PC Random Orbit Sander Problems

[allisnut]

I bought this ROS used a while back, and had to reattached the pad. It eventually wore out the mounting holes, so I bought this replacement pad at Klingspor a while back. It recently disintegrated on me. What causes the holes to wear out? Is it incorrect procedure causing heat, or some other worn part causing excess vibration? I don't know whether to buy another pad or junk it.

Thanks,

Adam

 

[JGregJ]

Hard to tell what's failing given the picture, those bolt heads look small for the size of the holes in the pad. Wondering if someone replaced the original bolts with ones that had too small of a head? Consider trying alternative bolts, or adding a washers if you can find some slightly larger than the head, but would still fit into the pad.

 

[Jeff]

Brand name and model number of your ROS for starters? Then maybe find a manual and schematics, etc.

 

[chris_goris]

As much as they cost, throw it out and buy another one. It looks like its been well used

 

[ehpoole]

A couple possible thoughts, are you by chance applying a fair bit of downward pressure during sanding? If so, most of the sanding will be done by the weight of the ROS itself and excessive downward pressure will certainly increase heating and wear on the pad.

Otherwise, the pads themselves are a normal wear item for an ROS, they are not intended to last forever and are considered a consumable. You can also get different hardnesses, or stiffness, of pads depending upon the sort of sanding one typically does and whether you need them dead flat or soft enough to conform to subtle curves -- most tend to opt for a medium pad.

That said, you could always upgrade to a 6" ROS where there are no bolt holes to wear out, just a single center stud that is part of the pad that screws into the sander. This allows one to swap out pads rather than change sandpaper when changing grits (most use adhesive backed sandpaper). But 6" sanders are much larger and heavier as well as generally more aggressive (though some permit selecting between two orbital choices to reduce aggression).

I do not know if any of the above will necessarily help you, but maybe they might give you some ideas or peace of mind.

 

[allisnut]

I guess I left out a few details...

It is a Porter Cable, no clue as to model number. I bought it used and it doesn't owe me anything, but I was confused as to why it failed rather quickly. I bought the yellow pad last November, as far as I recall I've sanded one cabinet, maybe a few odds and ends.. I have not used it much.

To make if clear, the failure is that the three mounting holes in the center of the pad are wallowed out so that the screw heads pulled through. You can tell from the gray circle that the pad was moving around on the sander.


Thanks for the help!

 

[Alan in Little Washington]

If the pad is 5" it is a PC Quicksand 335 (5 hole) if the pad is 6" it is a 336 (6 hole) (if it was a kit w/plastic storage box and dust shroud w/pu, it is a PC 9335 or 9336). Don't confuse it with the 7336 which is the PC right angle polisher/sander of the same vintage. The 7336 pad attaches by a single threaded stud so is not compatible with the 335 or 336 . I think a 336 pad will fit a 335. I don't have my unit available but think I did that.

My 335 pad wore out but I had a spare. I use Dynabrade pneumatic sanders now. Additionally, one of the 3 threaded holes in the pad mount got buggered so I had to drill it out and re-tap it for a larger screw.

The pad is under significant vibrational forces and will fatique and wear out. Like Ethan says, it is a consummable just like the o-ring belt. If you find a source for parts might as well buy a belt too. The older pads used to be black neoprene rubber which disintegrates from ozone over time. Later (after-market?) pads are/were yellow or blue and appeared to be made from a silicone or vinyl. They were available in different stiffnesses. My unit came with a plastic pad support disc installed between the pad and the pad mount.

#'s for the original dual-sided pad (psa and H&L) for a 335 5" unit:

Ref #: 85 Part #: 13906 Description: PSA Pad, Hook & Loop
Ref #: 37 Part #: 878198 Description: Belt

 

[Andy E.]

I had the same problem with my Porter Cable sander and ordered the new piece from Porter Cable, or you can go to one of their factory repair centers and pick one up. It was less then $20 if I recall.

 

[CDPeters]

Maybe "just right" sized washers to fit the pad mounting counter-bores under the screw heads might help? I'm thinking the washer might help reduce vibrational movement of the pad relative to the mounting screws. Also, I would check the screws from time to time to be sure they are snug and not allowing the pad to "slop".

 

[norm932]

As much as they cost, throw it out and buy another one. It looks like its been well used

Half the fun of woodworking is making other stuff last forever too

 

[sawman101]

My PC 5" random orbit worked well for a long time, then the pad came apart. Bought a new pad, and back to work. Eventually, the motor started running eratically, and I tossed it. Bought a new Bosch which does very well also, but it's also backed up by a Makita 5" ro. In reference to the above post, tye other half of the fun in woodworking, is buying a new tool! :rolf:

 

[chris_goris]

Half the fun of woodworking is making other stuff last forever too

'


I would rather spend my time working wood, not working on junky old machinery. To me, spnding $50 for a new sander every 5-10 years is not worth tinkering on for possibly hours at a time.