Kenny R

MinnFlyer, how did you get that picture of my bow?

MinnFlyer

My Feedback: (4)

I have my ways Kenny[>:]

Goggles

My Feedback: (4)

DMyer is exactly right.
I use to cut wings using the airfoil shape but I discovered using this top/bottom template to be much more accurate, and easier to make.
Using minn's graphic (great graphic BTW) you can see how to make them.

dmclearn

What do you use for a power supply? I'd like to try it!

DMyer

My Feedback: (2)

I have been using a 24V 2.5 AMP transformer from radio shack plus a rheostat to adjust voltage/temperature for years. This cost about $15. There are better power sources, which usually cost more, but this does an AOK job for my needs. If this ever wears out... I may break down and get a better power source.

Ron Owens

See attached diagram. The variable speed drill turns a threaded rod onto which a wing nut turns. The wing nut is stopped from turning by a piece of alumunium angle screwed to the bench (not shown for clarity) the wing nut is drilled and a line is attached between it and your HWC. By adjustin the speed of the drill, you will get constant speed cutting and hence a smooth finish.
Then make a similar unit for the other side, except this time, you don't need a drill, just a crank handle which you will have to experiment to get the correct speed. Use the drill side for the root cut
The threaded rod is held in place by 2 aluminuim brackets, nothing fancy, just 2 pieces of angle with a hole drilled into it. The rod turn slowly so friction isn't an issue.
Hope this is clear.

zero244

My Feedback: (1)

Cutting cores is an acquired science. Its not that hard......I looked at the make your own designs and adapted my own. Its very hard to cut cores manually. Setting up an inexpensive weight pulley system will get you great results. I cut only tapered sailplane cores......I just cut a pair of 68 inch cores that came out smooth as a baby's........???.
It’s very satisfying to cut your own cores........plus you can make virtually any wing platform you can dream up.
Try one of the pulley weight systems and with persistence you can get a perfect cut.
I use stainless still fishing line........and cut at the coolest temp I can. When I cut a core there is hardly any smoke or fumes. I use a 25 volt transformer connected to a variac. Just off the top of my head I think I have the variac set at only 80 volts.....which reduces the transformer to maybe 16 volts for the cut.
I know most people cut at a much higher temp.....but with my system I get true smooth perfect cuts.
My bow which is just wood and quarter inch spring rod......can cut up to 68 inch cores. Cutting at the lower temp......does cause some bow sag.....but if you look at my cores......the end result is satisfactory.

Unless you have someone who has done cutting before to help.....it will take some practice and experimentation to master.

Just to let you know.......it can be done by anyone. Just do your research and keep trying you will master it.

RAMFlyer

My Feedback: (65)

[sm=thumbup.gif]I agree Zero244. I think the cooler the wire is that can still cut gives you the smoothest and most accurate core. The zone of melting of the foam next to the wire is reduced, which means you are more accurately following the template.

I don't think you can cut a core manually that slowly and keep even tension on the wire the entire time. An automatic cutter is the way to go.

dmclearn

I know what a variac is , and I know what a rheostat is, but what do they call them at Radio Shack? They have no ID what I'm talking about, therefore I can't but one.

icerinkdad

Still having problems cutting foam? Give me a call I am in Omaha. Robert (Bob) Furr. I have cut over a hundred wings for CL combat models.

icerinkdad

Good To Go Models has produced a two hour video on cutting your own foam wings. It contains information on everything from finding foam locally all the way to coring wings and making the special templates to do that. Email me at [email protected] if you are interested. I have copies as the video was made in my shop.
Bob Furr

planebuilder66

My Feedback: (8)

The transformer is called a step down transformer, you can buy them at any supply house too, look for the higers VA rating(voltxamp) The new ones have a resetable breaker on the secondary side. The better ones are called a Multitap step down transformer. Multi-tap refers to the primary side(input) you can use 120,208,240 or 460 volt depending on which internal winding you choose. The beauty is you can just use the different input wires to very the out-put amps, 120 wire is hot, 208 is medium-hot, 240 is medium, and 460 is cold wire temp.
I just spent way too much time covering transformers in HVAC class and could go deeper in helping you figure out what the ratings are but this is the basics.
The VA rating is easy to figure out the amps, divide the VA rating by the secondary voltage and you'll get your amps.
A transformer that you need to produce 2.5 amps will have a VA Rating of 60 at 120volts input
Same transformer on 120 volts using the 208 volt wire input would produce 1.44 amps
on the 240 input wire is 1.25 amps using 120 volts
on the 460 input wire, .65 amps using 120 volts