7075 Aluminum integrity (a micromag 2009 discussion)

[Maghog]

As most of us have heard, the new micromag 2009 body is going to be made out of this very tough material, and I am excited about it. One thing concerns me though, and that is the absence of the steel washer which the main spring sits against.
6061 aluminum has a rockwell hardness of 60, and the 7075 is certainly much harder at 87, but is it enough to hold up against the million or so cycles that will be put through these bodies?
I'm not sure of the hardness of the main spring, but spring steel hardness can go up into the hundreds, and that's enough to possibly wear down even the toughest of aluminum alloys.
I always thought that the steel washer was a nice addition to the micromag design, and I don't see why it should be eliminated now. It may be desirable to erase a step in the production, however, if down the road there are issues with worn parts, it won't have been worth it to leave out.
I only mention this for the good of the product and no other reason. If the tests that the guys at Pro-Team make turn out to be favorable for the product, then I'm going to be happy with it.
Dan@Triggernomics

[Rudz]

I'm sure they know what they're doing, they aren't some rookies and they've been around mags for quite some time, and I'm sure they're mag shooters themselves, they know what the bolt can do, and if they trust the new stronger aluminum against it, I would trust them. I wish I could afford one of the new bodies, but hopefully someone I know picks on up and ill steal there's, lol

[MANN]

you will have to be careful asking questions. I started asking questions and it didnt go so well.

[don flame suit]

I asked this very early on

** what method is being used to prevent wear? Ie washer & c clip, PTP press in washer, etc - something that is going to pressed in ( listed in post 131) - nothing is needed (listed in post 153)

I at one time owned a XT body that someone did not believe needed the steel clip and washer ( a second hand user) and it casued slight mushrooming which I had to sand down. Given it is a lesser alum, but it sucks to have a nice body that does not work.

I own a PTP MicroEmag 2000, and upon recieving it I had a heck of a time getting lvl 10 to work on it. where the steel washer that is pressed in the old ptp bodies is was either not made to AGD tolerances, or someone at one time mushroomed it out. I have been told that they had some problems out of these "back in the day", but am not 100% sure on that. I had to sand the bottom of it out to get it back "in round" to work.

I will say tho that I have owned 4-5MicroEs that never had this problem.

IMO AGD did it right the first time when they used the ss washer in their alum bodies.

I am not going to tell PTP how to run their business, but IMO the body should be heavily tested before its sold. Not just by fireblade, but maybe a few other people as well.

I am not going to buy a body new so my opinion is probably considered null and void. I would never buy the first model of a car, and I am not going to buy a paintball part before it is tested/ all details have been released. (I have been there, done that, and wont do it again.)

something else to consider
** what color anno is availible? dust black, raw, and one other color (listed in post 1) apparently we cannot have these bodies polished or they will be out of tolerance (listed in post 57)

[MANN]

I'm sure they know what they're doing, they aren't some rookies and they've been around mags for quite some time,

GM, Ford, Toyota have all been around for a long time too. That does not mean that they produce products right on the first go around. Some things cant be "engineered", and you need real world testing to "know" Ford Explorers used a cheap alum on their transmissions, and they will not make it more than ~90k without inserting a hardened sleeve. It would have been a cheap 8.00 fix that they should have done from the get go.

[Maghog]

I don't see why I have to be careful...I think it's a legitimate question to ask.
It looks like a lot thinking went into this design, and I really look forward to building this into a super set up. I just want this thing to be perfect and last forever.

[MANN]

I don't see why I have to be careful...I think it's a legitimate question to ask.

HEY!!! I just have to say one thing!! personally from me, not Forest or anyone else!! You guys are trying to make us MENTAL!!! We have had a couple of restless nights. When this project began I had you all tell me what you want. I gathered all your input to give to Forest and Russell. They used that input to give you everything they possible could and do what we wanted to do as well. I don't mind the questions, but if you want to beat us up for doing what we can for you then why are we doing it at all???? If we banter back and forth now it is only going to stall a project that I have worked so hard to put together for all of you. I feel you either like it or you don't. I'm sorry if you don't,

from tht ptp thread

[tweter]

Relax

Im a CNC machinist for the past 4 years and have been around manufacturing for 10 years and basicly this is a very stong metal and I'm sure it will hold up just fine for paintballing heres some facts to soothe your mind....


Introduced in 1943, alloy 7075 has been the standard workhorse 7XXX series alloy within the aerospace industry ever since. It was the first successful Al-Zn-Mg-Cu high strength alloy using the beneficial effects of the alloying addition of chromium to develop good stress-corrosion cracking resistance in sheet products. Although other 7XXX alloys have since been developed with improved specific properties, alloy 7075 remains the baseline with a good balance of properties required for aerospace applications. This heat treatable alloy is considered high in strength. Corrosion resistance and machinability is fair. Rated low on workability and welded only by the resistance process.



General 7075 characteristics and uses (from Alcoa): Very high strength material used for highly stressed structural parts......




7075 is the other "aircraft grade" aluminum that is carried by OnlineMetals. Its principal alloying ingredients are Zinc and copper, which make it one of the highest-strength aluminum alloys that are available. In fact, its typical strength in the T6 temper is higher than most mild steels.

7075 also has average-to-good ratings for machinability, corrosion resistance, and anodizing response. Like 2024, however, it is not considered to be weldable.

[Maghog]

Well I don't want to make anyone mental at all. I thought it was worth asking, but now you guys are making me feel bad for starting this thread.
Tweter- your analysis is certainly comforting, and in the end, you and I are able to modify this body if so needed. I guess that's what I'll do.
Consider this thread ended for the sake of the Hatcher's mental health.

[CoolHand]

That's all well and good, but you forgot to list one thing:

7075 T-6 Hardness = Brinell 150

A228 Spring Steel Hardness = Brinell 411

That means that no matter what you do, eventually, the steel is going to win.

Ano will help, but type II ano is so thin that it won't last long. Even though the layer is technically slightly harder than the steel, it is also very brittle, so when the underlying aluminum distorts (which it will as the spring loads it), the oxide (ano) layer cannot flex with it, cracks, and ultimately disintegrates, leaving unprotected raw aluminum.

If allowed to bear directly on the surface as it works, the steel spring will eventually chew up the aluminum face it bears on. Placing a spacer in between the body and the spring (even a steel one) that stays static while the spring works will prevent this. Now the spring will chew on the easily replaced washer instead of the body.

It is a very simple thing to cut a washer to the correct size, and drop it into the body before you slide the valve in. If PTP won't do it, and you're worried about it, you can do it yourself without a lot of fuss.

That all said, I'd guess you would get several years of service out of a body before you saw any detrimental effects from the spring chewing on the body, aside from the odd flake of aluminum chaff falling out of the tube when you field strip.

A washer would be a simple and effective fix. I think a big pressed in cup deal is a bit overkill for the application. Honestly, I think that the retention ring that AGD uses is a bit overkill as well. The washer is necessary, but it can't go anywhere when the valve is in place, so it doesn't need a retainer (and thusly doesn't need the complex machine work to cut the groove that said retainer lives in). It's pretty much just there to aid field stripping, and nothing more.

[Maghog]

Okay, dropping a washer in is easy enough, but then aren't you changing your tolerances? Theoretically, whatever thickness that the washer has needs to be taken away from the seat, so in the end you're still looking at doing additional machine work in order to make things work at AGD standards.

Of the six micro mags that I've owned, I've never had any problems at all. In fact, the guns were so impressive that many people I knew decided to buy them as well. I've worked on at least 50 different guns from pro-team, and every single one was a high quality product. This is what makes me a more than satisfied PTP customer.

Coolhand-your assessment is exactly what I'm talking about. I'm not just looking for a few good years with this body, but a lifetime.
I will modify my own body as I see fit to make this the case.

[CoolHand]

Okay, dropping a washer in is easy enough, but then aren't you changing your tolerances? Theoretically, whatever thickness that the washer has needs to be taken away from the seat, so in the end you're still looking at doing additional machine work in order to make things work at AGD standards.

Of the six micro mags that I've owned, I've never had any problems at all. In fact, the guns were so impressive that many people I knew decided to buy them as well. I've worked on at least 50 different guns from pro-team, and every single one was a high quality product. This is what makes me a more than satisfied PTP customer.

Coolhand-your assessment is exactly what I'm talking about. I'm not just looking for a few good years with this body, but a lifetime.
I will modify my own body as I see fit to make this the case.

When you add the washer, you add preload to the bolt return spring, that's all.

With a LVL 7, I doubt you'd even notice, assuming you use a very thin washer (like 1/32" thin). With a LVL 10, you'll probably need to retune it, due to the added spring load at rest, but that should be it.

Also, you guys are all using the term "tolerances" incorrectly. The word you need is really "dimensions".

Dimension is the measurement from point to point on a piece. The addition of a washer will change the preload dimension of the bolt spring.

Tolerance is the allowable variance of the same dimension from piece to piece. It is a manufacturing term, about how closely a manufactured part must match the designed print.

For instance, if the OD of the body is called out on the print as 1.125" with a tolerance of -+0.005", then any piece produced with an actual measured body OD of between 1.120" and 1.130" is acceptable and will function correctly when installed. THAT is what tolerancing is for. It is impossible to make every single piece exactly alike, even on CNC equipment, so the designer decides how much variation he can stand in each part, and puts that on the plans. The wider the range, the easier the parts are to make, so the cheaper they are generally, and vice versa.

[Ninjeff]

The CoolHand has spoken!!!!