Getting tool marks on dense wood

[hsingyihsingyi]

Hi,
I've been turning for only a couple of weeks and I have real problem getting tool marks out of the denser woods, ie African Blackwood. I use a gouge then move to a scraper to shape the blank. Once the general shape is done, I sand starting with ~220, then 320, 400, and finally 600. Then I hit it with a coat of CA, the Triple E, and finally, shellawax.

The blackwood keeps giving me tool marks. I have even left more wood on the blank and started as low as 80 grit, then worked my way up to 600. I have stripped them back down and started sanding again, 220-600 grits. I have increased the speed of the lathe to keep the tools from digging as deep. I have changed the way I sand...sanding against the grain....to circular motion...to horizontal ("with the grain). Nothing seems to be helping.

I'm pretty baffled by this but I'm sure that this will be an easy question for most of the veterans. Do I need to sand to a higher grade, but that does not make sense to me since the lower grits did not get rid of the marks. i was told that I could turn a skew on its side and that this might would help some.

Any ideas would be greatly appreciated.
Thanks,
Jay

 

[woodbutcher]

Do you sharpen your tools often? What speed do you turn at? Ebony is so hard to get a slick finish on. I am assuming Blackwood is similar. On Ebony I no longer use a finish. I sand to 1500 and the Triple E is my finish. I will start at 150-180 grit if I am concerned about tool marks. You might also aquaint yourself with using a skew. I hope something in this is useful to you,
Jim

PS Welcome to the IAP!

 

[DCBluesman]

If you are leaving tool marks at 220 grit, you need to do two things. First, practice more with your tools. You should get a nice smooth surface with your tools before sanding. Until you get that comfortable with your tools, you will need to do some work with a lower grit...maybe as low as 80. Do not move up from 80 (or wherever you start) until ALL tool marks are gone. And you need to sand both cylindrically and longitudinally with all of your grits and on all types of blanks. I also recommend that you extend your sanding beyond 600 grit, but that's a personal call.

 

[Rifleman1776]

I'm thinking it might be the way he sharpens. What grit wheel do you use? A coarse wheel will give rough edges. Your tools should give a fairly smooth surface before sanding even starts. A skew might be a good idea. And/or try a round nose upside-down for smoothing. When I first started turning and was completely iggerant, I used the round nose upside down on my duck calls and loved the results. Then I figured out how to use it properly and ruined everything. [] Smooth tool edges, skew, round nose, you should get good results. Actually african blackwood is great turning wood and will give a nice smooth finish with tools.

 

[Ron in Drums PA]

1. Practice on a softer wood
2. Make sure your tools are sharp
3. Scrapers don't always leave a nice finish on bowls
4. Learn to make a shear cut with a bowl gouge. You may need to have someone show you this
5. Start sanding with a lower grit and do not proceed to a higher grit UNTIL the tool marks are removed! The higher grits are then used to remove the sandpaper marks

 

[wayneis]

Another this that helps while sanding is to use a sanding block. I use a 1" X 3" hard rubber block behind my sand paper, this sands the whole surface evenly.

Wayne

 

[Dario]

Reading through your post, I believe you really need to learn using the skew.

Chuck a piece of wood and start making shavings. Make the cuts as light as possible and keep on doing it until you have nothing but a toothpick LOL. Then chuck another piece []

Depending on the wood, I usually sand from 320 grit after. There are wood that are prone to tearout and with those I sometimes start at 120 [:0][!]...never due to tool marks though.

 

[KenV]

If the sanding is not taking the tool marks out, you are not sanding correctly.

Wayne is correct that firm backing for the sandpaper will help bridge the low spots. you can also glue or stick sand paper to pieces of wood. Lee Valley sells small steel flat fingers for sticking sandpaper to.

If all the ridges are not gone with the 1st sandpaper, get coarser sandpaper.

You may also be trying to make the sandpaper last too long and be burnishing the surface instead of abrading it. If a lot of dust is not being generated - even with P2000 paper, you are over working sandpaper.

CA is a sandpaper clogger. Use of DNA or mineral spirits or oil will help slow the clogging, but it will clog.


But best -- learn to use a skew and learn to hone the edge of the skew.

You will know when you arrive because it will seem like magic that the surface is smooth and burnished.

Blessings

 

[hsingyihsingyi]

Thanks for all of the suggestions. I am definately going to try some of these. The tools should be sharp but I'm going to check on them too. I'm going to start working with a skew, try a circular and longitudinal movement with a firm surface behind my sanding for starters. I may be overusing the sandpaper some too. By the way. I did sell several nicer pens and letter opens that are softer (wood) to a local jeweler today....these did not have tool marks[] I was pretty psyched.

Also, is there a good way to see if there are tool marks before I apply the CA? Until I apply the CA, I can't really see or feel the marks, but the shine and the black surface really makes them noticable. I thought about misting the wood, but I was afraid that that would open the "pores" in the grain and ruin the sanding. Thoughts?

 

[TomServo]

If you sand with micro mesh or (to a lesser degree) white scotch brite, the surface will become polished enough to see any leftover tooling marks... One thing I'd suggest, is to use an air chuck and blow air on the sandpaper often, it will help keep it from clogging and cool it down.

 

[KenV]

There are a few tricks for seeing tool marks. Dick Sing (who used to work in the tool and die trade) suggest a mirror to reflect light back.

Or you can shine a light across the surface at an angle to have a similar effect.

I can usually feel the irregular surface.

If you are watching, you can see the difference in surfaces when you change grit on sand papers.

Heavy hard oily woods do need a fresh surface pretty fast. Avoid being cheap with sandpaper, especially at the start of the sanding process.

If all else fails, use a 2 inch diameter hook and loop sandpaper holder and coarse paper in a drill to do the initial sanding. This is a bowl turning technique that levels the surface. Several vendors sell these in kits for a nominal amount. This tends to sand the bushings so plan on using calipers to set the end size in your future (good practice anyway).

 

[Scott]

Hi Jay,

You've received some great advice already! I'm wondering if what you are calling "tool marks" are really tool marks. With the sanding you have tried, you should be pretty free of tool marks, unless they are pretty sever to begin with.

Are the marks circular lines that go around the pen? Are they repeated marks that go both around and along the length of the pen? Please describe, or better yet show us a picture of what the marks look like. It may be as simple as sanding marks, and we can give you some ideas of how to get rid of them. Or you may be getting some chatter due to a vibration or out-of-balance situation.

Let us know what the marks look like, and lets zero in on what's happening!

Scott.

 

[hsingyihsingyi]

Thanks Scott. They are circular lines that go around the pen and lengthwise, kind of like a candy strip. I would like to not get them period but I did use the skew today and that worked great. I used it on a piece of pink ivory. Then I sanded with a small wooden block behind the paper that I rounded onthe edges so that I could work some corners too. The rounded corners helps me with a curve that i have at the base of the pen where the fingers rest. i am also cutting the lathe off and and sanding longitudinally with the grain at 600 which has been my final grit so far. I am going to "toy" with sanding at a higher grit for kicks too. Does what I am describing sound like tool marks.

 

[hsingyihsingyi]

I also want to that the rest of you who commented. I think that Iam going to try higher grits and I am very interested in trying the light reflection method as well.
thanks.