Thread: Blackwood couldn't stand the heat

Originally Posted by Oldgreybeard

Last Monday I started turning a piece of blackwood I found under the house. The piece was almost 900 x 300 and had obviously been there for many years - we have owned the house for over 30 years and I didn't put it there. Cleaned it up and got 2 pieces 285 x 285 x 105mm.
Started turning one piece late in the afternoon - trued it up and roughly shaped the outside. The intention was to turn a hollow form
Tuesday was 41 degrees and I didn't venture out to the shed until about 8pm.
Shock Horror a masty spit similar to this had appeared.
_DSC0548.jpg
I flooded the split with thin CA glue and checked next morning and thought I may have caught it in time.
Next 2 days were 43 and 45 degrees and according to the min / max thermomemter reached 53 degrees in the garage. That night I was greeted with this
_DSC0549.jpg_DSC0550.jpg
The next day was 44 degrees and the min / max thermometer topped out at 57 degrees!
This morning I built up the courage to venture out and see if there was anything to salvage.
_DSC0554.jpg_DSC0547.jpg_DSC0551.jpg_DSC0553.jpg
Side Top Top Bottom

Is there any chance that filling all cracks with CA glue and the securely strapping around the outside of the blank would allow me to hollow the inside and finish- the large cracks and knot on the bottom could become features

Otherwise It would make a good door stop or become more beautifully turned firewood for my sister-in-law. Not a good start for 2014.

Bob

You could cut it up and make pen blanks of it

OGB,

It's different up here in Darwin at the moment. It hasn't stopped pouring down for the pass week+ and I'm waiting for my dry wood to start sprouting leaves!
We had the coolest day of any capital city last week which is just about unheard of.

Oldgraybeard,

Just keep going and gluing and if you need filler, put some CA in and then cram used dry coffee grounds in, then more CA. Coffee ground look like a bark inclusion.

Put a few turns of tape around it and keep speed under 1000 rpm. Filament packing tape is the strongest. Finish it no matter what happens. Unless you have made a bunch of bowls, the practice is useful. I have made about 75 pieces good enough to sell, and unless something is a total loss; comes to pieces, or too much rotten wood, I complete it.

I have made a long post about finishing suspect bowls. You could go backward in my list of posts. I think it was middle to late 2013.

Good luck with it.

Instead of trying to hide the crack, what about making a feature of it?
Stone Inlay - Woodturning Tools and Timber, Woodturner Accessories, Woodcarver Supplies, Woodturning Equipment

One thing: for cracks larger than "hairline," I'd recommend using a 2-pack epoxy rather than CA.

CA is not now - and never has been - a crack filler, even though it can be used so. If it is used as such, it should only be used where it is not important for it to have structural strength.

The cracks on your blank are such that I'd use CA in the hairline cracks to stop them growing longer... and epoxy in the "open" cracks to hold the beast together when you spin the blank up.

Fillers can be used in the epoxy, with varying degrees of success. I like to use coffee grounds (they look like natural inclusions and aren't particularly hard on the tool steel) but powdered brass, ground stone and similar are all pretty much equally viable.

Further to the safety issue: even after gluing the cracks I'd heartily recommend running several wraps of good-quality duct tape or similar around the outside rim while refining the inside and what's accessible of the outside shape. Purely as a "just in case."

Also, after removing the duct tape it's a good idea to slow the lathe down as much as practical to clean up the rim and do any last minute sanding/finishing. Again, "just in case."

I've recovered quite a few bowls with similar cracks this way and some of them even look good!


Of course, even with all the above precautions in place, there are times when the cracks are more extensive than they appear... and/or I've simply misjudged their severity... resulting in UFOs ricocheting around the shed.


It's all part of the learning process - nothing teaches you to be careful what you spin up better than a close encounter of the UFO kind - but you still want to do things as safely as possible so that it IS simply a close encounter and not a severe probing.

Thank you all for the advice. I have filled the cracks with CA and will refine the design to provide a tenon to mount the chuck rather than using the original expasion fitting for the chuck. Depending on how it hold together, I may try carving out the cracked areas and filling - something I have not tried todate. I will post more photos as work progresses.
Bob

You can fill with CA or epoxy, with or without other fillers and it should be OK provided it is fully cured. Some packing tape certainly helps with security and safety.

Originally Posted by Skew ChiDAMN!!

..CA is not now - and never has been - a crack filler, even though it can be used so...

The good quality thick one was developed exactly for this purpose . BUT, you have to ensure it is set full depth, and this can take days! DO NOT use those $2 shop CA tubes, they are actually from CA wash, fine for decorative stuff but they have very little reliable gluing ability.

1. Any timber however dry is likely to shift once you've done some shaping/hollowing. Removal of mass releases tensions. Next time, rough it wait and see.

2. Under your house in Mt Waverley .. . wish I'd bought your house! If you have poor air circ there and brought this piece out in the heatwave, well, you get what you found. Sudden moisture drop in a timber that doesn't respond well to that.

3. Filling: as per other posts I like 2 part epoxy; mixed 1:1 with fresh coffee grounds. The coffee smell almost overcomes poxy epoxy. In the case of your piece, this fix ain't gonna emulate a sap line sadly; the eye will be drawn to it so think about that when you finish turn it. Can it be made a feature? Can you subdue it with a particular finish?

Thanks for the comments rsser. The area under the house is well ventilated and very dry.The piece had been in the garage for 2 weeks before I cut it into turning blanks on the Monday. I thought that would have been time enough for it to aclimatise -obviously not. The other piece shows no sign of checking , but to ensure I don't have a repaet of the problems with the first piece, do you have any advice as to how long I should leave it?

Bob

In the last heatwave garages and sheds will have worked like kilns. IMO that negatively affects blanks, rough-outs and finishes.

I have no answer to your question. In your shoes I would leave it for a few days, then rough turn it and watch what it does, and then finish turn it.

Mate,
Just an option - instead of epoxy glue, why not use acrylic resin coloured to your taste ?

Regards,
Cam

_DSC0560.jpgI have turned the outside and hollowed the interior. Must admit I "chickened out" on the 3mm wall thickmess - it is closer to 8mm, but I was getting concerned with the big crack

_DSC0558.jpgAs you can see it is still there and actually extends almost to the other side. Certainly to the other side of the rim. There is also another smaller crack an inch or so to the right which extends almost to the rim.

_DSC0557.jpgI am thinking that I have a some options to try to salvage something.
(a) Use the Dremel tool with a burr and create a 'roughened' feature around the rim and then extending down to the base along the paths of the 2 cracks. I could stain these areas in say a dark oak or walnut and then apply a lacquer finish.
(b) Carve out the areas affected by the cracks and then use a gas torch to the char the base and the edges of the cut outs. May not have to take the cutouts to the rim, but could continue the effect with a pyro pen to create a scorched effect up to the rim.
(c) I don't think that creating a feature of the cracks by filling with stone, coloured epoxy or similar will work (not to say that I am terribly confident that the other options will either) - the effect of filling the cracks prior ro turning does exactly produce a pleasing effect.
(d) Anyone know an artist who could paint a panorama on the outside of it?

Comments and suggestions would be appreciated - I have already thought of the option of just leaving it to burn rather than only creating a charred effect

Bob

You're wise to be concerned about the thing blowing apart from a serious flaw.

Epoxy is plenty strong if mixed and applied properly though.

If you have misgivings while hollowing, put a few wraps of non-stretch tape around the outside (sellotape, brown packing tape; this is a tip).

Looking at your work, I'd say you're entitled to call this 'rustic' and leave it as is. Everyone has their preferences of course* but this piece has plenty of character. Does it need tarting up or tweaking?

The test I apply I got from Guilio M. who was demo'ing at a WWW show: will you put this out on show and enjoy looking at it or will you stick it in a cupboard?

It can take living with it for a while to get your answer.

Is there any rush?

.............

*While I've had fun and some disasters pushing to get thin walls, thick is not a sin in my book. The only real sin for me is an ugly form. A minor sin is poor finish.

I've used some sellys Crystal clear epoxy it turns ok and have also experimented with ebony wood putty! with some pleasing results!