Couple of Questions

[Dave Fritz]

I'm finding some woods are harder to burn rings in using linoleum samples than others. Have you found that too?

When I wet sand the inside of a bowl, then reverse it to complete the bottom using a vacuum chuck I'm left with ring marks from the chuck and end up resanding the inside to remove the rings. How to you avoid somethng like this from happening?

Thanks.

 

[Richard Coers]

Linoleum samples? Linoleum is made from sawdust and linseed oil and is incredibly rare these days. Surely you mean high pressure laminate/Formica? No, I have seen no variation between wood species and HPL samples. Turn the speed up on your lathe.

 

[Dave Fritz]

You're correct Richard, thank you.

 

[Dave Landers]

I'm finding some woods are harder to burn rings in using linoleum samples than others. Have you found that too?

Countertop laminate aka formica? Haven't noticed anything. Wet wood may be tougher to burn because it's wet.

When I wet sand the inside of a bowl, then reverse it to complete the bottom using a vacuum chuck I'm left with ring marks from the chuck and end up resanding the inside to remove the rings. How to you avoid somethng like this from happening?

I usually put a ring of craft foam (2mm or 1/16" thick) between the chuck and wood as a cushion (also helps the seal if the wood surface has variations).

 

[John K Jordan]

I'm finding some woods are harder to burn rings in...

What species?

Are you wanting to friction burn rings on spindles or face turnings? (bowls/platters)

Some species naturally contain oils, resins, or even waxy substances. On these, a friction burn attempt sometimes fails. Some of the rosewoods and especially lignum vitae - the wood provides lubrication so the friction tool can't create heat. Some suggest wiping the wood with a solvent first, just as you would when gluing. Some info here:

Gluing Oily Tropical Hardwoods | The Wood Database

www.wood-database.com

I never friction burn with anything but a fine steel wire. If the wire gets slick, roughing it up with coarse sandpaper can help. But I usually friction burn on spindles.

If you want a black line consider another option: apply finish or seal the wood, then cut a narrow groove. I use a special tool I made for this. Then fill the groove with something black or dark such as dark wood filler, crayon wax, shoe polish, black epoxy, or draw the line in the groove with a archival pigment pen. If filling with something that sets up hard, you might cut a deeper groove then cut away any excess along with a little of the wood, sand and finish. I've used this method to fill grooves with metal powder such as brass, sometimes adding CA glue from a capillary nozzle to fix the powder. Might work on soft carbon, charcoal, etc. I wouldn't use powdered graphite. I would experiment extensively on a sample piece of wood before committing to the real piece.

JKJ

 

[Dave Fritz]

Thank you John. The wood was honey locust and it's on the bottom of a bowl. I think the edge of the rubber chucky seal actually compressed the fibers of the wood. I may have to resort to a hand scraper like you use sometimes.

 

[John K Jordan]

I may have to resort to a hand scraper like you use sometimes.

I use the hand scrapers on almost everything I turn, bowls, platters, spindles. Different scrapers for different tasks. The StewMac scrapers are usually my choice for the inside of a bowl, especially if it's off the lathe, something else for the base/foot.

JKJ

 

[Aaron Harris]

As for burning accent grooves, I usually use a .13 gauge E string from an acoustic guitar. It helps that three of my former Eagle Scouts are professional musicians and guitarists who perform all around town (crazy coincidence, huh?). They give me more strings any time I ask. I need to try the formica some time. It seems safer than holding onto a wire at 2500 rpm.

And as for the ring from the vacum chuck, take this with a grain of salt because I have only been using one for a few months, but I have learned to feather back on the gauge to less than full vacum for softer woods like cedar. About 15 to 18 pounds of vacum seems to be the sweet spot for me for a still solid hold without the dreaded ring. But again, I'm still very much in the learning/experimenting stage with the vacum chuck. Hopefully others with much more experience will chime in.

 

[Sam Fleisher]

I'm finding some woods are harder to burn rings in using linoleum samples than others. Have you found that too?

When I wet sand the inside of a bowl, then reverse it to complete the bottom using a vacuum chuck I'm left with ring marks from the chuck and end up resanding the inside to remove the rings. How to you avoid somethng like this from happening?

Thanks.

My vacuum chuck is an 19 inch diameter 3/4 inch thick piece of mdf mounted on a face plate. It will only work with a flat smooth rim and no holes in the bowl though. I was getting the marks like you describe on the inside with a smaller cup type vacuum chuck then I found this style somewhere and made one and pretty much use it on every bowl because you can use it on small bowls or up to an 18 inch one if needed.

It will draw through whatever finish you use like Danish oil or walnut oil if it's not cured but I just wipe it out good and keep an eye on it.

 

[Marc Banka]

About the dreaded black ring, I know it well! Used to get it nearly all the time, but no longer. Never, in fact. Here are my solutions,,or dos and don’ts.

You said this is after wet sanding the interior. So, you have oil on the inside of the bowl. That’s the first problem. The oil dissolves some of the neoprene seals used by oneway. The surface needs to be clean and dry. Bare wood or wood finished with shellac, lacquer,,or other fully drying seals or finishes. If your seal has gotten oil on it, you need to replace it. Both surfaces need to be clean and dry.

Second, are you using the vacuum chuck as a pressure chuck, while you remove most of the material before applying vacuum? If so, the rings are likely from the bowl slipping or scuffing. Any tailstock misalignment will scuff the bowl, and not sufficient pressure with tailstock will allow the bowl to slip, especially if you take too heavy a cut.

In my case, I had both slipping and scrubbing issues. I stopped using the vacuum chuck with tailstock support. So, apply vacuum, withdraw tailstock and then start the lathe. Have never had a mark since.

 

[John K Jordan]

I need to try the formica some time. It seems safer than holding onto a wire at 2500 rpm.

I have never been able to get a clean line with sharpened formica, nothing like what I can get with a wire. (I use galvanized steel wire) The wire burns a nicely line with a nicely rounded and polished sides and bottom - can reflect the light and look good on some things, especially harder woods.






But, yikes, I trust you have the wire tied to some handles, not in the fingers like I saw someone start to do once! Usually friction burn at close to 3000 rpm.



JKJ

 

[Aaron Harris]

About the dreaded black ring, I know it well! Used to get it nearly all the time, but no longer. Never, in fact. Here are my solutions,,or dos and don’ts.

You said this is after wet sanding the interior. So, you have oil on the inside of the bowl. That’s the first problem. The oil dissolves some of the neoprene seals used by oneway. The surface needs to be clean and dry. Bare wood or wood finished with shellac, lacquer,,or other fully drying seals or finishes. If your seal has gotten oil on it, you need to replace it. Both surfaces need to be clean and dry.

Second, are you using the vacuum chuck as a pressure chuck, while you remove most of the material before applying vacuum? If so, the rings are likely from the bowl slipping or scuffing. Any tailstock misalignment will scuff the bowl, and not sufficient pressure with tailstock will allow the bowl to slip, especially if you take too heavy a cut.

In my case, I had both slipping and scrubbing issues. I stopped using the vacuum chuck with tailstock support. So, apply vacuum, withdraw tailstock and then start the lathe. Have never had a mark since.

Marc-Do you turn away the bulk of your material with the tailstock up before turning on the vacum? And then engage vacum, remove tailstock, and just do light finishing passes and final sanding? That's kind of what I've been doing, mainly because I didn't/don't trust the vacum enough on a big fancy platter that I have spent hours on already. If that is what you are doing, I feel better about my evolving technique.

 

[Aaron Harris]

I have never been able to get a clean line with sharpened formica, nothing like what I can get with a wire. (I use galvanized steel wire) The wire burns a nicely line with a nicely rounded and polished sides and bottom - can reflect the light and look good on some things, especially harder woods.


View attachment 76292

View attachment 76293

But, yikes, I trust you have the wire tied to some handles, not in the fingers like I saw someone start to do once! Usually friction burn at close to 3000 rpm.

View attachment 76291

JKJ

John-I admit that I have been just holding the ends. I need to turn a couple of handles. I tell myself it's safer if I switch to reverse and hold the wire OVER the spinning groove after making sure my chuck is seated good and tight. But you're right-I should use handles! I've been mostly really upping my PPE game since I posted about that recent accident in another thread. I suppose even a 5/8" dowel cut to size would work just fine if I secure the wire well. I am not ever gonna get offended when a fellow turner holds my feet to the fire on a safety issue, so thanks again!

 

[John K Jordan]

I need to turn a couple of handles

Before I made some pretty handles I went outside and cut a couple of short sticks about 3/8" in diameter, maybe 2" long, from a tree, bark still on them. Used those for several years.

I just wrap the wire once around the stick, hold the loose end next to the straight length and twist the handle 4-5 times. I think my wires are maybe 10" long. I use galvanized steel lockout-tagout wire from a safety equipment store - soft enough to twist with the fingers to attach a tag to something.

I cut shallow starting grooves with skew or my point tool. With the lathe off move the tailstock out of the way, bend the wire maybe 1/2 way around the diameter, no more. The soft galvanized steel bends easily and stays bent - doesn't spring back like some wire high tension wire. (Seems to me springy wire would not work as well.) I friction burn in either direction, usually holding the two ends of the wire down below the spindle. (I've never done friction burning on a bowl but have on goblets and other end grain work.) Most of my spindle friction burns are on wood between 1/4" and 1" diameter.

Note that I've NEVER had a wire catch in even a deep groove. But...

JKJ