Tumbling... Vibratory? Rotary? Media? What setups do you guys have?

This is a great thread :thumbup:. I've been researching this, as I've been wanting to try the process out, and there is some great info provided here. Thanks very much to those who've replied with their experiences.


Jeremy
 
KalEl said:
I think the stonewash then etch holds up about as well as anything. I've beaten the hell out of the blade in the first picture and it still looks about them same, just has lots of wood gunk hammered into it. The great thing with an acid washed finish is that if it ever comes off it can always be reapplied by the customer with some vinegar etc...

This is why I'm against blade coatings in many circumstances, it eventually wears off and the customer can't fix it. I may coat some machetes in the future if the customers want it but from my perspective a finish that can be perpetually maintained and restored is the best.

Also maybe someone can shed some light on this. I swear acid etching is a dark art. Sometime Ill etch a blade and I can wipe all of the finish off with my finger. Other times Its very tough to get off and holds up well. Does anyone know why an acid etched finish sometimes doesn't "stick?"
Click to expand...

I haven't tried a cold blue as a blade coating, I do have some at the shop though and should probably give it a shot. As you said the idea of a renewable coating is one I can get behind. I'm clearly going to have to do some more experimentation with finishes...

EDIT: I mixed up your post with Eric's in my brain which is why I referenced cold blue above.

I liked the look of acid etched finishes when I was doing them. I'd like to try acid etching and then burnishing in stainless or porcelain media. I'm curious to see whether you can close the 'pores' of the acid etch without taking off the coloration.
 
KalEl said:
I think the stonewash then etch holds up about as well as anything. I've beaten the hell out of the blade in the first picture and it still looks about them same, just has lots of wood gunk hammered into it. The great thing with an acid washed finish is that if it ever comes off it can always be reapplied by the customer with some vinegar etc...

This is why I'm against blade coatings in many circumstances, it eventually wears off and the customer can't fix it. I may coat some machetes in the future if the customers want it but from my perspective a finish that can be perpetually maintained and restored is the best.

Also maybe someone can shed some light on this. I swear acid etching is a dark art. Sometime Ill etch a blade and I can wipe all of the finish off with my finger. Other times Its very tough to get off and holds up well. Does anyone know why an acid etched finish sometimes doesn't "stick?"
Click to expand...

BTW: I found that most of the time when I have issues with the acid etching not taking it's down to a thin layer of decarb. I had must more success with acid etching after I started doing more finishing after heat-treat.
 
LucyCustomKnives said:
Aaron, I have access to both types... vibratory and rotary... I have used both for gun parts and shell casings but just vibratory for knives. I tend to use dry media such as corncob and polish or walnut shell in the rotary and not the ceramic triangles. The triangles I keep wet with WD-40 and while you can switch back its a pain and never actually gets all the WD-40 out... So keeping the bigger rotary dry makes sense to me. It can do 1000-1200 pistol sized shelm casings as opposed to my vibratory doing 500. The finish with the dry media seems to be similar. The rotary has paddles and drops the media to a degree so it is similar. Will have to dive in and try it with the ceramic stones. Can fit a bigger blade. You can also change the angle of these machines and change the media flow and fall.

I don't think I can remember a single blade I've done where I didn't use the tumbler at some point. Even if its just to knock off decarb and then polish. It's a great elbow grease saver IMO and can leave a durable finish...

As to Superman's question... I love acid etching. On lots of stuff. It just leaves patterns that can't be duplicated by any mechanical process. In simple carbon steel, I have noticed a distinct relationship between martensite presence and the darkness of the oxide formed during FeCl etching. It seems to 'stick' best if neutralized quickly, usually with baking soda and water at a boil, and quick drying afterward with no contact of the steel and a finger, etc. It also seems to do with how smoked my FeCl solution is. Which, btw, FeCl PCB etchant can be freshened back up with addition of a little muriatic acid. And, in the case of my last but of damascus, what finish I left it at prior to etch. At a full polish I got contrast, but it just rinsed away. It looks cool and is a neat gray, but lacks the dark black that usually brings out the steel without having to etch as deep. This was forged very close so has a few marks, but this is what I mean. Gray...
38c6900fb68a8dfc791378d98adcf664.jpg


Here I left it at 5-600ish (trizact A something...) and tried the boiled baking soda deal. Straight from an etch to the baking soda water solution.
3042672520599cf3c0a1c5351a484002.jpg

This one wound up being rubbed to a little lighter tone with steel wool. But the finish was tough.

I feel the same way about coatings. I love them for guns, but for some reason not knives. There are exceptions, like when a color scheme is just right (newer member here just did one that looked stellar... sorry, can't remember screenname...) On the one tac knife I do, I resisted the urge to cerakote it. Instead etching deep and black oxiding it. The reports seem to indicate it holds up as well or better than some of the coated blades... And yes, easily repairable.... Deep scratches in my blade's particular case can be colored with aluminum black from Birchwood Casey. Available nearly everywhere.

So, basically I really have no idea either. But I love playing with the stuff and seeing what comes out. And I always like the down and dirty true hard use look of a knife with this treatment. Polished steel looks great for some stuff, but my hard users are gritty and grainy. BTW I really love the way etched WI looks...

Sorry to write the second book of 'War and Peace' on your thread Aaron. Hope it keeps going as I'd like to see more examples and descriptions myself.

-Eric
Click to expand...

With regards to coatings: I have been wanting to try TiCN again (I had a CRKT knife that had it and really liked it) but using TiCN means I would have to switch to a steel that has a secondary hardening range (like CPM3V) as the TiCN is applied at 950ºF+... I'm slowly coming to the conclusion that those kind of PVD/CVD coatings are really the only 'non renewable' coatings that should go on knives. I love the look of freshly applied Cerakote, but if you use a cerakoted knife for bushcrafting you end up exposing the underlying sandblast a little quick for my taste.

Using a cold blue (like oxpho blue or something) and then supplying the customer with a small amount of it when they buy their knife might be an option. Not sure how safe those cold blued finishes are for food contact though. I hadn't thought about etching and then bluing, I'll have to give that a shot.

I love the contrast and look that a dark finish supplies. Too bad we can't just buy steel that's black :)
 
Varga Knives said:
Aaron - this may not help you out much because you already have some tumblers but it could help someone. There is plenty of info on the web for going the cheap route and this is also great for someone just experimenting.

The blade below was taken to 400 grit then cleaned with acetone and then denatured alcohol. Dipped in a 50/50 FeCL and vinegar solution for five minutes. Sprayed and cleaned with windex and rubbed with 0000 steel wool. Repeat the acetone and alcohol cleaning and repeat the FeCL, etc. Put in a container with about 3 pounds of Harbor Freight ceramic media a handful of smallish smooth stones (for good measure) and WD-40. I used an empty rock salt container (I went through enough of them this winter) as it's tough plastic, large and has a handle. I let it dangle at the end of my arm and did a vigorous wrist twist for ten minutes. I think in this case I also cleaned it up, dipped it again and repeated the stonewashing. I love the finish (but not so much the handle on this one). I plan on giving it a lot of use in the next two weeks to see how it holds up. View attachment 423352View attachment 423353
Click to expand...

I think what you have there is the closest to what the finish out of a rotary tumbler is going to look like. I imagine it will hide scratches quite well!

Do let me know how the finish holds up, I like the look of that one!
 
Daniel Fairly Knives said:
I do a quick 5-15 minute stonewash in a small HF vibratory tumbler with ceramic media and windex. I find the key is to keep the media clean, put it in a colander and clean with soap and water if it appears to be dirty.

Here's a recent one done this way... maybe 20 minutes on the Titanium.




Dark pic but shows the bevel finish. I took the bevel to 600 grit and the flats to 220, blasted then tumbled. A quick acid etch will give the finish more contrast, this one was not etched.

Click to expand...

Very, very, cool looking knife Daniel. I like that a lot!

Have you tried the blast then tumble procedure on steel? I get the feeling it would be a little corrosion prone, not really a problem with the titanium.

I have a small vibratory tumbler that's the same as the HF unit. So it's clear I need to get some ceramic media and try it out! Unfortunately that little machine is a bit small for my fixed blades. The 4" Resolute just barely fits without handle scales, not sure if it will fit at all once the scales are on...

The least expensive big unit that I have found is the one from Northern Tool for $750 or so... Not too bad a price given that I was looking at spending probably $450+ to homebrew a rotary tumbler with similar capacity.

I think the range of tumbled finishes that I've seen in this thread indicates that I should take the leap. Even if I don't end up using it much on knives, I'm very certain it's something I'll end up finding unlimited uses for in other situations...
 
Yeah, meant to add... No go on the cold blue with food... I usually recommend mineral oil only ever touch a blade that's gonna be used for food. Well, and the FeCl etch since its cleaned and neutralized and of course any food patinas like mustard or vijegar...
 
LucyCustomKnives said:
Yeah, meant to add... No go on the cold blue with food... I usually recommend mineral oil only ever touch a blade that's gonna be used for food. Well, and the FeCl etch since its cleaned and neutralized and of course any food patinas like mustard or vijegar...
Click to expand...

Yeah that figures. I'd like to keep my coatings food safe if at all possible. Cerakote isn't though and I just had to make sure I warned my customers. That's another point in the plus column for TiCN and DLC, both are food safe (DLC is used often on medical implants even!)
 
aarongough said:
Yeah that figures. I'd like to keep my coatings food safe if at all possible. Cerakote isn't though and I just had to make sure I warned my customers. That's another point in the plus column for TiCN and DLC, both are food safe (DLC is used often on medical implants even!)
Click to expand...

Who do you use for DLC? There is a local company here I've used for DLC on carbide but it's not pretty enough for a knife. I've been wanting to put it on a knife but I don't know who does DLC with good aesthetics. It's been too splotchy.
 
Nathan the Machinist said:
Who do you use for DLC? There is a local company here I've used for DLC on carbide but it's not pretty enough for a knife. I've been wanting to put it on a knife but I don't know who does DLC with good aesthetics. It's been too splotchy.
Click to expand...

I haven't had them do any coatings yet, but I've talked to a company here in Toronto called Sputtek. One of the reasons I've hesitated is because of the color variations that you just mentioned. They don't really do coatings for aesthetic purposes and weren't really able to give me any guarantees on how it would turn out...

They also do TiCN which I believe has less color variation. But then I'd need to change to using CPM3V. I'm not necessarily against that, it's just much harder to source in reasonable quantities when compared to A2, to say nothing of the extra expense. Given how happy I am with A2 it's hard for me to be enthusiastic about the leap in expense for myself and my customers.
 
synthesist said:
I think this guy has solved your problem......................

OlKcgSs.jpg


a6VXHCu.jpg


MRX2Wyw.jpg


The plan and more photos are here:

http://www.ar15.com/forums/t_6_42/344986_How_i_built_my_own_rotary_tumbler.html
Click to expand...

That machine is a little on the small side unfortunately... I build a tumbler similar to that a while ago, but it was direct drive rather than belt driven, and that meant I couldn't get the speed low enough while still having the power to turn the barrel.

I think I'll be making something similar again but using a reinforced 5 gallon pail this time. Not 100% sure yet though. The other option is to buy the smaller vibratory tumbler from Northern Tool.
 
You must log in or register to reply here.
Back
Top