Sprue plate
- Thread starter Brad
- Start date
Pistolero
Well-Known Member
7075, when hard anodized, is naturally colored a dark grey to almost black.....
this is what the color is on most AR receivers, although some are painted.
I have the acid and the power supply, just haven't sat down an done some sample
coupons to get the process sorted out. Actually, just a sulphuric acid solution in
an ice bath, and apply a low voltage DC charge to the parts. Probably want a sparger
to mix it well, so a ss tube wiht tiny holes set into a SS container, with a low pressure air source
for the constant mixing. Voltage is around 15 volts, current density numbers are published, may
need to adjust voltage to get the proper current density. My power supply has variable DC
voltage and an output ammeter. After the anodizing process, rinse and then boil
for 1/2 hour in clear water to harden the surface. That's pretty much it.
Bill
this is what the color is on most AR receivers, although some are painted.
I have the acid and the power supply, just haven't sat down an done some sample
coupons to get the process sorted out. Actually, just a sulphuric acid solution in
an ice bath, and apply a low voltage DC charge to the parts. Probably want a sparger
to mix it well, so a ss tube wiht tiny holes set into a SS container, with a low pressure air source
for the constant mixing. Voltage is around 15 volts, current density numbers are published, may
need to adjust voltage to get the proper current density. My power supply has variable DC
voltage and an output ammeter. After the anodizing process, rinse and then boil
for 1/2 hour in clear water to harden the surface. That's pretty much it.
Bill
Last edited:
KeithB
Resident Half Fast Machinist
A friend/business acquaintance runs a place that does ceracoat, anodizing, and dip paint coatings. He would probably do a sprue plate for me for free or close to it if he was running it with another batch of parts. Want me to ask him about it? Be glad to do it, haven't talked to him in a while and probably should.
Nice job on the sprue plate.
Nice job on the sprue plate.
Thanks but not required at this time Keith. This one is a test bed on a brass mould.
I wanted to see if Al would hole up over time as a sprue plate. Not sure there is a real advantage to Al over steel for the plate. It does work easier, that is for certain.
I have some 1/4” 1045 I want to try next. Learned a bunch doing this one. Now I have the right countersinks and that will make it easier.
I wanted to see if Al would hole up over time as a sprue plate. Not sure there is a real advantage to Al over steel for the plate. It does work easier, that is for certain.
I have some 1/4” 1045 I want to try next. Learned a bunch doing this one. Now I have the right countersinks and that will make it easier.
Pistolero
Well-Known Member
Two kinds of anodizing. Type 2 and Type 3. Type 2 is clear and thin and good mostly for minor
corrosion protection and will accept color dyes for marketing purposes. Type 3 (III) is hard anodizing,
much thicker, typically twice as thick and has it's own color, mostly dark grey, to black, but some alloys tint
towards brownish in some of the sources I have read. Much thicker, stronger and harder. This is what AR
recievers (upper and lower) are treated with for wear resistance and for the color. A friend had a complex
aircraft pulley part hard anodized a year ago for wear resistance at a professional shop. Beautiful job.
The key with either type is that after the electro bath part you have to boil them to harden the aluminum
oxide layer or it will rub off pretty easily.
Most aluminum consumer products are Type 2 anodized for corrosion protection, and usually left clear.
Bill
corrosion protection and will accept color dyes for marketing purposes. Type 3 (III) is hard anodizing,
much thicker, typically twice as thick and has it's own color, mostly dark grey, to black, but some alloys tint
towards brownish in some of the sources I have read. Much thicker, stronger and harder. This is what AR
recievers (upper and lower) are treated with for wear resistance and for the color. A friend had a complex
aircraft pulley part hard anodized a year ago for wear resistance at a professional shop. Beautiful job.
The key with either type is that after the electro bath part you have to boil them to harden the aluminum
oxide layer or it will rub off pretty easily.
Most aluminum consumer products are Type 2 anodized for corrosion protection, and usually left clear.
Bill
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F
freebullet
Guest
Rub some dirt on it & get it hot. It'll be the color it wants anyway.
smokeywolf
Well-Known Member
I've always favored "Kopr Kote" anti-seize compound.