hello all
i thought i try some Al casting, but whatever i try there are always small groves and dents on the casted body, its not easy to use either vaccum or pressure casting for me.

anyway the surface is finished as good as i can, i wanted to paint it using electorstatic process, but with these groves i dont think it will work if i used electrostatic .

any other solution ?
i can only think of using bondo , sanding and then spray painting


Max

there are different epoxies on the market , jb weld and those types work ok on stuff like that

wish i were in canada
can u tell me the application that is norally used for these epoxys ,
so can ask for application rather than the epoxy name ?

they tend to be used as fillers or for minor repairs
jb weld is a 2 part epoxy http://jbweld.net/index.php
i don t know if they still make liquid solder but that stuff works ok
there are quite a few products designed to be used in the industries
i think devon is another product that has aluminum filler
i'm sure if you google there will be many aluminum fillers

what is the use? if the environment is not too demanding (ie a model) its standard to finished CI or AL castings with bondo followed by spot putty followed by cellulose primer with sanding in between and after. the difficulty in painting AL is that it gets a thin layer of oxidization almost immediately and coats don't stick to the oxidised surface as well.

i want to paint my cnc router parts
and i want it to look pretty.

will electrostatic paint work if i used bondo or epoxy to smoth the surface ?
if not
can i apply bondo all over aluminum part and then sand and paint over it ?

what do u think ?

What is the pattern like? if it has dents and grooves in it then you will have the same in the finished item. If the pattern is smooth and without grooves then it would appear that the AL is "sinking" into soft sand ie not rammed hard enough...mostly I like to ram good and hard :D Any pictures of what you started with and subsequently ended up with?

well actually i didnt start anything yet
i am waiting for some expert advice .
my main question is

will electrostatic paint stick on bondo or epoxy ?

thanks

electrostatic is a way to paint not a type of paint use automotive type paint
the gun is positively charged and the part is grounded. you get more paint on
the part and less overspray,less waste.yes you can paint over primered bondo
with electrostatic

Hi,
I agree with Kipper in that if rammed properly and having adequate gates and risers the aluminum castings should not have the mentioned defects. What kind of sand are you using? I have been using Petrobond for my aluminum castings with very good results for some time. Also keep in mind that patterns should have uniform thickness on the walls to help avoid shrink cavities, and special gating and risers may be needed where there are thick sections to be cast.
Regards,
Wes

well actually i didnt start anything yet
i am waiting for some expert advice .
my main question is

will electrostatic paint stick on bondo or epoxy ?

thanks
Hmmm well then my "expert" advice is suck it and see...ie at least try it before posting the "anomaly" my reasoning being that if you haven't cast anything yet then how can you have imperfections in the resultant casting :shrug: Oh and my opinion on painting is to use a brush as that eliminates the electrostatic part...hth

what i meant is that i havent started anything yet in the finishing part, appling bondo and so on.

and if i am going to do electrostatic i am not goint to do it at my shop
i will have to send it , to be done and pay for it

thats why i needed to understand before i act.

For a cosmetic finish, I think bondo would work far better than JBweld or other metal-filled epoxies. Bondo sands nice, epoxy usually dosent...

you have to be carefull with bondo.. pressure will crack it if under a joint..

good luck..

Devcon makes a 2 part epoxy putty that has aluminum dust in the resin.I have used this stuff before and it works very well.Just a thought.

Depending on how deep your defects are, you might do well with a spray type polyester filler/primer. From there, you're ready for a quick sand and paint. Polyester products stick great to Al and aren't expensive.

If you're talking about defects to a maximum of roughly 0.030, I suggest polyester filler/primer (or epoxy filler/primer but it is an order of magnatude more expensive and extremely dangerous to work with)

If you're talking about defects to a maximum of roughly 0.100", you could go with polyester or epoxy glaze compound. I recommend Metal Glaze because it goes on smooth and sands like butter.

If you're talking about defects over 0.100", you might want to consider the drywall compound jacket technique that some of the guys speak well of or otherwise improving your castings a bit. Alternately, you could use a bondo type product.

... just a couple of ideas from a bodyman.