Cracks in candlesticks

[nblong]

Any thoughts on what happened or what I'm doing wrong? These cracks just appeared the day after I turned the candlesticks (cocobolo). My shop is cooler than the house but it's still shirtsleeves out there. Could the difference in tmeperature make these cracks appear? The ferrules aren't driven in; they're pressed in by hand. They have three little bumps on the outside to hold them in. The shoulders are about 1/4" thick at this point. Both candlesticks are from the same piece of cocobolo so I suppose there could have been a hairline flaw I didn't notice but I think that unlikely since one of the cracks is in line with the grain but the other is almost perpendicular to the grain.

The only thing I can think of to prevent this from happening again (assuming it's the ferrule causing the problem) is to ream out the inside of the hole so the ferrule slips in easily then glue it in place.

View image in gallery​

ANY help would be appreciated. Thanks.

 

[Glennbear]

Just a guess on my part but since the cracking seems to irrespective of grain direction I would look at expansion of the ferrules as the cause. Back in my machine shop days we used heat/cold to fit bushings for exactly that effect, fit cold and tight when warm. :wsmile:

 

[FredP]

My best guess is the wood wasn't dry.:icon_scra

 

[NC_Horn]

How did you create the openings for the ferrules? Heat from boring/drilling could be the cause. I have seen it a number of times when drilling pen blanks.

Duane

 

[NCTurner]

Any of the above are possibilities, but my guess would be on wet wood. If the blank was an off the rack from KS or wood craft, do not assume these blanks to be dry, they often are NOT.

 

[nblong]

The blank WAS from Woodcraft and it was completely waxed on every surface. If you've got any idea how to tell if wood is dry before you buy it I'd love to know it. I just assumed if it was from Woodcraft it would be OK.

I used a Forstner bit to drill the holes but I lifted it quite often. Still, I suppose the heat could have caused a tiny crack that just got worse as the whole piece warmed up in the house. Would you expect to see the cracks right away if the piece got too hot? I do a lot of pens but I've never had a crack in a blank I could attribute to excessive heat so I'm not familiar with how to spot one unless it appears right away.

In any case, thanks for your comments everyone. I guess I'll just try again and hope for the best.

 

[stave]

The species of wood that are only available in small sizes such as ebony and some of the others from Woodcraft are not kiln dried. The wax coating is there to prevent cracking. Neither the supplier in the country of origin or the supplier to Woodcraft dry these woods. I have talked to the suppliers to Woodcraft (at least they were a couple of years ago) and that is the information I got.

 

[petebucy4638]

What was the moisture content before and after working the candle stick holders?

Pete

 

[boxxmaker]

Don't know if this is true or not,but I heard that if you get blanks that are completly sealed,it was suggested that you clean the sealer of the blank,but try and leave the endgrain sealed,then let it dry out.I cut a lot of my own blanks and never seal the whole blank,as you have to let the wood have a place to let the moisture out.

 

[nblong]

Pete,

I have no idea about the moisture content. I just picked it off the shelf at Woodcraft and turned it. Again, I just assumed that Woodcraft wouldn't sell anything unless it was ready to go. I'm pretty new to most of this. Should I invest in a moisture meter and start paying attention?

 

[Rob]

Should I invest in a moisture meter and start paying attention?

Yes, if your going to be heavy into turning, I would advise it, I use mine all the time.

 

[NCTurner]

Yes, if your going to be heavy into turning, I would advise it, I use mine all the time.

When I am active I turn pretty heavily, and I would have to politely disagree with Rob on this one. Sorry Rob. There are many ways around buying a moisture meter for turning, and while one does make life easier it is not a necessity.

First and foremost if you buy a blank it is a safe assumption that it is still wet to some degree, unless known to be otherwise. As Ken stated you can clean the sealer from the blank leaving the end grain coated, this will allow airflow to do it's job. HOWEVER if not stored in a cool, low airflow area you will still run the risk of splitting and checking. You are best advised to store them in paper bags or wrapped in newsprint to avoid this. The same applies to larger blanks however these can be roughed turned to approximately 10% of their final thickness with a uniform wall thickness. An inexpensive postal scale can be used to monitor weight loss, when you get the same reading for 3-5 consecutive weeks, the moisture content has reached equilibrium.

Additionally there is a very effective method used to speed this process up. You can soak the roughed blank submerged in a DNA bath, and follow the above protocol. Should reduce the drying time by half or better.

Please see these pages for more information on woodturning in general and specific articles about drying wood.

http://www.woodturningonline.com/Turning/Turning_articles.html

http://www.woodcentral.com/cgi-bin/articles.pl

http://www.woodturnerruss.com/

http://www.woodturningvideosplus.com/woodturning-tips.html

 

[petebucy4638]

Pete,

I have no idea about the moisture content. I just picked it off the shelf at Woodcraft and turned it. Again, I just assumed that Woodcraft wouldn't sell anything unless it was ready to go. I'm pretty new to most of this. Should I invest in a moisture meter and start paying attention?

I think that a moisture meter is a good investment. I don't have any idea as to what policies any of our local wood distributors adhere to relative to turning stock. Simply buying stock that is waxed could mean that it was dried and then coated to prevent it absorting moisture or that the wax was applied to keep the wood from drying out and cracking. I don't own a lathe so I can't speak with any authority about the moisture content for turning bowls, etc, but I do know that you have to know the moisture content of your materials when you make cabinets and other woodwork to avoid a host of issues.

Your problem may have nothing at all to do with moisture issues. I'm certain that the experienced wood turners who visit this forum can steer you in the right direction.

Pete

 

[Rob]

When I am active I turn pretty heavily, and I would have to politely disagree with Rob on this one. Sorry Rob.

No worries, I did it your way for a while. I just got tired of forgetting to weigh my blanks, forgetting to record, etc. IMO the money spent for a moisture meter out weighed the hassle of the other. Even with DNA which I'm doing now. I go to my storage rack every couple of days and measure the moisture content of the roughed out bowls I'm interested in keeping up with.

 

[Sandy Rose]

The first couple of times I tried turning cocobolo, the drilling generated a lot of heat and ended up cracking the blank - I;ve found out that not all blanks are completely dry when you buy them, I buy all my blanks from both Woodcraft and the Woodworking Shop and (though not very often) a few of those blanks have had some shrinkage and cracking after being turned and finished.