Anno: Add or Subtract Tolerance?

[nelsonizer]

Anodizing guys:

When you re-anno something, how does it affect the part tolerances.
Does it make your parts looser or tighter?

Example A:
- Existing Silver Anno
- Stripped Back to Raw (is this how the process works?)
- Re-Anno (solid base color with old school drip/splash)

Is there any chance your parts will not fit correctly or the marker might not work?

Also, could you add a splash to an already anno'd gun? If my gun is currently white, can they just throw on some splash or it needs to all be wet or fresh together?

[wthomas333]

I think this will answer your questions.

https://pctanodizing.com/faqs

[Magmoormaster]

IIRC, when you strip a gun, they remove ~..002 inches of material, and then anodizing adds ~.001. So the net difference is -.001 inches of material.

Unfortunately, you cannot add a splash to an existin ano. It has to be stripped and redone.

[BlindFaith429]

From my experience, stripping and re-anno makes the part smaller. Though, the parts I was dealing with were a type III hard-coat anodize (little bit different than a regular cosmetic anodize).

[russc]

You add on initial coating, and permanently subtract when you strip that coating away. Personally I think guns should have a maximum of 3 anodizing cycles, including the original coating. It worries me seeing classic guns anodized over and over.

[Tracker]

its both. you lose some, you gain some back, the net result will always be a loss of material though, so that will make your parts have a "looser" fit

and i agree with russc that more than 3 and ill start being extra careful, but unfortunately the shop plays the biggest variable, some shops and garage ops aren't as diligent with the stripping, some stuff doesnt survive the inital process in some shops.. meanwhile, if your careful, you can reano way more than 3 times and still be fine.

also it depends on what is being anodized, small fine threads are more susceptible to tolerance shift than large coarse threads

generally speaking, theres always a chance you're sending your part off to get ruined, but if you use a reputable shop, you'll be fine

[DocsMachine]

Simply put, anodizing oxidizes the surface of the metal, turning, of course, aluminum into aluminum oxide. (Same stuff as the grit in sandpaper, among other things.)

In the first place, adding oxygen to the surface causes it to, effectively, "swell" slightly. Same idea s the bubbles of rust on old steel- the iron absorbs oxygen, increasing in volume. Same game on the aluminum, just in a much thinner and more controlled manner.

But, as the oxide crystal is grown out of the parent metal, that metal is lost when the anodizing- the oxide layer- is removed. It's not a paint you're stripping off, you're actually peeling a very thin layer of the metal off.

As above, the general rule of thumb is you lose about one thou- .001" - every time the part is reanodized. As far as our paintball guns are concerned, that means bolt bores get bigger, barrel diameters get bigger, screw threads start getting sloppy, O-rings don't seal as well, etc.

Doc.

[Axel]

For a typical paintgun, what's a good rule of thumb for the number of times you can re-anno before tolerances become a problem? Once, twice, three times a lady?

[DocsMachine]

Personally, I prefer to never anodize more than twice- which, given the original anno, would be three times in total.

Doc.

[Tracker]

thats the same general rule i stick to as well. more than 3 and sometimes you have to start getting creative with o-ring sizes

[Euphie]

3 times does really seem like plenty to me, but maybe I am way off base, I took it that most markers weren't reannoed at all, they just get what the manufacturer put on. I would say only about 1 out of every 20 guns I see on the field has a custom anno, maybe even lower. The only marker I ever owned that was annoed more than once was my Viking, which supposedly had really tight tolerances at the start, but it seemed fine still to me.

Related does anyone know if different types of aluminum lose different amounts or are the sorts of aluminum used in Paintball all really similar?

[Spider!]

Most paintball parts are 6160 aluminum (extruded).

Every now and then, someone produces some parts in 7000 series and wishes they had not, mainly due to the more difficult machining. The oxide layer on 7000 comes out a little different given the same conditions, but a good anodizer can usually adjust given enough testing. There are some cast aluminums that can be anodized (like on the Trilogy).

Probably more important than the ano layer is how the parts are striped, polished, and cleaned prior to ano. You can lose more than a layer's worth in that process.

The other side of old (over-ano'ed) parts is that you can often go back with larger pins,screws, and o-rings and "make it fit". Smooth friction fit pins are real trouble-makers though. This is why I used to tinker with Superbolts; their tolerances were miserable to start with. They are pretty hard to mess up that way and the aluminum was decent.

Mostly unrelated to the aluminum grade, Type III ano (always a gray color) is thicker than Type II (lots of colors). Type III is thicker and harder as it is grown in different conditions than Type II. Type III doesn't have pores large enough to take dye, which is why you can only have whatever color it comes out with. You can make Type II look dark gray with dye, but you can't put color on Type III. IIRC, because Type III is more dense than Type II, it consumes more base metal. The overall part growth on Type III is not much larger than Type II, but when you strip it off, you can lose a few times more in layer height. This is why, as an industrial process, Type III ano is usually considered a one-way trip.

These guys were fairly early on the intarwebz;

https://support.caswellplating.com/portal/en/kb/caswell-inc

[Magmoormaster]

Mostly unrelated to the aluminum grade, Type III ano (always a gray color) is thicker than Type II (lots of colors). Type III is thicker and harder as it is grown in different conditions than Type II. Type III doesn't have pores large enough to take dye, which is why you can only have whatever color it comes out with. You can make Type II look dark gray with dye, but you can't put color on Type III. IIRC, because Type III is more dense than Type II, it consumes more base metal. The overall part growth on Type III is not much larger than Type II, but when you strip it off, you can lose a few times more in layer height. This is why, as an industrial process, Type III ano is usually considered a one-way trip.

Oh dang I didn't know that!! I've always wondered what Type III was, but never took the time to look it up. That's pretty cool.

Also, effing superbolts man!! Of all the guns I've owned, the superbolt was definitely my least favorite. I almost quit playing because that gun.

[Spider!]

Lol. We used to have a nice thread for customized superbolts. I think there was one post of a working stock superbolt. I learned a lot from working on them; they had all sorts of bad machining. They make nice pumps once you chase all of the gremlins out.