Polishing cast aluminum

[mpierich]

Originally Posted by customandsound

I have shot a valve cover right in to the yard .. my machine is in front of the door and a loose grabbed it and off it went.. i got to put ply wood up on the wall in that area .. the dry wall has some battle marks

Ha, I was thinking of hanging an old mattress...all polishers should be in a padded room anyhow...

the first time i shoot one i was amazed that it went as far.. they the last time i shoot one i had a shop full of customers. but in the new shop i am putting padding up on the wall i got that soft mat mat + it will cut down on the nosie alittle... either that or i am going to have the kid there with a catchers mit on just waiting ...

[sswee]

A shooting part is bad enough, but having to pick it up and see all the dings on a part that was almost done kills me.

[turbohardtop]

well, I tried to polish the valve colves last weekend and it did not turn out well at all. I sanded the covers with a 220,400 grit using the 1/4 sheet hand sander. then I manually wetsanded using 600 grit. After that I used the spiral sewn with black emery, spiral with brown, the lose with white. the result is depressing since it is now where near mirror finish. Infact, it looks like unpolished billet material instead how long do I have to spend on each wheel? how much pressure? I was using a 1/2 hp converted sander and I can only get in about 5-6 minutes before the motor heats up and lose power. If I need to get a new motor, any recommendations for a decent motor but not too much $$$. Thanks.

[pickleboy]

you need a new motor. i spend about 10-20 minutes on each wheel but i am running a 1.5hp at about 9000 sfm on the first wheel also you might need to use more pressure. there is no exacts in this game it is trial and error. if buffing didnt scratch or open pits/pores then you can rebuff until its as good as you want. i suggest the biggest buffing motor you can get/afford. if you are going to keep doing this kind of work it is a good investment to buy big and strong. quality is expensive but worth it. hope this helps bro.

[mpierich]

Obviously you need a better motor...I think Caswell has some inexpensive buffers and so does HF.

Did it look better after just the emery than after the brown (tripoli)? A lot of times I skip the brown and go straight to white.

Also, if you have pores/pits which are bubbles in the metal, they will prevent obtaining a real good finish. Only thing to do in that case is plate with copper so it fills the pores, repolish, and get it chromed.

[turbohardtop]

there is no pit or pores in the metal (anymore). The Palm sander took did a good job of removing the pits. I think I need a new motor. What size is sufficient? should the motor get hot fte a while? thanks.

[turbohardtop]

btw, after the black, using the brown and the white did not look any better.

[pickleboy]

i would recommend at least a 3/4 hp motor that spins at around 34-3600 rpm. try to find one with 3/4" spindles, mine has 7/8" and it can limit what wheels you can use due to center hole size. as for the finish it could be due to the motor. after the black were you getting the shine you were looking for or not? if so then it may be wheel speed on the brown and white. i personally dont use brown much on alum. i go straight to white. also make sure you clean the part between steps or you might contaminate your next wheel with the previous compound. i use brake clean or simple green and water, and dry off good before moving on to next.
as for the motor getting hot yes they all get warm/hot after a short bit of use. it should be fairly warm to the touch but not enough to cause you to jerk your hand away.
maybe mpierich also has some input on this? he is also a great source with a good background in buffing. are you out there Mike what do you think.
cliff

[mpierich]

Yeah, 3/4 horse minimum if you're gonna do much of it. I have 1-1/2 hp and it's still not enough for me, bogs down w/a 10" wheel.

I quit using tripoli (brown) too...but the white will make a difference in the "color" IF you keep everything clean.

BTW how's it goin' pickle...keeping busy?