Unwanted Outcome Bending Sides

[Tod Gilding]

I bent these low grade Tas Blackwood Sides on the weekend useing LMI blanket and my home made Fox style bender Side was spritzed and wrapped in foil placed onto steel slat then blanket then top slat max temp 170 C all over in about 8min and this is the result. I Can't work out what went wrong !!!!!

Does anyone have any Idea's ?

[Kim]

Wow, looks a tad dry... try 150c, 170c maybe too hot I reckon. Also, a spitz, then kitchen paper, then seal in foil, then between 2 x .010 spring steel slats and the blanket on top is what I have used to good effect.

Cheers

Kim

[Tod Gilding]

Yeah Kim I tried 150 c For a Max 4minutes and the result was better but still with charring here is the result of that.

[Kim]

Could just be the angle but the material looks to be too thick and it has acute run-out. Try taking the side down to .090" max .085 is better or even >.080 if you have a tight bend at a cutaway. Also, did you try kitchen paper on the wood sandwiching the foil pack between 'two' slats?? With that sort of short grain that stuff will need all the support it can get. One more thing, how are you measuring temp?? How reliable is the thermometer?

Cheers

Kim

[Tod Gilding]

Hi Kim , The sides are 2mm, and yes you do have a good eye, there is runout, it was only a cheap A grade set that I thought would be best as this is only my second Build,I didn't want to use good quality wood at my level of Luthiery, but as it turns out I may have to use good wood in future.
The thermometer I am useing is an oven digital thermometer that is very good quality, I also wondered whether the Thermometer could have been inacurate,but I have used it for bending Silky Oak sides on my first build and they turned out OK See my Avatar Pic at the left here <----- . Also the time 4 min shouldn't be long enough for the temp to get too high any way.

I'm Starting to think that I just got a set that wasn't suitable.

[jeffhigh]

I am just gearing up to do heat blanket bends myself, so no personal experience, but from all the research I have done, it seems that those who bend succesfully, have the bend done quickly in like 2 1/2 minutes, before the wood has dried out
It looks like a combination of too hot, too slow and the bad runout.
For speed check out Mario Proulx in this vid
http://www.youtube.com/watch?v=sUJbB0pa ... Q&index=77

[rocket]

Wow that really is an unfortunate outcome, the timber does look rather scorched doesn't it.
Although i take a lot longer than a few minutes to bend sides they always come out quite damp and i only give them a bit of a spray with water, wrap in brown paper and foil and bend between stainless steel slats, wrapping them up does preserve the moisture. Hope you have better luck on the next try.
Cheers,,,
Rod.

[Dominic]

I use a little thermostat and timer on mine and it runs at about 80% whatever that means. But I don't like the idea of letting this thing go to full power, its way too hot. I set the timer for 10 mins and bend after about 5. Bent a very tight cutaway on figured blackwood with no problems and it doesn't get hot enough to burn. Just takes a little longer to heat the wood to the right temp for bending.
Dom

[Clancy]

Tod, I know how you feel.
This is how I spent my first (and only) day using an LMI Blanket and a homemade bender.

Firewood.jpg (51.92 KiB) Viewed 14805 times

Six meranti uke sides shot to shit Nothing I tried worked!
Made some more & bent them by hand on the iron.
Been too scared to re-visit the blanket since.

[Allen]

8 minutes??? Good God man....my shed would have been on fire by then.

My procedure. Sides are wet under the tap. Use my fingers to squeegee off all excess water. Wrap in Al-Foil. Slat goes down. Wood / Al-Foil sandwich then heat blanket, and finally last slat. Turn on heat. 2 minutes later bend side. 2 1/2 minute all done and turn off heat. Repeat heat sequence once cool to the touch.

Another option that I've not tried, but Chuck Moore who is a luthier in Hawaii advocates is to not wet the wood, but instead uses burlap. He wets this, wrings it out and then wraps the wood in it with the customary Al-Foil and slats. He bends an awful lot of very curly Koa and says this has worked a treat for him.

[rocket]

Allen,, Burlap?
Rod.

[Allen]

American for Heshan....I think that is what you guys call it. Growing up in Canada I know it as burlap as well.

[Tod Gilding]

Good God Allen Slat,heshan,foil,blanket, slat Could you jump over that

[Allen]

Don't know. The heshan would't add any more than a millimetre. And Chuck gets way more for his ukes than any of us could dream of. Check out his website for a bit of inspiration. If you have a look at his "Process Page" you can see his side bender in action with a set installed.

Moorebetta Ukes.

[Allen]

Chuck emailed me today to comment on this post. Seems I got a bit of it wrong. I apologise for any confusion as to Chucks process. Here is his mail.

G'day Allen,

I was reading the posts on ANZLF and noticed there was some question regarding my side bending process. Unfortunately I am unable to respond on the forum because I've not been able to log in using my most familiar combination of user names and passwords. (Who writes this stuff down?) So maybe you can pass this along.

I place my sides in a canvas envelope. It's not burlap, I don't see how that could work. Here it is called canvas, duck, or awning material. It's very heavy gauge cotton, like the stuff your jeans (or Levi's) are made of. The envelope is dipped in water until thoroughly wet and almost all of the water is wrung out. The dry side is placed in the envelope and two pieces of spring steel are placed on either side along with the heat blanket. (Spring steel is far superior to any other metal I've used.) Doing it this way I am able to control the exact amount of water I need to bend. I haven't burned or cracked a side in I don't know how many years.
There are a couple of other controversial tips I can share with you for bending especially stubborn stuff.

Hope this helps. Aloha, Chuck

[Tod Gilding]

Aloha, Chuck, Thanks for shareing that and thankyou Allen for passing on the Info.

Tod

Chuck I'm sure that one of the Mods could sort out your login probs, they are good with those techy things

[woodrat]

Thanks Chuck and Allen for passing that on, Thats a great Idea...

John

[Tod Gilding]

Just a Footnote, I recieved another set of sides from a different supplier ( thankyou Tim Spittle ) I bent these sides today exactly the same way I did the first and it went without a hitch,no burning charing or breaking, So if nothing else I have found that all sides are not created equal,even the same species of timber,can give completely different results in the bender.

[woodrat]

Good to see that you had success with the new set of sides Tod....

John