LumberJocks

I need some crack advice

  • Advertise with us

« back to Woodturning forum

Forum topic by Rink posted 12-09-2018 05:04 AM 1224 views 0 times favorited 33 replies Add to Favorites Watch
View Rink's profile

Rink

122 posts in 457 days


12-09-2018 05:04 AM

I’m relatively new at woodturning. I’ve turned a few bowls and a couple of lidded containers. I’ve gotten some free wood recently from a couple of local sources. Older turners who are giving up the wood that’s been stored in their shed for a decade. So I know that the wood is pretty dry.

I’ve had 3 instances in the past week where cracks have appeared. I would like some advice as to:

1 – is this common? Do I just need to expect that a certain percentage of the wood that I use will crack?

2- How can I tell whether the piece of wood is worth trying to fix? At what point do I just give up on the piece of wood?

I was shaping this piece out for a lidded urn. The moisture level was 7.8%. It was fine. I left it for a day or two and when I looked at it again this is what I found:

Can this be saved? How can I tell whether it’s stable now or whether the crack will get bigger? I have epoxy and CA glue – which one of those would be better to use?

Then I was cutting a piece of wood that had some nice spalting.

Is this worth saving? Epoxy?

Today I was turning a bowl with the cracks as shown in the picture. The cracks are very shallow.

I’m thinking that I can just sand and finish it. Am I wrong?

Thanks for any insight.

David


33 replies so far

View 000's profile

000

2859 posts in 1319 days


#1 posted 12-09-2018 05:29 AM

Don’t buy from somebody you don’t know.

View AlaskaGuy's profile (online now)

AlaskaGuy

5316 posts in 2729 days


#2 posted 12-09-2018 05:41 AM

Whew, I glad you posted pictures along with that thread title.

-- Alaskan's for Global warming!

View GrantA's profile

GrantA

1607 posts in 1828 days


#3 posted 12-09-2018 05:44 AM

Don’t do crack mmkay

View Wildwood's profile

Wildwood

2673 posts in 2555 days


#4 posted 12-09-2018 11:15 AM

To salvage cracked turnings a labor of love that is not always worth the effort. To prevent cracks need to turn to uniform thickness and if going to leave for a day or two use to cover the turning with a plastic bag.

Wood is never as dry as we think, moisture meter only gives us a ball park reading on thick wood. Wood will gain & lose moisture content thru out it’s life. If wood store improperly, or not processed properly, and some species just prone to crack kind of learn as you go process.

Will get different opinions whether to use CA or epoxy both will work, CA might be little easier to work with.

To salvage cracked turnings very iffy. Neither CA or epoxy will prevent new cracks nor will filing crack with things like now or used coffee grounds, herbal or regular tea, saw dust, or other fillers. I only use coffee grounds, tea, or saw dust if blends with wood color. Have a cheap coffee/spice grinder which use to grind to fine powder. I use CA, after filling cracks, then sand flush, may take couple applications.

Lot of folks do use metal shavings, colored stones, or powder which highlight cracks.

The time it takes to fill, apply CA or epoxy not short! So really up to you with picture #1 and same goes for #3. You could cut or split away crack in #2.

-- Bill

View Nubsnstubs's profile

Nubsnstubs

1580 posts in 2150 days


#5 posted 12-09-2018 02:34 PM

After seeing a video by Chas Thornhill using dowels to stabilize one of his turnings, I started doing it for my stuff which always has cracks. It has worked for me. To drill a hole into the edge of the pieces you show, you would need a Kreg drill bit used for pocket holes. you might even have to sand dowels because some might be slightly oversized than the hole. Use wood glue, apply liberally, and keep the dowel within the wall thickness you are going to end up with. The dowel will also act as a thickness gauge as you expose the dowel while turning. Below is Thornhill’s video.

https://www.youtube.com/watch?v=NmgZG4xlFBw&t=16s

I would not recommend using metal rod. I had a piece blow up because the rod came out and caught on the tool rest.

Jerry (in Tucson)

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

View rockusaf's profile

rockusaf

77 posts in 522 days


#6 posted 12-09-2018 02:37 PM



Don t do crack mmkay

- GrantA

I was gonna go with Drugs are bad mmmkay

Rock

View GR8HUNTER's profile

GR8HUNTER

6223 posts in 1132 days


#7 posted 12-09-2018 02:54 PM

DONT SMOKE IT :<((

-- Tony---- Reinholds,Pa.------ REMEMBER TO ALWAYS HAVE FUN

View Rink's profile

Rink

122 posts in 457 days


#8 posted 12-09-2018 03:11 PM

I appreciate both the useful and not quite as useful responses.

Bill, thanks for the advice. I think I’m going to use #1 and #2 as learning experiences. I’m going to let #1 sit for a while and let it do what it’s going to do, and then I’ll use some epoxy, maybe with a contrasting color, and see how that works out. With #2, I’ll epoxy the crack, maybe try a dowel for the heck of it. #3, I’m just going to turn the inside and finish if it seems stable.

Jerry, that video is an eye opener for me. He put quite a lot of work into that bowl, and the size and the beautiful grain probably made it worth it. If I get into that situation with a unique piece of wood, I can see putting in the extra time. I’m going to use a dowel or two on #2 just for the learning experience. Was Thornhill spraying with shellac and then rubbing in CA? I couldn’t tell exactly what he was doing.

David

View OSU55's profile

OSU55

2359 posts in 2409 days


#9 posted 12-09-2018 03:19 PM

As Bill said thick wood is never as dry as one might think no matter how old. Always a chance for cracks. When cutting blanks either seal the end grain well or put in a plastic trash bag if for a week or 2 till you turn it. While on the lathe, cover with a trash bag, even during a 10 min break that becomes 2 hrs due to whatever comes up.

Repairing cracks is a judgement call – both time and safety. I use all the methods stated previously, mostly use a filler with epoxy, thin ca first to soak in and help hold together. I like coffee grounds and powdered metals, and use artist oil paint to tint the epoxy. All 3 of yours could probably be saved, but it can be time consuming. These may be good educational/practice projects – plan on throwing them away and try some different repair methods. If you get something useful great. Stop the lathe often to inspect what is happening as you remove material. If in doubt throw it out. Try to keep your body out of the line of ejection.

View splintergroup's profile

splintergroup

2730 posts in 1642 days


#10 posted 12-09-2018 03:47 PM

Wear a belt and don’t bend over 8^)

I’ve seen plenty of LJ projects where cracks are filled with epoxy and filler color (I’m partial to turquoise), but it certainly is a judgement call on the safety of finishing your turning.
Best advice I can offer is careful wood prep before turning, letting the drying stresses work out over time by doing partial turning, letting it set for some time, rinse, repeat.

Turning with end grain on the sides always seems to be a battle with how the wood wants to move.

View bilyo's profile (online now)

bilyo

739 posts in 1522 days


#11 posted 12-09-2018 04:13 PM

I don’t have a lot of turning experience and don’t consider myself an expert. But, I have learned through experience, reading, and what I’ve been told, that it is best to roughly shape a piece, including hollowing it, and let it set and dry some more before final turning. This can be difficult for me to do as I rarely know ahead of time exactly how a piece will look. But I have a number of roughed out blanks with walls around 1/2” thick in a box awaiting final turning. Many of them are no longer round because they have been able to shrink without cracking. When left in a chunk, the wood has no where to go when it shrinks. So, it splits. If you roughly shape it into a hollow form, the walls can move in and out in response to drying and are less apt to split.
Your photos show pieces with pretty severe splits. I can’t tell for sure, but I suspect that you haven’t done much, if any, hollowing yet. I suggest that when you start a piece you commit to completing it to a thick walled hollow form before stopping work. For the piece in your second photo, I would split away the smaller side and make a rough hollow form blank out of the larger chunk as soon as you can; before it splits. Also, as soon as you can, you can continue working with the other two, but do so carefully. Be aware that they may break into several pieces as you work. You can treat the cracking as a feature or fill them as you prefer. The cracks may worsen, but as you get the walls thinner, it becomes less likely.
Nothing you do now will make the cracks visually disappear. Nor will it prevent further cracking. Only getting the walls of the vessel thinner will have any chance of stopping or slowing it down. I would not advise you to try any repair until you have them close to final shape and know that they are going to stay together and be reasonably stable. Any filling you put in the cracks now will likely get cut away as you work. And, that’s OK as long as you understand that you may need to add more later.

View Nubsnstubs's profile

Nubsnstubs

1580 posts in 2150 days


#12 posted 12-09-2018 04:28 PM



I appreciate both the useful and not quite as useful responses.

Jerry, that video is an eye opener for me. He put quite a lot of work into that bowl, and the size and the beautiful grain probably made it worth it. If I get into that situation with a unique piece of wood, I can see putting in the extra time. I’m going to use a dowel or two on #2 just for the learning experience. Was Thornhill spraying with shellac and then rubbing in CA? I couldn’t tell exactly what he was doing.
David

- Rink

Rink, I don’t know what he did. I was just fascinated with how he was drilling and inserting the dowels. When done, it is a beautiful bowl…...... Look at his other videos. They are well worth watching…... His 20” Pecan bowl features my invention, the “Tail Stock Steady”. Another video worth watching. Subscribe to his channel. You can also go to my website listed below, and click on any video, which will take you to youtube, and subscribe to my channel if you want to be bored. .......... Jerry (in Tucson)

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

View LeeMills's profile

LeeMills

670 posts in 1721 days


#13 posted 12-09-2018 04:57 PM

The crack at A may be ring shake. At the very least I would use thin CA to try to stabilize.

I do not know the size of this log. If you cut along the line you will remove the crack and have 1/2 log for bowls. If the diameter is 8” and the length 24” you will have three bowl blanks.
The other half (blue line) can be used for spindle blanks or small bowls.

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

View Phil32's profile

Phil32

579 posts in 323 days


#14 posted 12-09-2018 06:04 PM

It is curious that you have no information as to the wood species. This could be important for determining whether the pieces can be salvaged. Photos 1 & 3 seem to show a grain pattern from a crotch or bend. This could infer stresses that will continue to cause cracks. If the cracking started when you roughed out the piece, it is unlikely that it has now stabilized.

-- Phil Allin - There are mountain climbers and people who talk about climbing mountains. The climbers have "selfies" at the summit!

View Rink's profile

Rink

122 posts in 457 days


#15 posted 12-10-2018 04:53 AM

More good info everyone, thanks. I thought that dry was dry, and that partial turning was for wet wood, but apparently I was wrong about that. I’ll try to make a habit of not leaving the wood in a “chunk” once I get started. And Phil, the first and third pieces are walnut, I’m not sure about the second one. Also, the pieces were in an area of crotch or bend, so maybe that at least partially explains the problem.

So I continued to work on #3 and I was wrong about the cracks. They are not shallow. These are pictures of the outside and inside, showing the cracks go all the way through (I only show one side, but there are cracks all the way through on both sides). The cracks are so tight though, I couldn’t even get a fingernail in them. The only way I can think to fill them is to actually enlarge the cracks (with a coping saw?) and then fill them. Any suggestions?

showing 1 through 15 of 33 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com