Queensland Maple bending problems

[Daniel_M]

Hi all,
I was after some advice regarding qld maple. Our LMI bender arrived yesterday, after we unpacked it, shook our heads at the price again, we got into some qld sides. But they are cracking. As we are at a loss, I thought that would seek out your collective wisdom. We have it set at 350 for the waist and 300 for the bouts. We lightly sprayed with water before bending. All as per instructions. Any advice is greatly appreciated. Thanks in advance,
Daniel.

[kiwigeo]

You're using bending slats etc? What's the stack sequence with bending slats, wood, blanket etc?

[Daniel_M]

Hi Martin,
Sure am. Small bending slat for waist, large bending slat, large heat blanket,wood, small heat blanket for waist, large bending slat. There is two heat readers in there a well - just small wires. This is per the instructions. The procedure is let it get to 350 then quarter turn every 30 seconds. Which is not very much at all. Do you think soaking the wood would help? Would this be a sign that the wood was not perfectly quartered?

Thanks again,
Daniel.

[jeffhigh]

Perhaps runout in the wood rather than off quarter.
I have only bent Qld maple by hand on a bending iron but found it one of the easier woods to bend.

[Bob Connor]

How thick are the sides?

[Daniel_M]

Hey Bob,
I took them down to 2.5mm. There is a possibility that they may not have been dry enough - I need to get a new moisture meter.

Thanks,
Dan.

[Bob Connor]

I used to take sides down to .080-.085" (2-2.1mm) when I was building with single ply sides.

I reckon they're a little thick. Moisture in them shouldn't make them crack when bending. Quite the opposite really.

I now build with laminated sides with each (of two) laminates being .045" (1.2mm or thereabouts)

Regards

[Daniel_M]

Thanks again Bob. I am about to build a double side sheoak OM so that info is handy! Will try with those at 1.2mm.

[Pete Brown]

We have it set at 350 for the waist and 300 for the bouts.

Daniel, I can't speak authoritatively as I haven't built with Queensland maple, but I"d suggest that by allowing the wood to reach 350 before beginning the bend, the wood may well have dried out completely before the bends are completed, thus contributing to the cracking you've experienced. Common wisdom has it that bending should begin at the waist when the temperature is at around 240F. For the majority of wood species, the maximum recommended temperature is around 300F.

For guidance from someone far more experienced than I am, John Mayes outlines his side bending process and recommended temperatures part way down this page:
http://www.lint.org/TechNotes/Mayes/MayesNotes.html

Cheers
Pete

[xray]

hi daniel, i have bent stacks of maple and as a rule of thumb soaking the stuff doesn't hurt. I usually find that the maple i have is not very thirsty initially and dries out fast under a heat blanket. Bend the waist first and stop to let it cool down. Take it out of your bender and re wet to be sure it is not too dry. You dont have to soak it at this stage just enough to wet the surface.
hope this helps.

[kiwigeo]

I wrap my sides in al foil after spritzing them with a bit of water.....slows down the loss of water as steam.

[Daniel_M]

Thanks all for all the great help and suggestions.
I am trying again next weekend, but after all the advice it seems like we had the heat blankets too hot and this was drying out the timber. As per advice I will be re spraying half way and also making seal with the tinfoil better - I just had it folded over and not really sealed. Thanks again gents.

[graham mcdonald]

Sides should be around 2mm /.080" thick. There is no need for them to be any thicker. Spray with water, wrap in paper towel (one layer each side), spray again, wrap in aluminium foil, as sealed as possible and mark with something so you know which side/edge is which so you can maintain the bookmatching. Place the wrapped package between slats - aluminium, stainless or whatever - and bend. When the temp gets up towards 300F they should just go like cardboard and you can pull them into shape with little effort. Getting the foil as sealed as possible keeps the steam in and they should bend with no problems. Qld maple is pretty good bending timber.

cheers

graham

[Drommy]

Hi,Daneil.
In the past i've soaked maple in warm water before bending and this has worked fine adding a spray of water as i bend. good luck.

[Daniel_M]

thanks gents,

I am bending on the weekend again so will no doubt post of my success (finger's crossed!)


Daniel

[Bruce McC]

Hi Daniel
I have just finished bending mahogany sides in a "Fox" type bender. As a heat source I use 3 halogen bar lamps (2 x 200W + 1 x 150W)
and use two stainless steel slats approx 0.6 mm. I prepared my sides as described by Graham McD above and the sides bent easily with out any issues.
Hope it all goes well for you on the week end.