My first build of the New Year

After rather hectic Christmas and New Year holidays, during which time my sons and their families visited, things have quieted down and I'm excited to start my new project. I'm excited because it has been requested by one of my sons, who, after close examination of my ukuleles, asked if I would build him one. Who could refuse, even if he's not a player?
I decided that I would go for the traditional ukulele shape, rather than my customary pineapple designs. Another decision was to build a side bending jig, rather than use my bending iron. I'm not great at bending, which is why I prefer the pineapple shape, so I doubt that I'd have great success bending the traditional hour glass shape. Besides, I liked the challenge of building the jig. Or so I thought until:
Challenge #1: Obtaining incandescent 150w bulbs for heating was zero at my local hardware store, not surprising, though, since they are being phased out.
Challenge #2: I couldn't find any thin steel flashing at the same store. Would aluminum suffice? I feel that it wouldn't heat up sufficiently, but I'd like to hear some views on the subject.
Also, regarding the heat source, I know that halogens put out a lot of heat. I'd appreciate opinions on what type to use.
Regarding the actual bending jig design, I think I must have Googled every one ever made, so I'm OK on that! I've come up with a hodge podge conglomeration keeping the KISS principle in mind.
The ukulele itself will be a concert size, probably all mahogany, with all the trimmings, which I know my son will love. Now if I can just get the jig built!

Bob

For the steel check out McMaster-Carr. They have all kinds and thicknesses.
I use heat blankets so I can't help with the light bulbs but my local ACE store in town has all kinds of bulbs still

I too live in California where incandescents are being phased out. However, our low-life Dollar General Store still sells them. Shop a little more low rent and you shall find what you seek...
Aluminum is great at transmitting heat, but not great at holding it thus I think steel would be better. But something is better than nothing...
As far as halogen goes, I have no experience. I do have reservations because of potential fire hazards. I'm absolutely paranoid about fire, but I'm pretty sure people use them with a proper rheostat no problem. Don't know.

One question though: Why concert size? If you go to all that trouble, why not tenor sized. Sorry, but I've never understood the concert sized ukulele concept. My girlfriend has one and loves it, but to me it is neither fish nor foul and it neither swims nor flys.

Different strokes and all that, I guess, sequoia, not only do I prefer concert size ukes, but it was my son's choice after checking out my collection, which includes an Oscar Schmidt tenor. Out of curiosity, what do you understand about the soprano size concept?

Bob

I use a single halogen 500 watt sun flood /security light with the glass cover removed...I recomend a thermostat controll, co's it can get very hot...Link to the OP http://forum.ukuleleunderground.com...nder-Getting-worn-out&highlight=bender+refurb

I got perforated stainless from McMaster Carr (ala David Hurd) to make a sandwich for my sides. I use aluminum flashing. 100 watt bulbs seem to work for me. David Hurd uses solid steel to join the sides and gets his thermal mass out of that. I used electrical conduit packed with sand to save money.

Nelson

Thanks Timbuck and Yankulele, that's exactly the advice I need!

Bob

I haven't progressed very far on my bender, having been assigned to jury duty all week, but I've had time to contemplate on design alternatives. I'm keeping the design very basic, similar to the two shown in the pics below, which I found online. I can't make up my mind whether to use springs, as in the first pic, or adjustable threaded rod, as shown in the second one, to compress the sides as they come around the upper and lower bouts. The springs would seem easier to use, but because of the irregular shape of the sides, it seems to me that the tension would vary as the clamping rod is rotated downwards. On the other hand, turning the adjustable clamping knobs with equal tension on the threaded rod could be tricky. I do intend to use the overhead method of compressing the sides into the waist area with a single threaded rod and caul. Anyone care to advise me one way or another before I proceed? Thanks.

Bob

I've used both systems and discovered a basic design flaw in the human body - a 3rd hand is required.
However, with practice, both systems can work well. I tend to favour the threaded rod system as the springs have given me a few unwanted surprises
Miguel

I've encountered that lack of a third hand problem on more than one occasion! After trying a mock up, I've decided that the threaded rod method is easier to manipulate. Also, the system used by Timbuck and Kawika http://www.ukuleles.com/BuildingHowTo/sidebend.html have merit. Having only built the lower box containing the heating elements, I still have the opportunity to continue one way or the other. Thanks, Miguel.

Bob

Here is my bender in action. Just put the timer on it today so it won't burn the house down if I forget.



Nelson

Thanks, Nelson, for your contribution. It's interesting to see the variations on a theme regarding side benders. Hopefully, I'll soon be posting pics of my version when it's completed.

Bob

Hi. I have built a couple of the light-bulb type benders with 2x100 watt bulbs in the box. I used threaded rod but with wingnuts instead of bolts as this allows you to tighten it up by hand, somewhat alleviating the third hand problem.
Also I used a sheet of steel that came re-drilled with holes (pic) instead of solid as I figured this might allow more heat to get at the piece. I have a few different moulds that can be fitted to the bulb box for building different styles
Max

My side bender is finally built. It took some time to get everything right, but I'm quite pleased with the result. It sure ain't purty, but then, there's no prizes for looks! I used aluminum flashing for the top and the slat and also lined the inside walls with the same material. I used 150 w bulbs which I found at Home depot. I added an on/off switch, but I'll replace it with a dimmer switch before using the machine again.
I tested it out using a 1/16" sheet of basswood I bought at the craft store. I realize that it's a pretty soft wood, but all I wanted to do was familiarize myself with the process. It went fairly well, much easier than I had anticipated, although the temperature had to reach 300 degrees before the aluminum slats were hot enough to start the bending process. Perhaps this is normal, but I had read of temps of 200 degrees being sufficient. Once the wood was completely bent and clamped down I left it overnight to dry. The following morning when I unscrewed the clamps, I was disappointed to find that the wood started to return to it's original shape! It soon became clear that it was still very damp. Not having used perforated slats, there was no way for the moisture to escape. I then re clamped the wooden sheets without the aluminum top slat and turned the heat on again. By the time the temp reached around 280 degrees, the wood had dried so I turned the machine off and left it for about six hours. This time when I unclamped everything, I was pleased to see two perfectly formed sides!
It seems like I will have to replace the metal foil with the perforated type. Unfortunately, I'm on a tight budget and I haven't come across an economical source of the stuff. Does anyone bend their wood without the top metal slat? I personally don't see why this would not work, unless I'm missing something.
One way or another I'm pleased with my new tool. Next on the to do list is building an outside form to match!
Thanks for all your suggestions, all very helpful.

Bob

I bend my sides wrapped in foil and the heating blanket on top. When they're bent I lift the blanket and remove the foil from the top side so the wood can dry overnight. Not the best order in which to do things but it works. I use my bender less now that I've gotten better with the hot pipe.

Thanks, Sven, for your contribution! I will try this on my next experiment, although I don't use a blanket.

Bob