Sanding problems

[Charlie Sandall]

I turn as few small bowls, 4 to 10 inches, I have never got the end grain portion of my bowls sanded to my liking, They always turn out not as smooth as the rest of the bowl.

What am I doing wrong, I even samd with a 2 in sanding disc on a drill.

Charlie

 

[Ruth Niles]

Charlie, you're not doing anything wrong, end grain can be a pain to get sanded smooth. Are you sanding those spots with the lathe off? Try putting sanding sealer or, I like, Johnson's Floor Paste Wax, to raise the grain. You may have to do this a couple times if the end grain is onery.

Hope this helps.

 

[MichaelMouse]

Charlie, you're not doing anything wrong, end grain can be a pain to get sanded smooth. Are you sanding those spots with the lathe off? Try putting sanding sealer or, I like, Johnson's Floor Paste Wax, to raise the grain. You may have to do this a couple times if the end grain is onery.

A shellac-based sanding sealer stands up grain and adds resin to stiffen wood. Lacquer based stands up less, but stiffens fine. Oil or wax flows around, but does not adsorb and expand fiber, and is softer, so does not stiffen but lubricates the wood. Why do both work? Because you sand more after "treatment." Which could be the same as saying neither works.

Good gouge work is the best answer, water a help. You can have torn fiber caused by a poor quality edge or presentation, or bruising caused by pressing the tool into the wood, heating and pressing it into ugly rings. Water helps both. It expands fibers which have been pressed down, breaking the heat hardening, and expanding and helping them realign when they've been twisted or torn. Let the surface dry, then sand with a grit coarser than you think you need. DON'T press, or you'll heat, harden, and re-create the bad situation.

Curved cabinet scrapers on static stock are pretty effective on spot repairs as well.

 

[Dave Moore]

Yeah..endgrain is where there will be any tearout from the toolwork, and if you don't get it all outtathere with the coarsest grit you use then it will likely re-appear when you get down to the 320 grit range or so. then you have to back up and start over.
The trick, if it is a trick, is to examine real closely when still down in the 120 grit range or wherever ...make sure there's nothing hiding.

MM's notion of starting with a coarser grit than you think it needs is valid too.
Varies with the type of wood at my house ..I'm finishing some roughed apricot bowls right now and it cuts so cleanly I can start sanding at 220 grit. If it was box elder I might have to start at 100, or even 80 sometimes if I've been lazy with the gouge sharpening.

 

[Steve Worcester]

Some of it is technique, some is the wood. If you attempt to sand your way out, you will get undulations in the wood because the differences in density of the early wood/late wood and the end grain/side grain, that get presented to the sandpaper as it spins around.

Hardening the end grain will help, keep at it and experiment and see what works for you.

 

[Jim Keenan]

Charlie,
Most everything we do in Hawaii seems to be end grain. Perhaps its because the timer tends to be smaller than on the mainland. Here is my system of sanding most woods.

Depending upon the wood, I usually apply a lacquer sanding sealer cut 3 parts thinner to 1 part lacquer. This seems to toughen up the end grain fibers but you don't want to fully seal them so the finish casn penetrate. Keep in mind, you guys have growing seasons, whereas in Hawaii we don't (it never stops growing). We tend not to see many growth rings in a great number of our woods so you will have to experiment with the sealer.

I find that using the powerlock flexible disks in the grits below 150 works best for getting out the tool marks. I then sand dry with really good wet sanding abrasives (up to 220). At 220, lightly dampen the wood to raise the grain and then sand in forward and reverse.
If you plan to use an oil finish, take the work off the lathe but leave it in the chuck or faceplate. Get a good flexible shaft and make a base for a corded drill with variable speed that can be locked in the run position.
Pour a little BLO (boiled linseed oil) into the bowl and sand with 320 and higher using the flex shaft running at about 200 to 300 rpm and just work the inside of the bowl constantly moving. It will create a slurry.
Wipe clean between grits and do a CSI flashlight in the bowl inspecting for visible scratches. Gray non-woven velcro backed disks are a great way to finish up using the flex shaft.

If you can see a scratch before you add finish, that’s all you will see when you do add finish.

If you plan to use other than an oil finish, do the same process as above but put in Howard’s polishing compound to act as the lubricant. I’m pretty sure it is pumice and orange oil mixed. They also have a burnish cream (probably rottenstone and oil) that I use as a final with a gray pad. It doesn’t seem to effect the adhesion of finish.

Sources for abrasives:
Steve Worchester http://turningwood.com/
Vince Welsh http://www.vinceswoodnwonders.com/
Bruce Hoover https://www.thesandingglove.com/The-Sanding-Glove-Woodturning-Supplies.asp

I buy the Howard’s products at our local ACE

I turn as few small bowls, 4 to 10 inches, I have never got the end grain portion of my bowls sanded to my liking, They always turn out not as smooth as the rest of the bowl.

What am I doing wrong, I even samd with a 2 in sanding disc on a drill.

Charlie

 

[Charlie Sandall]

You people have gave me some very good ideas. I really apperate all the help.I think I need to work on all three things, sharping, tool control, and going slower and more careful with my sanding.

Charlie

 

[MichaelMouse]

I find that using the powerlock flexible disks in the grits below 150 works best for getting out the tool marks. I then sand dry with really good wet sanding abrasives (up to 220). At 220, lightly dampen the wood to raise the grain and then sand in forward and reverse.

Pour a little BLO (boiled linseed oil) into the bowl and sand with 320 and higher using the flex shaft running at about 200 to 300 rpm and just work the inside of the bowl constantly moving. It will create a slurry.

Power-Lock is my system of choice as well. With the stiffer backing and the flex shaft I can let the wood come to the sander just as it comes to the gouge, and there's not a problem with differential softness, though it can be fun with spalted wood. Using nothing extra while sanding means I don't have to make compatability compromises on my finish.

Lots of people slap a piece of paper on a soft rubber back and don't realize that it's going to pack, squirm and heat on its own, and worse if pressed. That's a big advantage to the stiffer stuff, as is the ability to rest the handpiece of a flex shaft on the toolrest. Sanding in reverse isn't really any help. With the speed of the disk faster than the work, all sanding is by default sort of cross-grain. Sanding between 6 and 9 on the disk is like this \ , sanding between 9 and noon is like this /. Closer to the poles, closer to - in orientation. Makes reversing meaningless. Don't spin the work faster than the disk with a flex shaft. It's a twisted wire, and you'll untwist it.