Saskataper said:
Yeah a vault for your first go with the Planex would be tricky but here are some pointers.
I'm not sure what your sanding but I'm assuming just regular drywall joints
First get some 220 or 240 grit that 150 will be quick to burn the paper and will grab a lot.
Second I'd say ditch the harness it makes it hard to move around, I only use mine for taking down texture where I'm moving slowly. I was sanding a 15' vault the other day and was able to sand to 11' with only one extension (i dont have the second extension but I am 6'2 so that helps)
Third on a ceiling set everything to max, you need the suction to hold the Planex up and the high speed of the head will let it move around easier. You should be able to just walk along letting it do its thing.
I sand counter clockwise, so right to left across the top of the joint, then back across the bottom and the back again down the middle.
Also when doing a ceiling I turn the autoclean frequency down because I'm relying on the suction to hold it up and when the AC kicks in the head will lose contact, I just stop when I need to and hit the switch to start the AC manually.
Here is a pic of the house i just sanded last week with a 15' vault, I'm sure if I had a second extension I could have sanded pretty much the whole thing aside from the very peak.
Sorry, should have mentioned I'm sanding drywall clean of the acoustic residue which has already been scraped off, in prep for skim coating then sanded smooth. It's a workflow I've used before with excellent results but previously used a random orbital hand sander hooked up to a dust deputy. The results are excellent as is the dust collection but my shoulders and elbows were eager for a less physically taxing solution hence the planex with harness.
Anyway, I did some more testing with the Planex tonight and tried a bunch of setting combinations and found my best control was when I reduced the vacuum a bunch, the suction pressure causes the abrasive to bite harder and scoot the planex. Faster speed helped but that was getting too aggressive even with 240 when moving slower, switching to perimiter vac also helped but of course you loose the weight holding assist. After using the harness its pretty clear it is a bust for this type of work, especially since adjusting the pole is best done on the ground.
I also skim coat walls to fill in texture and sand them to make them smooth, and I tried that to see how smooth the Planex will do. Unfortunately the swirl marks were overabundant. Adding an interface pad helped but then the dust collection seriously dropped in effeciency even with pumping up the vacuum setting. Still theres a lot of swirl marks and I'm pretty sure some will print to my final coat of spray.
Again looking for suggestions, this time to make a super smooth, swirl free surface, while also preserving the dust collection. If only the Planex had a random orbital setting, problem solved (TBH I didn't realize beforehand that the Planex wasn't random orbital). Thanks everyone for all the suggestions thus far, hopefully I'll get to where I need things to be, that being precise head control, smooth finish with no swirl marks and good dust control.
Also curious how you all start the unit when working a ceiling. I got some gouges applying the unit to the ceiling after starting, seems safer to start after pressing it flush to the ceiling.