Sanding through the grits

Roger Tulk

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St. Catharines, Ontario, Canada
No, not the grits that look like day-old cream of wheat.

When I am sanding stuff, particularly bowls on the lathe, I can go through about every grit HD sells, and a few that Canadian Tire sells, too. I start with 40 if things are really rough, 60 if necessary, then 80, 100, 120, 150 180, 220 which is where I usually finish for ordinary work, but I may go on to 320, 400, and 800 if I want a really smooth finish, as I have done on some of my bowls.

Is all this necessary or useful? Could I miss some of the steps and save time and money? 800 seems to me like showing off, as I find 220 leaves a glassy smooth surface. I'd be interested to hear what you think.
 
I'd try skipping the 100 and 150 to see what happens. I'd also stop with 220 unless you're working with extremely dense wood that shows scratches readily.
 
The larger grits i.e. 40-80 are going to leave some significant scratches. The goal in sanding is for each successive grit to erase the scratches left by the previous grit... and your goal in tool selection and use is to produce a surface smooth enough to need only minimal sanding. Someplace in between is where most of us land. You can skip grits as long as previously made deeper scratches are being handled by your grit of choice. Often those scratches are not noticed until you are at 220, or even worse after you have applied a finish, and then you have to go back to something coarser and start again. Misting with mineral spirits as you near the end of the sanding process will help spot the scratches you missed.
 
Sharp tools and skill building should let you begin at 120-180. The species of wood will dictate where you stop. Harder woods = equal higher grits.

For me: 120 (if necessary). 150 (if necessary), 180, and 220. For harder woods, continue through 320, 400, and 600 as needed to get the finish you want.

Anything less than 120 should pint you to some skill building, even some lessons. Rather spend money on lessons than sandpaper!
 
Like Carol said I find 120?? grit is a good starting point, unless you're trying to reshape the work, sanding down hole plugs or dove tail ends, 100 grit works for that. Lath work might be different than flat work, l don't know. I sand from 120 to 220 thru the grits.

The Bosch random orbit sander instruction book claims it works so well you can skip a grit, but does' say which grit. I have not tried that yet.
 
120,220,320 call it done.

Yup about there. Sometime if there's a lot of bruising or tear out on some soft/punky wood I'll need to drop back to 100 or 80. On harder woods I'll go to 400 but rarely higher and then only after having put a first coat on to seal it up a bit (except things like ebony where I might go all the way to 1500 and just burnish in some wax for finish with a soft cloth). If you want a "glass" finish you'll need to go higher than 400, but I'm not really doing much of that kind of work.
 
I stress great sanding methods create great finishes on the student's pens. One of the hardest habits to break about 5 weeks into their second semester on pens and projects is not using the first two or three grits in our sandpaper box. Their skills with the skew create a better finished product and the first two or three grits ruin their hard won results due to the skews ability to create a remarkable finish of itself.
 
120,220,320 call it done.

That's pretty much my regimine too, although I'm not afraid or ashamed to use 80 grit if I have to, and I'll often go up to 400. As Ted mentioned, often you won't notice scratches that you've missed until you go to the finer grits, and for me, 400 grit is the real tell-tale stage. If any scratches appear when I'm at 400 grit, I generally jump back down to 120 and start again. (You can get them out with finer grits, but it takes longer than just running through the grits in order.)

For bowl sanding, things really improved for me when I started using a 2" sanding pad on a drill motor instead of just holding a piece of sandpaper on a spinning bowl. I absolutely hate seeing concentric circle scratches in one of my turned pieces, and using a powered sander really helps avoid or get rid of them. Vince over at Wood-N-Wonders has a good selection of quality sanding disks and drill-mounted sanding pads. I pretty much standardized on his blue flex sanding disks for both my drill-mounted 2" sander and my 2" pneumatic random orbital sander.
 
Thanks very much. My question mostly was for bowl sanding as I find spindle work doesn't need the lower grades at all. However, on a couple of bowls I've made, the end grain surfaces came out very rough, and I used the 40 and 60 grit to smooth that over, and then used the higher grades to smooth that out, and came up with a result that was more than acceptable. I like the idea of going 120, 220, 320 as the stuff gets expensive after a while. Let's see, that would be three grits instead of 11. Works for me.

My tools are definitely sharp, although I possibly should have run my scrapers over the grindstone again. I resisted doing that as it requires me to change from my Wolverine type home made jig to the sharpening platform that I use mostly for the scapers, and the couple of bowl gouges that I do with a traditional grind, and the roughing gouge. I will have to remake the jig next spring to accomodate those last two types. Anyhow, I get good long shavings off my tools, which I hear is a clue that I am doing something right.

Thanks again for your advice.
 
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