Replies

1. 
   Steinmetz | Sep 09, 2003 02:12am | #1

   Vinny, I have the same sander and at first it threw the disks with a vengence.

   Since I learned to start it while it slides along the wood in a light gliding pressure,they do not fly off any more. Stein.

1. 
   Elcoholic | Sep 09, 2003 02:34am | #2

   My Bosch RO started launching disks early on so I replaced the pad and it's lasted far longer than the original.  Sometime later I bought a Makita RO and a replacement pad in anticipation.  I still don't need the replacement pad.  I have noticed that disk backside quality varies as well as the front (sanding) side.  Resin bonded disks from Trendlines launched and had the backing peel off where Bosch disks didn't.  I haven't noticed any difference between the stickibility of Norton, Klingspore or Mirka's "gold" (aluminum oxide?) disks.

   FWIW a buddy in the business fulltime gave up on P.C. RO's and switched ot DW's because they just didn't hold up.John O'Connell - JKO Handcrafted Woodworking

   Life is tough.  It's tougher if you're stupid - John Wayne

1. 
   EdHarrow | Sep 09, 2003 07:04pm | #3

   My PCRO is maybe 5 years old now, and I've used it pretty heavily.  It's on its second pad, and it does seem to be mildly sensitive to 40 Grit discs (but that was true with the old pad as well).  I've also been known to reuse discs past their prime, LOL, and they don't stick so well.

   What grit are you using, and does it make a difference?  Also, who's discs, that may also contribute to the problem.

1. 
   Elcoholic | Sep 09, 2003 10:54pm | #6

   60 or 80 at the bottom and up to 220 on the high end.  I've noticed that it's the stiff, resin bonded disks that tend to launch, but I don't use them much anymore.John O'Connell - JKO Handcrafted Woodworking

   Life is tough.  It's tougher if you're stupid - John Wayne

2. 
   forestgirl | Sep 09, 2003 07:20pm | #4

   I would contact (by phone, not email) Porter Cable directly about this problem.  It's totally unacceptable!  Sounds like a quality control problem to me.

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl   ;-)

3. 
   Jamie_Buxton | Sep 09, 2003 08:18pm | #5

   The velcro on the pad eventually wears away, and can't hold the paper.   Depending on how much you use the sander, three years may not be unreasonable life.  You can buy a replacement pad and install it yourself without paying the shop to do it.

   The oval holes are a different problem.  They indicate wear from the pad moving around on the motor, and it should not.  Fortunately, the replacement pad will give you new smaller holes.  Tighten the screws down well, and keep an eye out for them loosening up.

1. 
   vincent843 | Sep 09, 2003 11:11pm | #7

   Hi All,

   Thanks to all of your quick responds.    As Jamie said , the three oval holes problem could be the screws were loose, but they seem ok to me.  That is why I bring it to the shop hoping with their  professional eyes could detect the ball bearing still good and there is hopeless.   The business man should know what an extra mile service means.  It may cost him 5 - 10 minutes , but the reward will come after that. vn.

1. 
   Tao | Sep 10, 2003 01:26am | #8

   You didn't say for sure what brand disks you were using.  I do a lot of custom finishing work, and have used my two PC ROS's very heavily.  I use Mirka disks, and have had no trouble at all.  I have seen cheap disks with a thin layer of loops that I would not trust to stay on.

   By the way, here's an interesting test:  Lay out two-foot squares on a large sheet of smooth plywood, and scribble all over the surface with a no.2 or 3 pencil, held on its side so as not to penetrate the wood.

   Time how ong it takes to sand the pencil marks off the first suare, and every succeeding square.  My tests showed that after less than ten minutes of actual sanding, it was taking twice as long to sand off the marks.

   I charge $60 per hour for shop time -- a dollar a mijnute.  I pay less than 15 cents for Mirka disks.   The economics is ovious; every wasted minute costs me a dollar, so I don't use a disk much longer than about ten minutes of actual sanding before changing.  You can make your own decision baqsed on how you value your time.  Another consideration is that as sandpaper wears, it starts to burnish rather than cut, and this alters how the wood takes a finish. 

   It could be that you are trying to use your disks too long and the resulting heat is damaging the pad.  Too much sanding pressure will generate heat and damage the pad, too, as well as giving a poor sanding job.

   Finally, beware fo using grits coarser than about 80 on an ROS.  The cross grain scratches get really hard to sand out.  I usually start at 100 or 120 on wood that's been macine planed.  I've tested ad found no time savings with coarser gits.  Removing old finishes is another matter brecause of clogging, and sometimes you have to use coarse grits and a light touch, although at this point I usually grab a scraper or some stripper.

   Just my experience.  It would be great to hear from other people who have done other tests with different brands, etc.  How well do different brands of H&L paper stick?

   Michael R.

1. 
   vincent843 | Sep 11, 2003 02:15am | #9

   Hi,

   I 've been using the Norton disks from HD.  Just bought some from Grizzly to see if any better, also it cheapper than HD  too.  I haven't use any grid bigger than 100, most ly were 120, 150 then 220.  Too much pressure, probably not.  Sand ing too long, could be, but, how do you determine how long is long?  Thanks. vn.

1. 
   Elcoholic | Sep 11, 2003 10:46pm | #10

   Too much pressure?  My Fein vac provides all the down force I need unless I'm hogging off a lot of wood with #60.  If you apply too much pressure with an RO then you slow it down so the upm's drops off so you end up sanding longer.  Sanding too long?  As soon as you notice any polishing the disk is done.  The vac really makes them last longer.  John O'Connell - JKO Handcrafted Woodworking

   Life is tough.  It's tougher if you're stupid - John Wayne

2. 
   TomFerreira | Sep 12, 2003 02:59am | #11

   Vincent,

   Are you sure you didn't get the pad made for adhesive backed disks rather than hook and loop?

   TDF

2. 
   Kevin | Sep 13, 2003 10:43pm | #12

   Great post, Michael. My experience has been the same on everything you said.

   BTW I use the Mirka hook & loop (Abranet) discs and am very pleased with them. Try your sandpaper wear test between an Abranet mesh disc and any paper-backed disc of comparable grit. My tests were less scientific but, the Abranet mesh discs consistently cut well for twice as long as the paper-backed traditional discs. I have to paint a lot of metal, so I keep a sander set up for paper-backed discs since the Mirka mesh discs don't work on metal very well at all. But, for wood I don't use anything other than the Abranet mesh discs any more. Although I do still use paper-backed sheet sandpaper for hand sanding wood and sealer coats where the RO won't reach.

   From my perspective as the finisher/painter at a semi-large company... much more important than the time wasted using a worn out disc is the fact that a worn out disc is no longer creating the advertised scratch pattern. When I need a 220 scratch pattern to get a given species of wood to stain the way I need it to... using a worn out 220 disc is counterproductive because it's not generating the scratch pattern that the stain pigments need in order to stain properly. By properly I mean in order to match the control sample that our clients supply or that I've generated for a given job. For me the time wasted issue is more a case of adding insult to injury. It's a double-whammy of unproductiveness that simply makes my job more difficult than it needs to be.

   Regards,

   Kevin

3. 
   johnnyinbda | Sep 13, 2003 11:52pm | #13

   Are you hooked up to a vacuum for 10 minutes or the canister? Johnnyinbda

1. 
   Tao | Sep 14, 2003 10:51pm | #14

   Johnny, that's a very good question.  The original tests I did were wothout a vacuum hookup.  The sander definitely cuts better with a vacuum connected, and the discs do seem to last a little longer, but not a great deal.  Haven't tested that specifically, though -- just going on experience.

   Kevin, you have it exactly right.  I do a LOT of custom finishing, and I hate to sand, so I do everything I can to get uniform results with a minimum of time and labor.  Sounds like your experience pretty much parallels mine.

   I use Abralon a lot on finishes, but haven't tried the abranet yet.  I'll sample some next time I'm buying abrasives.

   Michael R.

2. 
   Kevin | Sep 15, 2003 04:24am | #15

   I haven't used the Abralon discs. From what I've seen on their website, it looks like the only difference between those and the Abranet is that the Abralon have the foam backer between the abrasive surface and the hook & loop surface. I've talked to some guys who use the Abralon and they seem to prefer having the foam backer because they do a lot of polishing and it holds the moisture nicely when wet sanding with the fine grits. I imagine it would help conform to irregular surfaces too. Mirka makes a separate foam hook & loop pad that I have but seldom use. It's designed to go between the Abranet discs and the hook & loop sanding pad. The main difference between that and your Abralon would appear to be that this system has the hook & loops between the abrasive disc and the foam as well as between the foam and the RO pad. It does help to conform to irregular surfaces. But, even so it can burn thru on the edges if I'm not careful. So, I prefer to just hand sand the irregular stuff in most cases. An extra minute with the RO can lead to ten extra minutes trying to repair a burn thru... Better to be safe than sorry. LOL

   Regards,

   Kevin