Cut and Buff Not Going So Well

Discuss anything after that final masking comes off.



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PostPosted: Fri Dec 09, 2016 1:49 pm
I do not have a lot of experience with cut and buff. Only done a few small parts, but even with less than ideal materials they came out fantastic. I am now working on some motorcycle parts and things are not going so well.

The plan was to do a flow coat and not get into the cut and buff thing. Worked great for most of the parts but had a few specks of dirt land on each saddle bag lids and a 2”X10” section of decent orange peel on the lower edge of the tank. So I decided to try the cut and buff thing on worst bag lid as test. We are talking a flat surface about 6” wide by 18” long. Finish was glass with 4-5 specks of dirt sticking up. Should be simple enough right?

Spot sanded the dirt with 1000, then went over the top surface with 1000 3M Wet-R-Dry, wet on a soft block. Surface was already very smooth, so the 1000 cut evenly with no high/low spots. Then hit it with the 1200-1500 Trizact wet, followed by 3000 Trizact wet. Started rubbing by hand with Miguire’s 105, followed by their heavy cut, then medium cut, and last the light cut stuff. Used a black Turtle Wax pads for everything. That’s all I had and they worked fine before. When I was done it looked good up to about a foot, and as you got closer you could see a ton of tiny scratches.

So I ordered some more materials and tried again.

Started with a good wipe down with PrepAll. Hit the surface with 1500 3M Wet-R-Dry paper wet on a soft block, 2000 Wet-R-Dry soft block, and finished up with 3000 Trizact wet. Sanded in opposing directions so I could be extra sure I got each of the previous grits scratches out before moving to the next. Then I broke out the new pads and went to work. Buffed with Miguire’s 105 using a HF orange pad, followed by heavy cut with chemical guys orange pad, then medium cut and CG white pad, and last the light cut stuff with CG black pad. Spent probably 2 hours steady rubbing a 6”X18” area… and came out with the same deal!!! Looks great from a few feet, but if you get up close there are still a ton of tiny scratches going in every direction. WTF!!! :realmad:

Everything was as clean as an operating room. Towels were good quality microfiber, only used for painting, get washed and dried by themselves. One towel for each grit. One towel for each compound. Water was changed between grit changes. Pads were brand new. Compounds are brand new.

What am I missing?

By the way, both my shoulders are sore as heck.

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PostPosted: Fri Dec 09, 2016 4:19 pm
When you were done with sanding with the 1000 grit, did you clean the surface and check for scratches? You can wipe with W&G remover and look while it is still wet or you can keep a spray bottle of water and a rubber squeegee handy. Just spray the surface and run the squeegee over it and you should be able to see the spots and scratches that remain.
The entire surface should look dull with no shiny spots anywhere on it. Here is a pic of a dust spot not fully sanded out:
Image


In this picture you can see that same dust spot near the top left center surrounded by orange peel. I had sanded a lot with 1000 on a hard block to get to the point you see in the first picture.
Image


Here we are ready to move to next higher grit. All of the 1000 grit scratches must be removed before proceeding, so 1500 would be the maximum jump IMHO. I generally go to 2000 grit before getting the Megs 105 and a twisted wool pad out.
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PostPosted: Fri Dec 09, 2016 4:25 pm
Here's a couple of pics of my Harley Ultra Classic paint job:
Before cut and buff:
Image


During the sanding stage. I hit this quick with Megs 105 to see how things were coming. Notice the scratches around the flash.
Image


Finished:
Image
1968 Coronet R/T


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PostPosted: Sat Dec 10, 2016 8:08 am
Hey, BeoBob.... Did you notice this statement by Coronet in the first post.... " I generally go to 2000 grit before getting the Megs 105 and a twisted wool pad out."
Have you tried a wool or twisted wool pad on this? A lot of times scratches are at such an unknown "grit level" that you just may not be getting deep enough with your sanding to get down to them. When I see this happening twisted wool with a heavy compound is my "go to" process. Aggressive compounding like this can actually burnish the coating to a plastic like state. Just a warning.... twisted wool is very aggressive....its another one of those learning curve things. Dial up the speed slowly.....
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PostPosted: Sat Dec 10, 2016 8:36 pm
Still doing it by Hand? I know you have had success by hand before, but not all colors are the same...

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PostPosted: Sat Dec 10, 2016 11:36 pm
Wow, didn't catch that "by hand" thing.... seriously you need heat and pressure to start reforming a surface like this. If you don't feel comfortable with a full size rotary at least get a mini for stuff like this....your arms will drop off eventually....
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PostPosted: Sat Dec 10, 2016 11:41 pm
pontgta wrote:Still doing it by Hand? I know you have had success by hand before, but not all colors are the same...


Wow, I missed that too. Just assumed everyone has a rotary buffer I guess.
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PostPosted: Mon Dec 12, 2016 7:21 am
I went a got a cheap HF 6" DA polisher and a couple of their el cheapo pads. Wish I would have just bought the **** buffer to start with.

Started back at 2000 wet on a soft block. Blew it dry a few times to watch my progress. Then rubbed with 3000 wet till my arm fell off. The part was starting to shine just using 3000.

I just knew this was going to be it. Hit it with the buffer and the 105. Buffer did an hours worth of hand work in under a minute. Then hit it with the fine cut. Same deal. Fine scratches everywhere. Went back to the 105 and got more serious... until I was worried about rubbing through. Then went over it lightly with the fine cut. Finish is better, but there are still very fine scratches in every direction. The polishing process rounded the edges of the scratches, if that makes sense. I was like, what the he11 dude, I'm done!!!

Then I went and held the part up next to the Victory that I paid too much $$$ for someone else to paint. I immediately felt better.

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PostPosted: Mon Dec 12, 2016 9:25 am
Get yourself a 7" rotary buffer and your next buffing job will go much better. (Note: you always approach edges with the buffer wheel rotating "away" from the edge and not into it. Same with sharp body lines.)

Making sure you have all the previous grit scratches removed when color sanding is critical. Most buffing compounds will not remove 1000 grit scratches.

One all the scratches are from 2000 grit the buffing is much easier.

Here's my step by step for buffing:
Megs 105 on a twisted wool pad. This gets the surface free of sanding marks
Megs 105 on a Lake Country CCS white foam pad. This removes the twisted wool swirls.
Megs 205 on the same foam pad as above. This will start to add clarity to reflections.

This next step is really for that "like glass" show car look.
Menzerna 85 RF (may be called Final Finish now) on a CCS black pad. Removes any remaining defects and micro-fine scratches.
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PostPosted: Mon Dec 12, 2016 12:23 pm
Learning as I go.

The part in question has been cut with 1200 or 1500, then 2000, then 3000 three separate times since 1000 touched it… and we are only talking about a 6”X18” area. If there is a 1000 scratch left after all the sanding with higher grits my name is Snuffaluffagus.

That being said, I might be seeing where heavier grit scratches mapped up through the last session of clear. I had to cut the pinstipe down hard with 180-220-320-400 to get them good and flat with the rest of the part. I only laid down 2 coats of clear over the 400 scratches. I thought I got all the big scratches out with the 400, but maybe not. In any case I am scared to cut on this piece any more. It looks good, better than anything that has been washed and dried a few times. So I’m good with it.

I still have the tank to do, so I get to try again from scratch. I sanded the peel off with 600 and sprayed an extra 3 coats of clear on it yesterday. It was supposed to be a flow coat, but the first coat had a run. So I mixed up another cup of clear and sprayed 2 more good coats to give me plenty of material to cut and buff.

Learning as I go.
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