PDA

View Full Version : Bending with clay



dreamer9
10-01-2011, 10:12 AM
I have this idea, what do you guys think? Put clay in ziplocks and heat it in the microwave until it just begins to steam, then let it cool to 180-185 degrees. Then place the bags on damp towels on my side wood that I want to bend and let it sit for five minutes, then start my bending.

There's a company that makes a heat pad for sore muscles with clay inside plastic inside a thin fabric, microwavable. I just thought it might work well, easy to hit the desired 180 degrees target, and be really cheap and easy to work with. I've already spent a wad on wood and tools to get into uke making, so when this occurred to me I thought 'sure thing'.

Allen
10-01-2011, 10:35 AM
I'm presuming your talking Fahrenheit and not Celsius as you're in the USA. You might want to rethink those temperatures as I'd be stunned if you managed to do bend anything other than pasta a 180 F.

And just a heads up. Building instruments is not cheap. You're most inexpensive method for bending is most likely to build your own heating iron from a propane torch and alloy pipe. Do a search and you'll find lots of examples.

Sven
10-01-2011, 10:37 AM
Hot pipe.

But try any method you like. If you're determined you should do it to get it out of your system. And then you could try a

hot pipe.

dreamer9
10-01-2011, 11:23 AM
I'm presuming your talking Fahrenheit and not Celsius as you're in the USA. You might want to rethink those temperatures as I'd be stunned if you managed to do bend anything other than pasta a 180 F.

And just a heads up. Building instruments is not cheap. You're most inexpensive method for bending is most likely to build your own heating iron from a propane torch and alloy pipe. Do a search and you'll find lots of examples.

All the bending devices I've seen involve a thin sheet of metal housing a 60 watt light bulb and 180 degrees as the target temp. I think wood burns at high temperatures involving propane torches. I'll have to do a little more research.

maclay
10-01-2011, 11:47 AM
I think clay is a bad idea.
Use a hot pipe, or build a bender and spend a little more money on a heating blanket. Doing things correctly saves you time and money in the long run.

ProfChris
10-01-2011, 11:54 AM
Then you need to read more about a:

HOT PIPE

Sven has made lots using one. I've made a few, though I still get the occasional scorch mark to sand out. I got the idea from reading about the many pros, who use a:

HOT PIPE

[But, this needs practice and you will scorch some wood at first. A Fox style bender (lightbulbs) can still scorch wood.

Though, at 180F, all you'll be able to bend is some plastics, and few of those are tough enough to make a uke (think yoghurt pot).]

Seriously, a metal pipe (piece of dead auto exhaust) plus a propane torch is the easiest way to get started. Practice on 1/16 plywood. Smoke is nature's way of telling you the pipe is too hot.

Pete Howlett
10-01-2011, 11:59 AM
Ever tried a 4 sided wheel? I'm sure you have... :)

Hot pipe is how most of us learned to use a bending machine if you get my drift. There are no short cuts to acquiring skills.

Liam Ryan
10-01-2011, 01:34 PM
Why, Why, Why, Why, Why? Why? Just get a length of pipe and a propane torch. This is an absolutely tried and true method. Stop over thinking things. Temperature should be hot enough that when you flick some water on the pipe it sizzle and dances, ie doesn't just instantly vapourize. You don't need a thermometer.

Rick Turner
10-01-2011, 02:30 PM
We need a special section for all those who insist on inventing new and ever more obscure ways to do tasks that have been well worked out over the years by hundreds of skilled luthiers.

How about a hot clay pipe? Oh, that's a new thing for smoking crack...

fahrner
10-01-2011, 02:33 PM
Dreamer9, think you need to do a bit more research and re-think your idea.
Ziplock bags melt at 220 f to 265 f, depending if they are the thin or thick (low density or high density ) polyethylene.
While 180-190 f might be high enough to brew green tea (not black tea), it's not near hot enough to produce steam to successfully bend a piece of wood. There's more to bending wood than simply producing a little bit of steam.
As an aside, the fox style benders I built required a plate temp. near 300 deg. f. to almost reliably bend maple of mahogany. The thing was so in-efficient that it required 350 watts to reach temperature. And without a heating blanket, they don't work very well.
What finally worked for me was a simple pipe in a vise heated with a torch. Have finally graduated to an Ibex type bending iron.
If you do the research, think you'll find that wood burns from 390 deg to 550 deg. f.
Point is; Dont go melting plastic bags in your micro-wave. Also, the above numbers are approximate; there are plenty of other variables.

xtoph
10-01-2011, 02:44 PM
We need a special section for all those who insist on inventing new and ever more obscure ways to do tasks that have been well worked out over the years by hundreds of skilled luthiers.

I agree! We could call it: "The Woodpile"

Moore Bettah Ukuleles
10-01-2011, 03:18 PM
Bending sides can seem intimidating at first. Once you've overcome your initial fear, (and burnt a few sides) you'll understand the voodoo of it and it's really not that hard. When bending sides, get the dog out of the shop, turn off the cell phone and tell you wife you wish not to be disturbed. You need to give it your full attention.
When bending with the blankets (actually I use two), I like to start bending the waist at about 250 degrees, after I start seeing some steam. Within a couple of minutes the temp climbs up to about 325 or so, which is where I like it to cut the heat. Steam is good, smoke is bad! You want to be bending between the two. This is easily regulated when using electric blankets.
Honestly I almost never use the hot pipe any more for side bending. If your molds and forms are made correctly, you won't need to. But I'm alsway using the pipe for bending bindings for head stocks, fret boards, etc for obvious reasons.
When bending on a pipe you need to use your tactile senses; eyes, ears and smell. If you are paying attention you'll learn to know how far the wood will allow you to push it. The easiest way to determine the heat of a hot pipe is with a spray bottle, spritzing water on the pipe. If the water boils and sizzles lazily on the surface of the pipe you're probably too cold. If tiny droplets "pop" of the pipe wildly, your'e too hot. It's right for bending when the water droplets dance merrily on the surface. (You kinda have to be there to know what I'm talking about!) For stubborn bending on a pipe I've found that a water soaked rag placed on top of the pipe will provide enough steam and carry the extra heat you need. watch it, it'll burn. You've got to keep it wetted down.
Naturally, all safety and fire precautions are taken. The degree of focus you give the task is your responsibility.

Michael Smith
10-01-2011, 04:07 PM
I am almost completely for innovation and attempted innovation in all things, my brother saved thousands and thousands of lives by thinking outside the box and building a unique medical machine now in standard use, but in this case I have to go with the crowd. Heat delivered by hot pipe or other heated metal source, heating blanket or bender with built in heat by light bulb is the way to go. You need to get much hotter than 180 F.

dave g
10-02-2011, 03:28 AM
I don't think much of the clay in bags thing, but how about ceramic cauls for a fox-style bender? Seems like you could get really even heat distribution...

Tudorp
10-02-2011, 04:25 AM
I'm all for going against the grain and trying new things, but that just sounds too complicated and trouble. I found the old school way of hot pipe (built for pennies actually), and/or a $30 silicon heat blanket works great after you get the feel of the woods your bending..

Rick Turner
10-02-2011, 07:24 PM
Ceramic cauls?

Too much thinking about it with too little information.

Go ahead and try it. Spend the many hours on it. Spend the dough.

When I see Bob Taylor using ceramic cauls, I'll believe in it.

Besides which, have you checked the refractive index of ceramics vs. aluminum? If you want even heat distribution in a solid, aluminum or copper are the way to go.

Do you know what they made the space shuttle heat protective tiles out of? Ceramics...

Let's get back to what works here... Throwing "innovative" ideas out on the Internet without having tried them is a cheap trick. I want to know what people have done that works, not what they're thinking about that they want other people to try first. Less speculation, more real experience, please.

Besides which, what's the big freakin' deal about bending sides? Why do all the newbies want NOT to do what clearly works just great? Sorry, I just do not understand the avoidance issues here.

Michael N.
10-03-2011, 01:07 AM
Here's one that does work:


http://i56.photobucket.com/albums/g193/mignal/sidebend.jpg


Big deal you say. Plenty of folk do that. Of course you would be correct in that assumption, except that I use the foil in conjunction with a hand bender. It makes certain woods easier to bend, probably because the foil contains the natural moisture in the wood.
Unfortunately on certain woods (Maple) it works a bit too well. The wood becomes too pliable and has a tendency to straighten out too readily. Works great on Rosewood though.
Oh and the foil gets HOT.

Rick Turner
10-03-2011, 05:06 AM
Yes, Michael, that's what I'm talking about...what's been tried and what works. That's a good one. You've got the foil helping to spread the heat and also hold in the moisture. Perfect.

Note that the foil is aluminum...or aluminium for those who know where the name came from!

fahrner
10-03-2011, 08:14 AM
Here's one that does work:

Big deal you say. Plenty of folk do that. Of course you would be correct in that assumption, except that I use the foil in conjunction with a hand bender. It makes certain woods easier to bend, probably because the foil contains the natural moisture in the wood.
Unfortunately on certain woods (Maple) it works a bit too well. The wood becomes too pliable and has a tendency to straighten out too readily. Works great on Rosewood though.
Oh and the foil gets HOT.

Good one Michael. Thanks for that.