Sanding procedure: dropping one grit when changing from disc to paper?

[Odie]

Just wondering what ya'alls procedure is.......?

Normally, I go to the sanding discs first when finish sanding a bowl. Hopefully I can go right to 150 and then 180 before switching to paper.....that is, if I can get a good enough cut with the lathe tools!

I usually stop with the discs at 180 grit, and switch to paper to finish it out.....but, occasionally I go to 240 with the discs, but that isn't very often. After using the 180 grit disc, I find myself nearly always dropping down to 150 grit when I go to paper. It's darn near impossible to get all the swirly scratches going the right direction with the discs, but once in awhile, I can manage it. (Normally, the more simple the shape, the easier that is to accomplish.) Because the swirly scratches left by the 180 grit disc aren't eliminated very easily by using 180 grit paper, I most often drop one grit and start paper sanding with 150......and then on up to 180, 220, 320, 400, or higher, depending on the wood. (I find myself using the Grex orbital sander on 320, or higher.)

Because every piece of wood, or bowl shape has it's own peculiarities, there is no hard rule, but I'm wondering what your usual procedures are.......

otis of cologne

 

[MichaelMouse]

I'm three and off. CAMI 150/220/320 in hard disks. My velcro disks are all European series, so my final hand sand is normally P400, which is about the same as 320. I sand power on, which makes my scratch pattern pretty random. Straight line after the water set.

If I'm not going to put a surface finish on it, I grain set with water twice, rather than once. Same if I'm burnishing the wood.

 

[john lucas]

I usually power sand up to 400 and then hand sand with 400 and go up from there if necessary. My decorative bowls are finished with lacquer and I can't see the difference between 400 and 1200 once the wood is finished . My usuable bowls are sanded by hand from 400 to 1200.

 

[Frank Kobilsek]

Odie

I hand sand in reverse then power sand in forward. So 120 paper in reverse by hand along with spot sanding then 120 disk power sand. I run this procedure 120, 150, 180, 240 and 320 on everything. Piece I think might benefit from further steps get 400 and 600 both by hand and power.

Frank

 

[Steve Worcester]

If your sanding pad is spinning in the same direction as the wood, you get less scratchs and marks, but less aggressive sanding.
Sand in the opposite direction and you will take out more material at the expense of marks.

Personally, I will power sand to 1200 on some work, but stop between grits to inspect for marks. Most of the marks you are seeing are likely remnants from the low grits. The idea is to use the highest grit possible to start with. IN your case 150. Sand with the wood turning, and sand with the face of the pad as parallel to the work as possible. Take out all the tool marks, etc., then stop and look for any gouges from the paper, blow out with dry air if you have a compressor, then go to the next grit. If sanded properly, each grit will take out the marks from the previous.

As far as how high up to go, that depends on the usage and what finish will be applied over it.

 

[robo hippy]

I agree with Steve, that the sanding disc marks you are removing are probably left overs from the lower grits. For me, the rule is sand till you think you are done, then hit it again. I frquently will stop the lathe, especially with the lower grits, then hand spin the bowl while sanding, just to make sure. I watch the sanding pattern to make sure that all the swirl marks change as I go over them. I never bother to blow out the bowl or wipe it out after each grit. Never noticed that it made any difference. Havin excellent lighting also is necessary. I have one of the full spectrum lights that are advertised in Woodturning Design (oops, not in the current issue, but I think it was Blue Max lights). This type of light is almost as good as direct sun light. I do hand wipe the bowl from time to time. the finer dust of the higher grit will go into scratches from lower grits and high light them. I also used to switch back and forth from hand to power sanding. Primarily this was because the different scratch patterns would high light the left over scratch patterns.
robo hippy

 

[Ron McKinley]

I only power sand if I've got a lot of tearout. Usually I start with 80 grit and hand sand up to 400. Sometimes I get lucky and start sanding at 150....Ron

 

[Odie]

Hey......great!

I see there are a lot of different methods used by other turners. I've been very satisfied with my methods, but have a few comments and questions about what's been said so far.......

It will have to be later, though......because I've got other things to take care of tonight.....and gotta go!

Thanks for the replies so far.......

Any additional comments?

otis of cologne

PS: Odies crazy idea #16 has just been posted on the "tips and tricks" page of this forum..........

 

[John Nicholas]

Bowl Sanding

I use discs to start. I don't do much power sanding. I do use an inertia sander. I find this, as Steve said, slightly slower. I'm not into speed yet. I can many times start at 120 or 150. When done with the disc at that grit, I switch to paper of the same grit to sand with the grain.

When I think the first grit is done, I grab a 3M pad, and wipe the piece down. Then I get some Naptha on a paper towel and wipe the piece down. Look it over carefully and you can usually see the bad sanding marks. It will also show the grain as a finish would. If I find any more tearout or sanding marks, back to sanding at the same grit. If I get some extreme tearout, I will power sand that area, same grit. I try to get everything right at the starting grit, before I move up. I have, at times, started at 150 and dropped back to 120 for a spot or two.

I do use the 3M pad between grits. I always hand sand after using each grade of the discs. After 320, I stop the discs and just move up to 400 or 600 by hand sanding.

John🙂