stem laminations breaking

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anthony karakas
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Location: st louis Mo

stem laminations breaking

Post by anthony karakas » Sat Oct 15, 2011 3:28 pm

Greetings everybody;

I'm steaming my stem laminations, pine for the inside stems and cherry for the outside; unfortunately, the cherry laminations keep breaking when I try to bend them around the stem molds. I've been steaming them for half an hour each time.

Am i doing something wrong?

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Glen Smith
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Re: stem laminations breaking

Post by Glen Smith » Sat Oct 15, 2011 4:10 pm

First of all, I find that the strips bend more easily if they were cut so they have face grain on their wide surfaces. Second, steaming should be for 1 hour per inch of thickness. If you have laminations that are 1/4" thick, you steam for 15 minutes, 20 max. Third, you only have seconds to bend the laminations so work quickly. One good tip is to use an extra strip on the outer surface of the stem laminations. This strip will take most of the bending stress.

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Patricks Dad
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Re: stem laminations breaking

Post by Patricks Dad » Sat Oct 15, 2011 4:52 pm

One more tip to add to Glen's list.... Soak the strips in water overnight before steaming. Alternatively, pour boiling water over them or soak them in hot water before steaming.
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anthony karakas
Posts: 39
Joined: Fri Apr 29, 2011 2:37 pm
Location: st louis Mo

Re: stem laminations breaking

Post by anthony karakas » Sat Oct 15, 2011 5:06 pm

Thanks guys, i will try all of those suggestions :applause

wb9tpg
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Re: stem laminations breaking

Post by wb9tpg » Sat Oct 15, 2011 6:27 pm

I cut my strips thinner (1/8") and didn't steam them at all. It was still difficult and I had to use a sacrificial strip on the outside.

sedges
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old trick

Post by sedges » Sat Oct 15, 2011 7:54 pm

I have used a strip of galvanized sheet metal on the outside of the bend to keep the outer strip from breaking. Make sure you smooth and round the edges of the metal so they don't cut you up when moving fast to clamp.

finrod
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Re: stem laminations breaking

Post by finrod » Sun Oct 16, 2011 4:37 am

a longer steaming time helps, i had the same problem over and over, steaming them for 45 min or 1h will help alot!

succes! :smile
"what's the point in talking about freedom, if you don't have the guts to build your own boat and sail the seven seas"

fonz
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Re: stem laminations breaking

Post by fonz » Sun Oct 16, 2011 6:30 am

you have been given some great suggestions from others but I have one other. In the past when I have attempted to bend very dry hard wood I steam it twice. I steam it at least an hour then bend it on the form half way and release it after a minute. Then return it to the steamer for another half hour and do your final bend. This allows the cells and fibers of the wood to be slightly stressed and the cells will absorb more moisture on the second steam as the fibers and cells have stretched . It takes a bit longer but less broken wood.

wb9tpg
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Re: stem laminations breaking

Post by wb9tpg » Sun Oct 16, 2011 9:46 am

One tip I got from a famous woodworking instructor was to only steam bend air dried lumber and not to do kiln dried. Something to do with the lignin in the wood changing in the kiln drying process.

anthony karakas
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Joined: Fri Apr 29, 2011 2:37 pm
Location: st louis Mo

Re: stem laminations breaking

Post by anthony karakas » Sun Oct 16, 2011 12:40 pm

Hi everybody,

I ended up putting the lams inside some wet towels and soaking them overnite. I also used an extra sacrificial lam on the outside. I then steamed them this morning for 20 minutes and they bent like wet noodles around the forms!

Thanks for all the other insightful comments :dancing

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