DIY
How to clear aluminum from grinding drum?
I'm grinding out the aluminum bottom bracket to fit a diy e bike conversion kit and the dremel tool is full of aluminum. I've tried a wire brush, but can't seem to get the stuff off. Any tips?
Discussion
This is why you should never grind aluminum with grinding wheels not appropriately rated. While your small drum is not likely to cause issues, doing the same on a bench grinder wheel can see the wheel explode as the metal is forced into the grain structure - a very dangerous situation.
As the other poster said, the wheel is finished. Throw it out. If you have more to grind away use a carbide or HSS burr. Or a sanding wheel on a drum.
The little ones explode too.
And they hurt when they do
What happened to the bit when it did? Large pieces flying in chunks or a full on disintegration?
That’s the fun part. You don’t.
Immediately what I was thinking, haha
Only use grinding wheels specifically for aluminum
Count yourself lucky this drum did not shatter.
Since pretty much everyone is just telling you you fucked up and not being helpful, what you need for this job is die grinding bits Use cutting oil with them and WEAR EYE PROTECTION. When you use them they shoot tiny razor sharp aluminum needles at 99% the speed of light, but they won't clog up on you like a grinding wheel.
So thats how particle colliders work.....
They generally use monkeys that chase bananas.
Sounds like you'd want more than just eye protection then.
I mean, I bet mercury would do it… I’ll see myself out
Sodium hydroxide or hydrochloric acid would be cheaper and easier to get in volume than mercury and would likely dissolve the Al, but still probably more expensive than a new grinding bit, plus the whole hydrogen explosion potential.
I used to clean aluminum off of steel punches with oven cleaner. Has to be the yellow can.
Walter ALUCUT™ Aluminum Cutting Lubricant - Solid Stick
I grind aluminum every day. Put this on what you’re grinding and the bit you’re using. It stops the aluminum from sticking. If you plan on doing this alot there are die grinder burrs for aluminum ( non ferrous).
Crisco also works.
Those are disposable. It’s ready to be disposed of
I love how only one answer really helped the guy, and the rest were telling him he bought the wrong bit, despite the bit he bought being labeled as for aluminum. Dude ground it against a rock a little bit hours ago and went back to work and never saw the over abundance of "tough love" responses.
Oh I saw them. But the negativity just shows how helpful they are.
Probably nothing will work so the best option is to bin the part.
He could soak it in a hydrochloric acid (HCl), sulfuric acid (H2SO4), or sodium hydroxide (NaOH) solution. It will definitely get the aluminum off. It'd be way more cost and time effective to just buy a new one though
Oven cleaner. The yellow can. No idea what the wheel is made of, though. Might eat that, too.
You might get away with still using it since the RPMs are low and there are wheel dressing tools that will help. The danger lies in the differing expansion rates of the material that can cause the grind head to come apart.
You get a new one or grind it against something like concrete.
This is magical what I ended up doing. Ground it on a rock for a bit, cleaned up pretty well. Well enough to use it again at least.
This is exactly what we do at my work (deburring/polishing at a precision machine shop). We use old grinding wheels from the grinding department to shape and clean our rotary tools but any stone should do
My workshop has a giant (12"x 3" x 3") natural rubber "eraser" that gets gummed-up sanding discs (epoxy, glue, etc) looking completely new in a few seconds. I haven't tried it on aluminum gunk but I would recommend one for any shop doing lots of sanding or grinding.
Old shoe bottoms also work for any hobbyists that don't want to buy a dedicated eraser.
But then you have a GIANT eraser with which you can gleefully erase the construction marks off of any piece in a single swipe!
Nice that you get to give all the naysayers the middle finger
I think the middle finger is a bit much, but it was pretty frustrating to see the amount of negative comments
A cinder block would be better if you have one laying around and need to clean it up again. There'd be less risk of the bit shattering from heat on a softer but capable material.
You’re not wrong but the tool costs more than the bit lol
You're not wrong but the tool can dress more than one bit. lol?
you said that way better than how i would have tried to explain it.
Use the correct tool instead of the wrong tool. Try a carbide rotary burr.
Further, burrs for aluminum are very course (fewer widely spaced cutting edges) and often have continuous spiral edges, not the more common diamond pattern.
still gonna have to clean them shits out
I think I saw suggestions to dunk them in lye/bleach to clean off aluminium?
Toss it and get a sanding drum bit with replaceable drums. Can be found locally at HD, Lowes etc but the Dremel brand are crazy expensive compared to what you can order on Amazon.
A grinding wheel dressing tool takes the aluminum off grinder wheels of all sizes. Cheap solution here:
Dip it in Gallium.
JK... but I can guarantee that if you did then something would happen. LOL
With a trash can.
You use a dressing stone or diamond tip wheel dresser.
Grind steel. Next time spray with wd40 whilst grinding
You don't ando you should use one designed for aluminum since normal ones shatter when used to for soft metals
This one says specifically for aluminum and steel
You can use this for aluminum. You need to provide lubrication/a place for the heat to go, and you need to reduce the amount of heat generated by slowing down. Grinding is an abrasive process, which means that it's cutting little chips with each abrasive edge. This generates heat, and the heat needs to go somewhere. Spinning faster generates heat faster, and if you're generating it faster than it can dissipate, it stores up, and eventually instead of creating small chips, you're smearing and then melting. The secret to metalworking in all forms is managing the heat. So, some WD40 will go a long way, and slow down the rpm, and grind for a second, then stop for a second, and check every now and then with your hand that the part isn't hot. In short, slow down, a lot.
Soak it in the works toilet bowl cleaner, the aluminum will dissolve. Make sure you have proper ventilation and don't put it in a sealed container
This, and make sure the active ingredient is sodium hydroxide. In fact, look for drain cleaner instead! Be careful though! Drain cleaner will strip the flesh from your bones if you give it long enough. Wash the area immediately if you get any on your skin, and wear gloves when handling it. It usually comes in pellet form, so you'll want to be careful and slowly mix it with a little water first.
God help us, you're going to make the bike heavier and faster by removing bottom bracket material? Do you hate your teeth or something?
Grind copper. It works for metal files not sure if it works for Dremel tool heads
Muriatic acid
You won’t get it completely clean, but if you find a harder surface to grind then the aluminum you might be able to clean a little bit out. It will be ultimately ruined now.
HCL will dissolve it!
And also the shaft.
Did anyone else read "how to get clear aluminum"
Star Trek 4 (I think) has the answer.
Edit: Star Trek IV : The Voyage
When in doubt, look to start trek
Lye crystals. It dissolves aluminum and also skin so be careful with it.
Dissolve 1 teaspoon in a glass jar of water and stir well (it's exothermic when dissolving). Use tongs when placing bits in the jar so you don't get any on your skin. The aluminum will bubble away after a few hrs, then rinse the bit and it's back to new!
Protip: Don't spin the tool to dry it off.
Buy a new drum.
You can use a file to take some of it out? Just give it a quick rub. But once they're gummed up it ruins them. The aluminum consumables work way better.
The ABCs of grinding: never grind (A)luminum, (B)rass or (C)opper.
Use it on concrete or a stone outside to clean it, it will shrink a bit tho
Lye (drain cleaner) will dissolve the aluminum. The rest of the bit should be ok, but worst comes to shove, just buy a new one.
Put the grinding stone in Sodium hydroxide solution, wait. When it's not bubbling hydrogen anymore, it is finished.
The car body shops segregate steel work and aluminum work.
And throw the bit away.
Step 1: Take it out of the drill
Step 2: Throw it in the trash
Step 3: Buy a new grinding drum, they aren't that expensive
Use it on steel, the aluminium will flake off.
That's the neat part!
You don't.
Soak it in lye(sodium hydroxide)-based drain cleaner. Be careful, esp with your eyes.
Throw it away. Loading a wheel with soft material like this can cause it to overheat and fracture. Possibly flying to pieces.
These things are disposable/consumable. This one is ready for the bin.
Try running it on some candle wax
The package for this wheel specifies it is for use on metal, steel and aluminum. Maybe it's a cheap pos, maybe i ran it at the wrong speed?
Tools tips like this are designed to be expendable. Also, you should be using a die grinder tip for something like this to hog off material.
You should throw it away, but gallium might work then just soak it in water and it should all come off
Try grinding it lightly on a stone. At my work we use old/broken grinding wheels to shape and clean our deburring and grinding tools. You would be looking to remove that first layer of material just until it is usable again.
So if you can't get the right but, use gallium, melt it with a lighter and soak it. It eats up aluminum. But gallium is expensive and it would be cheaper for a new bit
Grinding aluminum i drip ethanol on it, the heat generates vapor and helps keep the stone clear. Sometimes grinding something steel will clear it too
I've had luck using wd40 on my grinding wheel for aluminum. It's not perfect, but it's better than your situation.
Put it in some drain cleaner lol
Run it on steel. It won’t be perfect again but it will help.
You could buy a grinder dressing tool .
There's no good way to clear aluminium packed into files and sanding discs, etc. You're better of buying new.
I’ve never used this too,d and have 0 exp with this but hear me out.
Aluminum has a pretty low melting point… heat it to the melting point then rip the tool on and fling the molten metal off the bit.
Just try not to get hit by the hot metal drippy drops when you turn it on
Mercury but I don’t recommend it
Dip it in mercury for a while. Wear gloves.
I've had luck with a diamond dressing tool meant for bench grinders.
Dremel accesssory kits often come with a little bar of some coarse abrasive, probably silicon carbide. Mine didn't work at all on my aluminum-clogged dremel grinding bit. But that diamond tool worked perfectly. This is the one I used.
I've also used a diamond dressing tool that was just some diamnod grit plated to a piece of square steel tubing on a handle. I don't have a link to it, but it was similar to this one. Be sure to hold only the diamond-crusted face to the grind stone.
Grind it on some steel scrap and it will clean up. But if you’re doing aluminum use the dremel tile grout bit 562 or 570 that’s carbide and use a lower rpm. Heat is not your friend.
Gallium lol
Just use a diamond dressing tool or you could improvise with some sort of diamond tooling
Not sure if this will work, but there's a technique to get rid of glazing on sanding disks, which is to blowtorch it for a bit. You might need to blowtorch it while spinning and you'll want to make sure that you're not flinging hot metal around the room.
Aluminum can cause the wrong grinding drum to explode. I think it’s the thermal expansion.
How much gallium you got laying around? If you do this often you'll want quite a chunk. Warm gallium destabilizes the aluminum oxide formation... It almost washes off with acid. Maybe don't do it very often though.
Oh I should also point out, this doesn't work great for aluminum based abrasives, or certain stones.
Anybody ever try open flame? Al melts at 1220F I would think you could melt it enough to burn off
Gallium
Sodium hydroxide will dissolve it, but that would take a little while. Easier to get a more appropriate tool.
Soak in concentrated lye solution. Then rinse off. This will react with the aluminum.
Try a HSS burr, will work much better than a grinding wheel. You "might" have luck clearing it by gently touching on some stone or somesuch, but it's probably cooked.
Use a cylindrical burr and load it up with beeswax before grinding aluminum. Re-apply beeswax often!
Scottish accent That's no how ya grind aluminium.
Strong solution of sodium hydroxide will dissolve the aluminum.
I use a course diamond disc for that. You run the clogged tool against the diamond disc. It will grind the stuff away and you have a good tool again. Works wonders on cleaning and re-shaping grinding tools like that.
Trip to Home Depot?
You can dissolve alumium buildup using caustic soda (lye). In this case it will probably eat away at the drum so I wouldn't bother trying - buy a cheap multipack of those drums as consumables. You might get better results with a coarser abrasive so that it is taking away a larger amount of metal each time.
Lye vs Aluminium on cutting tools: [Title] Salvage Carbide Tools with Lye | SCIENCE! https://www.youtube.com/watch?v=wi4vaOTWYOo
I'm sure this has been said already, but aluminum is very gummy, and it easily clogs up instruments that are too fine.
It might be overly aggressive, but I suggest SINGLE CUT high-speed-steel or Carbide burr / rotary file. You'll need a 1/8" shank to fit your Dremel.
Aluminium can’t practically be ground and you’ve discovered why.
Muriatic acid like you can get at the hardware store for cleaning brick. It’s not the fastest but works without dissolving the steel shaft on the bit.
Use Dressing stone same one used by stationary grinder wheels
That's the neat part. You don't
Try a sanding belt cleaning stick? Its a big hard stick of wax.
Low quality DYI.
Exactly this.
You'll notice on some workbenches (even in private spaces) people go out of their way to label equipment and consumables "no aluminum".
This is because even experienced, veteran professionals aren't going to be able to set this issue right, and they need TFNG not to mess it up
Also because there have very rarely, but NOT NEVER, been cases of grinding iron and aluminum on the same bench grinder and accidentally producing thermite.
This would be a Bad Day.
(The Department of Energy used to have browsable accident reports, a "Lessons Learned Database" on a public website; this was one of them)
Had too many folks use my grinding station to adjust magnesium parts when I was out on vacation for a week. First thing I worked with when I got back was tempered steel.
The grinder went up in flames pretty quick.
Oh noooooo
Did it clear it?
If you're looking for more "Lessons Learned", the U.S. Chemical Safety Board has fully 3-D animated step-by-step recreations of industrial accidents that explain in detail every step that led to the event.
I'm a little addicted.
And to the surprise of nobody these days, they're getting shut down.
The administration claims in the CSB’s budget request that the agency ‘duplicates substantial capabilities’ in the US Environmental Protection Agency and the federal Occupational Safety and Health Administration (Osha) to investigate chemical-related mishaps.So where can I find the EPA & OSHA Youtube channels?
The administration is currently busy upgrading your access to the EPA and OSHA accident recreations from 3D animated youtube videos to a live show. Remember to say "thank you".
I didn't know how much I needed this.
It’s unironically one of the best channels on YouTube. They have to be saved :(
Best channel! 🥳🎉
Some of this stuff just blows my mind. I didn't even know that was physically possible nor have I ever thought too long or hard about it. 🤯
Fine alu dust is pretty evil stuff all by itself, you dont need to mix with anything other than air and heat to have a bad time.
The iron oxide in thermite is just an oxygen source to make the Aluminum easier to burn (and keep it burning). It'll go off just fine in air given the right conditions.
The department of energy used to have all sorts of great tools and resources! It's too bad someone just decided to delete them for no reason.
There's a concept of a reason
Concept of a reason... or very real treason.
Good times.
Not for no reason. So rich people could get richer.
Follow the money
I've never seen thermite made on a grinding wheel, but I have seen embedded aluminum crack the grinding wheel and fling high speed grinding disk chunks everywhere.
Either it cooling and shrinking causes the crack or the next attempted grind causing it to heat up and crack things. Either way it is a time for a change of pants for everyone in the room.
Brings back memories. I had several volumes of their "Handbook of Hazardous Chemical Reactions". Great read.
More often what happens, in my experience, is someone uses aluminum on a grinding wheel and then when someone uses steel on the same grinding wheel the aluminum, now embedded in the wheel, expands and cracks the wheel.... at high speed.
I'm going to need a source for that. I've been told that countless times and every time I've seen a writeup it is covered in urban myth red flags. Stuff like
"Several years ago I saw an article in one of my Blacksmithing Newsletters where a blacksmith had been grinding steel. Later his son came in and use his grinder to grind some aluminum. The next day the blacksmith started using his grinder again and was engulfed in a ball of flame. There were pictures of him in the article. ... It is surprising how little steel filings and aluminum filings it takes to make a very violent explosion"
Fine aluminium is flammable and possibly pyrophoric, flammable dust in air is an explosion hazard, grinding iron creates very hot sparks - these are all real hazards but anyone who has worked with thermite knows it doesn't really explode and it's surprisingly difficult to set off even deliberately.
Can we not just accept that grinding aluminium is a fire hazard and might make your wheel explode without invoking bad chemistry?
https://ncsp.tamu.edu/reports/DOE2/doe2_0017.htm
Source no longer available (I've been looking!), but it was an accident report in a DoE "lessons learned" database. Not a forwarded copy in a chain letter, but an official accident report from a facility workshop directly on the department website. Fwiw, it didn't use the word "explode", it probably said "combust".
The chain of events was roughly what you just said, replace the characters with co-workers, and I have no explanation for the temperature thing.
I've got no way to fact check them, obviously; they could have been full of shit, but they don't really seem to have a sense of humor about accidents.
I guess I can't rule out that it was actually a dust ignition and they got it wrong in the investigation? Or a dust ignition produced enough heat to also ignite piled up shavings in the recesses of the machine?
It's a shame the source is missing - if I could read what you describe I'd stop being such a skeptic, I'm sure an official incident investigation would be as thorough as they needed to be about the conditions leading up to it.
I have no doubt grinding aluminium and steel is a fire risk, I just wish people wouldn't uncritically believe (and disseminate!) everything they read with a source of "dude just trust me, it happened to a friend of a guy I know 10 years ago" especially when safety is concerned.
It's not too far fetched to imagine someone believing the problem is mixed grinding dust forming thermite, fastidiously cleaning up all the steel grinding dust then having their grinding wheels shatter because it's gummed up with aluminium and overheated or got out of balance
I hear you! I did find what may be the modern descendent of that database (linked in another comment), but I wasn't able to find this specific report in it - nor another interesting one I remembered. Might have been a different branch of the department, or maybe they didn't carry over all the old reports.
ETA link: https://doeopexshare.doe.gov/
Aluminum powder+iron oxide=thermite.
Yes, that is an example of the exact kind of overly simplistic thinking I'm talking about. Al + Fe2O3 is the mixture but you're missing
Isn't it enough to say it's a fire hazard? Why do people insist on it being this one particular reaction which is notoriously difficult to initiate on purpose?
I desperately want to read that
I haven't been able to find it in years. I think this is the modern version of the database it was in, but I probably read it first 15+ years ago and it was a very Web 1.0 site at the time.
https://doeopexshare.doe.gov/
Might be in the Wayback machine internet archive?
As someone who has less experience than the unborn offspring of those veteran professionals but loves your profile pic, could you eli5 why do you need special wheels?
EDIT: Just want to say thanks for all the informative responses, it’s amazing having knowledgeable people basically on tap for things you don’t understand but are curious about!
Aluminum “gums up” instead of being flung off the wheel.
Is that because aluminum is softer or less brittle and so it doesn’t “shatter” off like other metals would?
Aluminum melts at a very low temp and is pretty soft. So add high speed friction and some.grit and you've got yourself a gummy boi.
Just bring the wheel up to speed and hit it with an oxy torch to loosen up the aluminum, it'll come right off!
(DO NOT ACTUALLY DO THIS)
You had me in the first half.
This sounds like a fun outdoor activity
It does work, though. The aluminum is nowhere to be found when you're done.
...and trying to get all that off there will ruin your day and make you one very Sour Patch Kid. 😏👍
So what if hypothetically I put a heat gun facing upwards and spun this aluminum gummed up bit above the heat gun, could I melt the aluminum and then fling it all off the bit to clean it? Shouldn't it flick aluminum everywhere but clean off the bit if it's hot enough and spinning fast enough?
I don't think heat guns often get to 1300⁰f but you'd likely damage the plastic on the tool or just make the backing and the grit super fragile.
In general it's just not gonna be worth the effort.
Okay I misunderstood "very low temp" haha, thanks for the clarification!
Yeah it's not quite like lead solder lol
Aluminum tends to fill the pores of a grinding wheel and it can cause the wheel to overheat and explode,... which is something that you generally want to avoid, if possible.
TFNG?
The Fuckin New Guy
Thanks!
I work in a shop full of supposedly trained professionals, and I'm throwing out $50 bench grinding wheels every week because one of these idiots gummed it up with brass or aluminum.
I don't even want to talk about the carbide grinder. I gave up on it.
Get a dressing tool for your wheels. As a toolmaker apprentice many years ago, every grinding wheel was signed out, logged, ring tested, and dressed before use.
That's just it. Next guy comes up, has to dress off 1/16 to clean it up. Idiot comes back and loads it, repeat.
1) worked in machine shop as teenager 2) ground aluminum on bench grinder 3) got yelled at 4) learned
OP is also potentially creating a tolerance problem too. Bearings are designed to bear loads in a very specific way and with very specific fits for each bearing specification. There is no way to ensure you're not accidentally taking the BB shell out of round when opening it up via this method. An out of round BB shell will support or squeeze the bearings asymmetrically which causes uneven wear on the bearing races and eventually a failure. Wear creates debris/particulates, those create friction, friction creates more wear, and the process repeats until the BB no longer spins freely.
Yeah when I read they were grounding out the BB I was like WTF? You buy the part to fit your BB or you buy a frame that fits your part. That's the end of it.
Ohh come now, it's not real r/DIY if it isn't at least mostly dangerous.
I think that would depend on how much material he is removing and where on the bottom bracket he is removing it. Given he is using a dremel and a tiny stone bit I am confidant he is not removing much. We also don’t know how much torque his motor puts out. Or if his bottom bracket is aluminum tubing or if it is solid, the wall thickness of the piece, etc, etc. To many uncertainties to say for sure.
Also use cutting wax or oil
Edit: only do this if it's the sandpaper drum. If it's a solid stone burr then nooooo.
I use WD-40 (basically mineral oil) to help keep aluminum from galling up my files. Works really well actually.
Bit of chalk works for files too.
I'll have to try that next time.
This one says for steel and aluminum on the package
Got a picture of the package? I've never seen a grinding wheel/stone/bit that can handle both ferrous and non-ferrous metals as they're made of two very different abrasives that don't work (as you've found out) on the other.
Dremel's website shows them.
They have orange stones that look just like OP's listed for both ferrous and soft metals like aluminum and copper.
Scotch Brite Cut and Polish wheels work very well in steel and aluminum. They are specifically marketed as "low loading". I have one on a grinder that's gone through so much steel and aluminum it's half it's original size and never loaded up
I suspect he misread. The ones for steel are often composed of aluminum silicates.
he didn't. Dremel 8193 most likely what OP has. Definitely an orange grinding stone with the same style plastic insert on the shank meeting the stone.
Listed for use in ferrous metals, stainless, copper, aluminum, brass.
Oh, yeah. I have one of those. I forgot they existed.
Same thought, but trying for benefit of the doubt.
Grind into a wax candle or a bar of soap before aluminum, won't get rid of them problem, but itll help. Bonus points if it's scented because treatyoself.
https://benchmarkabrasives.com/products/sb-3-nf-aluma-cut-cylinder-shape-end-premium-cut-tungsten-carbide-burr?variant=46461352588¤cy=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gQT=1
You want something like this for aluminum.