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Re: what am i doing wrong.... [wetsand/buff]

PostPosted: Mon Jul 23, 2018 9:20 am
by DarrelK
I've always thought that learning to do a good cut and buff was harder than learning to spray. It's all about stages of sanding, refinement of scratches, picking the right pads, the right compounds, too much pressure, not enough pressure, too fast/too slow, and on and on. Spray guns are like mix according to spec.s and lay on wet even coating..... I know I am over simplifying that but I can fix my gun technique/problems in minutes. After 37 years of car and furniture coatings I STILL feel like I am working out my cut and buff.....

Re: what am i doing wrong.... [wetsand/buff]

PostPosted: Mon Jul 23, 2018 9:40 am
by '68 Coronet R/T
Well said! :goodpost: :goodpost:

Re: what am i doing wrong.... [wetsand/buff]

PostPosted: Wed Aug 15, 2018 3:32 pm
by d3r
welp… im back LOL

ran into trouble again.... still fighting these darn scratches.

on the passenger side of the car I skipped the 1000 completely and started with 1500 then 2000 then the compound.

ive tried a few combinations for my first step as suggested;
DA- Yellow heavy cutting (hexlogic) pad w/V32
Rotary- Heavy cutting (meguiars) wool pad w/M105

followed by;
DA- Orange med cutting pad w/V34
DA- White polishing pad w/V36
DA- Black finish pad w/V38

my problem is somewhere in the first step. There are no small/shallow scratches when I run through the whole process.. only deeper ones.
all the scratches are running in the same direction so they are 2000 (or 1500 at worst)
im not 100% sure how deep M105 will get out but V32 is rated for 1200-1500scratches so im convinced its something with my technique.

so frustrating.

Re: what am i doing wrong.... [wetsand/buff]

PostPosted: Wed Aug 15, 2018 5:52 pm
by DarrelK
And this is what I'm talking about.....even seasoned people can chase their tails on this....
Well, I've got kind of a theory about what we call "scratches" in the finish. I think it is more like micro dirt that builds up in sandpaper and in pads as well not just the "straight grit" of the sandpaper/polish. It makes a much lower grit type of scratch that the 105 is not taking out. I absolutely hate to suggest something like this but it could prove what I am saying....try something like 3M SuperDuty on an aggressive twisted wool pad. If you find this is eliminating the scratches that would confirm what I have said. I have done this several times myself (no rhyme or reason to it, happens at random to me no matter how clean I think everything is....) and it did allow the rest of the process to proceed as normal...

Re: what am i doing wrong.... [wetsand/buff]

PostPosted: Wed Aug 15, 2018 8:45 pm
by d3r
I mean these are deep.. like not micro scratches... these look like full on 800grit or something LOL

what RPMs do you suggest with a Meguiars heavy cut woo pad? the M105 bottle suggests 1500-2000rpms and the Chemical guys v32 suggests 1200-1800...
just for craps I turned my Rotary up to like "2800" and it seemed to take out almost all of the scratches but 2... I wonder if the Eastwood brand rotary wheel style settings aren't very accurate with RPMs?

like I said this is my first time doing body work so I wouldn't really notice if the Rpms were off... maybe setting it for "1500" rpms on the eastwood brand would equate to only 800rpms of a different rotary.... you see what im saying?

I think tomorrow ima find a spot loaded with a wet sand with 2000 and then crank up the RPMs to "2500-3000" and see if the remaining scratches come out.

…..hopefully I don't burn the paint. but at this point I NEED to know lolol

Re: what am i doing wrong.... [wetsand/buff]

PostPosted: Wed Aug 15, 2018 10:37 pm
by DarrelK
You just really have to watch it with the speed thing and yes, a lot of these machines are not that accurate in my opinion. If you get the surface too hot you are a heartbeat away from melt/ripping it off. Experimentation is the way to go from here....hard for us to troubleshoot over the net when you are getting down to these "finer" problems with the cut and buff...

Re: what am i doing wrong.... [wetsand/buff]

PostPosted: Thu Aug 16, 2018 8:35 am
by '68 Coronet R/T
The rotary buffer and a twisted wool pad is the way to go IMHO. I read all this hoopla on the DA with special foam pads but have never had them work for me.

Generally I start the wool pad at a slower RPM like those listed. Work it for a while moving slowly over the surface and then jack the speed up to around 2000 and rework the area being careful to speed up my travel just a bit and not stay in one place too long. Again edges and body lines will be the most susceptible to burn through as the pad can "grab" those edges. Always approach those areas with the pad spinning off the edge and not into it.

I highly recommend Meguiars M100 to replace the 105. Longer working time, less dust and splatter, better cut and finish.

Re: what am i doing wrong.... [wetsand/buff]

PostPosted: Thu Aug 16, 2018 12:10 pm
by d3r
alright so finished the testing I started lastnight.

I used the rotary with twisted wool and M105
aswell as
rotary with twisted wool and v32

this time instead of following the bottles, I sped it up to what is "2500" RPMs on the dial
and it took nearly all the scratches that have been haunting me out. there was 2 left over on the whole roof that I had to sand.

i ended up liking v32 better as it took out the same amount of scratches while remaining workable longer and easier to wipe off afterward. I will track down some M100 soon and give that a shot.

anyway, so I think my buffing ignorance was in full effect and I just didn't realize the RPMs were too low. I went back and looked at the reviews for this buffer one more time and "underpowered" came up twice although the dial goes up to 3100RPMs. so maybe that is what im experiencing.

I appreciate yall.

Re: what am i doing wrong.... [wetsand/buff]

PostPosted: Thu Aug 16, 2018 8:29 pm
by '68 Coronet R/T
Remember that certain clears are harder than others and if you get on to any clear too soon it can cause problems. Hence the manufacturer rpm suggestions will be on the safe side.

By starting out slow and working up to the higher speed you can determine what will work best on that particular clear.

My rotary buffer has seen better days and the rpm selector really doesn't work right. I just find the lowest rpm that removes the scratches by increasing the rpm as necessary until those scratches start disappearing.