I would like to build a small fluid bed for powder coating. The purpose is for quick and efficient but thorough coating of cast lead bullets (this removes the need for a wax-based lubricant and allows for cleaning feeding through bullet collators and also less mess in suppressors).
My current method to apply this coating is via a vibratory tumbler, which is totally satisfactory, but I just want to try something different. The perfect setup would allow me to drop a bunch of bullets on a mesh tray made out of something like hardware cloth, heat it up slightly, dunk it, and pull out some perfectly coated bullets.
I am hoping somebody here has used an industrial sized fluid bed machine and can weigh in with their observations.
Total coating depth required will be under 2 inches.
I am familiar with the basic principles of a fluid bed setup, and there really isn't a lot more to one than in the picture shown (like always, the devil is in the details and implementation of course).
My questions are:
1) Has anyone determined a durable but effective membrane to use for this? I am considering an air filter cut to fit my apparatus but people have used everything from paper towels to brown paper bags in smaller setups for fishing lures. Average size of powder coat particles is going to run from 25-50 microns.
2) How many "bubblers" will I need for, say, a 12x12 inch bed? You can note in the diagram where the air is released in the device. Do industrial PC fluid bed tanks have many "ports"? I cannot find many/any good pictures, and almost any industrial tank is made to deal with far greater "depths". Is there an effective PSI for a fluid bed in general? Is more pressure better (until it flies out of the machine)? When using an electrostatic powder coat gun I always find a psi in the low teens to be the most effective.
I think I have this planned in my head better than I articulated, but I am just hoping someone else has tried to build one of these for hobby work.
A picture of some pc'd bullets I made for anyone interested. These are for 40 cal / 10mm, weigh about 185 grains.
>>984890
Those look really cool
>>984891
Thank you. I have a few other pictures just in case somebody is interested, I suppose it is a pretty DIY topic.
The ones previously pictured were applied with a vibratory tumbler filled with BBs.
This one is was applied with an electrostatic gun, which gives a very smooth feeling coat, but wastes a lot of overspray compared to tumbling, and takes much, much, much more time.
The bottom is shiny because there is an aluminum gas check attached to the base.
These are .45s, also applied electrostatically with a gun. The pointy ones in the back are for .44 special / magnum.
458 socom and 9mm. The blue is tumbled on, the black is sprayed on. Blacks rarely tumble on well and always look splotchy... I have never ascertained any performance difference in terms of accuracy and neither coat is heavy enough to inhibit expansion, although logic would seem to dictate that the sprayed coating is probably more consistent. As bullets are resized after being coated I suppose it doesn't really matter as they are squeezed into a round shape if there were any minor irregularities.
This picture is very bad due to my garage lighting (and none of my pictures are good) but these are 308s loaded subsonically. If you have never shot a suppressed subsonic rifle you are missing out! It really is hollywood quiet in a bolt action.
Wasting expensive heavy jacketed bullets on subsonic loads that will be used inside of 150 to 100 yards is a huge expenditure, and lead bullets by design tend to be better performers at low velocities.
>>984888
Wow, I wish I could offer advice because this looks really cool. Unfortunately I don't know much about the topic, good luck OP
A powder coated 45 bullet of a different design next to a conventionally lube-sized bullet. Lube-sizing involves squirting a wax into grooves in a cast bullet which lubricate the bullet as it travels down the bore and prevent lead from being deposited in the rifling. Lube grease can also in some applications help seal the bore better and prevent gas blowby, known as gas cutting... but mainly it is just to stop leading.
Now that more people are trying to coat bullets in more modern ways and doing away with old lubes, you see more bullets like in
>>984890
which lack lubrication grooves entirely (as they do not need them). The powder coating acts as a jacket and encapsulates the bullet from scraping off on the rifling.
This is not a new concept, and even back in the 1800s people would wrap solid lead bullets in paper to achieve this very effect... paper patching is still used by some enthusiasts today and can make for spectacularly good groups even with old rifles, but is extremely time consuming.
Here are some bullets which I recovered from a berm after shooting them. It can be difficult to tell from the picture, but the coating stayed completely intact where contact was made with only the rifling (bullets which hit rocks or other debris were damaged, obviously, but unless lead was actually removed the coating did stay in place).
Expansion was nowhere near consistent, but that wasn't the goal, and these projectiles were recovered from plain old dirt and mud anyway- not a good test bed for bullet expansion.
In general a hollowpoint cast bullet will outperform a solid one due to have the center of gravity moved a bit further back. This is far from a hard and fast rule, though.
>>984913
Here is another, much simpler diagram. It makes me wonder if multiple "ports" are needed or if a pressurized lower chamber separated by a membrane alone is adequate. Information is so scarce I have no idea, but it seems to me like multiple discrete air outlets would be preferable... but I don't know.
This diagram introduces the idea of adding a charge to the powder, which is logical given that an electrostatic charge is how the powder is applied in many applications as is. this would be very simple to implement in any working bed, I would think.
This is a beautiful example of what I have in mind and seems very simple.
https://www.youtube.com/watch?v=XF-bNVqlB_g
No idea, good luck though.
What's the point, people pay for these? Or just for fun?
>>984942
Just another way to skin a cat, so fun I suppose.
I remember your ass. I am still waiting for ballistic comparisons with factory and handloaded plated bullets against a control group, but they look fucking beautiful.
>>984998
I've made a few posts about bullets like this over on /k/ and occasionally do an intro to casting thread or a powder coating thread, but you might have me confused with another guy, or maybe somebody reposted some pictures.
I'd be glad to try and get you the info you want, if I am able, though. What would you like me to try out? If it's anything involving setup or something I don't have handy it could take a while, though.
Some of the pictures I posted are pretty old, too. Most of them, actually. The only recent one was the one with the 185 grain 40s, as I just got that mold last week or so.
My pistol pit I built last month or so (if the backstop seems low it's because there's a giant fucking hill behind it)
Your only real concern is going to be the uniformity of the membrane; nothing else is really going to affect it.
Given that, look into air filtration cloth, like what's used in dust collection bags. Beyond that, possibly the best thing you're going to find is some fine-mesh screen, like:
http://www.ebay.com/itm/16-Pack-400x400-3-x3-Stainless-Steel-Mesh-Cloth-ECIG-Atty-Vaporizer-Vape-Wick-/351020140288
...or just type "400 mesh" into eBay or whatever and you'll find larger stuff that's much cheaper per square unit.
Ideally, you'd also add a sort of spreader under it. Cotton or something else loose, but won't let any significant air current to form in a particular spot. Leave a small gap between that and the filter/mesh, and you aren't likely to do better in terms of fluidizing a powder.
>>984888
I have absolutely zero interest in guns and bullets but always was interested in powder coating.
Not really googled it but never even thought it was be possible as DIY! I could even probably make this (if I had any spare time).
Post back with updates, please!
>>985120
>>985124
Looks like fluidization plates are available, although generally as an industrial item in some quantity. They are not inexpensive for single pieces, although variety is limited.
http://www.powderbuythepound.com/13_x_13_Fluidizing_Membrane_for_10_LB_Bucket_Hopper/ looks like just the ticket for what I have in mind.
Your advice on cotton to diffuse the air supply is a good idea. I was considering all sorts of crazy ways to do it, but cotton is a good idea. Failing that I will buy an air manifold for aquarium tanks an use multiple outlets for air that way.
>>985205
>Your advice on cotton to diffuse the air supply is a good idea
Remember to leave space between the air supply cotton/wool/polyester filter media/whatever in addition to above it, otherwise you're going to need a lot more material to diffuse it.
(I made a laminar water jet a couple years ago. Turns out the construction of most of it is really similar to what you're doing.)
