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Forum topic by Karda posted 02-21-2018 05:11 AM 744 views 0 times favorited 15 replies Add to Favorites Watch
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Karda

1222 posts in 671 days


02-21-2018 05:11 AM

I have an impossible question. I have found that in my turning bowls I always have a high spot in the bottom of the bowl and have a very hard time leveling it. I also develop a ridge at the transition from the side to the bottom. does any body have any ideas what I am doing wrong. Its not something that will be fixed by watching a video. thanks


15 replies so far

View OSU55's profile

OSU55

1834 posts in 2107 days


#1 posted 02-21-2018 01:13 PM

I never can get the surface very flat with gouges. A sharp tool and delicate handling. I use a scraper at a sheer angle to smooth up inside and out.

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soob

269 posts in 1326 days


#2 posted 02-21-2018 01:31 PM

Take a small ruler or the edge of a small square and set it across the bottom to see if it’s flat.

If it ain’t, you can flatten it with… well, anything. But to completely remove the lathe marks the best way to do it is with a card scraper, sandpaper, etc., with the lathe off.

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Nubsnstubs

1362 posts in 1848 days


#3 posted 02-21-2018 02:33 PM

Mikie, you ain’t been paying attention to all the suggestions LJ members have given you. Bowl bottom cleanup is the easiest thing to do. If your tool is long enough, use that as your straight edge to check for bottom flatness. Like soob said, a ruler will work, but anything straight and small enough that will clear the space between your live center and bowl bottom will work also. Of course, the nub you still have on it won’t allow you to get a good visual, until it’s removed.

If you had my Tail Stock Steady, you wouldn’t be asking these questions. If you go to my website, www.woodturnerstools.com , you will see what it is, and maybe how useful it really is. Who knows, you might just buy one. .............. Jerry (in Tucson)

-- Jerry (in Tucson) www.woodturnerstools.com

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Lazyman

2387 posts in 1505 days


#4 posted 02-21-2018 02:36 PM

For the bottom of bowls I find that a bowl gouge with a traditional grind (rather than an Irish/Ellsworth profile) is better for the inside bottom of the bowl. The smaller bevel allows you to more easily ride the bevel along the bottom to get a cleaner cut. It is also important that you do not pause during your last pass so that it is one continuous cut. It also helps if you have a curved tool rest (I use one like this) that will fit deeper into the bowl for better support and less chatter. Even then, I often use a half round scraper with a good sharp burr to clean up any ridges and the transition area from side to bottom, especially if my last pass was not continuous and I had to stop because I was approaching the minimum thickness on the bottom.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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LeeMills

583 posts in 1419 days


#5 posted 02-21-2018 05:51 PM

How large is the high spot? Some may be small (<1>) or it may be a wide area.
The best way I found for the small area is to use a wide scraper very gently and start just below center leveraging up taking small bites. The rest must be high enough that the tool will still be pointed down unless it is a negative rake scraper.
For a wide area, and depending on the depth of the bowl, you may be able to align your tool rest parallel and make a cut with your bowl gouge. The key is stance and being able to lean into the cut without swinging the tool handle.
If the bevel is aligned straight it has to cut straight. Not as simple as it sounds.

Not sure what is causing the ridge. That is a high area? Some times I have a depression from riding the bevel too hard and burnishing the wood with the heel of the bevel. If it is a high area you should be able to remove it with light passes with a rounded scraper at a sheer angle.

-- We cannot solve our problems with the same thinking we used when we created them. Albert Einstein

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Karda

1222 posts in 671 days


#6 posted 02-21-2018 06:17 PM

Hi, thanks for your suggestions, To be clear I am referring to the inside. I would love to have your steady Jerry but I am retired and not that well healed. I try to get a clean uninterrupted cut but I am or am not doing something where the gouge starts a a depth cut good but as I move through the cut down the side and across to the center bottom I lose the cut and have to start over. it just keeps cutting less and less until it don’t cut. I think that is where the ridges are coming from. Hence when I do the bottom I am cutting up toward the center. And yes Jerry I do pay attention to your advice and the videos on turning as well. But that don’t correct my mistakes at the lathe, also I forget. I try yto do as demonstrated. A lot is said about controlling the cut with your body and not your hands, but what do you do when you are hanging over the lathe to be able to make cuts on the inside of a bowl

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LeeMills

583 posts in 1419 days


#7 posted 02-21-2018 09:07 PM

Maybe this will help…

I try to get a clean uninterrupted cut but I am or am not doing something where the gouge starts a a depth cut good but as I move through the cut down the side and across to the center bottom I lose the cut and have to start over.
It sounds like you are swinging the handle a little too fast. If you have a small straight edge to place on your bevel to see it with the both the heel and cutting edge cutting that is the direction of the cut. Now move it away from the cutting edge where you see a small gap, at that position you will gradually be making a thinner cut until you come out of the wood. If the cutting edge is touching and there is a gap at the heel you will be making a deeper and deeper cut. You are only changing a few degrees with the handle but over a couple of inches it adds up.

Hence when I do the bottom I am cutting up toward the center.

I may not be reading what you are saying (cutting up). It sounds like your tool rest is positioned too low. Ideal will be to have the rest where with the tool on it and parallel the tip (cutting tip) is exactly center of the work. This means for a 1/2” bowl gouge the rest may be about 1/4” below center.

”A lot is said about controlling the cut with your body and not your hands,”
Sorry, I was referring to making a flat surface, this does not include the normal forming of the bowl shape.

”but what do you do when you are hanging over the lathe to be able to make cuts on the inside of a bowl”
It has quite a bit to do with the bevel angle. Given you are wanting to start the cut with the bevel pointed in the direction of the cut. I had the same problem and it finally hit me when I watched an old (well sort old…30 years ago) video by Del Stubbs. He showing starting the cut with his bowl gouge and then with a spindle gouge. With the bowl gouge the handle was pointed well behind the lathe, with the spindle gouge it was well in front of the lathe. I do not know the angles but maybe 30 deg and 55 deg. If so the bowl gouge had to be pointed towards the rear 25 deg more than the spindle.
My remark on the stance was for cutting a flat bottom. For most of my interior bowl cuts my body is basically stationary, the left hand brakes the tool, and the right hand makes the swing or arc.
If you are making a fairly steep sided bow with a flat bottom then you will start with almost no swing, then a fairly rapid swing in the transition, then back to no swing.

-- We cannot solve our problems with the same thinking we used when we created them. Albert Einstein

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Karda

1222 posts in 671 days


#8 posted 02-21-2018 09:24 PM

thanks lee I’ll try your suggestions. I have my rest so the handle is a little low generally when I do the bottom I try to keep it level so I can do the center. when I started I ground my gouge to 40 degrees same as my spindle gouge but changed that because I couldn’t do bottoms. I am currently using 65 degrees

View OSU55's profile

OSU55

1834 posts in 2107 days


#9 posted 02-21-2018 10:12 PM

You can start your gouge at the hi spot to clean it up. All cuts do not have to be continuous. Perhaps some day I’ll be able to do a coninuous cut final pass that meets my standards, but after a couple hundred bowls Im not there yet, and very few are. Sheer angle scraping will refine the form and smooth the surface.

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LeeMills

583 posts in 1419 days


#10 posted 02-22-2018 01:31 AM

OSUSS is right. I only seldom make a continuous curve (especially a final pass) even though most of my bowls are fairly shallow catenary curves. Most of the time I will have varying wall thickness to correct which requires starting at many places other than the rim.
I have three bowl gouges but use two the most. I can’t do like some folks and follow the bevel when the bevel is only 1/16” wide with a triple grind; I have to hold my mouth just right to use the double grind properly.

-- We cannot solve our problems with the same thinking we used when we created them. Albert Einstein

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Karda

1222 posts in 671 days


#11 posted 02-22-2018 03:43 AM

ok thanks I’ll try that

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MrUnix

6887 posts in 2316 days


#12 posted 02-22-2018 04:25 AM

does any body have any ideas what I am doing wrong.

No clue. I rarely have any problems with the transition, and typically will do it with a homemade thumbnail ground gouge with the final passes going from the center out and then up the side, then final smoothing if needed with a round nose scraper. There are way too many ways that it can be done, so the best method for one may not be the best for another. Only advice is to practice, practice, practice… eventually you will hit on a technique that works for you.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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Karda

1222 posts in 671 days


#13 posted 02-22-2018 05:25 AM

I knew when I asked the question you couldn’t give me an definite answer with out watching me. But you all have given me a lot to try and think about. an yea i know a lot of it is practice. I wonder could the ridge I get at the transition be because the transition is to sharp thanks mike

View Lazyman's profile

Lazyman

2387 posts in 1505 days


#14 posted 02-22-2018 03:29 PM

With an Irish grind bowl gouge a sharp transition can be very tough especially if the bowl is relatively deep as well. This is where the traditional grind bowl gouge excels over the Irish grind. I was amazed how much easier it was to get a nice cut at the transition and along the bottom with a traditional grind when I first tried that approach.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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Karda

1222 posts in 671 days


#15 posted 02-23-2018 01:08 AM

ok thanks, I read the link that is a nice bowl

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