coltrek

Drywall Sander for Bottoms

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I am contemplating buying a Porter Cable 7800 Drywall sander for sanding bottom paint. Mostly Ablative.  I was wondering if anyone has ever heard of someone using one of these, (or similar, like a Wen, Festool, etc) and had good luck.  It looks like it would be a back saver, as well as easier on the arms, and hopefully faster and do a good job.  One of my concerns is it gumming up, but the speed is adjustable, so that *might* be avoidable.  Any input?

porter-cable7800.jpg

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Just a guess here, but that may not have enough power.  Drywall is really light to sand so not much pressure is needed.  

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I used to repair them not a very good tool.They have problems with the switch with drywall dust bottom paint would kill it for sure.

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For race the only way is to block wet sand ~~~ lash a garden soaker hose to the side of the boat below rail and have at it...you and a cooler of beer for your closest friends :-)

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2 hours ago, SeattleB said:

Just a guess here, but that may not have enough power.  Drywall is really light to sand so not much pressure is needed.  

it has a higher amp motor than the 6" RO mentioned below..

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I've been using a rotex 125 with great effect. you can even 'wet sand' with it with a water bottle and some good paper, but make sure you've taken your heart meds before looking at the sticker price.

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get one of these and a large compressor

And buy your sand paper here

https://klingspor.com/

main_dynabradeextreme.jpg

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1 hour ago, VWAP said:

get one of these and a large compressor

And buy your sand paper here

https://klingspor.com/

main_dynabradeextreme.jpg

they make great sand papers...don't know if they made the open weave mesh/screen paper (not really paper) but that stuff worked great ! on a pad sander....the OP did not say if this was a racing bottom, if it is not DA is a good choice...as with all machine sanding tools it is the operator that counts 

 

https://www.lehighvalleyabrasives.com/abrasives-5-mesh-grip-discs-150-grit-box-of-50-mirka-autonet-ae23205015-ae23205015

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I use a Festool ETS EC 125/3 EQ-Plus with Festool Granet net sanding disks. Coupled with a Festool CT MIDI Hepa dust extractor. There is no discernible dust but I wear a mask regardless. Since I sand my bottom every fall I wanted to make the experience as pleasant as possible. I may have a cruising boat with ablative bottom paint but I have a smooth, fair, bottom and I have no paint build up. 

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Festools are deluxe.. what did that rig cost ?

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About a grand. It’s made an arduous task ALMOST fun. The brushless motor has nearly no vibration. The dusk extraction unit stops and starts when you turn the sander on/off. Very quiet....almost pleasant. Like everything else for a boat it’s money well spent.

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Here's what you want to start with. KTI85800.jpg

Then use this for wet sanding   Pole Sander w/Wood Pole, 9 x 3-1/4 In

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On 5/5/2020 at 9:05 AM, coltrek said:

I am contemplating buying a Porter Cable 7800 Drywall sander for sanding bottom paint. Mostly Ablative.  I was wondering if anyone has ever heard of someone using one of these, (or similar, like a Wen, Festool, etc) and had good luck.  It looks like it would be a back saver, as well as easier on the arms, and hopefully faster and do a good job.  One of my concerns is it gumming up, but the speed is adjustable, so that *might* be avoidable.  Any input?

porter-cable7800.jpg

Get one with a vacuum attachment...

I flip houses and this looks like a great product but is kind of a pain in the ass. If your drywall/mudder is any good, it's really not needed.

Sanding bottom paint off your boat...??? Find out and let us know!

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Thanks for the responses.  I too,  have been doing this for a long time, so I have been through all the DA sanders, RO sanders, etc, I have a collection of new and old and rebuilt.  I am just getting to the point where I want to work smarter than harder.  I can't believe that I can't find even one YouTube video using one of these.  I didn't want to be the guinea pig for this, but looks like I might have to.  I suppose if it doesn't work, I can always sell it on EBay and recoup some of my losses.  I would feel better if this 7800 was RO rather than just rotary, because of course they seem to work better on bottoms. I think the reason they (rotary) never succeeded is because they are too high a RPM, and gum up the disks. This might be slow enough to avoid this.  I will report back.

Oh, and by the way, I am not trying to get a racing bottom any more, just fairly smooth.

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I have had both these Porter Cable tools for years. I never have tried the drywall sander on my boat but the problem that I can see is with the size of the disk you wouldn't be able to keep enough contact to the boat so the vacuum would pick up all the dust. Obviously, this tool is made for a flat surface. In my area most yards won't let you do your own bottom prep and painting. For the few yards that do, they are very fussy about dustless sanding.

Moe

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