- Joined
- Feb 24, 2019
- Messages
- 957
Back story.
I was drilling 1" thick aluminum with a 1/8" drill bit. It broke (shattered) and left almost the entire bit embedded in the block with just a dimple on the back where the bit was about to break thought.
I was using a cheap, Harbor Freight, drill bit (yeah, yeah) that was TiN coated. I've used them a lot for thinner material up to a half inch thick so I thought it would be OK.
I could have thrown the block away but where's the fun in that. I had a few different methods I was willing to try to get the bit out but someone mentioned dissolving it with Alum.
I thought they were nuts. There's not a lot of talk about it on the interwebs but I am all about trying something new.
Yes, it works!
I bought a small container of Alum at the grocery store. Apparently it's a food additive but it tasted awful. (had to try it).
I took a quart sized pyrex measuring cup and an 8-9" saucepan. The idea was to make a basic double boiler.
I filled the pan @ 1/4 of the way with tap water.
Then I put about 12 ounces of HOT tap water into the measuring cup and dumped in all the Alum. Stirred til it was dissolved. Then I dropped the part in. It was decently submerged.
I put the measuring cup into the pan and the water level went up to about 3/4 of the pan.
I put the rudimentary double boiler on the stove and turned it on high. Once the water in the pan started boiling I set the burner to it's lowest setting.
I waited.
It took a while but I finally started to see a few bubbles. Not the large quantity I had seen in the tutorial videos but there were some.
I left it on the burner all day. I checked on it every hour and replenished water as needed. I topped off both the pan and the measuring cup.
ALL DAY.
I finally started seeing a few more bubbles around the second hour. Nothing near what I imagined.
I had to turn it off to go to bed but fired it up again the next day. I left it on the burner ALL DAY.
Checking on it in the morning, the shard at the top where the bit broke was still there. I tried to grab it with a very basic set of needle nose and it broke right off. Obviously something had weakened the metal in the bit. But not enough to be worth the time so I bailed on the experiment.
I did get some pretty cool crystals from when the Alum cooled though.
Second try was exactly the same but I purchased 2 pounds of Alum. The original tutorials said to add Alum until reaching the saturation point. I hadn't done that before because I didn't have enough Alum to reach saturation.
This time it was saturated. I couldn't get it all to dissolve so I left the little extra bit in the measuring cup and put them all on the burner.
It took about a half hour to see bubbles but they did show up. Quite a stream, actually. It was definitely reacting.
I probed it a couple times in the process and I could see it was making progress. I was using a wooden toothpick as the probe so it was much softer than the metal.
I left it on the stove, again, ALL DAY. I almost forgot to turn it off when I went to bed. That might have been bad.
When I probed it before bed it probed a little more than 1/4".
Next day (this morning) I fired it up again. I ran it for about an hour before first probe but it came in a little more than 3/8.
Remember that the broken piece was about 1" long.
It was progress but very slow.
A couple hours later the bubbling was slowed way down. I was thinking about mixing up more solution but before doing that I decided I wanted to try a metal probe.
The most handy metal probe I had was another 1/8" drill bit (much higher quality than HF). It probed almost a half inch. I twisted it by hand a little and it wanted to catch. I didn't see anything on the tip of the drill bit when I pulled it out so I assumed it was catching on the broken bit inside.
I was tired of all the waiting. Caution to the wind.
I chucked up the drill bit in my hand drill and carefully chased the hole. I felt the catch point but the bit went right past it and bottomed out. The old drill bit was GONE!
I went ahead and drilled through the last part of the block and now I have the hole I needed.
The secred was saturation and time.
I think it took so long because the bit was TiN coated. The solution couldn't work from the outside so it had to squirm it's way down through the bit.
The end result was a slightly anodized aluminum block with a pefect hole.
I thought I had damaged the saucepan with the bottom of the measuring cup scratching it but it was just a little Alum residue. Same thing with the measuring cup.
Doing the cleaning of thos with the hottest water I could tolerate, the Alum residue came right off. I suppose I could have used boiling water with some soap to keep it from redepositing but I didn't try that.
At any rate, I call this SUCCESS and would highly recommend this if you break off a HSS bit in aluminum and don't want to damage or replace the part you're working on.
I might, for fun, make a youtube video on a sacrificial part just to help out others. Not using a TiN coated bit, though.
I was drilling 1" thick aluminum with a 1/8" drill bit. It broke (shattered) and left almost the entire bit embedded in the block with just a dimple on the back where the bit was about to break thought.
I was using a cheap, Harbor Freight, drill bit (yeah, yeah) that was TiN coated. I've used them a lot for thinner material up to a half inch thick so I thought it would be OK.
I could have thrown the block away but where's the fun in that. I had a few different methods I was willing to try to get the bit out but someone mentioned dissolving it with Alum.
I thought they were nuts. There's not a lot of talk about it on the interwebs but I am all about trying something new.
Yes, it works!
I bought a small container of Alum at the grocery store. Apparently it's a food additive but it tasted awful. (had to try it).
I took a quart sized pyrex measuring cup and an 8-9" saucepan. The idea was to make a basic double boiler.
I filled the pan @ 1/4 of the way with tap water.
Then I put about 12 ounces of HOT tap water into the measuring cup and dumped in all the Alum. Stirred til it was dissolved. Then I dropped the part in. It was decently submerged.
I put the measuring cup into the pan and the water level went up to about 3/4 of the pan.
I put the rudimentary double boiler on the stove and turned it on high. Once the water in the pan started boiling I set the burner to it's lowest setting.
I waited.
It took a while but I finally started to see a few bubbles. Not the large quantity I had seen in the tutorial videos but there were some.
I left it on the burner all day. I checked on it every hour and replenished water as needed. I topped off both the pan and the measuring cup.
ALL DAY.
I finally started seeing a few more bubbles around the second hour. Nothing near what I imagined.
I had to turn it off to go to bed but fired it up again the next day. I left it on the burner ALL DAY.
Checking on it in the morning, the shard at the top where the bit broke was still there. I tried to grab it with a very basic set of needle nose and it broke right off. Obviously something had weakened the metal in the bit. But not enough to be worth the time so I bailed on the experiment.
I did get some pretty cool crystals from when the Alum cooled though.
Second try was exactly the same but I purchased 2 pounds of Alum. The original tutorials said to add Alum until reaching the saturation point. I hadn't done that before because I didn't have enough Alum to reach saturation.
This time it was saturated. I couldn't get it all to dissolve so I left the little extra bit in the measuring cup and put them all on the burner.
It took about a half hour to see bubbles but they did show up. Quite a stream, actually. It was definitely reacting.
I probed it a couple times in the process and I could see it was making progress. I was using a wooden toothpick as the probe so it was much softer than the metal.
I left it on the stove, again, ALL DAY. I almost forgot to turn it off when I went to bed. That might have been bad.
When I probed it before bed it probed a little more than 1/4".
Next day (this morning) I fired it up again. I ran it for about an hour before first probe but it came in a little more than 3/8.
Remember that the broken piece was about 1" long.
It was progress but very slow.
A couple hours later the bubbling was slowed way down. I was thinking about mixing up more solution but before doing that I decided I wanted to try a metal probe.
The most handy metal probe I had was another 1/8" drill bit (much higher quality than HF). It probed almost a half inch. I twisted it by hand a little and it wanted to catch. I didn't see anything on the tip of the drill bit when I pulled it out so I assumed it was catching on the broken bit inside.
I was tired of all the waiting. Caution to the wind.
I chucked up the drill bit in my hand drill and carefully chased the hole. I felt the catch point but the bit went right past it and bottomed out. The old drill bit was GONE!
I went ahead and drilled through the last part of the block and now I have the hole I needed.
The secred was saturation and time.
I think it took so long because the bit was TiN coated. The solution couldn't work from the outside so it had to squirm it's way down through the bit.
The end result was a slightly anodized aluminum block with a pefect hole.
I thought I had damaged the saucepan with the bottom of the measuring cup scratching it but it was just a little Alum residue. Same thing with the measuring cup.
Doing the cleaning of thos with the hottest water I could tolerate, the Alum residue came right off. I suppose I could have used boiling water with some soap to keep it from redepositing but I didn't try that.
At any rate, I call this SUCCESS and would highly recommend this if you break off a HSS bit in aluminum and don't want to damage or replace the part you're working on.
I might, for fun, make a youtube video on a sacrificial part just to help out others. Not using a TiN coated bit, though.
