What am I doing wrong?

[Jerry Toschlog]

I am somewhatnew at turning and I have a question. When I turn a bowl and I am at thesanding stage, sometimes a nice surface starts getting rough and pitted spotson the bowl. I had assumed it was the wood. Today I turned my first segmentedbowl and much to my surprise it happened again. It crossed into both types ofwood in the areas it was happening in, so it has to be my technique. I am at atotal loss, the wood was not green by any means. ..EDIT I typed this in word and the words wore not ran together, not sure what happened, sorry guys..

[Harry Robinette]

It sounds like end grain tear out to me.

[Josh Bowman]

Jerry, I start my sanding with 80 to 120 at about 500 to 600 rpm with an angle drill going in the opposite direction. I use only lite pressure, avoid any heat. Then I go up though all the grits to 400 or 600, slowing the lathe down each step and getting lighter with my touch as I get finer.
Vince at http://vinceswoodnwonders.com/ has solved a lot of folks problems here. Give him a call, he's a very personable guy. He knows a lot about sanding and most likely will solve you issues.

[Jerry Toschlog]

Harry, that was what I thought until today. Josh, You may be right I really push when sanding and yes it gets warm, never thought that could be the issue.

[Scott Hackler]

Jerry, when sanding you should use light pressure and slowed down to a speed that allows for sanding without the generation of heat (or much of it). You should also start at the appropriate grit and don't skip grits. Keep in mind that the next grit is scratching the wood and only used to remove the scratches from the previous grit. The best advise on sand paper I can give is to use sand paper as if someone else is paying for it. On any given piece I will use 1-2 discs of each grit and they get thrown away after use, unless they are completely clear looking and I can physically feel the grit with my fingers. Go to Vince's site and learn more or better yet call him and get schooled in proper sanding! He's a good guy and a lot of us use his products.

[Jerry Toschlog]

Thanks guys I have been reading since I seen Josh's post and yeah I have been really over doing it... I do use all the grits but I need to lighten up and slow down... I am so glad I ask. I did check his site ...

[Reed Gray]

Slower speeds on both the lathe and drill let the abrasives cut much better. It seems to be just the opposite with your lathe tools in that they seem to cut better at higher speeds, though you still can cut efficiently at lower speeds. High pressure, high speeds, and dull abrasives generate enough heat to cause heat checks, which are a bunch of tiny lines, and are cracks.

robo hippy

[Jerry Toschlog]

Heat checks!!!!!! So that must be what I am calling rough spots and pits.. Ok, nice to know. I have been back on Vince's site reading, etc. I am now excited to turn something and to get to the sanding part. I had a mindset that faster was better with sanding...

[Faust M. Ruggiero]

Jerry,
Somehow all the comments revolved around sanding but I believe Harry may have hit the nail on the head when he said tear out. There is a place on a side grain bowl where the cutting edge is cutting directly into the mouth of the grain. Imagine what would happen if you tried to slice a bunch of straws that are leaning toward the cutting edge. The grain gets disturbed and unevenly cut resulting in a rough area that almost no amount of sanding will remove. If I am correct that this is your problem, you need to begin learning a technique to deal with that grain. In some woods, even the sharpest tool may still "bruise" the grain. Often a light touch with a freshly burred scraper will clean up the end grain but sometimes scraping makes it worse, especially is you present the tool to the wood with too much pressure or at an improper angle. Some people talk about a negative rake scraper that handles this grain better. Either way, begin your search for a way that eliminates tear out before you begin sanding. If not you will have to sand so deeply to eliminate it you will spoil the flow of the bowl.
faust

[John Beaver]

Faust. If you read the post closely you will see that he says "a nice surface starts getting rough during sanding." It may be happening more in the endgrain area, but I agree with the others, that it sounds like sanding too aggressively.

[Reed Gray]

Well, without actually seeing the piece, or a picture, I can't say for certain. He did say he was doing a segmented piece, and cutting technique is a bit different for those, and generally there is no end grain, it is all pretty much side grain.

robo hippy

[Jerry Toschlog]

I can get you some pictures... Here is why I think it is not end grain, please correctly me if I am wrong as I am always open to suggestions as I am new. The last bowl was segmented and lets say I have a spot the size of a quarter. The roughness was on BOTH types of wood and in a somewhat oval shape. Faust, I just re-read your post and what you are saying also has happened while turning. such as with the bowl being smooth then as I am about done it starts getting rough. I want to thank everyone who has responded here, as I wish I would have ask this question a year ago. I have leaned a ton about sanding in the last 24 hours.

[Jerry Toschlog]

Ok here is what I am talking about, and a lot of times it starts showing during sanding. Several times I am very happy with what I am getting when sanding then all the sudden these start showing. Last night I did another turning with very slow sanding and same thing... 272571

[Reed Gray]

Jerry,
That is tear out, and it is in the end grain. If you divide a bowl up into 15 minute sections of a clock. for each rotation, 1/4 turn is cutting down hill with the grain, and 1/4 is cutting up hill against the grain, then it repeats. There should be tear out 180 degrees around the bowl from what your picture shows. Some times it is invisible till you go up to a fine grit, then it highlights. If you spin the wood slowly, by hand, both forward and backward, you can feel it. So, high shear angle, and very light cuts. Shear scrapes will do it as well, and it takes several passes to remove the tear out. Cut from the base to the rim for best results. If there is any one to mentor you where you are, it is a huge help.

robo hippy

[Jerry Toschlog]

Mentor... I wish there was !!!!!! I keep asking if anyone turns around here... I will check the bowl and see about the 180, BTW that is a close up pic with low angle lightning, that pic makes it look horrible but either way I wanted to show the issue as I want it perfect as it can me. I want to lean to correct or not have these issues. Thanks Reed

[Reed Gray]

Jerry,
I don't know where you are, but there seems to be turners every where. If you go to You Tube and type in robo hippy, my video clip on the fluteless gouge explains a bit about shear angles. I talk a bit about shear cuts on the two where I turn bowls with a scraper, and some when I turn with a gouge.

robo hippy

[Jon Murphy]

After some years of making bowls, and having sanding problems, I sprung for a "self propelled" disk sander. Actually I'd bought the Sorby a few years back and didn't like it - gave it away. I went to using my angle drill with soft disks that I use for finishing off lathe. Finally I bought the "spinner" from The Sanding Glove - which is expensive I confess. I'm getting good surfaces even on junk wood. The problem with hand sanding is the tendency to make grooves or tear the grain. The power sander avoids that, but one can over sand an area. The "spinner" sands across the piece much better than you can by moving the sandpaper. I have a box of soft faced disks (which also fit my angle drill for when I sand off lathe). I can sand at about 1500 rpm without overheating as I'm moving the sanding point all the time.

[Faust M. Ruggiero]

Jerry, There is a reason tear out shows up during sanding. When you sand with a fine grit, the sanding dust finds it's way into the rough spots and can easily be seen. I use that technique to look for minute scratches before finishing. Actually, you took a great picture. There are lots of reasons this happens to you but rest assured, it happens to everyone until we learn how to deal with it. Any time you turn a cross grain piece, even segmented pieces to a small extent, you are cutting into the end grain, then straight with the grain then down hill from the grain then all over again. Trying to explain a technique to deal with the problem on this format would be difficult. It may require different sharpening techniques or different tools or a different way of presenting the tool to the work. You really would benefit from hands on help from a great turner. Find a Woodcraft near you or Google for "turning club" in your area. I am sure they will show you a technique to make this easier. The struggle to learn is part of the fun.
faust

[Dwight Rutherford]

Reed's suggestion to find a mentor is excellent. You should be able to find one by going to the American Association of Woodturners web-site. They have a "find a club near you" feature. Put in your Zip Code and they give you a list of turning clubs in your vicinity. All of the clubs have a mentoring program. Nothing beats hands on training.

[Jerry Toschlog]

Thanks again for all the comments, Faust, as a pro photographer for 25 plus years I understand lighting :) ..... I am located in Centerville Indiana 35m west of Dayton Ohio and 80 miles E of Indy. The closest club seems to be Cincy and that's a good hour away, or more depending on meeting location. I also see they are having a symposium starting tomorrow but I do not see any programs listed for beginners. A bit of background, I had a retired IA teacher get me started on the lathe less than two years ago, a shopsmith. The time went on and I wondered if my tools were sharp enough, and he seemed to think they were. 3 weeks ago I came across a super craigslist deal and bought a dream lathe, at least for me. From that deal I learned a lot, mainly my tools were dull vs the ones I bought from the seller. The seller was full of info and she was a great turner. Since I now have such a nice lathe I really want to learn all there is to learn. I want it as close to perfect as I can get. I liked Faust's comment "The struggle to learn is part of the fun." I am having fun, lots of it, and this seems to be my main struggle.

[Richard Coers]

Thanks again for all the comments, Faust, as a pro photographer for 25 plus years I understand lighting :) ..... I am located in Centerville Indiana 35m west of Dayton Ohio and 80 miles E of Indy. The closest club seems to be Cincy and that's a good hour away, or more depending on meeting location. I also see they are having a symposium starting tomorrow but I do not see any programs listed for beginners. A bit of background, I had a retired IA teacher get me started on the lathe less than two years ago, a shopsmith. The time went on and I wondered if my tools were sharp enough, and he seemed to think they were. 3 weeks ago I came across a super craigslist deal and bought a dream lathe, at least for me. From that deal I learned a lot, mainly my tools were dull vs the ones I bought from the seller. The seller was full of info and she was a great turner. Since I now have such a nice lathe I really want to learn all there is to learn. I want it as close to perfect as I can get. I liked Faust's comment "The struggle to learn is part of the fun." I am having fun, lots of it, and this seems to be my main struggle.

An hour each way is a small price to pay for really good instruction. You can grind away for months and not get the help you can get in an afternoon. I wondered about your eyesight and lighting when this post started. When I was a young turner, I was shocked to see what some of the "old timers" brought to the club meetings with tear out and sanding scratches. Now that I'm over 60, I have to take great effort to see all those imperfections. Bifocals really don't help either!

[Jerry Toschlog]

Update,
I was workingon a platter this weekend and had some of the same issues. I then remembered Ihad 3"273027273028 sanding disc set from the craigslist deal. Thinking about what Jonsaid, I pulled them out and used my cordless drill. WOW what a difference, Iwas so impressed I went back and redid the bowl. I am extremely pleased withthe results. See the attached picture as it shows the same location on the bowlwith the same low angle light...... BTW this bowl is cut from a segmented maple and cherry flat board with1/2 rings glued together then stacked, and turned. Here are the after and before