Hardwood Furniture

[silentC]

I have a question for anyone who has experience making furniture from Australian hardwoods. The ones I'm using are Blackbutt and Bluegum.

I'm making a bathroom vanity. The cabinet is frame and panel and made from the blackbutt. The top will be bluegum. I've seen some finely crafted benchtops made from hardwood turn into horribly twisted messes after a couple of years, especially in wet areas. I'm reconciled to the fact that the bluegum is probably going to move, but what I want to know is how to minimise it?

The sections I have are 40mm by 250mm. They are milled from old hardwood bearers, so it's pretty well seasoned by now. Would it be best to make the top by laminating the full-sized sections side by side, or would it be more stable if I ripped it down and laminated it rotated 90 degrees?

Anyone done this? Any opinions?

[TOMARTOM]

I have little experience with australian hardwoods, limited to tas myrtle and jarrah which seem to be reasonably stable in service, although where there has been either sap or splits in the wood I would use a good quality epoxy and mix with a bit of graphite powder to resemble sap, and use it for gap filler, and minimising any movement thereafter.

regards

tony

[DaveInOz]

I've no experiance so feel free to ignore this but ...

to me it would be an idea to sit the pieces in the bathroom for a few weeks before joining them. Let them acclimatise to the high humidity in the bathroom and do their initial big movement before they are joined.
i would also join the boards with alternate grain direction, that is end grain pointing down, then end grain pointing up to try to minimise the effect of movement.
Then use those joins that allow for table top movement.

Remember this could all be crap as I'm only guessing.

[silentC]

Tony,

Good tip, thanks. The blue gum looks pretty free of gum veins but there are some shakes that worry me a bit.

Dave,

It sounds like a good idea to me. Only trouble is the bathroom isn't in use at the moment, but I suppose I could stick it in the other one for a week or two.


Then use those joins that allow for table top movement

Are you talking about breadboard ends? I thought of doing that. It's a bit tricky because it's a corner cabinet, so the top isn't rectangular. I guess it would still work though.

[DaveInOz]

Originally posted by silentC
Are you talking about breadboard ends?

I don't think so I think it was more to do with skrewing in to the top via a slot in the case rather than a hole, but my memory really is bad.

[Rocker]

Darren,

I think your alternative proposal in your original post is the way to go. Since you have a jointer, it would not be difficult, and you could make the top a bit thinner than 40 mm, which would probably look better. If you do take this path, I suggest you use urea formaldehyde glue rather than PVA, since PVA is prone to creep and form a ridge along the join lines.

Rocker

[silentC]

Rocker,

Thanks for the confirmation on that. It seems to me that's the way to do it. The ones that I have seen fail have consisted of only 2 or 3 boards. In one case, the benchtop lifted the end of the cabinet clear off the floor!

I wonder if I should also use splines in the joins....

I'll have to find a source for urea formaldehyde. I don't think the local hardware has it. I supose I'll have to order it from Carbatec or somewhere, or else wait until I'm passing through Sydney at the end of the month.

[Wood Borer]

Silent C,

Have you considered using sliding dovetails? Underneath the bench you can have several beams (at right angles to the planks on top) but dovetailed into the top.

See attached photo where I made a sliding dovetail for the top of this box. All dovetails were done by hand except the sliding dovetail which I used a router.

The Hoop Pine was 32 mm thick.

- Wood Borer

[silentC]

OK, that's a nice idea. Presumably you laminated the top as normal and then fitted the rails afterwards? I have a slight problem in that there has to be a hole cut for a basin, but that can be worked around.

Good one :)

[Wood Borer]

The top was just glued edge to edge with a couple of biscuits.

I have been told if you taper the sliding dovetails, gluing isn't necessary especially if you use tapers coming in from opposite sides but that is getting fancy.

The advantage of doing it this way is that you can make the top not as thick but many times stronger because of the 90 degree sliding dovetails.

Make sure you don't glue the sliding dovetails to allow the top to move.

- Wood Borer

[Rocker]

Darren,

I have found Timbecon's UF glue to be more satisfactory than Carbatec's. The Timbecon brand has a liquid hardener, whereas the Carbatec brand has a powder hardener which also contains a filler powder, which tends to make the glue too viscous and granular. I suggest you order from Timbecon by phone, rather than online, since they are sometimes out of stock, and their website does not warn you when that is the case. They may have improved their website by now, but that was the case some months ago in my experience. It might pay to remind Timbecon to pack the glue in a box, not just stick it in an air-bag as they did for me once - a very sticky bag was delivered to my door.

Another advantage of UF glue over PVA is that it allows more working time, but you will still need to work fast, preferably using a rubber roller to apply the glue. I would use biscuits to help in alignment, if you have a biscuit joiner, rather than splines. Alternatively, you could just use a couple of dowels per join to help with alignment. The joints would be plenty strong enough without dowels or biscuits, if you use UF glue.

I think if you laminate the top, it would not be necessary to use any cleats to keep it flat.

Rocker

[Baz]

Darren, I believe there is someone in Pambula who make hardwood furniture, I have no idea who or where, a mate of mine bought a bedroom suite off him out of red gum. If you can suss him out he may be able to help you.
Cheers
Barry

[silentC]

Rocker,

Thanks for the tip. I'll give them a call tomorrow. Called the local hardware and they have a Bostik product which "does the same thing". I'll take that with a grain of salt. I had to spell "Urea". I think he gave up when I got to "Formaldehyde". Tried to ring Bostik customer service to find out what it might be but they were surprisingly busy for a Friday afternoon (all in the pub by 4:00 no doubt).

Barry,

Thank you for the tip as well. I'm sure I can find out who it is - it's only a small place. Although I'm pretty sure he's not in town, so it's probably someone out in the hills. Might need to wait until the Landcruiser comes back from the mechanic.

Cheers all.

BTW I have a bet with my Brother in Law. He thinks that within 5 years my hardwood bathroom vanity will be a twisted mess on the floor. Mind you he's bitter and twisted because his first job in town was making skirting and architrave out of old hardwood flooring and it's turned him against hardwood for life.

[silentC]

Rocker,

The glue turned up today. There's no info on how to use it though. How much of the hardener do you add to yours?

[jacko]

You might like to check out the following web site. These guys know what they are on about and can be very helpful.
http://www.avsyntec.com.au Look at their FAQ's. Also refer to the attachment.

[Rocker]

Darren,

I had the same problem. When I called Timbecon, they suggested, without much conviction, that I mix them in the same ratio as the hardener volume and the glue volume. From memory, I think the ratio was 1:8. This worked fine for me. It is amazing that they still seem to think it acceptable to send out a product without any instructions on usage. They made out that it was an oversight when I called them, but it seems as though they don' t have any instructions.

Rocker

[silentC]

I thought of working it out that way too but the bottle the hardener comes in makes it looks suspiciously as though it's a product in it's own right and I wasn't sure. Anyway, if it worked for you, I guess it'll work for me.

Their glue products have an air of 'backyard factory' to them. I've bought some of their yellow glue as well. I don't mind what they look like as long as they work but a data sheet would have been reassuring.

[Rocker]

Darren,

Your only problem now is what to do with the other 750 mL of urea formaldehyde glue, once you have glued up your vanity top. Might I suggest that, since UF glue is perfect for bent laminations, you make one of these? Its relaxing properties would be perfect to soothe away the ravening cravings that Mrs Silent is prone to when she sees another $300 driver in the Pro's shop.

Rocker

[silentC]

what to do with the other 750 mL of urea formaldehyde glue

No problems there, Rocker. The bathroom vanity is a trial run for the kitchen and I'll have plenty of benchtops to laminate! Thanks for the suggestion though ;)