Sanding scratches...any ideas?

[Headlight 911!]

Hey all,

Starting up a little headlight resto business.

Using a 3" drill adapter with a soft foam meguiars unigrit thing inbetween the pad and the sanding discs, I'm getting scratching while wet sanding.

Process went from wet sanding 800-1000-1500-trizact 3000 disc, then using an yellow pad with meg 105 and following up with an orange pad and plastx. Tons of scratchmarks.

Could it be the wetsanding, because i'm not using a 2000 grit, or something else?

Thanks.

[C. Charles Hahn]

Got any pics?

One thing to keep in mind is that if you're using a drill to "sand" with you're essentially using a rotary in which case it's more like "grinding" than "sanding." That could be part of your issue.

It would probably be a smart investment to pick up a DA polisher to use for sanding if you don't want to work by hand. Depending on how much business you are getting that equipment would pay for itself fairly quickly.

[Headlight 911!]

Got any pics?

One thing to keep in mind is that if you're using a drill to "sand" with you're essentially using a rotary in which case it's more like "grinding" than "sanding." That could be part of your issue.

It would probably be a smart investment to pick up a DA polisher to use for sanding if you don't want to work by hand. Depending on how much business you are getting that equipment would pay for itself fairly quickly.

Yeah I'm using high speed on my 18V drill. Maybe I should go back and do one by hand with the same type of method and see what type of difference there is. Grrr.

[Innovative]

My suggestion is that you get away from a drill and use either of the following for the lens resurfacing.....

a) Metabo 3" D/A
b) Griots 3" D/A

Both spin if I am correct at 0-10,000 rpm which works great for electric tools

or use a pnuematic D/A which spins at 15,000 rpm and it also adjustable

Here is a video that shows how my technique works for me....

[ame=http://www.youtube.com/watch?v=ruB1sgZ8diU]‪Headlight Lens Restoral with a 2 part wipe on coating on 2002 VW Jetta lights‬‏ - YouTube[/video]
Unfortunately many times the drill technique will not finish off the polycarbonate lens correctly, resulting in scratches that are still visible........

When wet sanding, I like to keep the area wet working up and down, side to side then up and down again, going over the whole lens 3 times. You should be seeing a light slurry develop as you work the 1000 and 3000 grit....Wipe clear and inspect in between steps for clarity.


800 is too fine of a grit to start off with on many failed lenses, usually I like to start with at least 500 grit. You must be certain that you are removing the failed sacrificial UV coating. Many of the european cars, Porsche, BMW, Benz tend to have a harder coating which I use 320 to start then work up.

You did not mention what machine was used for cutting and polishing the lens....Drill, D/A, Rotary?

To finish off what you have done already you may try using a 4" Meg's Burgandy cutting pad on a rotary, then 205 with a 4" Megs polishing pad then wax or seal.....you should see some very improved results...

In my Headlight Lens Restoral service I always recoat with a polycarbonate specific UV coating, whether it be a wipe on or a spray on application.

[billsmars]

Another thing is to clear coat. It will do away with the scratches and you don't have to be concerned with the job not holding up.