Yeah, it's certainly possible to take the zinc coating off of some parts that have that.

Depending on what you toss into the bowl, parts could potentially get wedged together and could get damaged that way. Also, if a part gets wedge a certain way against the bowl, it can potentially eat a hole through the bowl (I've had that happen before).

Yes, if you let them tumble for days or weeks on end, parts could potentially get worn down in places that you might not like.

Certain parts are zinc or nickel plated, so it is possible to wear through or strip that plating.

Also, I don't mix small parts (screws, nuts, small brackets, etc) with large parts. That way the small parts aren't banging against the larger ones.

I generally try to check the tumbler every 2-4 hours or so to make sure things are ok, rather than leaving it completely unattended.

I have been tumbling for 4 years now and yes some parts will but most don’t even when your using walnut media and flitz I most use the same thing and learned u can’t hurt with that ,the longer it’s in there just makes them shine more

I usually give a quick check once every night when I turn it off for bed

Only real damage I've had is cases where I made the mistake of tumbling 'smooth polished' metal parts like mirror plated guides/etc with small sharp things like screws, and then they got all scratched up

Yes I try too keep the same things in there at the same time

Yes u can but I only have the 18lb one from HF and I just do almost the same parts together so things don't get marked up as much

The steel parts you tumble will always be harder than any media you use. If you leave it on for a month, it won't grind your parts to dust. The media will probably be dust, but not the parts. Just check it every few hours. The tumbler is doing all the work, you just need to check to see when it's done.

Also, use a quality polish to speed things up. I use and recommend Blue Magic metal polish. Available at many auto parts stores. Works great and leaves a thin protective film on your parts.

I'm so glad I'm not the only one.

My tumbler has some, uhh, battle scars. I slightly overfilled it once and it ate several holes in the bowl. After patching them up with resin, I ran it a few more times. Then on its first job in my new house, the wingnut came loose on the lid, and the tumbler shook itself to failure until the wire connections pulled right off the motor tabs. I think it's pretty much toast at this point, unable to tighten.

Just don't over load it and check every few hours too see how it's doing that's what I do and seems too work well ,when u check and if it's good for u great if not turn it back on and I don't think with using walnut media u won't ever hurt the parts

I use walnut media and find that with the 6/32 metal posts the threads get totally ruined and the nuts won't thread on them so the only way around that is to put double nuts on them first

Looking great bud