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Mark Allen

Bending African Walnut

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I have African walnut 2mm X 6mm strips for the hand rails on an Oc Cre models the San Marcos.  I need to bend the strips for a 90 degree bend.  I tried bending by soaking and then applying heat and using a plank bender, but it will not bend.  Can anyone advise me on how to bend the hardwood strip?

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Which way are you trying to bend the wood??  With the grain or laterally??  I have just bent some boxwood through 90 degrees laterally and it was very time consuming.  The only way I could do it was by soaking the wood for 24 hours and then applying heat with a heat gun as I bent it around a former that I had previously made.  I cannot tell you the amount of wood I wasted working this out so  feel your pain.  Soak for as long as you can so that the wood really absorbs the water and then apply heat as you form the wood.  It will steam as you do it - its very satisfying once you've done it though.

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African Walnut is one tough wood to bend without splintering.   The big thing is heat and lots of it.  The soaking is just the means to transfer the heat.  You might try putting on a pot of water to boil, insert the wood and then after boiling for a bit, depending on thickness, try bending.  It may take repeated times to do this.

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You can also try laminating thinner strips over a form. Shape a piece for wood to the curve you want (add a little extra curve to allow for spring back). Glue and clamp the 2 or 3 thinner strips together over the form. when dry they will retain the curve.

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Well, the topic starter never revealed in which plane he has issue  bending his rectangular profile 2 x 5 mm. If issue is bending along wider 5 mm plane side to side I was successful by using a steam iron at full power and stroking the strip in a radial motion on the wooden board.

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Posted (edited)
On 8/11/2019 at 5:53 AM, Y.T. said:

I believe you mean bending at sharp radius? I made a notch in bending template, soaked strips for 30 min and very slowly bent them with sharp end of plank bender. 

46763C23-A7FC-4FF1-980B-CFE87212A2F7.jpeg

 

 

I'm not sure if you are aware of it or not, but the Aeropiccola plank bender pictured above is missing the spring-loaded roller bracket that mounts in either of the two holes in the iron head as pictured below.. The purpose of the bracket is to slide the strip under the spring-loaded roller "stirrup" so it can be held while the plank is bent to the desired shape. The plank strip can be slid against the edge of the iron while the roller maintains pressure against the iron edge. The bracket is placed in either hole and swung into position along the edge of the iron according to the shape of the bend desired. The use of this "holder" and the "French curve" shape of the iron pretty much eliminates the need for separate shop-made shaping jigs like the one pictured, which is what makes the Aeropiccola plank bender so desirable. (They are no longer in production.) Obviously, if the strip-holding fixture is missing, the shop-made jigs are required, or the tool has to be held in a vise so that both ends of the planking strip can be held, one in each hand, and the strip bent over the iron head in the vise. With the holder, the iron can be held in one hand while the end of the strip can be held in the other and the bend worked to suit using the roller bracket.

 

  • post-6458-0-39943100-1393164101_thumb.jpg

 

 

  • th?id=OIP.guPWCdYheBK4pCmkAwNdxAAAAA&pid=Api&P=0&w=206&h=155
     
    The "French curve" shape of the iron and this holding device is head-and-shoulders above anything sold today for the purpose. I don't know why somebody hasn't started selling them again. I suppose there's some sort of patent on the design, although it's been around for close to fifty years that I know of and has to expire one of these days. Aeropiccola is out of business, I believe, but they do still have a website and facebook page for their fans.
Edited by Bob Cleek

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Posted (edited)

I have this spring loaded fixture but I dismantled it. I tried hard using it but never got any positive results.All this fixture does is holding end of wood strip. One still applies pressure to a strip with their hand. I hold strip down on flat wood board on curvature of bender for radius required. I t appears to be less cumbersome. I have a better control of a process. I normally do not use a curving template I pictured but for a sharp radius bend on hardwood it was required. 

Edited by Y.T.

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Posted (edited)
4 hours ago, Y.T. said:

I have this spring loaded fixture but I dismantled it. I tried hard using it but never got any positive results.All this fixture does is holding end of wood strip. One still applies pressure to a strip with their hand. I hold strip down on flat wood board on curvature of bender for radius required. I t appears to be less cumbersome. I have a better control of a process. I normally do not use a curving template I pictured but for a sharp radius bend on hardwood it was required. 

If it works best for you that way, by all means, do it that way. It's a challenge bending walnut in any event. Some woods are suitable for bending and others really aren't.

 

 When I use the spring-loaded strip holder, I progressively work the curve desired into the wood by repeated small bends along the curve desired with the holder holding the strip in various points on the curves on the iron. Sometimes the workpiece doesn't fit under the holder roller because the fixture was designed for the straight, narrow strips of "planking" commonly found in kits in the days before laser-cut kit planking and I'm using it to bend something differently shaped. As you do, I don't use the holder when I find it isn't helpful. 

Edited by Bob Cleek

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Thanks everyone for you advice.  To clarify, the wood strip is to be bent so it forms a 90 degree radius for the hand rail.  I have used a softer wood and bent it successfully, but it is a light coloured wood which I was planning to then paint a dark brown.   I had been toying with the idea of soaking the African walnut in very hot water and then trying to bend.  I must admit, I have not seen the Aeropiccola plank bender before.  I just have the one that resembles a pair of scissors; which finally broke the other day.  I will buy some extra strips when I get the chance and perform different techniques as suggest.  I tried to find a video on Youtube, but I couldn't find any on such a hard wood.

 

Thanks again for all your advice.  This is only my fourth ship and I am still learning heaps.

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Why not spill and build up from pieces?  Bending thru the thick dimension is fighting against the nature of the wood.

 

Dziadeczek,    I am betting that the wood in question is kit supplied.   African Walnut is probably relatively low cost and

can be advertised a something special by kit mfg.   Black Walnut ( Juglans nigra )  is in a class by itself. I would guess that

although a reasonable cost and available here, it is probably neither in OZ.   Queensland Walnut is native to OZ and may be

superior to the African species - if Mark can mill it.

All Walnuts share a problem for our purposes  - open pore and some have grain that scales poorly.

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As others have said, just layer and build.

 

BTW,  a low price method for bending with heat is a curling iron.  The come in assorted sizes but I've found I can pretty much get away with the 1".   

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Thanks for the replies again.  The African walnut was supplied in the kit.  I have been able to bend some ramin wood, supplied with the kit as the hull planks.  They fit the sweeping 90 degree bend well.  So, I'm tossing up whether to use ramin for all the hand rails and painting them mission brown.

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Mark,

Check out this thread:  

I wholeheartedly recommend this heat/water bending technique, especially the method presented by Mr. G. Kammerlander about 3/4 down that page - a piece of video in German, but the pics speak for themselves.  Long time ago there was an article on this very topic in the "Ships in Scale" magazine, where I discovered his technique, and it still works for me. I am quite convinced that you should be able to bend your piece of walnut 90 degs, as you want it.

 

Recently I managed (with some difficulty and patience, I must admit) to edge-bend a 2 mm thick piece of ebony (for some curved railing) with my electric plank bender (well..., converted soldering iron, but it WORKS just as well)! And we all know how difficult is to bend ebony!

 

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Thanks for that Dziadeczek, that video has given me an idea on how to use my homemade plank bender (soldering iron with two sockets on it to dissipate the heat) in a different way that just may do the job.  I will practice on some old hard wood piece I have and let you know how it goes a little later.

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I used the method in the video Dziadeczek directed me to yesterday and what a success!  I soaked the African walnut for 24 hours and used the bending technique in the video and I couldn't believe how easily it bent.  Thanks again for the post Dziadeczek.

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In video you were referring to, they used some electric heating iron This iron is almost nowhere available. So please confirm what kind of heating iron you used, so you were happy so much with results. 

Edited by Y.T.

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