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Thread: High Speed Sanding

  1. #1

    High Speed Sanding

    A few months ago, Woodturning Design had an article about high speed sanding where the turner was sanding with a Makita (I think) grinder which ran at 10,000 rpm, and he slowed it down to 6,000. Well, I had to experiment. I have a couple of the Sioux/Milwaukee high speed angle drills which run at about 3,200 rpm. I had abandoned them for all but sanding the insides of a recess because the older discs would fly off, and go zinging past my ears. Not because of the heat melting the glue, but because the early adhesives just didn't hold very well.

    My observations after 100 or so bowls:

    It does throw the dust out a lot farther than the slow speeds.

    It doesn't work well on my warped bowls. I have to use my hands/arms as a spring tensioned bar to keep the pressure constant, which is difficult enough to do at slow speeds. I am able to get my lathe speeds down to 10 to 15 rpm.

    One key to having the high speed sanding work is keeping a constant pressure which is feather light. Mostly I use the weight of the sander for the proper sanding pressure.

    It works okay on more open and flatter forms than it does on one that are deeper and have more of a transition in the bottom. Almost impossible to get it into the transition area without it skipping all over the place.

    At first it seemed to remove the tool marks faster than the slower speed sanding, but I don't really think there is much or any time savings. You can use high speed and a very light touch, which will take a few more passes over the same area, or use slightly more pressure and slow speed, which cuts more effectively, and progresses at a slower rate. Six of one, half dozen of the other.

    I think it could be more effective on non warped forms, especially if you can rest the grinder on a tool rest while sanding.

    Summary is it can work, but I find the slower speeds to be better all around for me. I keep the drill at 600 to 800 (I am guessing here, but full throttle is 1200 rpm). for all grits.

    robo hippy

  2. #2
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    Feb 2009
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    Reed if memory serves me correctly the author also stated that it was much better on larger forms, and not as much on smaller.

  3. #3
    Join Date
    Jan 2005
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    Goodland, Kansas
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    Reed I am going to do more experimenting with the lathe running faster and slow speed on the drill. The last couple of days I have found that it does work quite well with pens. I forgot to turn the lathe down (1500 rpm) which is not fast for pen turning but I was in conversation with my BIL while sanding. I looked at the wood surface with my jewelers loupes and it looked pretty darn good. Surface was clean and no tool marks that I could see. So I thought about trying a bowl or two at maybe 1000 or 1200 rpm and see how it goes. I know I have to be aware heat but hopefully the surface will be as good as the pens.
    Bernie

    Never put off until tomorrow what you can do the day after tomorrow.

    To succeed in life, you need three things: a wishbone, a backbone and a funnybone.



  4. #4
    I think spindle sanding is totally different than bowl sanding. Diameter of the pieces make higher rpm possible on spindles than would work on bowls.

    As to the higher rpm speeds on bowls, if the bowl is perfectly round, then it should work, but I would think that with high rpm, you will get some distortion due to end grain/side grain, and I don't think any bowl is perfectly round because wood moves. Don't know for sure as I have never tried it before.

    robo hippy

  5. #5
    Join Date
    Jul 2007
    Location
    Childress, Texas, USA
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    1,930
    Reed, I've tried some "high speed" sanding with my inertia sanders that I made from Rollerball wheels. I normally sand the outside of every piece, before I hollow the inside, and I normally sand at 800 to 1000 rpm. But I've tried at 14-1600 rpm at times, when I forgot to reduce the speed. This is on Hollowforms and vases, and on bowls up to about 10" dia. You have to really be cognizant of the heat, but it works well. It does throw the dust out farther, and it also clears the wheel/disc better. I don't know about faster speeds on larger bowls... I think that would be too dangerous.
    Allen
    The good Lord didn't create anything without a purpose, but mosquitoes come close.
    And.... I'm located just 1,075 miles SW of Steve Schlumpf.

  6. #6
    Join Date
    Jan 2008
    Location
    Chicago Heights, Il.
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    2,136
    I wondered about the effectiveness of those angle grinders. They seem rather large and bulky. Right angle drills are harder to get in the bowl and don't appear to be as easy to control. I do use a Milwaukee 3/8 ths. drill (runs at 2800 rpms) on as much as I can. With a 3" disk it is quite fast at removing wood. Inside small bowls I still prefer a Milwaukee close quarter drill (1300 rpms)with a 2" pad. I make my own pads using the foam from garden kneeling pads or stadium seat cushions. It is soft and relatively tough.

  7. #7
    Join Date
    Apr 2010
    Location
    Adelaide Hills, Australia
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    Have always run my power sander at 2800rpm on faceplate work and the lathe at the max speed for the particular piece. Rarely ever see any heat effect, but I do use a light hand. Also use the toolrest to anchor my elbow to increase my control, particulalry when working next to details like beads and transitions around lips and feet.

    I usually sand pieces before they warp, so slow speeds not needed for that.

    Have occasionally experimented with slow speeds but haven't found any noticeable advantage, but I'm always open to learn new and better ways.

    .....
    Neil

    About the same distance from most of you heading East or West.

    It's easy to see the Dunning-Kruger Effect in others, but a bit of a conundrum when it comes to yourself...



  8. #8
    Join Date
    Oct 2006
    Location
    Manistique, Michigan
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    1,367
    I just bought some sanding supplies from Vince when his website was in transition. I had to call him to place the order and we had a very good talk.

    One of the issues I was having was heat build up causing the velcro pad to come loose from the foam pad. I had started experimenting with slower speeds to reduce the heat build up and like the results so far. The sand paper seemed to cut faster. I also reduced the pressure on the sand paper.

    Vince confirmed this obeservation. He said that the faster the grit goes over the wood, the less chance it has to do the work. It seems like the grit cant bite into the wood like it should, so it doesn't cut as well. It does heat up very nicely.

    He said he puts his lathe on the slowest speed possible (50 rpm) and runs the drill slow. This gives the paper a chance to work. Light pressure also works better.
    Thank you,

    Rich Aldrich

    65 miles SE of Steve Schlumpf.

    "To a pessimist, the glass is half empty; to an optimist, the glass is half full; to an engineer, the glass is twice as big as it needs to be." Unknown author



  9. #9
    Join Date
    Feb 2008
    Location
    Cullowhee N.C.
    Posts
    991
    Let me start off by saying I hate to sand so I've always tried to find the quickest way to get thru the sanding step. SHARP Tools and using the tool in the correct way helps a lot but doesn't get one out of this boring task..
    I think one advantage of using the grinder converted to a sander is that the bearings in the grinder are made to hold up to prolonged use where as a angle type drill bearings aren't intended for for prolonged use. With this said I still use a angle drill, but blow the dust our of it at the end of ever use. It seems to be holding up good even though when sanding a cored set I will some times sand for hours until all are done to a certain grit. On most of my open bowls I start with 80 grit and sand with the lathe off just using it to hold the bowl. I can turn the bowl by hand if needed, but some times lock the spindle and sand by moving the sander. I can blend a hump in the bowl down and take care of any pressure ridges that appear with the 80 grit. After ever thing is taken care of with the 80 grit I then sand thru every grit down to 320 with the lathe tuned down between 50 to 400 rpm's depending on the bowl, which takes little effort or time if you get the bowl sanded well with 80 girt first. I then like to sand it with 0000 steel wool with the lathe up to turning speed. On some woods this step makes it look like it has finish on it it shines so much.
    For spindle work which includes end grain HF's or Vases I hardly ever start with a heavier grit than 150 and on wood like cocobolo 0000 steel wool is all that is needed some times. It is much easier to get clean cuts on spindle work or end grain HF's for me than it is on a side grain open bowl. The inside of a flat grain open bowl can be a bear to get a clean cut on with some wood grain.
    You should shop around and find some good sand paper or disk. I bought disk from one supplier and the velcro comes off within a minute on every one of them. After that I started buying rolls from Klingspor and cuting my own They work great and I found out if you just cut them in squares and nip the corners off they work as good as a round disk except when geting near a bead. Since finding good paper I havn't had any problem with the velcro coming off.
    A 5" random orbit sander can work wonders on larger open type bowls as well. They work best with the spindle locked and move the sander. You have to look close and make sure that you sand all the swirls one creates with such a sander out before going to the next grit. My students in High School do better with this sander since it helps them blend out bumps that they leave when turning.
    Jack

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