4" range.

How do I keep the solution full and hot?

Thanks for your advice.

PS: On a past post someone mentioned using EDM but this cannon weights over 200 pounds and is not easily transportable.

[Wirecutter]

The parts I was working with were small enough to do this on the stove. As those with chemistry experience know, the solution will dissolve more alum when warm. I kept an eye on it and replenished water as needed. The aluminum I was working with took on a very slight discoloration, but I hit it with a little 600-grit wet-dry sandpaper and it cleaned right up.

When I read of this process here, initially it was mentioned that you simply soak the "victim" in the alum solution, but it was reported that it could take a week. Warming to a simmer speeds it up a lot, and I could remove a 1/8" drill or a 4-40 tap in about 2 hours. Taps take a little longer, because the threads have more grip than a drill.

mcostello may be on to something about "dirtying up" the stuff you don't want attacked by the solution. My understanding is that this process will attack pretty much any ferrous metal, so stainless would be hurt.

In the case of this cannon, I can think of a couple of ways you might be able to "dam up" an area around the broken drill and fill it with the solution. Maybe an RTV like thing, or the sticky puddy used where the cable TV line comes into the house.

Another possible option is the old "battery charger de-ruster." That operates on the principle that dissimilar metals in an electrolyte will act as a battery, and one will plate the other. The battery charger part can force it in one direction or another, and speeds the process up considerably. Maybe you could set it up so that the broken drill will "plate" onto some other metal there. I know that, in ocean water, stainless steel will try to plate onto aluminum. Others here with more knowledge of metallurgy may be able to fill in more info on this.

What do you think, folks? Can it be done?

-M

[cmiller231]

Does any body know what ratio to use?
Thanks in advance Chris
Ypsilanti Mich

[Evan]

For alum just keep adding until it won't dissolve.

[Wirecutter]

<font face="Verdana, Arial" size="2">Originally posted by Evan:
For alum just keep adding until it won't dissolve.</font>

That's exactly how I did it. I think I got about a cup to dissolve in 2-2.5 cups of water. When warm, you can really use a lot. If it boils, it likes to foam and boil over, making a mess. Keep it as warm as possible w/out boiling.

[Mcostello]

Heating up the solution would speed it up right? What if a battery charger was hooked up then? would it also help remove a stuck object/ sort of like throwing everything at it at once.

[Rich Carlstedt]

I tried the Alum trick on a broken 0-80 tap in Aluminum and it did not work
Put it on a hot plate, supersaturated the solution ( had crystals on the bottom.
Next day, the solution all boiled off, and the tap was still there.
I think the tap was so small, maybe a air buble kept the solution from touching it.
I don't have to worry now however, I built a Ben Fleming EDM machine ( see Lindsey's books).
haven't had to use it yet.

Alum is used in Pickles. It keeps them "crunchy" when canned.
Found mine in the spice section of the supermarket.....maybe it is not as strong ??

[Duct Taper]

I have not tried this, but maybe one way to remove a tap from steel would be to make a wax barrier for the solution. If you first pour hot wax into the hole with the broken tap to seal off all the surrounding steel and then scrape the wax off the tap only, the alum should attack the tap first. Keep an eye on it until the tap is dissolved enough but without letting the alum get to the base part through the wax coating. I will have to try it.

[Herb Helbig]

I used alum to remove a broken steel screw from a brass weather vane. I rigged a small battery powered toy motor to spin a paddle wheel (made from a plastic tooth pick) near the hole to sweep away the bubbles that formed. Otherwise the bubbles stuck in the hole and killed the action. I wonder if anyone has tried doing the alum soak in an ultrasound bath? Might be good for small items - not cannons!

I got the alum at exorbitant price in the spice section of the supermarket. Thanks for alternative sources!