Using a PC 7424 as a sander on wood siding

[tguil]

I know the Porter Cable 7424 was a sander before detailers discovered it for polishing paint. When I bought my PC about ten years ago I bought it as a polisher not expecting to ever use it for sanding. Well, the time has come to use it for what it was intended. I have a considerable amount of 4 inch clear cedar lap siding that requires a bunch of sanding and cleaning before restaining/resealing. The old stain/seal is a real pain in the butt to remove.

All the information I can find says that a random orbital sander is the best machine for the job. Is the 7424 the sander for this job or should a I look at purchasing another type of sander? I'll be working outside and don't need or want a sander with a dust collector

If I choose to use my 7424, do I use the the present 5 inch hook and loop backing plate (not my good Meguiar's Plate) or is there another type of backing plate that is required?

Using a 5 inch disk on four inch siding may be a problem but it appears that all the orbital sanders use a five inch disk. Any problems with this if I am careful?

I'm sure that I am not the only detail guy who has ended up with a job like this. Any suggestions for my project would be much appreciated. For what it's worth if a building contractor tells you that clear cedar siding is low maintance stuff, he is not telling you the truth. In the past twenty years, I have had to strip and reseal the siding on my house four times. Yuck! But is sure looks good when the job is done.

Tom

[mwoolfso]

The PC 7424 DA will likely be problematic at best on wood. You will constantly need to ensure that the backing plate is spinning. An orbital won't have this characteristic.

[SR99]

Nope, the 7424 would not be a good choice for that. It doesn't have the muscle for it, and you'd probably never get it clean enough to use again on a car afterwards.

You'll have a good deal of weathered material removal to do, and probably the best place to start would be to get something like a Hyde paint scraper and a wire brush. Even if you have no actual paint to remove and just the weathered sealant/stain, the scraper is the best place to start.

You might be tempted to get a wide scraper to cover the full width of the planks but the wood will not be flat and you be better able to get the full surface prepped with a smaller one, maybe a 2 to 2-1.2".

If you also want to try a sander, I'd get a 1/4 sheet or 1/3 sheet pad sander, and probably start with 100 grit. I find them more effective than an ROS for this type of job, plus they have square not round corners, and flat edges, so you can get right up to the seams, which you can't do with a round pad.

Depending on the condition you may need to start with a coarser grit than 100. If it's really bad and a lot of discoloration and material removal to do, a rotary or even a belt sander might be called for. But those won't be your final step, they just speed the process.

[wild.bill]

In bought my PC as a sander at Lowes and it came with a 6" backing plate that takes paper with a sticky back. I usually use 100 or 120 grit with it.

It works better than any palm sander that I have ever used. Its also a great way to learn to keep it flat because it will try to walk on you if you don't keep it flat.

[Mike Phillips]

Here you go Tom...

Sanding Wood with a Porter Cable DA Polisher

[tguil]

Thanks Mike and others,

A little more information. I am not removing a heavy layer of paint. I only have to remove as much of the old seal/stain as possible. The product is water based and only a very thin layer is on the surface of the wood and much of it is already flaking off. The product is supposed to penetrate the wood and is not supposed to flake, but it is. The removal of the product is very labor intensive. First I have to use a finish stripper and then a brighter. The removal process involves a lot of scrubbing and rinsing with a hose. Power washers really shouldn't be used on cedar. :-( In the past, I have not sanded the wood when I have done the refinishing. A factory rep for the product that I am using suggested sanding to lessen the workload. I have already tried a palm sander using 60 grit paper. It doesn't seem to have enough "umph". I also considered a belt sander but it is much too cumbersome and with it's power I may really mess up the wood.

Is there a random orbital sander that would be better for this project? One that handles more like a palm sander?

My PC is ten years old and I have considered replacing it with an XP so if it gets messed up a bit, I'll have a good reason to get the XP. :-)

More suggestions would be appreciated. Polishing paint is sort of fun. This job most certainly is not.

Tom

[SR99]

Hi Tom, I've done exactly the process you describe, removing exactly the same kind of pre-existing flaking stain/sealant from 4" cedar plank, and re-staining. I used some Okon semi-transparent cedar stain the first time around, and it only lasted about 4 year before flaking started.

The scraper is really the way to go, and it leaves you with a finish-ready surface and it is surprisingly fast, once you get the hang of the way to use the scraper. One or 2 scrapes with the scraper and you are at fresh bare wood.

Sanding is very messy, and you also have to spend a fair bit of time dusting/vacuuming it off afterwards (or hose it then wait several days so it is thoroughly dried before refinishing).

About the only difference is I only had to do this on about 120 square feet whereas you have an entire house.

[Mike Phillips]

Find a way to attach some Scotchbrite to a day poilsher and go to town with this...


I've used Scotchbrite on a body shop Jitterbug sander to scuff paint before re-spraying and it worked very well.


I have a picture somewhere....