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Oldgreybeard
11th Nov 2014, 01:25 PM
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I found this blank hidden away in a corner of the garage - may have been there for 20 years or more. There is something written on it but is almost unreadable. It could be "Tas Oak Burl". It has been dipped in wax. The size is 175 x 175 x 75mm.

I am concerned with the two areas shown in the closeups. Image 2 shows the chip on the top which has completely separated from the blank. It is 45 x 25 x 6mm. The larger 'knot' is still reasonable well attached and is 135 x 70 x 25mm (image 3).

The gum veins shown clearly on the left side of image 2 and upper left of image 3 might also be a problem when I start to turn so would like to stabilize them now to avoid or minimize problems later.

Put simply my problemis that I have no idea of how to proceed, so would welcome your collective advice.

Thanks

Bob

wheelinround
11th Nov 2014, 02:14 PM
If you are turning it will you be cutting it round first ?? If so most of the edge will be cut away.

If leaving it as is stabilising options are. Either of the first two you can add some colour to when mixing.

Good dose of CA and let it soak in and add more again.

Gaffer Tape all sides but one so it doesn't leak and pour some resin into it allow to harden.

Cut it round gaffer tape the outer edge and turn


Last resort send it to me :U it looks a top piece to good to waste

Hope this helps and show us what you did with it when done.:2tsup:

Oldgreybeard
11th Nov 2014, 02:55 PM
If you are turning it will you be cutting it round first ?? If so most of the edge will be cut away.

If leaving it as is stabilising options are. Either of the first two you can add some colour to when mixing.

Good dose of CA and let it soak in and add more again.

Gaffer Tape all sides but one so it doesn't leak and pour some resin into it allow to harden.

Cut it round gaffer tape the outer edge and turn


Last resort send it to me :U it looks a top piece to good to waste

Hope this helps and show us what you did with it when done.:2tsup:

Thanks wheelinround.
My first thought was to make a square lidded bowl with the top concave down from each corner to a recessed lid. But after closer inspection, that could be somewhat hairy, so will probably end up round.
Regarding using resin, I seem to recall reading somewhere that if resin was applied under pressure (as in a pressure vessel) that the resin would be forced into all the voids. Is that what you meant?

Its a pity you aren't closer to Mt Waverley, might have considered last resort in return for completing new selving and drawers in the garage.:;:; Next project is roll out drawers for turning chisels.

Bob

dai sensei
11th Nov 2014, 03:49 PM
Casting with resin under pressure forces the resin into the exposed holes but will not fill internal voids etc.

You can have it stabilised with Cactus Juice or similar under vacuum, but that only stabilises the rotten wood, it doesn't fill voids. Similarly you can stabilise with wood hardener from you hardware but it can take weeks to cure the stuff at depth, and it too will not fill voids.

You can also stabilise with thin CA (not that cheap $2 stuff) but it will take a fair bit and you will need to leave for a decent period for it to cure depending on thickness of penetration (full thickness penetration can take a week). It will need to be completely dry before you start otherwise you will get heaps of bubbly white foam.

Any voids can be filled as they are exposed with clear or coloured resin or more thin CA with infill (coffee grinds, crushed stone, glitter etc etc) just ensure time for curing or just leave the voids as features.

You will need to sand or cut off wax before you start.

Personally I would cut out the shape I wanted and rough turn it first to give a better idea of what I had

Oldgreybeard
11th Nov 2014, 04:03 PM
Casting with resin under pressure forces the resin into the exposed holes but will not fill internal voids etc.

You can have it stabilised with Cactus Juice or similar under vacuum, but that only stabilises the rotten wood, it doesn't fill voids. Similarly you can stabilise with wood hardener from you hardware but it can take weeks to cure the stuff at depth, and it too will not fill voids.

You can also stabilise with thin CA (not that cheap $2 stuff) but it will take a fair bit and you will need to leave for a decent period for it to cure depending on thickness of penetration (full thickness penetration can take a week). It will need to be completely dry before you start otherwise you will get heaps of bubbly white foam.

Any voids can be filled as they are exposed with clear or coloured resin or more thin CA with infill (coffee grinds, crushed stone, glitter etc etc) just ensure time for curing or just leave the voids as features.

You will need to sand or cut off wax before you start.

Personally I would cut out the shape I wanted and rough turn it first to give a better idea of what I had

Thanks for the advice. I am really going to show my ignorance now. Is Cactus Juice a trade name and where would one buy it?
For casting with resin, would a pressure vessel used for spray painting (holds 4 ltr can) be suitable and at what pressure and for how long?

Bob

wheelinround
11th Nov 2014, 04:21 PM
I see Neil has filed you in on filling in the voids :p etc

Cactus Juice is from 043turning.com.au

dai sensei
11th Nov 2014, 05:44 PM
Thanks for the advice. I am really going to show my ignorance now. Is Cactus Juice a trade name and where would one buy it?
For casting with resin, would a pressure vessel used for spray painting (holds 4 ltr can) be suitable and at what pressure and for how long?

Bob

Yes Cactus Juice is a trade name, and as Wheelin advises available from Mark at 043, or direct from USA from Curtis (uncatalysed). You use it in a vacuum chamber and then bake it, see http://www.turntex.com/index.php?option=com_virtuemart&Itemid=121

Yes paint pressure pots are used for casting, plenty of threads around on how to convert them, pressure should be what ever is max working load of pot (usually around 45psi unless you have a strengthened pot). Very slippery slope going into casting and stabilising :rolleyes::U. Next you will be into dyes/pigments/pearlex/metals/stone and you start looking at seed pods, bark, any bit of crap you or others would normally throw out, even start going through other's scrap bins :doh: (http://www.woodworkforums.com/showthread.php?t=183917&highlight=dai+sensei :U:U)

Oldgreybeard
11th Nov 2014, 06:27 PM
Thanks Neil for the info and warning of the addiction which my await me. I will have to check out the max. working load of my pressure pot.

Bob

hughie
11th Nov 2014, 08:15 PM
It looks like either celery top burl or resinous eucalyptus burl, of the eucalyptus burl I have turned a fair bit of it. It is prone to flying apart and it does need some careful consideration. I think I have a couple of WIP's on doing this stuff somewhere on here.

But what I normally do is re-view carefully and fill it with el cheapo CA that I buy from one of those discount shops. No good using your good stuff as most of it will be turned away. Then leave over night to go off thoroughly then rough the outside at low speed as these burls often soft its not a big problem.

I also keep on hand some five minute araldite or similar, this is for any big cracks or chunks that may want to peel off as you rough the outside. If you do fine a chunk coming loose then use the araldite as a bridge to hold it together. If your worried about the glue showing try rubbing coffee grounds into it as it goes off.The coffee ground look just like a resin veins and blend in very well.

aha found it, have a look here.
http://www.woodworkforums.com/showthread.php?t=181161

...and if you have any questions free free to pm or whatever. What ever way you do it, this stuff comes up a treat.

Oldgreybeard
11th Nov 2014, 09:03 PM
Many thanks Hughie. I had a quick look at you WIP - I will need to study it in more detail. Your offer to contact you if I need assistance is greatly appreciated.

Bob

Oldgreybeard
1st Jan 2015, 03:52 PM
If you are turning it will you be cutting it round first ?? If so most of the edge will be cut away.

Hope this helps and show us what you did with it when done.:2tsup:

Here is the end result. Basically, I cut the blank to a round an as you suggested almost all of the damaged edge was cut away. I thought of filling the voids with resin, but in the end decided to leave it in its natural state. The wall thickness is about 15mm as the risk of sections of the resin dislodging was becoming a concern. Also there was some very nice figure showing up out side of the resin voids, as well as a nice wavy pattern in the resin voids in some places. I did not want to cut too deep and loose these.

335594335595335596

Size: 170mm x 70mm
Finish: 3 coats of Raw linseed oil thinned 60:40 with mineral turps. Allowed 3 days to dry between coats.

Bob

Paul39
2nd Jan 2015, 12:22 PM
Bob,

That is just beautiful!

Oldgreybeard
2nd Jan 2015, 01:24 PM
Bob,

That is just beautiful!

Thank you Paul.
Bob