Power Sanding More Info

[Mike in CA]

I read Lankford's post & replies on power sanding with some interest. Not having done any power sanding, I may have to try it on my next project. I've only seen it done in a couple videos.
I notice many use electric hand drills for driving the sanding pad. That sounds like the prefered method. I assume one way to step into this would be to get just a sanding pad, and chuck it in my drill motor.
Another may be to consider the type that has just a handle and a sandpaper pad head that rotates, but is not driven under power.

Is that just as effective as the electric hand drill method?, or maybe it's a toss up between the two?
Robert Sorby tools is comming to a local woodworking retailer the first if July, and this may be my chance to pick up the passive varity of rotating sander, as well as some other tools.

Thanks for all comments, Mike in CA

 

[john lucas]

Mike I built one of the selfpropelled sanding pads and it doesn't even come near the efficiency of power sanding I don't think. Especially near the center of the piece where the surface speed is quite low.
I use a dewalt hand drill that ran about $64. I burned up a bunch of the cheap $30 drills before I changed to this one. I've been using it for about 5 years now and I turn quite a bit so it has taken a lot of abuse.

 

[MichaelMouse]

No fan of power drills as sanding devices, personally, but it stands to reason that the more grit that passes over the surface in a given period of time, the more potential for removing wood. Thus the use of powered sanders. You must balance this against friction and the heat that can build and damage your wood, however. That's why I like to use the supported sander which doesn't have to do anything but be in the way when the wood drags by, even though it's also rotating on its own to give me more chances to hit with grit. Easy to sand without pressure, and a lot easier on my wrist than trying to heft a tool to do the job.

Tried the pressure-driven varieties and found them slower and no better than power at surfaces. Seem to be popular, so perhaps I'm missing something. Have a sneaking suspicion that they're just easier on the wrist than hefting a noisy drill motor.

 

[Mike in CA]

Another sanding question

Thanks for the comments about power sanding. Until I decide weather or not a sanding tool is for me I'm still doing it by hand. But I've noticed a couple things;
As the work spins, (small bowls) I assume it is the folds and creases of the paper that cause light and dark lines to occur and then disappear as the paper rubs by. Still using a light touch and avoiding to much heat.
I wipe the previous grit off with mineral spirits and let evaporate. Maybe this is not such a good thing. While it may show if I have a scratch or line to remove, I think it's filling the paper and in some cases becoming worse, leaving very small tar like lines in the wood, barely visable. As though there was something sticky that I left behind as I sand. I wonder if that is due to heat because the paper seems to turn black with streaks very fast.

Any ideas.
Mike

 

[tdrice]

I would suggest that rather than using mineral spirits you blow it off with compressed air.

 

[MichaelMouse]

I wipe the previous grit off with mineral spirits and let evaporate. Maybe this is not such a good thing. While it may show if I have a scratch or line to remove, I think it's filling the paper and in some cases becoming worse, leaving very small tar like lines in the wood, barely visable. As though there was something sticky that I left behind as I sand. I wonder if that is due to heat because the paper seems to turn black with streaks very fast.

Would be nice to know what kind of wood. Better answer possible then. If it's a resinous wood like the conifers, you may be dissolving, surfacing, and then consolidating resins from the wood which clog the paper and make the lines as they bake in. Could also just be sanding slurry brought up by the mineral spirits that were close enough to the surface to be influenced by heat, but far enough below to no longer look dark, too.

In general people use a liquid compatible with the expected finish to highlight scratches against the shiny background. If you're going to use oil-based finish, mineral spirits are ok. You might want to consider using them as a sanding lubricant and sand the piece wet. This tends to pack the pores a bit, but not as badly as those who use the finish itself, or oil as a sanding lube. Keep the paper clean with a margarine tub of the appropriate solvent near at hand, and you'll increase your stock removal rate.

Here's a weird idea. After blowing,brushing, tacking or vacuuming your piece, take a piece of brown paper bag and hold it to the surface and let it warm as the piece rotates. This will give a good burnish to highlight residual scratches, but will require you wet with grain-raising water to break the hardening before general sanding again. It's a good idea to to a set or two between your semi and final grits anyway, especially for "User" bowls that are going to get wet.

Your light and dark lines while sanding are probably slick versus dust, and can be caused by gaps between paper and the surface. I've heard it said that you ought to sand only rim to bottom so as to not resand your dust which was trying to spin up the diameter and dump. Makes sense if you think of it. Dust gently with a crumpled paper towel or brush once you're at the bottom and do it again.

Your final should be with the grain to the greatest extent possible. Means turning off the lathe, and I like those sanding sponges because I can grip them and they conform better than stiff-backed paper.