# porter Cable 7800 tips, tricks and techniques



## mudforbrains (Mar 23, 2017)

Hello All,
I've been lurking in the shadows here for some time trying to learn from this great wealth of experience and knowledge. I thank you all for your sharing.
I just purchased the PC7800/ dewalt vac with radius 360 adapters for the sanding head, 220 grit disks. For the life of me, I can't make this thing sand smooth; swirls, gouges where the angle meets the joint etc.
I've cruised the internet and have found fragments of advice, but nowhere is there a solid tutorial or one place for one to learn how to use this tool. 
Please help me through the learning curve before I fire this tool though the wall.


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## gazman (Apr 29, 2011)

I have tried a few backers (not the 360 though) and the only one that I will use is made by Norton. It is important for the backer to be soft. Is the head stiff? If it does not flex freely it can gouge, the length of the drive cable can cause it to bind up and stop it from moving freely. The cable can be removed and trimmed for length, only do an 1/8 at a time though. An angle grinder works best with the thinnest blade available. When using the sander I run the speed at around 4 1/2. When starting dont start on the join, start on the sheet and move it onto the joint, and always keep it moving. Let the machine do the work dont press to hard. Hope this helps.


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## mudforbrains (Mar 23, 2017)

Hey Gazman 
I appreciate the response, it does help. 

So you prefer the Norton pads over the joest ones? I have limited options where I live and will have to order online, I will try these then. The pad I have doesn't seem to sit flat,it is warped and one side protrude past the bristles at rest. That could be an issue.
the heads movement on mine is quite stiff, maybe I'll try snipping the cable down then. What end do you cut (head or motor), or does it matter?
thanks again, I'm hoping I'll get this down.


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## MrWillys (Mar 10, 2014)

Keep in mind you are only trying to sand large flat areas and save detail and corners for hand work. Welcome.


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## mudforbrains (Mar 23, 2017)

Hey MrWillys
thanks for the welcome.

You don't go over your angles with the PC? I always light check my work before handing it over, but do you PC users pole sand after using the PC?
Obviously the angles would need some love, but the PC should give a similar finish to the pole sander though, right?
Thanks again!


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## gazman (Apr 29, 2011)

The Joest pads are #1, I use the Norton backer not the pads. The cable is reversible so it doesn't matter what end you snip. You can use it on the angles but I find that the Spear corner sander is a better option, it does both sides at once. Then detail with a block.


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## All-Wall J (Feb 21, 2017)

When it comes to use of the PC7800 there are a few tips that I like to mention:

1. Let the machine do the work. Resist the temptation to scrub sand as you would with a traditional pole sander. Putting extra effort or force into the PC7800 will ultimately lead to swirls and imperfections - it's a power sander so let the power do the work. 

2. Avoid extreme angles for long periods of use (ceilings). The head will tilt to almost 90 degrees, but I would caution users against sanding ceilings at the 90 position for extended sessions. The extreme angle puts additional pressure on the drive shaft against the casing, and is a sure way to blow through both parts and fail the machine.

3. There are a variety of hook and loop based sanding discs and backer pads available - you can get better quality abrasives at a big savings over the stock PC system.

4. Raise the grit - I advise most people to increase (finer) the grit one unit over their pole sander usual. The machine will be more aggressive, so best results are found when you adjust your typical abrasive formula just slightly.

Good luck


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## Mr.Brightstar (Dec 2, 2011)

Joest pads work for me, with the norton backer. Check the edges of the pads. Sometimes the edge will be folded up a little, and that will cause swirling. Good luck and welcome. 


Sent from my iPhone using Tapatalk


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## Cletus (Jan 15, 2017)

Before you use a new piece of paper. Turn on the machine and but it in a corner with the paper facing you. Take a old piece of paper or sponge and slowly make contact with the outside of the spinning disk...go in about 1 or 2" taking the grit off the outside of the disk..take it down to very smooth...now the outside of your disk will not cause you problems!:thumbsup:


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## mudforbrains (Mar 23, 2017)

Awesome! Thanks guys! 
there are quite a few aha moments for me reading those replies! Just alone the time it would take to trial and error through to find the Norton Joest combo is a huge help to anyone who finds this thread.
I'm going to take all of your great advice, I start a new project tomorrow, I'll practice on fill coat to see how it goes.

couple more questions: how long does it generally take to break in the PC?
with consideration to not using the sander at 90 degrees, do you generally get on stilts to sand your ceilings?

thanks again guys!


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## gazman (Apr 29, 2011)

mudforbrains said:


> couple more questions: how long does it generally take to break in the PC?
> with consideration to not using the sander at 90 degrees, do you generally get on stilts to sand your ceilings?
> 
> thanks again guys!


It should be right from the get go, providing the head is not too stiff as I mentioned earlier. 
I can san 10 foot ceilings from the floor, just hold the machine above your head and keep the angle as flat as you can. Stilts leads and vac hoses are a recipe for disaster. :whistling2:


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## endo_alley_revisited (Aug 9, 2016)

As with any sandpaper used for sanding drywall mud, it is best to soften the paper before putting it on the sander. Using both hands, grab the paper with the sand side facing you and the paper face facing away. rub it back and forth over a vertical square corner bead or he corner of a vertical wood stud. After doing this, spin the paper 45 degrees and rub the paper face against the corner, back and forth in a slightly different orientation. This will soften the paper without damaging the sand paper side. Most sandpapers will be less likely to edge after being softened.


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## Cletus (Jan 15, 2017)

I remember when to PC sander first came out. I must of gotten my first one around 1998. I remember the disks from porter cable were rounded in on the outside. When the hook-n-loop paper came out, the disk was flat and just a bit proud on the outside edge.. that made for a lot of swirls and trails


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## mudforbrains (Mar 23, 2017)

For the sake of anyone cruising the forum looking for advice on the 7800: 
All the above advice is great and helped me get to the point of being able to use the 7800 for finish sanding (thanks to all!)
here is a point form of what worked for me
- cut the drive shaft on the unit. For me, I needed to cut a half inch. This allowed the head to loosen up a bit.
- use Norton backing pads. They work great. I modded mine a bit though. I watched this video but don't know French I took this guys lead: https://m.youtube.com/watch?v=BVcantyF614
Beveling the outside edge reduced swirls big time.
- break in the paper on an outside corner by running the backside back and forth in a few different directions.
- joist disks are the cats ass. If you only have solid paper disks that do not allow airflow, pope or cut a hole dead center so the suction doesn't affect the way the paper sits on the wall.
- use an old piece of sandpaper/sponge to smooth the outside edge of the disk, this is where most of the swirls come from.

if I learn anything else I'll post it here. Again thank you to all who helped out on this, my body and wallet are in better shape knowing how to wield this awesome tool. I don't think I'd want to consider not having a power sander now, less time on sanding and clean-up and I still have energy left to continue after I'm done.
Cheers!


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