Official Luthiers Forum!

I'm hoping to bend the sides of my first build within the next few days. I built a fox-style bender that uses three 150w clear bulbs as a heat source, but I'm just a bit nervous about using it. It seems like a process with relatively no room for error. I've done a good amount of reading and watched plenty of videos on youtube of people using fox benders, but most people seem to be using a heating blanket. I just want to know any tips, tricks, or procedures for using one with light bulbs. Also, if you could direct me to any videos or picture tutorials that might help, that would be great. Any help here is appreciated!

I used bulbs alone for the first 3 guitars but they were three 200 watters. I measured the surface temperature and didn't start bends until it reached 225*F. Take your time and learn to read what the wood wants to do. I'd recommend starting out with something easy to bend first like EIR or Walnut.

BTW...since purchasing the heating blanket and using both heat sources, bending has been a breeze.

Good luck!

_________________
JJ
Napa, CA
http://www.DonohueGuitars.com

I use light bulbs. They may be 200 watts, however. I'd have to check but I'm not at home. I've only bent 7 sets of sides so far but I haven't broken a set yet (knock on wood) though I've not bent any real "difficult" woods -- only EIR, cocobola, yellow heart, pau ferro though I did do a set of padauk.

I use two metal slats, wet and wrap the wood in aluminum foil (which most people don't use but its worked for me) and get the temp hot (approx 300+) and bend, taking my time.

No real tips or secrets that I know -- I focus on the waist bend first, get it most of the way there and then do the ends a little at a time until they're done. Works for me. Good luck.

Years ago, I taught a guitar-building class in my high school (Ah- ignorance is, and was, !).
We used a Fox light-bulb bender and it worked fine.
I can't recall the wattage of the bulbs, and we did let it warm up for a good while, so that water would 'dance' on the slats. Also, the sides were mahogany, bending to dreadnought shape, so not a huge challenge. Nothing broke and the kids all got their guitars built- after a fashion- eventually.
So, don't be too nervous!
Cheers
John

p.s. my bends have included dreds, OM's and parlors so don't be too nervous.

I use 3 -200 watt lamps and so far I've bent two sets of EIR and several practice sets of red oak without any problems.
I must say for safety sake, I have a mechanical timer on it and I hang a caution sign on the kitchen door so I'll remember what's cooking and not wander off.
Also I think the heat is uneven and confined mostly to the waist but that's expected I guess.
I plan to upgrade as soon as I can budget it in to a proper heating blanket and spring slats.
I use thin gage galvanized slats, they work even though I have to flatten them after every use.

Rene

I used to bend with 3 200 watt light bulbs also, it works fine, although I like the heat blanket better. Be sure to attach some Aluminum foil to the inside of your bend form as a reflector as you can char it with the light bulbs.
Close the unit up with out the sides in it and preheat for 10 minutes or so, open up the slats and slide your damp wood in and bend away. Not too fast, not too slow.

_________________
Jim Watts
http://jameswattsguitars.com

I also use a light bulb bender. I use 3 X 150w (& change the upper to 200w for cutaway side). Ram(s) contact damp, foil-wrapped sides. then advance about .100" per minute 'till bends are complete (I used 5/8" x 10tpi threaded rod for the rams, so 1 turn/min.) It takes a while (which is why I think it works)....about 40 min (55 for cutaway side).

_________________
Dave
Milton, ON

The best trick I can give is don't waist your money on light bulbs. They are so vastly inefficient compared to blankets. When using light bulbs you get no real heat on the wood until you start pulling the bend in. A blanket heats the wood much better and evenly which is really important.

That said I used bulbs for 2 years before switching to blankets. Use 3 200W clear. Set each up on independent 600W dimmers. For best results and far less risk you will need to control each bulb separately. Because the waist is the first bend and will end up close to the bulb when finished it will be the first bulb that you will reduce poser to. The upper bout is the second bulb to reduce power to as you finish the upper bout bend. Then the last is the lower bout. Once the bouts are bent you need to cook to set the bend you need to control the heat so that you do not scorch the waist and upper bout.

Back when I built my first bender with bulbs it cost close to $40 for ceramic fixtures, dimmers and bulbs. The first high figured set I bent on it I fried the waist on it. That cost me a new set of curly Koa. That cost me $150 way back when. When I bought my first blanket with controller it cost me $120, today $145 more or less. The Koa today would cost me $250 plus and I will never bend with bulbs again.

Now lets compare the cost of the two options: $40 for bulbs and a higher risk of bend failure or scorched wood with bulbs as your heat source or $146 and far less risk to the wood that cost way more than a blanket and controller. Easy decision for me to make.

Help me out here Jim. I use 3 200 watt bulbs, I do want to upgrade to blankets soon.
Last set of sides I bent were lace wood. I took close to 2 hours bending each side.
Can you realy bend too slow?

_________________
Say what you do, Do what you say.

OH yes you can bend to slow!! infact using bulbs if it took that long to bend then I suspect you have case hardend the wood. making it very brittel and easy to damage.

The most dificult wood ever bent on bulbs took me 15-17min. that same wood with blanket is a 6 min bend less cook off time

Thanks, I didn't think of case hardening.
I'll hang onto this one and learn to play "Handle me with care" on it.

_________________
Say what you do, Do what you say.

I will say that yes , light bulbs may work but they are difficult to control . The biggest reason that I can give you to not use them is SAFETY . I now know of 4 shops that have burnt to the ground because of them . I as a supplier will no longer sell them with light bulbs.
Please do not leave the bender un attended and keep a fire extinguisher handy. I would rather you argue with me than agree with another burned shop .

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I agree with John Hall- heating blanket is definitely the way to go, and it's an easy switch-over if you have the bender built already.
Put the blanket on the list for Santa.

Cheers
John

Where might one find a $145 blanket and controller? I have the bulb bender also, but cannot seem to find the blanket and controller for that great price.

http://www.bluescreekguitars.com/catalo ... 20a&page=2
If you have a timer on your machine you can use the timer to kill the controller when the timer goes off.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Blues Creek Guitars. See link at top of page

I am sorry the 36 x 6 with controler is now $165 when I bought my new on early this year it was $145 up like most thing it has gone up some still a good price and well worth it.

Thanks for the education.
I'll put it on the Christmas list.
I presume the controller maintains a constant Temperature?

_________________
Say what you do, Do what you say.

I still bend with bulb , but have a blanket also which i put on the outside of the bend, that way i have heat on both sides while bending and it works great.I use a router speed control for the heat controller with a timer as well.

Dave-
I think the controller regulates the energy going into the blanket- like a dimmer switch.
In practice, this will regulate the temperature to some extent.
However, the controllers I've seen/used are not thermostats (ie no measurement of blanket temperature), so the temp may not be constant. For example, the controller will not 'boost' the energy to the blanket when the wet wood hits the blanket and cools it down.

Cheers
John

check out this link and it will explain the blanket and it role in the bending operation
http://www.youtube.com/results?search_q ... ues+creek+

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

On my first build I started with some practice sides and a light bulb bender. I had a lot of springback.... tried another set - same thing. I tried two more and got some results on the fourth one but it seemed tempermental. I asked the same question you just asked and got this back for most of the replies....

I got a heating blanket and it works like a dream. It's so easy in comparison. If you really want to stay with a bulb bender I suggest you search the archives. There are some good discussions with specifics.

I too use a lightbulb fox-bender. Three, 200W bulbs. I also have a timer wired in so I don't have to worry about burning the shop down. I let it heat for about 10-15 minute, soak the wood during that time, and bend away. I've done 8 guitars this way, and am very pleased with the results.

_________________
Jake

~Make a joyful noise unto the Lord~

Of the 4 shops that burned all had timers . What the concerns is , the refractive heat can cause the plywood to become hot , as the wood gases out that is what is flammable , Yes the risk is slight but it is there . NEVER LEAVE THE MACHINE UNATTENDED . Also light bulbs will not give you repeatability but I agree , they will give acceptable results in most cases. Your tare fall out will be about 10 to 15% , so if you bend 10 sets expect 1 to crack , With a blanket you have about 2-3%.
The heating process with a blanket is controlled and you will be done bending in less than 5 minutes.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it