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Good point. I was just down there level sanding - I'm using a new gun and haven't got it figured out yet so had a bunch of orange peel to knock down. I was using the sander and noticed I use it for no more than 30 seconds, usually more like 5 or 10. I just try to knock down the big parts and then put it down and grab a sanding block, felt or an eraser in this case.

Right! A lot of the time I spend leveling a finish is actually with the sander in the air while I wipe the surface(be it wet or dry, it needs wiping), so if I stopped the sander each time, that gives the compressor time to catch up.

Adding a tank would be easy to do but would also increase the recovery time.

And that's a good thing. All electric motors run most efficiently when they are running, and least efficiently when starting up, so we actually want to have longer run times and fewer start/stop cycles. A larger tank provides this. Set up the secondary tank with a by-pass valve setup and you won't need to fill it for small tasks; just large ones. And heck, as you noted, your current compressor and tank might well be just fine. You have me thinking that I might be good to go with my current system, too... <bg> There -is- a reason I hang-out on these forums, ya know. I can still learn some things, too.... While my wrists are still good, at 46 years old, I should be thinking ahead and finding smoother, lighter tools. Now.

My compressor runs about 4.4 CFM at 90 PSI. The Dynabrade sander takes about 14 CFM at 90 PSI. Not sure how much run time I would get so will try to figure out a way to test it (obviously I need to get my hands on a Dynabrade sander).

One other option for me is to put a larger compressor outside. I have an enclosed but unheated shed attached to the side of the shop. I've worked in shops with compressors outside but wasn't spraying finishes. We rarely get below 20F here in the winter so it is not bitter cold. Anyone know if the colder outside air would be a problem for spraying finishes?

If I go electric my short list right now is either the Mirka Ceros or Festool 5".

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Steve Smith
"Music is what feelings sound like"

I'm in the same boat you are looking for a new sander, and I came across this the other day...
http://www.toolsofthetrade.net/industry ... ionID=1493

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Brad

That was interesting. I was surprised to see PC at the top of the heap since their tool quality has gone downhill in recent years.

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Steve Smith
"Music is what feelings sound like"

Don't be cheap, buy a new air pig or 2 at harbor freight etc....to increase your shop air volume.
Using a tank in unknown condition is not safe. Just watch the video below to see the power involved....

http://www.youtube.com/watch?v=68p4ngS-yME

Steve, I was surprised as well. Pretty noticeable difference in the scratch patterns left behind by the 3 they show in those images. I'm thinking the PC may be worth a shot after reading that article.

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Brad

As I said earlier, I own that PC sander and I love it. I have replaced the pad and clutch plate once (piece of plastic). I attributed that to sanding with mineral spirits. Given the long ship times at ereplacement.com parts, I recommend u keep spares in ur shop. But it is an exceptional sander at a very reasonable price. I would buy it again.

Mike

Don't be cheap, buy a new air pig or 2 at harbor freight etc....to increase your shop air volume.
Using a tank in unknown condition is not safe. Just watch the video below to see the power involved....

They used a lot more pressure to blow that tank than any compressor can ever put forth. A water heater tank is thicker and stronger than a compressor tank.... Those little wee air pigs hold what, 5 gallons? Waste of time and money.

BTW, I have 3 Porter Cable sanders; they're the only sanders I own. The newest one is 13 years old...

"seems to" are the key words here. The Festool Rep loaned me a ETS 125 and the Festool Vac to go with it. It worked great, and there was no visible dust in the air, but the dust count on my air quality monitor went up about 6 fold after only a few minutes of sanding. So the Fesstool dust collection is not near as good as most people believe based on my use and air quality measurement. And yes, I was using it properly with the Festool vac. Of course, sanding without any dust collection would probably yield 50 fold increase in fine particle dust in the air.

I asked some folks who know compressors what the failure mode is. Explosion was not considered remotely normal. And the pressures required were way beyond what the supplied pump can do. Not even sure if a piston pump can do that. There is a huge difference in the water heater test. Once the tank ruptures, remaining water in the tank is super heated and instantly expands (1600 x) to vapor. The mass involved is way higher than what is in a compressor tank.

regarding compressor tanks, the ones that blow up are the ones that have standing water in them because they are never drained, and they rust through and weaken over the course of many years...
i have the Rigid orbital; it only got 2 stars! boo. works fine for me, i don't use it a whole lot. the coarsest grits leave deep circular(cross-grain) scratches so for that reason i think orbital sanding is not the best application for material removal, just final smoothing

I've been using a Bosch 6" for at least 17 years, and it has been one of my best tool investments. Bought a 6" Rigid as well, and like nyazzip says, its a 2 star.
I've had the Ceros on the radar for a while, and will likely take the plunge in the new year.

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

I've got a Porter Cable finish sander that's been going for over 10 years. I'd been disappointed in their tools several times a few years ago but looks like I should keep them in consideration.

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Steve Smith
"Music is what feelings sound like"

Steve, that 390K is a great tool!

Everybody - Thanks for all the comments; I really appreciate the discussion. As usual there is no consensus but there are 4 or 5 front runners so I will have to make my own decision

My first decision will be air or electric.

Air: There is a good selection of very good air tools available and they aren't all that expensive. The pneumatic sanders are small and lightweight so would be easier on my carpel tunnel. A Dynabrade ROS can be had for under $200 and they don't get much better than that. I don't know if my little 4.4CFM@90PSI compressor is going to cut it even for a relatively short duty cycle so I may have to get a larger compressor which would probably run around $800. The only space I have for a bigger unit is outside the shop so I need to find out if using colder air is an issue for finishing.

Electric: If I stay with the same size I have now I would look at the PC unit - no need to spend extra money if I don't have to but I will go test the Festool just to satisfy my curiosity. If I go with something smaller to make it easier on my wrist then looks like the Mirka Ceros might be the answer.

I'll try to remember to update the thread after I make a decision and let you know how it worked out.

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Steve Smith
"Music is what feelings sound like"

Steve, what did you decide?

I'm considering the PC 390 and the Bosch ROS20VSC as I can get either locally. PC is the one rated high in the test linked to earlier but it is twice the cost of the Bosch. I'll go 5" pad as it seems a 6" would tend to flatten the dome of a top/back even more tan a 5".

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Formerly known as Adaboy.......

Darryl, I ended up getting the Mirka Ceros 5". I agree that the 5" size is better for a guitar sized object. As far as getting the Ceros, I figured I'd try it and if it wasn't as good as some say then I would send it back. Turns out it's as good as folks say - light, powerful, very smooth, and with good dust extraction. That said, I would not have spent the extra money if I didn't have the carpel tunnel to deal with.

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Steve Smith
"Music is what feelings sound like"