Cleaning Up Castings

[xtremek]

Hey folks I need some help. Somewhere I saw where someone cleaned off the parting lines of an aluminum casting, then hit it with shot or a descaler or something so that it looked like there was never a part line. Anyone have any clue how to do it?

 

[RoninB4]

I've done this on several types of castings from motorcycles or where an appearance was important. Use a file, then some type of abrasive in either hand or power tools. You'll have to blend in any mis-match of halves and create a uniform finish over the entire area/part so it doesn't look different.

Perhaps you could include details/photos of what you're trying to work on and what you have to accomplish this.

 

[Benw455]

I have done that to intakes and then put into my **** Blast cabinet. It makes it all uniform looking.

 

[BillK]

It depends on how the original casting looks and if you are trying to make it look original. I have done a few repairs on castings and then used various methods to "hide" the repairs. A needle scaler works good. I have also used very course (40 grit) sand paper and hit it with a hammer to put a texture in the aluminum. A shot blaster will even it out some but not hide it.

 

[garfunkle24]

^ +1. I usually see a needle scaler used for this.

 

[Firebrick43]

Heavy blasting or hitting it with a needle scaler will both accomplish the same thing.

Harbor freight has a couple of needle scalers. They are cheap, slow, and they are terrible airhogs compared to the same size Ingersoll rand or CP but if you just doing a small project they may work well for you.

If you doing a lot, get a name brand needle scaler.

 

[xtremek]

....Perhaps you could include details/photos of what you're trying to work on and what you have to accomplish this.

It's the transmission for a Dodge truck.

 

[RoninB4]

It's the transmission for a Dodge truck.

Ok it's a die cast transmission housing. What do you have to work with in tools, abrasives, and how much of the housing do you intend to work so the parting line finish matches the other visible areas? I may have worked on the mold for this while at Atols in Schiller Park, don't know or remember. Why are you wanting to remove the parting line if it's installed in the truck where it wouldn't normally be seen?

 

[xtremek]

Ok it's a die cast transmission housing. What do you have to work with in tools, abrasives, and how much of the housing do you intend to work so the parting line finish matches the other visible areas? I may have worked on the mold for this while at Atols in Schiller Park, don't know or remember. Why are you wanting to remove the parting line if it's installed in the truck where it wouldn't normally be seen?

I have grinders (4 1/2", die grinders, Dremels), a blasting cabinet that I can probably fit the housing parts in, air hammer, air file.... The entire driveline will be visible, top, sides, and bottom.

Looks like I might be adding cast iron to the mix.

This won't be a high number of parts, maybe a dozen over the next few years.

 

[RoninB4]

I have grinders (4 1/2", die grinders, Dremels), a blasting cabinet that I can probably fit the housing parts in, air hammer, air file.... The entire driveline will be visible, top, sides, and bottom.

Looks like I might be adding cast iron to the mix.

This won't be a high number of parts, maybe a dozen over the next few years.

-It will depend upon the level of surface finish you're seeking. Follow the advice from others that have posted previously for the "as cast" look. A finer finish like satin will require more work or a finer media in the blast cabinet so it's all about the results you'll be wanting. Anything resembling a polished surface will be very time consuming. I suppose you've already considered powder coating and epoxy paints?

 

[Steve_P]

I can't imagine using a needle scaler on a die cast aluminum part. Even the HF needle scaler I have will do a job on cast iron- it'd make aluminum look beat to hell. He's looking for a die cast finish.

If the OP can get it wet blasted once it's sanded smooth, this produces the closest finish to new die cast that I've seen. If not, dry bead blasting and some light work with a scotchbrite pad is what I use. PPG sells an aluminum treatment. I'll see if I can find the post...

Edit: https://www.garagejournal.com/forum/threads/bead-blasting-help.533076/#post-10692971

 

[Firebrick43]

I can't imagine using a needle scaler on a die cast aluminum part. Even the HF needle scaler I have will do a job on cast iron- it'd make aluminum look beat to hell. He's looking for a die cast finish.

If the OP can get it wet blasted once it's sanded smooth, this produces the closest finish to new die cast that I've seen. If not, dry bead blasting and some light work with a scotchbrite pad is what I use. PPG sells an aluminum treatment. I'll see if I can find the post...

Edit: https://www.garagejournal.com/forum/threads/bead-blasting-help.533076/#post-10692971

That’s quite pretentious

We didn’t know it was a die casting until after those recommendations were made.

 

[xtremek]

I don't want a polished surface. I want the finish of the parting line to match the rest of the housing, an aluminum trans housing and a cast iron transmission housing. They'll end up getting a paint job, but I want them to look consistent over the entire surface. I don't want the housings to lose their original texture.

 

[Steve_P]

Bead blasting will lose the original texture on a die cast aluminum housing. Sand blasting is fine on cast iron. Both of these will be fine if you want to paint over them.