DIY powder coating

Two: Is there an exam? Do I get college credit? :) Good post.

Why does the oxide of aluminum cause problems for powder coating? It's electrical conductivity is much lower than aluminum (mebbe even an insulator?), but that shouldn't affect the static electricity effect, unless alum oxide in fact affects that as well.

Speaking of alum oxide/powder coating, I guess that's why god invented anodizing. Which is another option.

That was cool, machining the powder coat itself! Super-neat! Some creative engineers, on that one!

Reply to
Existential Angst
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The insulating properties are not the problem. It is that the oxide coating acts as a contaminant and prevents a good bond between the powder and material. Then the paint fails. Same problem with chrome plating on aluminum.

Yup, and it's a better one for some applications.

They picked up that trick from one of our other customers. Small outfit called GE Turbine Systems. We coated ALL of the shaft seals used on the various turbines they made for about 10 years. In that case we used a special powder that provided insulation properties for the shaft.

We also did some parts for Raymond Corp. (fork lift parts) Those were interesting. The powder was a special high temp cured nylon blend. Cure temp was 650 degrees. Those parts had to be preheated, coated then cured. ALL of this had to be done HOT. These were done in a batch oven. You would hang the parts, let them get HOT, then open the oven door, grab a couple parts, close the door, spray them, open the door, then hang them back up. Repeat until you finished the batch. These parts and items like the seals and some medical items we did were done by two people. We also were the ones who taught all the other sprayers the ropes and did all the gun maintainance as well.

AHH the good old days.....

Reply to
Steve W.

No, this is a fitting that has a pin that fits into a socket on deck.

I suspect powder coating will get chipped, and in a salt water environment aluminum would corrode away rather quickly.

I've never had the chance to machine stainless - or any steel for that matter. I've whittled aluminum with a mill though, and could make what I needed. So the idea of making parts from stainless is kind of over the top for me. I honestly don't know how hard it is to do, or how long it would take. But if I have the choice - all other things being equal...

Like Forest Gump always said, "One less thing to worry about".

Reply to
cavelamb

You got it.

Gunner

"Aren't cats Libertarian? They just want to be left alone. I think our dog is a Democrat, as he is always looking for a handout" Unknown Usnet Poster

Heh, heh, I'm pretty sure my dog is a liberal - he has no balls. Keyton

Reply to
Gunner Asch

I'm thinking E-field (volts per meter), not H field. The current is microamperes. But it's a DC field so I'm probably being over-conservative. The voltage is typically developed by a Villard cascade or Cockcroft-Walton multiplier, both of which usually have enough capacitance in the string to not have much ripple.

Reply to
Don Foreman

I'm not quite that stupid, though dissenting opinion is probably available.

Not understanding fields or electronics certainly does not imply stupidity, but disdaining guidance from those who do could be foolish for those whose lives depend on having their implanted electronics work without fault.

Electronic devices can be affected by both E-fields and H-fields. E-fields are due entirely to voltage regardless of current. H-fields (magnetic) are due to current regardless of voltage. Frequency is a factor with both. We're talking near fields here, not far fields as in radiation where alternating H-fields and E-fields are causally linked by the characteristic impedance of free space or the medium at issue per Maxwell's vector calculus differential equations.

One medical device mfr's spec for E-field is 1000 volts/meter. An electrode at 50KV at arm's length can easily produce an E-field well in excess of 1000 volts/meter.

I'll say again that I do not mean to be alarmist here. I'm a bit chicken about getting kicked in the chest by the 750-volt 42-joule mule that resides near my collarbone, but that's just ol'candyass me. I don't hesitate to MIG weld because I know the H fields are within limits if I dress the leads carefully. I know this because I measured them pre-implant. I'm still a bit antsy about TIG with HV HF start because of my E-field measurements last January. Making a Faraday cage garment is on my ta-do list.

Reply to
Don Foreman

I can see Al2O3 being a problem for chrome plating, which depends on where materials fall in the chemical "emf series", but it is less clear why such a stable compound, useful in its own right, could not be powder coated. Surely Al2O3 can be *painted*, right? Epoxied? Glued?

Seems to me it should be powder coat-able, which is, in essence, a kind of melted polymer/paint? Not argering, just thinking out loud.

From what you describe, it seems like there are various chemical configurations for powder coats beyond simple pigments, for different applications/properties -- none for oxided alum, or even anodized alum?

Reply to
Existential Angst

Heh, be nice to the missus, lest she start powder-coating as a hobby, with an evil grin on her face. :)

Reply to
Existential Angst

The thing is that the design of the gun shields the user from the effects. On the pro guns the guns grip is coupled to the system to prevent the user from having problems.

While in operation there is no arcing or any other discharge. Believe me you do NOT want an arc with all the explosive powder dust in the air, Seen the powder ignite twice. Not pretty...

Don't worry about the implant. You WILL KNOW if it trips. I know about 3 people who have them and when they fire it's REALLY obvious. Maybe it's the "HOLY FU&*" you hear from them or the instant grabbing of the chest and the panting when they try to breath...

Reply to
Steve W.

The oxide forms a layer on the aluminum which acts almost like you coated the part with some dust prior to coating. The way the powder bonds is interesting.

There are literally thousands of different chemical blends for powder coating. For instance lets say you desire a flat black coating 1 mil thick. What UV stability do you need? Will the part be inside or outside? What final surface finish do you wish, smooth, pebbled, sand textured? Does the coating need to be temperature resistant?, How many degrees? What temperature will the substrate withstand and for how long? What wear characteristics do you need? Electrical Characteristics? Gloss retention? Fade resistance?

These are just a few things that you decide prior to making the blends. All of them have to be determined PRIOR to producing the powder. They cannot be changed later, Unlike a liquid paint which you can add a pearl or a flatting agent or a gloss additive or whatever.

Reply to
Steve W.

I'm highly motivated to skip that experience.

Reply to
Don Foreman

Eastwood (

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) also has a good line of hot coat guns and powder. Their forums helped me out quite a bit when I first started too.

Reply to
Rhon Wite

or try here

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Reply to
charlie

Been following this part of the discussion only tenuously, but I just now read an article in New Scientist about the effect of the current crop of tiny headphones on pacemakers. Since I don't know if non-subbers can access this, I'll risk some copyright issues while exercising the "fair use" clause; to wit:

People with pacemakers know to keep magnets and electronic devices, such as cellphones, away from the implant to avoid interference. But now it seems even the tiny magnets in headphones pose a risk.

It's still safe to use them, says Kevin Fu at the University of Massachusetts Amherst, who carried out the study. Just don't keep them in breast pockets.

Fu and colleagues tested eight different headphones by holding them near the implants of 100 people. They found that in nearly a third of cases the magnets interfered with the device (Heart Rhythm, DOI:

10.1016/j.hrthm.2009.07.003).

Headphones containing neodymium were the most problematic, as the magnetic fields generated were very strong for the headphones' size, says Fu.

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FWIW

Joe

Reply to
Joe

Amazing what crap poses and passes as science these days. Holding headphones near the implants of 100 people to see how many malfunction is an experiment a dim adolescent could do if she could recruit enough implanted fools to assist.

The safe limit specified by one ICD mfr for static (DC) B-field is 1 millitesla, and B-fields are easily measured.

Reply to
Don Foreman

cavelamb wrote in news:2bSdnXm4EdN6vYrWnZ2dnUVZ snipped-for-privacy@earthlink.com:

Stainless isn't too bad to machine, depending on thge alloy. However, I woudln't be surprised if the best stainless for marine use is harder to machine. The problem with SS is that machining it work hardens it. You want to be more agressive with it than aluminum, which might tax your machine tools. Carbide helps a lot because it doesn't care so much that the work is hardened.

Doug White

Reply to
Doug White

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