I use a heat gun
@Christian_Schulz I would use that method too, but it’s not just PLA - there’s char on there too - like the PLA broke down into its molecular component and baked on there. The brass brush with 160C wasn’t taking it off.
@ThantiK maybe try some steel wool? It’ll probably scratch the aluminum but maybe that’s what it needs? Kind of like how a magic eraser works.
Belt sander? Pretty sure you could clean up a block in seconds with the right grit.
Recycle. I don’t think anything you do is viable if you do this at work when someone has to pay you, unless you really don’t have anything to do. I would melt them and cast a new life out of them, but if you want to save them, milling (fly cutting) is the only sane idea.
Fluidized bath, or bead blaster booth with walnut shells.
as others pointed too, the best method I found is heating to 400-500°C (I used red hot spiral stove). PLA or ABS go away in smoke, only fine ash remains that can be wiped/rinced off. Nothing else comes close. Works great on plugged nozzles as well.
5 Minute cleaning with a welders torch. You can clean the ashes/remains off afterwards. They will still look a bit ugly, but they are clean then.
Generally I use a Blow torch to soften and then a Stanley (Box Cutter) Blade to scrape the crap off, if you want them shiny, then a high grit belt sander as @Ryan_Carlyle suggested or just some high grit sand paper on a flat surface will do the trick.
Example of heat/scrape/sandmissing/deleted image from Google+
Heat
Ultrasonic cleaner?
I’d go for a scrapping, blasting, and then sand/polish method. A mirror fonish polish will keep it easy to clean(in theory).
@ThantiK honestly, I bet a palm sander would work wonders. Lol. Sure it’ll scratch the hell out of it but if you then go to a high grit paper, I bet it would look more like brushed aluminum.
@Kevin_Danger_Powers I really hate to shoot down all the people who keep suggesting sanders and stuff, but my boss isn’t going to pay me to work on these and I’m not going to spend my personal time doing it. Was looking for an automatic solution – gonna buy a heated stirplate (or see if I can borrow a friends) and go with the lye solution.
Any thoughts how a rock tumbler would do?
@ThantiK if you had a stationary disc/belt sander with a 90 degree tool rest handy, I think it would seriously take under a minute per block to sand them clean. Wouldn’t even try a palm sander though, that’d be a hassle.
@Ryan_Carlyle No disc/belt sander - though you’re right, out of all the manual options, that would clean these up super quick.
I’ll see if a local space has one of these in working order.
Yeh. Going to echo from the above.
Toss the used blocks into the recycler. Order new from China (Aliexpress, with some effort to find a good source). These simple bits of aluminum are cheap as shit. Your time is more valuable.
Though it is severely odd that we are shipping simple blocks of fabricated metal half-way around the planet.
@Preston_Bannister The best explanation I’ve found is that China seriously overbuilt fabrication capacity for literally everything over the last 10 years or so to feed their own crazy rate of economic growth, and now that growth is a little bit slower they have tons of slack/underutilized/idle capacity for metal production, machining, etc. So they’ll do work very, very cheap now just to keep people and machinery running. Kind of incentivizes them to find lots of small markets like this that wouldn’t be worth a US company diverting resources towards.
Now, why air freight shipping costs across the Pacific are so low, I have no idea.