Uke Side Bender Progress.

fahrner · Apr 17, 2010

The pictures tell all. The base completed, the smoke test. My initial run was with the bender plate open. My hope was that it would get hot enough to start the bend at the waste with full contact of the wood. With 300 watts of power the plate reached 65.8 degrees C after 25 minutes. Closed up, the results for the bari were improved to 81.9 degrees C after 25 minutes. Still not a good cup of tea. The tenor's performance was not much better. It finally reached 85.9 degrees C after 30 minutes.
Even though it did bend a short piece of Doug Fur, my conclusion is that I need more power. Think I can get 200 watt lamps in the same size bulb so can increase to 400 watts. The heating blankets for 80-90 bucks at Lima and LMI are 525 watts so that will be my next step up. Pretty sure I need to see some steam so need to reach 100 degrees C or so.

Darrel · Apr 17, 2010

My first bender was light bulb heated and I did with mine a little different than yours. I used directional bulbs, I think they were spot light bulbs of some type, so that they directed the heat up. I also lined the inside of my forms with tin-foil in an effort to keep from burning the sides. My lower stainless slat was tacked down to the form (thinking about this now, I was probably bending my waists without heat and just setting them with the heat once pulled down to fully contact the form). And finally I elevated the bulbs to be closer to the top of the bender. I would only need about 2-3 minutes before I'd generate steam by spritzing water directly on the bender. I never measured the actual temperatures I was achieving but if I didn't modulate the power to bulbs during the bending I would cook the wood.

I now use a heat blanket I bought from MSC supply (they have 3" wide ones that I think are easier to use with narrower uke sides, they won't work for a wider guitar side though).

Good luck with it.
-darrel

fahrner · Apr 17, 2010

The rest of the pics.

SweetWaterBlue · Apr 17, 2010

Bummer. Good suggestions from Darrel. You might also try lining the sides and bottom with insulation that has the aluminum foil on the side (let the aluminum face the bulbs). That will cut down on the amount of heat lost through the sides from conduction, as well as reflect radiated heat back. Shorter sides would also get you closer to the bulbs. The heat has to go somewhere, so do your best to make it go to the top - easy for me to say lol.

fahrner · Apr 17, 2010

Darrel said:
My first bender was light bulb heated and I did with mine a little different than yours. I used directional bulbs, I think they were spot light bulbs of some type, so that they directed the heat up. I also lined the inside of my forms with tin-foil in an effort to keep from burning the sides. My lower stainless slat was tacked down to the form (thinking about this now, I was probably bending my waists without heat and just setting them with the heat once pulled down to fully contact the form). And finally I elevated the bulbs to be closer to the top of the bender. I would only need about 2-3 minutes before I'd generate steam by spritzing water directly on the bender. I never measured the actual temperatures I was achieving but if I didn't modulate the power to bulbs during the bending I would cook the wood.

I now use a heat blanket I bought from MSC supply (they have 3" wide ones that I think are easier to use with narrower uke sides, they won't work for a wider guitar side though).

Good luck with it.
-darrel

Good input Darrel. Thank you. Good stuff. Thanks also for the lead on MSC. They've got a boat load of heating blankets.

lefty dan · Apr 17, 2010

May I suggest using clear bulbs and lower the jig as close to the bulbs as you can within reasion. I use two clear bulbs and in twenty min. I cant even touch the top. I will say it does not make the water drops dance but it sure gets hot. I dont know what deg. but clear bulbs are a must in my opinion.
Dan

fahrner · Apr 19, 2010

Just to finish this up; got clear bulbs and found some light bulb extension sockets that in effect raised the lamps about 1.5".
To cut to the chase, with one 200 watt and one 300 watt bulb, it reaches 107.8 deg. C in 15 minutes. The temp increase slows down to about 6 degs. every five minutes thereafter, which is good.
It actually fizzed when spritzed at 10 minutes.
Bent lots of scrap pieces including a slice of curly maple that was .125" thick. Was pleased with that.
Couldn't find the insulation I was looking for but as suggested, anything to improve the efficiency or decrease the volume would help.
In use, as it is now, my practice will be to pre-heat the waste of the wood at the lower bout of the bender otherwise the waste does not get heated until it is bent.
For now, it works. Think before I put any more into this I would go with a heating blanket.

Matt Clara · May 27, 2010

Darrel said:
I now use a heat blanket I bought from MSC supply (they have 3" wide ones that I think are easier to use with narrower uke sides, they won't work for a wider guitar side though).

Good luck with it.
-darrel

Like this? http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=4627382&PMT4NO=0

Uke Side Bender Progress.

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