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I need some crack advice

by Rink
posted 12-09-2018 05:04 AM


33 replies so far

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000

2859 posts in 1259 days


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

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

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AlaskaGuy

5233 posts in 2669 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!

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GrantA

1481 posts in 1768 days


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

Don’t do crack mmkay

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Wildwood

2622 posts in 2495 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

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Nubsnstubs

1534 posts in 2090 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

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rockusaf

64 posts in 462 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

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GR8HUNTER

5961 posts in 1073 days


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

DONT SMOKE IT :<((

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

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Rink

110 posts in 398 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

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OSU55

2244 posts in 2350 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.

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splintergroup

2637 posts in 1582 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.

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bilyo

655 posts in 1463 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.

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Nubsnstubs

1534 posts in 2090 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

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LeeMills

660 posts in 1661 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

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Phil32

533 posts in 263 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!

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Rink

110 posts in 398 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?

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Wildwood

2622 posts in 2495 days


#16 posted 12-10-2018 10:33 AM

JMHO, would give up on that bowl! Just to many cracks inside & out to fool with but I am not you.

Might try very sharp awl or dental pick to widen cracks so can fill & glue.

-- Bill

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OSU55

2244 posts in 2350 days


#17 posted 12-10-2018 01:05 PM

For the tight cracks I would use thin ca first to help hold it together, then either mediun ca or epoxy to fill. I would not try to widen them.

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HokieKen

9221 posts in 1499 days


#18 posted 12-10-2018 02:53 PM



For the tight cracks I would use thin ca first to help hold it together, then either mediun ca or epoxy to fill. I would not try to widen them.

- OSU55


+1

-- Kenny, SW VA, Go Hokies!!!

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Nubsnstubs

1534 posts in 2090 days


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

Rink, below is only a suggestion on what I would do or already have done on stuff that looks like what you have pictured. As wood workers, we all know that there is no such thing as SCRAP in a wood shop. It’s only clutter that must be thinned out every now and then. The same goes for wood turners. No such thing as crappy wood if you have the desire to what is available and can make it secure. Usually, what people call crappy wood turns out to be some of the best looking wood around.

I’m sticking with my dowel suggestion. Instead of actually using a dowel, get yourself some shish ka bob skewers(100 in a package for $1.98). They are 3/32” (.093 od and about 6” long made from bamboo. Bamboo is pretty stout stuff.

A #40 aircraft drill bit will be the one to use. The aircraft designation only means it’s 6” long and has a point angle different than woodworking bits.

On the bowl side, start the hole about 2” from the crack 2” down from the rim. Try to stay parallel with the rim. You can also drill down from the rim at an angle of your choice to bridge the cracks. If you punch through the other side of the wall, it’s no big deal as it will become a feature. With a little planning, you could do this along the top of the rim with evenly spaced skewers just to give a design feature while giving it a little more security. Just make sure the skewers bridge the larger cracks.

If you want more info, PM me with your email and I’ll send you some pictures of a couple pieces I’ve done. ......... Jerry (In Tucson)

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

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Rink

110 posts in 398 days


#20 posted 12-10-2018 04:37 PM

Wow, three completely different suggestions: give up, CA glue, and dowels. Good to know that there is no right or wrong – just different ways of doing things.

For education sake, I’m going to try the thin CA and the dowels. I actually have a 100 pack of those skewers at home that I use for grilling. I can look it up, but if someone here knows: when using the thin CA glue, do I have to wax or shellac the surrounding wood so that the CA doesn’t get on the surface? Or will it come off anyway as I re-turn the surface of the bowl?

Thanks again,

David

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Phil32

533 posts in 263 days


#21 posted 12-10-2018 04:44 PM

Rink – I’d like to share my recent experience turning walnut. This wormy walnut burl was salvaged from a dead tree still standing on a local citrus ranch. Members of our local woodturning club were invited to come and “help ourselves.” Most of the members were interested in clear, solid chunks, but I was intrigued by burls riddled by wood boring insects.

I cut some suitable size chunks and roughed them on the lathe:

With this chunk I proceeded on to a finished shape almost immediately. There have been no cracks! Fortunately the worm holes haven’t weakened the walnut to where it disintegrated on the lathe.

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

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Rink

110 posts in 398 days


#22 posted 12-10-2018 05:24 PM

That’s beautiful, Phil. I also got a piece of burl that was in the same shed as the above pieces (I don’t know what kind of wood it is). I was scared gouging it, but I like the way it came out. Not perfect, but I’m learning. And yes, the cracks go all the way through, but these are good cracks!

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mramseyISU

572 posts in 1905 days


#23 posted 12-10-2018 07:05 PM

Take this for what it’s worth coming from a novice turner but I have seen a guy on youtube who will make a rough turning and throw into a homemade drying box for a couple days before finishing the turning. He made it with a cardboard box and a heat lamp. I think he used some hvac foil tape to attach the lamp to the box. That might be worth a shot.

-- Trust me I'm an engineer.

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Nubsnstubs

1534 posts in 2090 days


#24 posted 12-11-2018 04:52 AM

Rink, I wouldn’t use thin CA.Thick would be better because it takes a little long to cure. I use Titebond glue. Glue up the whole surface of the skewer, and try to get some glue into the hole from both ends, and then insert the skewer. Test fit it before you glue it up. Snug is good, with Titebond. If it goes partway, sand the skewer to allow a slip snug fit. ................... Jerry (in Tucson)

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

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Wildwood

2622 posts in 2495 days


#25 posted 12-11-2018 04:30 PM

Think wood in those first pictures already had those defects before he started turning. So kiln would not save items pictured. Part of turning burls is living with what you get!

Simple homemade kilns with light bulb, fan for air circulation all you need. Have seen cardboard boxes, beer coolers, old appliances, with fan & light bulbs speed up drying process for rough turned bowls, vases, & hollow forms. Drying times could be as little as one month or more.

Simple to understand if know moisture leaves wood thru evaporation! Increasing air circulation with moderate constant temperature allow rough turned items to dry enough to finish turn. Not a couple day process!

We had a member here build a super kiln with high temperature lamps and cooked the wood bowls attempting to dry it. So he filled those cracks with turquoise people looked but didn’t buy his bowls.

Drying wood more art, luck, than science! Appropriate chapters in this reference will help you understand drying wood better.

https://www.fpl.fs.fed.us/products/publications/several_pubs.php?grouping_id=100&header_id=p

If going to harvest your own wood for turning couple different approaches.

http://customwooddesign.com/turninggreenwood-1.html

http://honoluluwoodturners.org/16_tips/rough%20turn%20bowls%20--%20HWT.pdf

-- Bill

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OSU55

2244 posts in 2350 days


#26 posted 12-11-2018 05:50 PM

The key to drying rough turned pieces is limiting the evaporation rate – its science, not art. Heating the ambient the wood is in can work, but the humidity level must be controlled as well in order to limit the evap rate, just like a kiln. Unless one is going into volume production its not worth the development time and cost. Wrapping in heavy kraft paper with chips and placing in an ambient environment of fairly constant temp and humidity has worked very well for me. Weigh the wrapped item, put it away, weigh it periodically (weekly), when it stops reducing weight it is ready. I find 2 weeks to 3 months time, depending in shape, thickness, beginning moisture, storage environment – many variables. Weight change takes out the guess work.

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Rink

110 posts in 398 days


#27 posted 12-11-2018 06:21 PM



Rink, I wouldn t use thin CA.Thick would be better because it takes a little long to cure. I use Titebond glue.

I agree. You misunderstood me. I wasn’t going to use the thin CA for the skewers. I was going to use Titebond for the skewers and thin CA in the cracks themselves. Except now I see that the cracks are widening a bit and thin CA may be too thin. So my thought is to let it stabilize for now, use the skewer method and fill the cracks according to how wide they are. I’ll post the result when it happens.

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Rink

110 posts in 398 days


#28 posted 12-11-2018 06:28 PM

To those who are giving drying advice…. These pieces were (I’m told) in a covered shed for about 10 years. I assumed that they were as dry as they were ever going to be. In retrospect, I think that I should have let them sit inside my shop for a few weeks to acclimate to a different humidity level.

But assuming that these pieces were drying for 10 years (I checked two pieces – one was at 7.8% and one was at 13.1%), other than letting them sit in my shop for a bit, do I still need to go through the makeshift kiln or paper bag and chips routine? I guess, to be on the safe side, I can weigh each piece before I bring it inside and then weigh it again after a few weeks to see if there is a change?

David

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Wildwood

2622 posts in 2495 days


#29 posted 12-11-2018 08:46 PM

More questions than answers, especially when you say wood stored in a shed for 10 years. There is a little science, but not rocket science involve in drying wood. Controlling the drying process is key. Uncontrolled drying leads to defects as seen in first 3 picture OP posted.

Chapters 4 & 13 of the Wood Handbook already links will give you the basics of drying wood. Art & luck come into play based upon your location, and experience harvesting different species of wood at different times of the year, end sealing, proper storing & protecting from the elements. Even with art, luck, and bit of sciences there are no guarantees!

Yes based upon where you live, average annual relative humidity, affect wood gaining or losing moisture content. Hopefully if skim thru the Handbook will come to understand a process that will work for you.

Based upon where I live plastic bags only used if leaving something on the lathe temporarily. Paper bags or cardboard box only used for temporary storage of roughed blanks, if stored with chip don’t like to leave them in a bag or cardboard box due to staining or mold growth. Lot of times just put rough blanks on floor at back of my shop. I never reseal roughed blanks with Anchor Sealer or other coating, other turners say it’s mandatory.

Homemade klin just little insurance and does improve your success rate with green wood roughed turned, may not work on wood been in storage for ten years with drying defects!

-- Bill

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OSU55

2244 posts in 2350 days


#30 posted 12-11-2018 09:48 PM

Rink, I think there might be some confusion here. For the 10 yr old wood you got, you dont need to do anything before you turn it. When you turn it, you are opening up areas down in the blank that are still wet. Some folks turn to size and want the warping created by drying in the finished piece. Im making the assumption you dont, and in that case rough turn the item to about +10% wall thickness, dry it, remount and turn round – finish turn. Same process for new green wood. I have wood thats years old that is still wet 2-3 inches down.

While rough turning an item, cover it up with a plastic bag if it is going to sit more than 5-10 min, which could end up being all day. It appears your urn was turned some and left out in open air for a while and cracked, or did it crack while actually turning it?

As for not sealing wet cut blanks Wildwood’s experience is different from mine – if I dont seal end grain or put in a plastic bage they start cracking, sometimes within a day or 2. Not all will, but enough do that I dont trust it.

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GreenfireLatheLady

30 posts in 1869 days


#31 posted 01-11-2019 12:02 AM

Just went through this with some cherry that developed hairline cracks…if the wood you’re working with is carrying a lot of tension (i.e., crotch, burl or curly), you may develop cracks as the tension is released. I’ve also found that I go through this a lot with oak, whether it’s dry (less than 7% moisture) or wet (14-20% moisture).

I used CA glue for the hairline cracks, then sanded those areas to 400. For larger cracks, I fill with colored epoxy…it’s worked well for me.

Hope this helps!

-- --I live for sawdust.

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steve104c

52 posts in 1598 days


#32 posted 01-13-2019 10:15 PM

Fill cracks of partially turned bowl with thick super glue. Make sure cracks are fully filled. Spray with accelerator to dry. This should make piece stable to turn.

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spiritbeaver

3 posts in 127 days


#33 posted 01-15-2019 09:35 AM

I use polyester resin which is normally used for fiberglass reinforced plastic. Or an epoxy resin which is frequently used for building boats like cedar canoes.
I have used the polyester type to fill large spaces (in a tabletop) between slabs of small trees. There were some initial problems with shrinkage likely due to shrinkage of the wood. Repairs were easy. That all went away.

I have also used epoxy to fill cracks, knotholes and spaces in flooring and various things.

-- James H. - https://wisepick.org/best-cabinet-table-saw/

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