Sanding Headlights Help?

[willowcat11]

I started doing some pretty bad headlights this weekend. I began with 3" sanding pads, and went from 500-800-1500-2000-3000. 3000 was a Wet sand.

I used my 18v Drill, with a 3M cushioned pad attachment found in one of there kits.

From there, I continued through the grits. When I finished the 3000, I noticed some burn out marks from probably pressing down too hard with the drill. I found hand sanding the 500 helped get rid of the marks.

So I went and completed those steps again, then finished that off with Ultimate Compound with the burgundy pad and the DA.

But there is still some fine scratches squiggled all over that are bugging me.
They are greater than what the UC and burgundy can take out.

My Question is: how can I tell that I am done with 500, and it's now ok to move to 800, then from 800 to....... and so on.....

So that I am making sure to get rid of the previous grit scratches. And to do it in a Uniform way.


Thanku!


Ray


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[Eldorado2k]

Any pics?


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[DetailedByPrecision]

3" sanding pads or discs? I currently use Meg 3" sanding discs with a foam interface to contour/maneuver better

500-2000 dry sand all the way? 500 grit is pretty harsh, but sometimes necessary to level out the existing clear.
IME, jumping from 800-1500 without using 1000 is too big of a gap. I tried to save time before and the 1500 grit just doesn't quite refine the deep scratches from the 800 grit.

Are you using a drill for the sanding process as well?

Uncontrolled speed and pressure, and heat build up probably caused the burn out marks you're describing.

Are you using the drill to polish the headlight as well?

Meg UC have decent cut,paired with the burgundy pad should be able to remove 3000 grit scratches

Not all plastic headlights are the same. Some are easier to buff than others. Yes, they are polycarbonate, but IME, not all are equal
You could be instilling some micro scratches due to the aggressiveness of the approach, or there are leftover sanding scratches that were not leveled out properly

Each step should look like a white sheet of paper after sanding. The more you progress forward with refining the clearer/hazier the headlight should get.
Sand in a cross hatch pattern. Left to right. Up and down to ensure uniform sanding.

[willowcat11]

Whoa!!! Thank you for that Awesome Response! I hear ya with the big jump from 800 to 1500. I'll pick up some 1200 from the shop.

I was using all sanding discs, similar to the Meg's ones. I used them with my 18v drill. I got scared away from the drill because of those burnouts, I don't want to do that again. I'll try by hand.
Thanku for the help man!



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[GSKR]

I use a rotary for the intial cut with compound then a da to finish them down.

[Crispy]

I think you should reverse your sanding order on a small section first.

Try 3000 Trizact damp sanding discs which will not over heat the plastic (burnouts).

Then medium cut Compound on medium cut pad.

Check results.

Need more sanding go to 2000 grit (always wet to reduce heat).

Repeat Compound step.

Once you figure out the least aggressive method apply to rest of the project.

The problem with starting with low grit is it takes lots of steps to get you to the compound/polishing step.

[rlmccarty2000]

Where can you purchase 3 inch sanding discs with Velcro backing for use on DA polishers? I have seen some in boxes of 50, but I don't need that many.

[willowcat11]

Sound Advice Crispy! Thanks a ton man!


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[willowcat11]

When using my cordless 18volt drill, should I have it on the low or hi setting when sanding?


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[mikejames]

Where can you purchase 3 inch sanding discs with Velcro backing for use on DA polishers? I have seen some in boxes of 50, but I don't need that many.

+ 1 I am interested in the answer on where to buy small quantities also?

[Dereksdtail]

I found doing every stage wet, has improved my results.



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[detailsbydennis]

For wet sanding applications we cross sand for complete removal of sanding marks. Anyone else use this technique?


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[willowcat11]

Do you do this Cross Sand technique by hand or by machine? And how is this technique performed?

Do I just sand up and down across the headlight, then go side to side on it?


Thank you, this helps a lot!


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[detailsbydennis]

Say we start out with 400 grit wet horizontal strokes using a foam sanding block until all yellowing is gone. Then we go with 600 wet vertical strokes with a foam sanding block after wipe dry and inspect for all horizontal 400 grit to be gone if you still see horizontal scratches continue with 600 until they are gone. Then proceed to 1200 or 1500 horizontal strokes wipe dry and inspect for vertical 600 grit scratches to be gone. This method takes a good hour for each lens including polishing.


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[AuroraDetailing]

I found doing every stage wet, has improved my results.



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I do the same thing. Doesn't even matter if the pads aren't designed for wet sanding, though most of the finer grits usually are. I find you don't use the heavy grits long enough for the water to have an impact on the pad itself, but does wonders for keeping the surface cooler and helps shed away the residue.