wet sanding questions

[cantex]

now that my motorcycle project is coming to a close,
i have a few questions / observations about the project.

when wet sanding, do most people use a sander or do it by hand.
i did it all by hand and noticed a couple of things. the sandpaper gummed up very quickly, and you could always see where my fingers were.

i used a high speed drill ( 3850 revs) with 6" wheels, and found that i got enough heat, but always left micro lines (never did get a mirror finish)
should i go with larger wheel?

everyone says it looks good, but i am more of a perfectionist, and expected better. i have some other, more complex pieces (front caliper, rear drum cover) i want to polish, but dont want to start unless i can get better results.

[fxstcguy98]

Re: wet sanding questions

use WD40 instead of water when wet sanding, it won't gum up as quickly. If you are seeing wavyness from your fingers, use small pieces of wood as a sanding block. Micro lines are a problem in alum. the softer the alloy, the harder it is to avoid the lines. They can be minimized by rakeing the **** out of the buffs, then rake every 6 or 7th time you apply compound. When doing the final buff, you may have to rake as much as every other time you apply compound (little compound often). Another thing to watch is when cleaning the compound off to be mindful that there are abrasives in it. Use a soft cloth and try to get as much off as possible without wiping.

[rides20]

Re: wet sanding questions

Also..some of the lines could be left over from the Machining marks....On the lips and spokes where they were milled, you might not have sanded deep enough to get ALL of the marks.

[mpierich]

Re: wet sanding questions

I still get microscratches - I've asked customers about it and they tell me even at the highest level of custom auto shows, they see it in polished parts. Sometimes the best you can do is get them going in the least visible direction. A buff with felt/white followed by felt/red can help, but use little pressure. Cleaning causes a lot of the scratches - the big polishing shops have dips and sprays so there's no wiping motion to add scratches.

If your paper is clogging while wetsanding, you're not doing it right. You need to keep it absolutely flooded while sanding - I use a spray bottle, and I lift the paper every so often and wash it off. Use a few drops of dish soap in the water.

I recommend not using a wooden block as it will dig in and won't conform to the proper shape - go to the local auto body shop and get a few small rubber sanding blocks - the ones I use have a hard rubber side and a firm foam side so you can vary the pressure, etc. They work great.