Drying timber blanks

[Arron]

Hi. Will a bowl blank dry faster if it is slabbed? Put another way, will the blank on the left dry faster then the one on the right (assuming both have their ends sealed in due course)?

Also, is one more likely to split then the other ?

cheers
Arron

[Alastair]

IMHO answer is yes to both.

Not sure exactly how much drying time you save, but blank will be able to "bow" while drying, which will reduce radial splitting

regards

[robutacion]

Hi. Will a bowl blank dry faster if it is slabbed? Put another way, will the blank on the left dry faster then the one on the right (assuming both have their ends sealed in due course)?

Also, is one more likely to split then the other ?

cheers
Arron

Hi Arron,
Just a few pointers on your question(s), based on what I do and see (results) from timber I dry. First- If you are going to let the timber dry slowly / naturally, use the half log with bark on and a good end-grain sealer or a couple of coats of gloss acrylic paint. Second- Based on the principle that the more timber you remove from the half log, the quicker it will dry (less mass/thickness), also bowl blanks are normally round for this same reason. Removing all corners/excess timber (rounding) of the half log, you are basically leaving only the workable timber you require, making the half log volume/mass reduce, therefore less timber to dry and easy access for air to do its job. Don't forget to have it sealed all around and possibly an inch or so the outer edge of the flat surfaces on both sides.
Third- The location where you put these timbers to dry, will determine how well or not they will dry, there is, under cover in a well ventilated area, and if in Summer time gets a bit hot, keep the timber as close to the ground as possible, to void the excessive heat from the tin roof. While all this is very important, I found one of the most effective and quicker ways to safely (no mold/fungus/bacteria/rot/etc.,) dry particularly round blanks, is to put them on "mesh" made shelves (example,old fridge inside shelves, etc.,). This way, the air circulates all around evenly. Remember that any water or liquid (resins, sap, etc.,) being heavier, they will settle on the bottom, reason why is important to allow them to evaporate/disperse freely. This can also be achieved by using soaking material like news paper on the shelves before you put the blanks on top but, if you do this, you have to replace that paper once a week, otherwise you have a good chance to have your blanks getting rotten from the bottom up, together with lots of fungus and bacteria attached. This is even more critical in places where the temperatures are low and the humidity is high.

I'm sorry if this sounds a bit "daunting" but, I found these to be the best procedures to get good results, in my case!
Is always the "other" natural option to accelerate the drying time by rough turn green, coat it with a good timber stabiliser, let it settle for a couple of months and finish it then. I can also say that, "with most timbers" the rough green turning process will reduce approx. the drying time to 1/4, which means, from tree to finished product in 3 months, instead of 12 months (minimum). As I said, exceptions do apply!:D

Hope some of this to be of some help to you...!:wink:
Cheers:2tsup:
RBTCO

[Arron]

cheers Rubatcion.
can you clarify
when you talk about rough green turning to a bowl shape, do you mean that it should be convex on one side and flat across the other, or convex on one side and concave on the other - in the sense of looking like a bowl but with very flat walls.

Also, what is a recommended timber stabiliser. I have seen blanks done with wax - is that the best choice. How is that wax usually applied.

I dont really understand how the blank will continue to dry when it is covered in wax, surely it will not loose no moisture at all ?

thanks
Arron

[robutacion]

cheers Rubatcion.
can you clarify
when you talk about rough green turning to a bowl shape, do you mean that it should be convex on one side and flat across the other, or convex on one side and concave on the other - in the sense of looking like a bowl but with very flat walls.

Also, what is a recommended timber stabiliser. I have seen blanks done with wax - is that the best choice. How is that wax usually applied.

I dont really understand how the blank will continue to dry when it is covered in wax, surely it will not loose no moisture at all ?

thanks
Arron

Hi Arron, this matter has been discussed a few times before, and I'm certain It will be discussed many other times also in the future. I could spend some time searching the links to those threads/posts but, I reckon it will be quicker to explain it again. Green turning / rough turning, you basically work the blank outside and inside, giving it the desired unfinished shape but the trick or rule is to leave about 1 inch thickness all around, some say 10% of its diameter, but I stick to no less than 1 inch. Is extremely important to leave an even timber thickness on the green piece in process, as the timber will react, stress, to compensate itself for the structural loss of balance.
Now, this rough turned bowl will need to be soaked with a good stabiliser, this will soften the tissues and fibres making them flexible, work as a lubrication on the grain layers and most importantly, allows the timber to dry in an even and controlled manner. The stabiliser I use is the Fungishield from Feast Watson, normally available at Mitre 10, Bunnings etc. Two soaking coats (generous with the brush) within 8 hours apart, will normally soak straight through, this sometimes can be achieve on the first coat but I always give it a second coat. Put it to dry in a nice dark, ventilated place and in within 2 to 3 months, its ready for finishing with any product you wish. Timber stabiliser does allow timber to breath, just slows the drying process to the stabiliser requirements and timber composition.

Hope this helps,
Cheers:2tsup:
RBTCO

[Arron]

thanks heaps.

Interesting point you raise about it being discussed many times before. I've read it many times before as well - but for some reason it never seems to make sense. The photo is a big breakthrough though. I take it these are green, rough turned blanks with walls of approximately 1 inch thick, right ?

I assume that at a later point, you will finish these off by turning them to the final dimension inside and outside. This raises one point - how do you rechuck them to re-turn the outside?

cheers
Arron

[Alastair]

Couple of rechucking options I have used:

When rough turning, make your dovetail chuck recess reasonably deep, and enough oversize to allow it to dry oval, but still allow the chuck jaws to fit in. Even though oval it will usually hold well enough. This allows you to prepare the 'hollowed " side to allow you to rechuck to return the outside. Several options for this:

I have the "old" Nova chuck, with the tommy bars. This is small enough that for any reasonable size bowl, it will give you enough clearance to reverse the bowl "over" it. With the dried bowl mounted on the (ovalled) chuck recess, as above, carefully turn a shallow dovetail recess in the bottom of the hollow. This works better with wider, more shallow bowls, where there is enough clearance. Then, with spindle locked, reverse the bowl over chuck, and use suitable sized allen key as a lever to expand the jaws into this recess. Return outside, and chuck recess, then reverse again and return inside.

Another option I have used, has been to leave a "column" in the bottom of the bowl, big enough to be gripped as a tenon, after truing up.

Or leave base thick enough to drill with a 7mm hole, and use woodscrew.

Drawback of both of these is that the greater thickness in the bottom can increase the likelihood of the rough turned bowl splitting while drying. Have also compromised, by turning an annular flat in the bottom of the bowl, and then glueing in a waste plug, which can then be held either in jaws, or drilled for woodscrew.

One which I no longer use, is to mount "between centres", using a suitable sized "scrap" mandrel in the chuck, and tailstock. Return outside, and finish, leaving tenon on base. reverse and rechuck to refinish inside, and then make jam chuck to reverse again, to clean up base and tenon.

An older method I used before I had a chuck: With the bowl chucked in base recess, true up the rim, so that it is flat and square. Make up a wooden faceplate larger than the rim, and true up. Using white pva, and copier paper, centralise the bowl on the faceplate, and glue in place using a "paper joint". Mount faceplate, and return outside , cutting into the faceplate. When finished, split the paper joint with knife of chisel, and rechuck to turn inside.

Hope some of these help

regards

[TTIT]

thanks heaps.

Interesting point you raise about it being discussed many times before. I've read it many times before as well - but for some reason it never seems to make sense. The photo is a big breakthrough though. I take it these are green, rough turned blanks with walls of approximately 1 inch thick, right ?

I assume that at a later point, you will finish these off by turning them to the final dimension inside and outside. This raises one point - how do you rechuck them to re-turn the outside?

cheers
ArronAlistair made some good suggestions regarding rechucking but I'll throw in one more. On mid-to-small sized bowls I mount them by the foot/recess and cut another recess in the hollow of the bowl to suit my Vicmarc extended jaws. Remounting the bowl using that recess with the extended jaws allows you to hold a fairly deep bowl and still get your chuck key in to tighten up - easy to do and gives a good clear shot at the outside.
As to drying roughed out bowls, I've never used any sealers or such like. The most I do is wrap some newspaper over the outside to slow it drying and let the inside catch up - works for almost every aussie timber I've got and most other timbers I've used. As for wall thickness, with the acacias and a lot of dense aussie timbers, you can drop the 10% of the diameter rule to about 5% as they hardly move at all and just need a tidy up once dry.
Just my 2 bobs worth!

[robutacion]

Hi Arron & everyone!

Thanks Alastair and TTIT for your assistance and opinions on this matter. These, Arron, are common practise among wood-turners, with many more other designs that can do the job. Obviously, everybody has their own preference based on various factors but, about 75% of wood-turners, end-up making their own tool/jig/gadget to tackle the situation. From totally genuine ideas to mixed, odd, strange, useless, to brilliant, you will find your preference also, not forgetting the already made (brand names) tools/gadgets/jigs, specially made to assist with the requirements, there is, if you can afford them...!:doh:
With this in mind, I have also made my own "tool" to address your question, which you can easily see at; http://timberssoul.webs.com/flatplatebowlholder.htm to void unnecessary copy & past.
Now remember, they "all" work, some better than others, depending on the object's size, shape and weight but with the number of options already mentioned to you, I'm sure you will find one that you will try first!:D

Yes, the pic is of bowls that have been rough turned, stabilised (Fungishield) and let to dry. Unfortunately, not the best pic example of how rough turned bowls should look like, as the majority don't show the thickness left, and the ones you can see the neck/ throat/opening, I got a little to excited when cutting/shaping the neck, cutting a lot more than I should, risking to lose the piece because of it. I was lucky this time, as the timber didn't move much but, I will recommend/suggest you to leave about 1" or so all around.

I actually have some better examples in the shed, of how rough turned bowls/etc. should look like so, I will take a couple of new pics and add them here, I promise...!:)

Ok, I'm back with some pics...

Cheers:2tsup:
RBTCO

[Rum Pig]

Hi all
I'm Trying a new way of drying blanks (new to me anyway) it is a method I was told to be good and stable.

You put your blank in the freezer wrapped in a plastic bag for 24hr and then remove the bag and place it in the fridge for 10 days and it should be dry I have tried it on some pen blanks and they all turned out good but I have 2 large bowl blanks and should be able to turn one this weekend will post how it goes.

[Arron]

Lots of good information here, thanks guys.

First time I've seen your website too (RBTCO). Brilliant.

Arron

[Sawdust Maker]

I just returned an english oak bowl that I left dry for about a year
it ended up oval - I'm sorry I didn't take a photo of it so all could see

thanks for the tips TTIT and Alastair and robutacion

robutacion
a comment on your website if I may, beside that of it's looking good and coming together well. The blue lettering below timbers soul in the heading is very hard to read, just thought I'd let you know

[robutacion]

Thanks Arron and Sawdust Maker.
I will try to correct that colour problem if I can, thanks!.

Rum Pig, I'm not sure if I'm surprised or sceptical, never the less, if that procedure works, that would be the quickest and easiest way to ever dry timber. I will be looking forward of some more info from you, and from your tests, as I would be grateful if anyone could explain to me what does actually happen (process)...!

Cheers:2tsup:
RBTCO

[woodturner2]

Hi. Will a bowl blank dry faster if it is slabbed? Put another way, will the blank on the left dry faster then the one on the right (assuming both have their ends sealed in due course)?

Also, is one more likely to split then the other ?

cheers
Arron

Hi Arron, if you rough turn them into bowl blanks and then bury them face down in a pile of sawdustand leave them for a couple of months and then they shouldnt split or crack.

cheers, Lloyd

[Tony Morton]

Hi I Have tried this method with the freezing and then refidgerator but I turned the piece to shape and wet sanded 1 week in freezer in bag then 1 weeks in fridge no bag. It was a liquid amber blank cut that same week so realy green didnt crack bur the 340 mm bowl ended up 340 mm x300 oval turning with standard chuck.

Cheers Tony

[tea lady]

Hi all
I'm Trying a new way of drying blanks (new to me anyway) it is a method I was told to be good and stable.

You put your blank in the freezer wrapped in a plastic bag for 24hr and then remove the bag and place it in the fridge for 10 days and it should be dry I have tried it on some pen blanks and they all turned out good but I have 2 large bowl blanks and should be able to turn one this weekend will post how it goes.My book restorer friend used this once when another friend's office got flooded. Apparently if your books get wet you put 'em in the freezer and you can just shake the ice out of them. Ice is ostencably "dry" and squeezes out of the pours in the paper. I reckon it should work on wood too if its not too big. :shrug: (Soon we'll take over the whole kitchen. :D ) (and not for food either.:rolleyes: )

[Evan Pavlidis]

Hi Arron, if you rough turn them into bowl blanks and then bury them face down in a pile of sawdustand leave them for a couple of months and then they shouldnt split or crack.

cheers, Lloyd

I second that; after rough turning green/part green blanks, I collect all the chaff, place the bowl in a cardboard box and completely cover with chaff.
Record the weight and date before hand and every month weigh the blank and record the date. Keep doing this until there is no loss of weight as this indicates the rough out is ready to turn.
I've tried the freeze dry method with tassie myrtle and it doesn't work for me; had too many cracks and became expensive to continue experimemting. It could have been a one off cranky blank, but after using the above method the results were more satisfactory although took longer, which is more acceptable than a cracked blank.
I also smear paste wax on the rim, inside and outside walls 1 inch down from the rim liberally to slow down the drying process as these are the areas most prone to crack split first.

Enjoy the adventure,
Evan :)