Powder coating

[Janger]

On my last visit to the states I picked up a powder coating gun and some powder on sale from Harborfreight. I also found a counter top pizza oven at a garage sale for parts baking. Here are some photos of it in action. It's much easier than anodising. The sample parts are a galvanized wrench and a piece of 6061 Al tubing.

Edit: added photo of the transformer which puts a negative charge on the part and a positive charge on the powder as it is blown out of the gun. You can see the alligator clip wire attached to the part on the stand. The gun has another wire to the cathode in the gun tip.

 

[Jwest7788]

Hey @Janger,

That looks fantastic, How much did the powder coat kit run you?

Re: anodizing VS powder coat. Any idea which one will last up better to high heat over time?

The part I am working on is a muzzle brake for my hunting rifle:


(For anyone who doesn't know, Muzzle brakes go here on a rifle: http://screencast.com/t/kIL6wJgFyJc3
--> Exposure to hot gasses.)

I imagine the powder coat would be fine, but am not 100% sure. Any thoughts?



Were those your first pieces? Seriously good results!

JW

 

[Janger]

The powder gun was $100usd including some colours. I really don't know what coating technique would be better for durability. I would think either would work well, much better than paint. The results are my first attempt!

That is some cool machining. Your own design?

But - I do Josh have safety concerns - if anything goes wrong could that part become shrapnel? Is Al the right material? What kind of over pressures might be produced? If it works fine but if it fails what are the consequences to you or others? Sorry to be a downer - I'd rather see you buy this particular item from a respected manufacturer. I'd be happy to help you finish the part with a coating if you can agree it's only to be an exercise and not used on your rifle. I simply can't gauge if this kind of part is reasonable or not - and I'd rather be safe.

That does bring up another topic - general safety of things we make for ourselves or for others. Nobody here has insurance if stuff we do fails in use. I don't weld trailer structural members for example. Some guy I know wanted me to machine up some engine mounts. No. I don't want to be liable or responsible for an injury or death. Never mind the financial legal horror that could ensue- I simply couldn't live with myself.

 

[Jwest7788]

Thanks @Janger,

$100 isn't bad at all!

With regard to the machining, thanks! I have sunk a handful of hours into this little guy. Learned alot as always.
This is based off of a design that is not mine originally, but I did modify the original design to reduce amount of stress put on the brake, as well as increased the sidewall thicknesses.

With regard to usage and safety, I would be lying to you if I told you I wasn't planning on using this on my rifle, but I want to assure you that the risks involved with this particular project are well known.
The involved risk is no greater than usual when out shooting at the range.

It's pretty safe as long as you follow standard gun safety rules, but I totally understand and will not push if you choose not to help in this case, all good!


Aluminum is a pretty common material for Muzzle brakes, as is steel.

Muzzle brakes have two typical failure modes that can come about from poor engineering or machining

The first is the bullet hitting the inside of the brake as it passes through. (example)
This causes your bullet to fly off of the side by a large margin, sometimes even keyhole (tumble in flight). Either way it's a loss in accuracy we're talking about here.
Here's some guys talking about it, as I couldn't find an article --> http://www.theakforum.net/forums/14-general-discussion/67967-if-bullet-hits-muzzle-break.html

The other common failure is the brake slipping off of the gun due to damaged threads, or poor clamping, or a bullet really "striking" the brake.
(skip to 0:35 - He noticed the slip before sending it down range)

(skip to 2:00 - Sent his down range)

In both of the above failure modes, there is risk of being struck with the brake or pieces of the brake, or a stray bullet, but only if you are down range of the gun!
(To be clear, you never stand downrange of an shooter preparing a shot, and you never shoot when someone is down range. This is standard gun safety)

Even with an aluminum block right on the end of the gun in the path of the bullet, all of the force involved is headed down range. (Here's a new police gadget that does just this:

http://www.alternativeballistics.com/)

So really, pretty safe (No more dangerous then regular target shooting anyways!)

It's interesting, in the US hobbiest gunsmithing is a thriving branch of hobby machining. So fortunately the science and failure of most of this stuff is pretty well understood.
As with all hobbyist gunsmithing the first shots are done in a control environment with appropriate safeties put in place just in case. (This is for safety, but also to get the gun re-sighted to keep accurate after you make changes)

I would just buy one, but the cost is exorbitant.
--> In the states you can buy muzzle brakes for $10 from discount stores, and though I am not speaking to their safety standards, I'm pretty confident I put more thought into my design, haha.
Here's a good example of 3.4 oz (96 grams) of aluminum (Sold for $80USD south of the border) listed for $330!!, here in Calgary at wholesale sports. http://screencast.com/t/L0bA6pULtlX

That's like, $1100 per pound of aluminum if you buy a muzzle brake, vs making one.



Anyways, let me know if you're open to showing me your powder coat setup with my muzzle brake! Really, no worries if not though, I respect the decision either way.

Should we start a thread to chat about safety, ethics, and responsability around metal working? Probably get a good conversation going.

JW

 

[Mphenley]

I feel I should put in my $0.02, as I've been a range officer for over a decade and a shooter for longer (target only)...

Anything that has a possibility of getting in the way of the round should be avoided, so powdercoating, while typically more durable to physical damage, may not the best choice. The thickness of each coat is an art more than a science, and if the exhaust gasses get the attachment close to or past the curing temperature, I believe it will possibly run or sag. Physical damage to the coating may also peel some of it off along the bullet path, which could cause deflection in the least case and shrapnel in the worst case. If you leave more clearance along the bullet path, it becomes less efficient in redirecting gasses to reduce recoil (or flash, if you're worried about that), but would be more forgiving with the coating tolerances.

I'm not sure how anodizing stands up to heat, but as it's a chemical/ionic process instead of the electrostatic process of powder coating, it should wear off, as opposed to possibly chipping off. The only question there is heat and physical durability. I know dyes for anodizing metals will scratch off relatively easily, while the oxide forming the anodized layer should still provide corrosion protection... not that corrosion will typically be an issue with aluminum.

A third option for coating/protection is blueing or parkerization. These (I believe) will only work on steel, so you'd have to do a prototype for fitment with the aluminum, then duplicate it in steel for coating. These two processes are standards for firearms, and while they aren't identical, they're more or less the same results. At the end of it, the part will have that "firearm color" that is ever so slightly blue and takes forever to wear off. And therefore is also highly temperature resistant.

As long as the metal of the brake is less hard and/or tough than the barrel (which is almost 100% the case) then the threads or material of the brake should fail before causing issues to the firearm itself. Are you using an existing thread on the barrel to mount the brake, or are you manufacturing some sort of clamp? Obviously a thread would be far more likely to be fully in line, but most civilian firearms (especially in Canada) don't have threads for barrel attachments... something about most attachments being highly illegal... Clamps would then work, but being in perfect alignment is then an issue.

I have other insights/knowledge rattling around in my noggin somewhere as well, if you're interested...

 

[PeterT]

I don't want to make false claims that might be bum advise, but a lot of our aluminum RC engine heads are anodized & see ~350F+ continuous. Not sure how that relates to a firearm instantaneous or average between rounds. Also, I gave some of those blackening & bluing kits a try (intended for aluminum) & my results sucked. On steel I seem to have no issues with the solutions & the instructions are pretty similar - good surface finish, cleanliness, dipping, buff it off... For some reason the aluminum kit was very reactive, it fizzed in the solution but the coating was anything but nice. I didn't experience the blotchyness people talk about but it was a cross between flat finish & animal fur. So just a heads up to coupon test before relinquishing your prize object to the colorization gods. Anodizing would be my choice if you have the connections.

 

[Janger]

So forum says I could anodisze this part for Josh without him blowing himself or others up?

 

[Mphenley]

Seems to be accurate, yep

Sent from my HTC One using Tapatalk

 

[Jwest7788]

@Janger
Don't worry about it if you're truly not comfortable with it though!

Re: powder coating. how many colors did you get in the kit? Were they included?
How much are they standalone?

 

[Janger]

Check out kms for colours. They have loads. I bought a bottle of red black and white at harbour freight. It's all they had.

With my compressor being down I can't run the powder gun. Unless you want to haul yours over here.

 

[Krprice84]

Just gonna throw in my two cents here.

I wouldn't powder coat, but not for safety reasons. Just because it's going to wear off easily I think.

If you got paint in the way, the first bullet would instantly deflect slightly and clear the path perfectly.

A good way to powder coat it would be to put a rod down the bore of the brake, then you know your bore dimension won't change. But realistically, the first shot would clear it out.

The real danger with things being lodged in the bore comes from overpressure. So you'd want to make sure there's no paint in the area before the first ports, but once the bullet has cleared those, the pressure can no longer build up.

Anodizing would likely be a better bet though anyways. Not for safety reasons though.

And if Josh is following normal everyday range safety rules, there's no danger to anyone. If the brake blew up (almost impossible with an ounce of care and attention when making it), it would almost solely fly forward and outward, it wouldn't come back. There just isn't enough room for the bullet to get that sideways.

I think I'm going to make a brake now too.... My CZ858 needs something cool on the end.

Josh, why aluminium? Just easier to machine or a specific design reason?

 

[Jwest7788]

Josh, why aluminium? Just easier to machine or a specific design reason?

Few things pointed me to aluminum actually:

Preceding my actual thought to machine a brake was a bunch of shopping online for them, Came across this:
http://www.grizzlygunworks.com/D1_Rifle_Muzzle_Brake.php
In particular the line:

Material: Steel, 416 Stainless Steel, 7075 Aluminum

Which got me looking into using Aluminum instead of steel.

Other factors that contributed:
Had lots of aluminum on hand, in a variety of alloys.
Did not have steel stock large enough on hand
Easy to machine, as you noted
I built a clamp style brake, as my rifle isnt threaded, so wanted to be sure I didn't damage my barrel. Aluminum if over-clamped will just damage the brake. (Actually more likely to make it form fit, haha)

The only downsides I can see to aluminum are:
Will likely wear down much faster than steel. (hundreds/thousands of rounds fired?)
Will deform to all hell if the bullet clips it (wreck the brake, but should be safe)
Can't use with full auto (not an issue in Canada) -- Heat melts aluminum, not enough time to cool off

 

[John Conroy]

I am a target shooter also and a member at the Sherwood Park Fish and Game Association range. Another thing to consider about muzzle brakes is the noise factor. Instead of the gasses and noise going straight out the end of the barrel toward the target, some of the muzzle blast is directed sideways which reduces recoil but also make a hell of a racket for the other shooters to deal with. I always annoys the crap out of me when a shooter with a muzzle brake sets up beside me at the range.
Rant over!!

 

[Jwest7788]

I am a target shooter also and a member at the Sherwood Park Fish and Game Association range. Another thing to consider about muzzle brakes is the noise factor. Instead of the gasses and noise going straight out the end of the barrel toward the target, some of the muzzle blast is directed sideways which reduces recoil but also make a hell of a racket for the other shooters to deal with. I always annoys the crap out of me when a shooter with a muzzle brake sets up beside me at the range.
Rant over!!

Agreed!
Save the brake for shooting solo. I do a bunch of shooting in the woods near my parents place in the crowsnest pass, so no worries there!

 

[Wayne]

On my last visit to the states I picked up a powder coating gun and some powder on sale from Harborfreight. I also found a counter top pizza oven at a garage sale for parts baking. Here are some photos of it in action. It's much easier than anodising. The sample parts are a galvanized wrench and a piece of 6061 Al tubing.

Hi Janger,
Can you run through what steps you have to take to powder coat something? I thought there was current involved some where in the process to make the powder coat adhere to the metal?

Wayne?

 

[Janger]

Hi Wayne
Welcome to the forum!
I added another photo and a bit more description to the original post. Ask away if it's not clear.
John

 

[Wayne]

Hi John,
Okay, I'm a little slow on this, are you running a current through the stuff your painting while your painting it or after? Or at all? I always spray paint my stuff but would LOVE to learn how to powder coat.

 

[Janger]

Oh yeah the operation didn't mention that. There's a foot pedal, press it and it charges the part and then while pushing the pedal press the trigger and the compressed air (yes u need a compressor too) blows the powder out of the reservoir and out the gun. It's a lot like spray painting. The powder sort of curves through the air and gloms on to the part. The powder is a lot like photocopier toner and just as messy. The powder then clings to the part. Carefully unhook the wire, and gently put it in the oven at 400F for 15-25 minutes. The powder melts and adheres just with the cooking.

It's pretty easy to do. The problem is many parts don't fit in the oven. If you have space buy an old crappy oven.

If you go find my thread on curtain stands you can see the results.

 

[Wayne]

Thanks for the info,
Can you use a microwave or do you need an actual oven? I think a stove oven would hold most of the stuff I would be powder coating. I really like the finish that powder coating give you. I want one!!! LOL.

 

[Wayne]

Edit: added photo of the transformer which puts a negative charge on the part and a positive charge on the powder as it is blown out of the gun. You can see the alligator clip wire attached to the part on the stand. The gun has another wire to the cathode in the gun tip.

Sorry to keep asking silly questions but...The alligator clip when attached is not going to let the paint pass. Does it leave a unpainted spot where the clip was or is there a way to prevent that?