I have a bunch of billet machined parts that were one off made. I do not want to polish these parts is there a way to achieve a cast look on these?
yep round the edges and corners with a file, and sandblast the crap out of it. try not to get things to uniform around the edges http://www.jalopyjournal.com/forum/showpost.php?p=5945892&postcount=174
the bigger the grit, the rougher the fiinish will be. So skip the glass beads and go straight for playground sand
I'm a cylinder head guy in a race engine shop. Garnet media in a blaster works great for making machined steel or cast iron look as cast. On softer metals back blaster nozzle away from part. If you want a section of your part to not get texured tape it off with heavy rubber tape. The tape that powder coaters use should work. Duct tape just gets shredded to a gooey mess. You can even file in small grooves to make fake casting seams. On soft metals sand like Da Tinman said works good. Smokey
A needle scaler works, but it's slow, tedious, and requires some practice/skill to get a good result. I found you get a better look by contouring all the needles to look like a sharpened pencil, but with the points radiused round. At the same time, all the needles should be kept the same length. Over time, and depending on the material of the parts, the needles will require re-radiusing. Blasting with sand, grit, etc. will produce a rough satin finish, but careful blasting with appropriate sized shot or large diameter glass beads(on aluminum) produces a finish more like a casting. Be aware that overly heavy blasting imparts a lot of stress into the part. That can cause distortion, and even break small parts. To avoid problems, especially on thin/delicate parts; all you want to do is alter the surface using as little pressure as possible/practical, nothing more. Whether blasting or needling is done, on aluminum I have found that a light final finishing with fine Scotch-Brite and phosphoric acid(Alumi-Prep or aluminum cleaner) rounds off the worst of the surface roughness, giving a nicer finish that is easier to keep clean and less susceptible to fingerprints etc.
I did this to a few parts including this water neck. I softened the sharp edges with a grinder, went over the parts with a needle scaler, then sand blasted.
The definition varies a little from one field to another. Foundries call rough poured blocks of metal billets. The forging industry calls raw forgings billets. In the hot rod crowd, in the minds of most, billet is the fully machined, machined from solid look. In the automotive world, a forging is a forging, a casting is a casting, and a billet part is one machined from a solid chunk(billet) of material. For example, billet gears, crankshafts, connecting rods, and cylinder blocks are carved/machined from a solid block of raw material. Although a casting can be fully machined to look like a billet part, in automotive terms it really isn't billet, it is a fully machined casting.
Lots of good info here I have a modern billet Aluminum head that I want to make look like its cast and the intake which was custom machined for me. I just want to make the modern engine look like it was stock from the 1960's
If doing just some touch up on freshly machined, or welded sections of a cast part, I just grab a piece of sandpaper, and hammer some texture into the surface. You can vary the roughness with different grits!
Was just thinking about this very topic... Now THAT is an interesting approach! Probably works well on aluminum...
Well, if you are going to paint the part, after correct prepping, spray on your "tack" coat. Sprinkle some clean sand (your choice of grit) and follow up with subsequent coats for complete coverage. Works great where a cast iron or aluminum repair was made and the part was originally painted.
Fresh out of the blast cabinet, sprayed with flat clear. Knocked most of the street rod right out of it, they was brushed when I got em. makes them almost invisible when installed. I made new brackets to mount them upright and those arent the correct screws.
Here's my try with a needle scaler. Larry T http://www.jalopyjournal.com/forum/showthread.php?t=356311
these started off as 6.5" dia. carbon bar stock Before I machined them. Just grind and file all the sharp corners (irregularly makes for a more casted look), Then media blast. I used glass, but a coarser sand would have worked better Jeff
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