Fox Bender adventures

[Bob Howell]

Here are my first tries with junk wood sides.

It will take a lot of faith to move on to my carefully crafted Weissenborn ribs.

Looking for more junk wood to try.

I brushed on water and wrapped in al foil. Baked for 45 min. Then clamped down.

Using walnut and 3, 200 watt bulbs.

Saw a picture long ago of a towel placed over the bender to contain heat.

I will try that and more time. Like an hour.

[Barry Daniels]

Your process does not sound right. Baking for 45 minutes certainly dried the wood to the state of a crispy potato chip. If you want to make this process work you would be wise to go ahead and take the plunge and get an electric heat blanket. There is a reason why 98% of all Fox benders have been upgraded to the blanket. (I just made up that percentage but I am probably not far off)

[Bob Howell]

There was no scorching at all.
Wood damp when I opened it 12 hrs later.

I think the heat is not building up properly.

[Barry Daniels]

Yes, it sounds like it is not getting hot. How thick is your wood? Do you have a close-up photo of the bender?

[Brian Evans]

Most fox benders that use lights use three 200 watt lights. With the length of your sides, maybe four? It shouldn't take more than a few minutes to get the sides to where they will loosen up and start to bend, surely not as long as 45 minutes, more like two or three, maybe five?

[Charlie Schultz]

Probably a really dumb question, but you are using incandescent (not CFL) light bulbs?

[Rodger Knox]

I use two 150 and one 100 watt bulb, and half an hour is all it takes. The catch is you have to find an alternate method to heat the waist area because the light bulbs don't heat much unless there is direct contact. You can place the waist at the top of the lower bout until it heats up enough to bend, or prebend the waist on a hot pipe, or use another heat source like a clothes iron or heating blanket.

[Brian Evans]

What does "direct contact" mean? You physically have the light bulb touching the wood?

[Rodger Knox]

Not the bulbs themselves, the metal slat that covers them. The waist doesn't make contact with the slat until it's bent to shape.

[Waddy Thomson]

If you wrapped in foil as you said, you are trapping the water in the wood. As I understand it, when using foil, it should be in strips and open on the sides to let the moisture out of the wood. I use foil and wet kraft paper, but do not wet the wood directly.

[Bob Howell]

I have fashioned a 2" pipe bender with a propane torch and spent an hour last night bending scraps. Scorching is a big issue now but making progress. This works great... till it breaks.

I plan to bend the waist and rough out the rest to get it into the bender and then smooth it out.

I'm making a Weissenborn so, 41' long ribs. Sapele is all I have that long. I have re-sawed quarter sawed walnut but it has come apart in my thickness planner as it approached 1/8". New knives are probably in order.

Slats are galvanized(bottom) and al(top) flashing.

[Chuck Tweedy]

Woah! Thickness planer ... 1/8" !!! did i read that right?
No no no no no!

You cannot machine plane down to that thickness!
You need to use a thickness sander, or tune up that bench plane.

[Chuck Tweedy]

By the way - sapele is a bitch to bend - certainly relative to walnut

[Bob Howell]

By the way - sapele is a bitch to bend - certainly relative to walnut

I am finding that out. The cross grain just breaks. I used scraps of sapele to develop my skill on the 2" bending pipe. It burns but still doesn't bend.

[Bryan Bear]

What chuck said about the planer!

I once had some mystery wood that seemed similar to sapele. It just did not want to bend. I couldn't get the temp and timing right on the bender and kept breaking the sides (luckily, I had a lot of this mystery wood). I finally got it to bend with the hot pipe. If I remember correctly, I ended up using more water than I thought I would need and got the temp dialed in where I needed it (i don't remember if it was hotter or cooler than I expected) so it would bend without scorching. Once I got it down, I was able to predictably bend it every time. My point is, keep experimenting with scrap as long as your supply holds out. Once you figure out what it wants, you'll be in good shape.

[Bob Howell]

Today I bent one side on the pipe. A lot of scorching but it is 1/8" so I hope to sand it out.

I then set aside it match and went to a second set that was planed down a bit to .09-.10 and proceeded to break both.

So now I am back to the other half which I will go after tomorrow.

This sapele is tough. I read somewhere it needed little water and found water made little difference on the first one.

I have several pairs of walnut sides that I (almost)successfully got down to 1/8" on the planer. My neighbor with the thickness sander is due to return in a day or so from a 3 week trip. By then I will have destroyed my supply of stock and perhaps I can dress the walnut and start on it. The walnut does have a few tare outs.
Also a crack which I repaired with super glue, which is on the top edge and will probably go out when the bindings are cut out.

[Barry Daniels]

You need to get the wood thinner to keep it from breaking. A thickness of from .060" to .070" is standard and should bend much more easily.

[Bob Howell]

That is thin!! Like a 1/16"
The plans show .10"

[Chuck Tweedy]

0.100" is too thick for almost any wood.
0.080" is good for "easy" woods - EIR, walnut, etc.
0.070" is what I try for with tough bending woods - mahogany, sapele, maple, cedro, etc.

[Bryan Bear]

I agree that 0.125" (1/8) is way too thick. When you first start bending, there is a temptation to error on the thick side to give you more room to sand. You have to remember the cube rule for stiffness and thickness. A small increase or decrease in thickness has a great effect on the stiffness. The range Barry recommends above is roughly half the thickness you are trying to bend, that is a huge decrease i. The stiffness and make for much easier bending. Depending on the wood, I stay a little thicker than he. I just bent some cherry somewhere between 0.085 and 0.09. That works well for easy to bend woods like walnut. A tougher to bend wood would get thinned more. I have never gone as thin as Barry but even small decreases make it much easier. I use a thickness sander. Towards the end of the process, I can actually feel the wood loosen up with each new pass.