DA Backing plate "wobble"

Bruce B · 01-02-08, 09:36

Happy New Year to all !
After "polishing/waxing" my cars by hand for 40 years I discovered detailing forums (my head is still spinning from all this great info !) and recently purchased a PC 7424 detailing kit supplied with a 6" urethane b pl. To my surprise, when I installed the bpl and gave it a spin it has about an 1/8" of run-out (wobble). Didn't seem right to me so I called the vendor and they sent me a new one. Same problem only not so bad (.070" vs .085" runout). Now I know that this doesn't spin like a rotary where this wobble would beat the snot out of the paint but it can't be that hard to make these things so they spin true. So should I be concerned or just live with it ?

Thanks,

Bruce

jshillin · 01-02-08, 09:55

Are you talking about the random orbit???

Bruce B · 01-02-08, 10:06

No, with the machine off, if you spin it by hand and look at the edge you can see it wobble up and down. basically the stud is not perpendicular to the backing plate.

jshillin · 01-02-08, 10:35

I'd just try the machine. I think that the foam pad will easily absorb that little bit of runout...

a.k.a. Patrick · 01-02-08, 11:17

Im certain you realize the machine operates off concentrics, in other words there are two orbits or rotations off of one axis.......Even with the machine off, you can spin the pad or BP and not have a perfect rotation. This is what gives the PC the wobble.

boogiejoe · 01-02-08, 11:20

I've noticed the same thing with the plate on my rotary. Doesn't seem to spin really true. It's not really bad, just slightly noticeable.

BigJimZ28 · 01-02-08, 11:23

Quote:

Originally Posted by a.k.a. Patrick

Im certain you realize the machine operates off concentrics, in other words there are two orbits or rotations off of one axis.......Even with the machine off, you can spin the pad or BP and not have a perfect rotation. This is what gives the PC the wobble.

I think he know this and is saying it wobbles in the third axis
as it the face of the BP does not stay flat

a.k.a. Patrick · 01-02-08, 11:42

Quote:

Originally Posted by Bruce B

No, with the machine off, if you spin it by hand and look at the edge you can see it wobble up and down. basically the stud is not perpendicular to the backing plate.

Ah, ok......Ya know Ive been through several PC's and never noticed a problem with that. It is more then likely some of us have the same dilemma as you but never even noticed. With that said, I think your ok.....

Bruce B · 01-02-08, 11:50

You are correct Big Jim, I definitely understand the orbital part, it's the movement in the "Z" axis ("X" & "Y" being the orbital axis) that bugs me.