Free spin vs forced rotation

[joleyred]

I started out with the Flex 3401, so I guess you could say that is what I learned with. Not that I'm an ace either, but I've learned to get good results. Always learning more though. This spring I bought a Rupes Mark II. My first adventure with the new polisher was on my RV, I thought it might make less work of this massive chore. I learned after awhile that if I lightened up on my pressure that I was not having stall issues. It took me awhile to figure this out, but then I started wondering if maybe I use too much pressure with my 3401 too. I mean with this Rupes, almost NO pressure. But I think I was really horsing the Flex. Would it be safe to assume down pressure on both machines be at least similar?

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[Dr Oldz]

I personally find myself giving the flex 3401 more downward pressure especially when compounding or trying to remove defects. Now when finish polishing the pressure really depends on the abrasives that I’m using. Meg’s 205 actually need some pressure for the Smat abrasives to work properly. Anyway I love the 3401. Just ordered one for the gentleman who helps me as a gift to him.

[dlc95]

One thing to keep in mind is that the 21mm tool is making larger lateral motions across the paint. This is what makes these tools so unique. Rupes actually recommends little to no additional pressure on the tools.

That being said, I rarely use any more pressure than the resting weight of my hand on any polisher. There is some weight, but I'm not crushing the foam much if at all. This is for the rotary, the 3401, and the 7424.

The idea for me, is to allow the abrasives to roll around the paint. Chewing the defects off, rather than mashing under high pressure. This also allows for higher back plate roataion, which translates to more action on the paint, and much less heating of the paint.

[Joel1979]

Flex has 8mm orbit so pressure is a must to get good level pf correction. With 15-21 you dont need that pressure but atleast Rupes mk2 will work well with loads of pressure and you get more correction than with 3410 or Mille. And im 220lbs gym guy

[Mike Phillips]

With the RUPES long through tools, you apply light pressure, enough to keep the pad flat against the surface and buffing smooth. Abrading comes from the long orbit and rotation stroke. With short stroke polishers, both free spinning and gear driven, you can and in most cases apply some pressure to push the abrasives into the paint to force them to take little bites out of the paint.


Have you seen my article on FLEX vs RUPES?

It's easy to find with a few key words and my name via Google.

[Mike@ShineStruck]

Long throw Free spin is smoother
less stress on the body
I believe its cuts swirls faster on the flat
Finishes better

Cons
Typically need a dedicated 3in machine to compliment it.
Pad ghosting
More movewnt across the panel means more pad heat/wear.
Have to pay attention to pad rotation to not stall in the curves

Forced DA
Will always spin, no bog/stall
No real need for a dedicated 3in
Murders wet sanding marks

Cons
If pad isn't flat it can walk
Stresses body more during detail
No real pad ghosting (more so with the new short throw mille and Makita. PO)

Depending which machine, vibration can be worse leaving your hands with tingle sensations

[joleyred]

With the RUPES long through tools, you apply light pressure, enough to keep the pad flat against the surface and buffing smooth. Abrading comes from the long orbit and rotation stroke. With short stroke polishers, both free spinning and gear driven, you can and in most cases apply some pressure to push the abrasives into the paint to force them to take little bites out of the paint.


Have you seen my article on FLEX vs RUPES?

It's easy to find with a few key words and my name via Google.

Thanks Mike. I have one of your books but I have not seen that article. I will find it and absorb it. As with most technical things, the more I learn, I find out how much I don't know. It's great fun though.

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