Anodized 80% Pretty Rough After Machining

[Nate74]

Has anybody else had the experience after finishing an anodized 80% AR in a CNC machine, where the anodizing is in pretty rough shape? Like to the point where the aluminum is showing through in some of the areas where the lower was clamped into the CNC? I paid a couple extra bucks on an anodized 80% thinking it'd be good to go with a quick blast of duracoat on the inside, but there are some serious wear areas on the outside... thinking of looking for an anodizer who can strip the original anodizing and refinish the whole thing. I guess I wasted the extra $$ getting an anodized 80%...

[Zartan]

Unless it was pounded around in hard jaws while indicating the lower into the machine, then maybe ano may wear off. Maybe. I've done a few black ano 80% lowers in the past couple of months with zero blemishes.

Pics would help

[-hanko]

The usual process to produce a metal part is to machine completely, prep the surface, and then finish.

Machining an already anodized piece is bass-akwards. Start with metal in-the-white, bead blast, and have it finished by a shop who can certify, in writing, that they meet or exceed the relevant mil-spec.

hth

-hanko

[VictorFranko]

Machining an already anodized piece is bass-akwards.

Ummm, not if you buy an already anodized 80% lower.

Machining an anodized lower is fine, but it helps to have a proper vise, vise jaws and, oh yeah, it helps if you know what you are doing.

Here's an anodized 80% lower I machined, not a mark on it.








OP, yes, a plater can strip and re-anodize your lower for you, don't panic.

[Nate74]

OP, yes, a plater can strip and re-anodize your lower for you, don't panic.

Awesome to hear. Thanks. Now to find an anodizer around me...

Also, that setup looks different than the one that was used on my lowers

[edgerly779]

I used a mill jig and no marks. I have more coming that have already been anodized and am not worried about marks. Clean vice jaws and if needed use pvc jaw protectors that apply even pressure to clamp lower.

[3RDGEARGRNDRR]

+1 with my $.02

I used a mill jig and no marks. I have more coming that have already been anodized and am not worried about marks.
Blow out any debris with an air compressor and wipe down vice jaws and use pvc jaw protectors that apply even pressure to clamp lower.

[3RDGEARGRNDRR]

Oh. If you are going to use the gun just go ahead and sand down the rough areas and duracoat it. I think they make the self lubricating additive if you want to clean it out easier although personally i have never used it

[Nate74]

Well, I've found a place that will replate it for me for $60 and do the stripping and prep work. Turn around time is only 2 weeks too. Shouldn't have paid the extra for the anodized 80% but will at least end up with a nice finished lower. Thanks guys for your input and thoughts.

[Varg Vikernes]

Jesus Christ that is a lot of money when you coulda just got a new complete lower for $120 or something

[Flintlock Tom]

I have had 5 anodized 80% lowers machined at two different shops and had no unusual wear on the outside.
I think you picked the wrong machine shop.

[12GAUGE]

.01Cent of masking tape would of prevented that. No?

[VictorFranko]

Also, that setup looks different than the one that was used on my lowers

Programming CNCs and cutting metal is what I do for a living. I just do these set-ups in a vise and run my program. Many novices or newer professional machinists overcomplicate their set-ups because they don't yet understand the cutting forces that will be applied to their workpiece and they fear the workpiece coming loose.

.01Cent of masking tape would of prevented that. No?

You have to be careful using masking tape in milling operations. Masking tape is thick and compresses. The coolant can break down the glue on the tape, the tape can then compress or 'slide', then you get movement of your workpiece, never a good thing while milling. I prefer a simple sheet of paper as protection, when needed. Paper does not compress like tape and there is no glue to break down.
I just clamp a clean lower directly in a clean set of vise jaws, tighten the vise properly and machine away, no paper.

[SOAR79]

where did you machine the lower OP?

[Nate74]

Jesus Christ that is a lot of money when you coulda just got a new complete lower for $120 or something

You might be missing the point of an 80% build...

I have had 5 anodized 80% lowers machined at two different shops and had no unusual wear on the outside.
I think you picked the wrong machine shop.

The guy has glowing reviews here and elsewhere, so I had no reason to suspect I'd get anything but a pristine product. Really strange as I see the results others have gotten with similar starting points...