5" vs 3" - When to use each

[rover137]

Hi all

my new 3" 9mm throw DA arrived the other day (well refurbished and 1/3 the price!) and i was just looking to get a feel for when you would use this vs my 5" 12mm throw machine.

For context, i have used my 5" once on the car during a full detail but left some parts that were definitely reserved for the smaller machine until i forked out the money for one. For e.g. the boot on my hatchback black i30 Nline Turbo has many small intricate curved panels and large lights, badges etc. The front grille area, mirrors, A pillars etc are also all areas also exclusively reserved for the small machine.

For panels that are say 6-7" - it makes sense to use the 3" as the 5" you can move side to side and then have to get the remaining 1-2 inches.

The parts of the car that are causing me confusion are the side panels near the wheels on either side of the car. These are broken up with wheel arches, corners, edges etc. The areas are around 8-9 inches. So, you can actually get the 5" there then overlap the 3-4icnhes you miss for a second pass. But, just having a bit of a play with the 3" pads up against the panels - it just feels like the 3inch would be more comfortable in these areas and you can do say 3 passes rather than 1.5. It's not to say you couldn't use the 5" here - because I did previously.

Just trying to get a sense for where others use their 3inches vs 5/6inch machines.

Thanks all!

[rick100]

I use 3" for very hard to get spaces and I also use 3" if there is a deep scratch that needs some heavy compounding, I do not see the need for a big 5" to remove a deep scratch that is small. I just feel like I m removing more clear coat than I need. As a matter of fact if the scratch is just to deep , I ll hand sanded the best I can and just use a 3" to compound to bring back gloss and a 5" as a final polish to even out the panel

Other than that 5" all the way for regular polishing , or a light compound . I find the 3" is harder to use on big panels

[rover137]

Using the 3" for isolated defects makes sense. Would you use a 3" for areas where a 5" fit but can only go side to side, performing one pass? As in the area is 5" wide or so?

[rick100]

Using the 3" for isolated defects makes sense. Would you use a 3" for areas where a 5" fit but can only go side to side, performing one pass? As in the area is 5" wide or so?

I use 5" almost everywhere , unless I can't get to it . I feel much more comfortable using 5" . But I guess its dependent on how comfortable you feel with a 3"

My friend is a detailer and he uses 3" quite a bit , he even has smaller pads that he uses.

I almost regret buying the 3" , it does not get used much. I even prefer to wet sand by hand to be perfectly honest. I feel like i m just removing a very little portion of clear coat, even with the 3" I still feel like I m removing clear coat I should not be removing. Plus I really dont do too much heavy correction, maybe if I have some type of paint thickness gauge I would get more comfortable doing that.

I wish I bought a smaller pad, like 2" or 1 " for those tight places and deep scratches. Would make my job much easier

[rover137]

I use 5" almost everywhere , unless I can't get to it . I feel much more comfortable using 5" . But I guess its dependent on how comfortable you feel with a 3 - or to use the 5" where possible and reserve the 3" for very tight spots.

My friend is a detailer and he uses 3" quite a bit , he even has smaller pads that he uses.

I almost regret buying the 3" , it does not get used much. I even prefer to wet sand by hand to be perfectly honest. I feel like i m just removing a very little portion of clear coat, even with the 3" I still feel like I m removing clear coat I should not be removing. Plus I really dont do too much heavy correction, maybe if I have some type of paint thickness gauge I would get more comfortable doing that.

I wish I bought a smaller pad, like 2" or 1 " for those tight places and deep scratches. Would make my job much easier


Thanks for that. I couldn't touch many areas of my car without a 3", but just trying to get a feel for if i should use it on areas that would also seem to be more comfortable using a 3".

Are you uncomfortable because the 3" cuts more? my paint is very soft but I am only using fine polishes with polishing/finishing pads? Are the results that different with a 3" vs 5" even if you use the same pads/polishes?

I dropped in to a high end detailer here in town for a paint thickness reading. He was more than happy to do it for me. Offered him some cash but he wouldn't take it. Maybe you could do that to get a feeling for how thick your paint it? My paint is around 100-130 microns - which is about avg for a new car today from what i can tell.

[MisterSnoop]

For me, the red highlighted areas on the side/hood in the picture are examples of where I opted for the 3". The other areas on the side/hood just would have taken longer with it.https://uploads.tapatalk-cdn.com/20201209/cfc4f94610d099574d2739a2473f5ae2.jpg

[rick100]

Thanks for that. I couldn't touch many areas of my car without a 3", but just trying to get a feel for if i should use it on areas that would also seem to be more comfortable using a 3".

Are you uncomfortable because the 3" cuts more? my paint is very soft but I am only using fine polishes with polishing/finishing pads? Are the results that different with a 3" vs 5" even if you use the same pads/polishes?

I dropped in to a high end detailer here in town for a paint thickness reading. He was more than happy to do it for me. Offered him some cash but he wouldn't take it. Maybe you could do that to get a feeling for how thick your paint it? My paint is around 100-130 microns - which is about avg for a new car today from what i can tell.

On all my 3 cars the paint is thick. I have done a civic too and the paint was on thin side. The 3" does not cut more than the 5". I just happen to use the 3" with a more aggressive compound and speed to remove deeper scratches. If I use the 3" with a finishing polish it would cut the same as the 5". I use the 3" for some panels where the 5" has a hard time getting to . On my BMW the side skirts are hard to do with a 5" a 3 works better; in the front bumper areas is another place where I use a 3" instead of a 5". Everywhere else a 5 is fine for me
I feel like I have better control with the 5" than the 3". Its hard to explain.

I m sure if I use the 3" often I ll just get used to it. I just don't do enough paint corrections to really practice with both. All my jobs have been on my car and family cars. I focus more on my technique with a 5" and trying different pads and compounds for the job . I m still starting .

I bought a 3" because I was seeing that people were using them to correct deeper scratches and to do panels where the 5" didnt fit. Its good for that , I just don't happen to run into those situations too much. Now that I have tried 3" and 5" , I would like to try something smaller like a 1" or 2" , I feel like that would get used more in my applications.

I find that more of the deeper scratches I encounter required some type of wet sanding , doing it by hand gives me more control , but having a smaller pad may make it easier for me .

There are many tutorials online, check them out. Mike P himself has some I believe. I watched so many of them that I tend to forget.

You know , I did the same thing with my detailer, I took my car to see the paint thickness reading on the hood of my bmw that has been through some hard paint correction in the past. Lucky enough I still have enough there for a few more corrections , so I m planning just to do a polish on the hood early next year. I was very skeptical about touching the hood, but my detailer was nice enough to give me some readings for free

[rover137]

For me, the red highlighted areas on the side/hood in the picture are examples of where I opted for the 3". The other areas on the side/hood just would have taken longer with it.https://uploads.tapatalk-cdn.com/20201209/cfc4f94610d099574d2739a2473f5ae2.jpg


Thank you! I feel like the parts you've identified as 3" are probably the parts i was most confused about similar on my car. I've watched many vids and the approach from many pros varies - some will use 3" on those parts, others won't. Even the same pro on a diff car but similar spaces will switch between 3 and 5.

These are the areas i've marked up that confused me. This was after the car had been detailed by me with a 5" using Scholls S30+ and an orange LC SDO. Sealed with Megs Hybrid Ceramic wax.

The side one is where the panel either contours or edges. Similar to yours with the wheel arch and bonnet (hood), but maybe slightly more 'edgey' on the side panel?

The bit above the arch is perhaps big enough to use a 5"?



71873


The two front parts in this image is a little larger, but I'm still not sure which way to go about it? I did this before with the 5" and it turned out ok.


71874


Hopefully i have attached these correctly!

[rover137]

On all my 3 cars the paint is thick. I have done a civic too and the paint was on thin side. The 3" does not cut more than the 5". I just happen to use the 3" with a more aggressive compound and speed to remove deeper scratches. If I use the 3" with a finishing polish it would cut the same as the 5". I use the 3" for some panels where the 5" has a hard time getting to . On my BMW the side skirts are hard to do with a 5" a 3 works better; in the front bumper areas is another place where I use a 3" instead of a 5". Everywhere else a 5 is fine for me
I feel like I have better control with the 5" than the 3". Its hard to explain.

I m sure if I use the 3" often I ll just get used to it. I just don't do enough paint corrections to really practice with both. All my jobs have been on my car and family cars. I focus more on my technique with a 5" and trying different pads and compounds for the job . I m still starting .

I bought a 3" because I was seeing that people were using them to correct deeper scratches and to do panels where the 5" didnt fit. Its good for that , I just don't happen to run into those situations too much. Now that I have tried 3" and 5" , I would like to try something smaller like a 1" or 2" , I feel like that would get used more in my applications.

I find that more of the deeper scratches I encounter required some type of wet sanding , doing it by hand gives me more control , but having a smaller pad may make it easier for me .

There are many tutorials online, check them out. Mike P himself has some I believe. I watched so many of them that I tend to forget.

You know , I did the same thing with my detailer, I took my car to see the paint thickness reading on the hood of my bmw that has been through some hard paint correction in the past. Lucky enough I still have enough there for a few more corrections , so I m planning just to do a polish on the hood early next year. I was very skeptical about touching the hood, but my detailer was nice enough to give me some readings for free




Sounds like you are keeping busy! I'm the same, i have only done my car and am yet to find the time to do my wifes SUV. It took me 20 hrs to do my hatchback so i'm not sure how i will go doing an SUV.

ah ok, that makes sense then. I feel like my car has so many areas for for a 3" - especially the front and back.

I have watched so many online videos but it appears a lot approach things differently.

Yeah i find most detailers to be very helpful and happy to help someone out, which is good! I have certainly learnt alot from both local detailers and those online who are willing to respond to my questions.

[rick100]

Sounds like you are keeping busy! I'm the same, i have only done my car and am yet to find the time to do my wifes SUV. It took me 20 hrs to do my hatchback so i'm not sure how i will go doing an SUV.

ah ok, that makes sense then. I feel like my car has so many areas for for a 3" - especially the front and back.

I have watched so many online videos but it appears a lot approach things differently.

Yeah i find most detailers to be very helpful and happy to help someone out, which is good! I have certainly learnt alot from both local detailers and those online who are willing to respond to my questions.

I also found the 5.5 pads can make a big difference. Some are low profile while others are thicker . Some 5.5 glide better on the spots you highlighted while others have a hard time. The lake and country orange pad had no issues for me on those spots. I have also seen detailers use 3 and 5 on those spots.

[rover137]

I also found the 5.5 pads can make a big difference. Some are low profile while others are thicker . Some 5.5 glide better on the spots you highlighted while others have a hard time. The lake and country orange pad had no issues for me on those spots. I have also seen detailers use 3 and 5 on those spots.

I just redid the car and ended up using the 3” on most of those spots and I found it much easier. It was the first time using my new 3” and paired with the Lake Country pads I found it so nice to use. I wanted to do the whole car with it!


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