The 10 most common errors in foam core cutting are.

  1. Too much heat on wire.
  2. Not enough heat on wire.
  3. Using the wrong type of wire. NEVER USE NICROME WIRE.
  4. Not enough tension on wire.
  5. Too much tension on wire.
  6. Electrical short of the wire support arms on the cutting bow,
  7. Wrong template material.
  8. Moisture in the foam. (stored outside in rain)
  9. Never use a little wheel to support the bow during a cut.
  10. Wrong angle of the pull wire to the template.

If you avoid these problems your foam parts will be great. Your rejects will be low if at all. And you will enjoy the whole thing more.

To make the hot wire bow:

Now if you have assembled every thing on the bow. (wheel collars, electrical wire, screw eye, and electrical connector) and you have your power supply, you only have to hang the bow above your table. It should hang so that it is pushed to the rear of the table to start the cut. When it is at rest the cutting wire should rest near the center of the part to be cut. to set the cutting temperature. Put a piece of foam on the wire and slowly increase until it cuts the foam. You are now ready to cut cores.

I would recommend several. I have a 10 , 15 , 24 ,36 , 50 and a 72 inch bows. I also have a vertical bow. If you are interested email me and I will tell you how to add this to your cutting table. Don't be afraid to ask me any questions.I have been doing this for a long time, and what might seem easy to me could be confusing to someone else.

Study these drawings, go out and buy all of the hardware on the parts list. If you can not locate all of the parts, call or Email me and I will get what you can not find, and send it to you. If you do not want to hunt these parts down I can put together a kit of some of the parts or for those who want I can purchase the whole thing and ship it to you. I do not know what this would cost. but if you are interested I can check it out and let you know. It would be based on the item price, my time and shipping and handling costs.

This system is designed to work hands off , but make sure that it is starting ok and after it starts moving make sure that there are no obstacles in the path. The ceramic insulators allow you to use your hands to help it get started when needed.

I would start with the table top. Assemble the melimine boards. I had to buy two and join them. Put the 3/4 " aluminum channel on the front then mark it carefully and drill the holes for the pulleys. assemble the drop arm and secure on the front of the table. Layout and mark the top as in the drawing. this helps in positioning the wing core blank.

A good place to find parts for the power supply is in a surplus electronic store. Be sure to insulate the electrical connections for safety.

When you are blanking out the wing cores place the piece of foam on the table. Let the amount that you are cutting hang over the table. Make certain that it is level. Place a weight on it to keep it from moving.Then use the hot wire bow for a drop cut.

Be ready to catch the blank when it gets cutoff.

When you start to cut the wing you will place the blank with the red line spacers on top of the table. Then with the bow hanging on the bungy cord, place the cutting wire on the leading edge. Then let it travel across the blank until it gets to the trailing edge. It should be in line with the trailing edge. If not then adjust the anchor point (B) until it does. Good luck. Do lots of testing to learn before taking on a big project .

The video that I have is almost two hours long. It is in two parts. The first part shows the wing cutter and the second part is about vacuum bagging wings. I sell it for $25.00 plus $2.00 for shipping. You can learn a lot from it. You can see the hardware and how it works.

Parts List -- Table

  1. 6 ea plastic screen door rollers
  2. 5 ea 1/4"x 2" standoff threaded for 6-32 screw
  3. 5 ea 6-32 x 1/2" socket head screws
  4. 2 ea aluminum window locks (drilled and taped for item 5 below)
  5. 2 ea threaded knobs (for item 4 above)
  6. 1 ea drop arm 1x1x3/4" ID channel aluminum (approx. 70" long)
  7. 1 roll of pull wire by Berkley 30ft nylon coated black D45BL
  8. 1 ea 2"x1 1 /2" dia. standoff with l/4" hole
  9. 1 ea 1/4x28x4" bolt
  10. 2 ea 1/4" roller bearing (for pivot point)
  11. l ea front edge 1x1x3/4"ID channel aluminum x length of table
  12. 1 ea table top 40"x74"x3/4" melamine with white plastic surface. sold as shelf material,

Parts list - Hot wire bow

  1. 12' electrical extension cord
  2. 5/16"x 36" landing gear rod (music wire)
  3. 4 ea 5/16"ID. wheel collar
  4. 1O' x 1/8" bungy cord
  5. 1"x3"x the length of bow desired, pine or spruce
  6. 4 ea screw in eye hook
  7. 1 roll stainless steel wire, Berkley catalog noSS8BR .020 dia,
  8. 2 ea ceramic insulators
  9. 2 ea torpedo shaped fishing weight. (drill out lengthways, place over 5/16" rods to give added weight to follow template with a fast drop. When not needed slide up to top of rod) 6 to lO oz.

Parts list - power supply

  1. 1 ea variable AC transformer (variac) 10 amp rated
  2. 1 ea transformer step down (1lOvac to 30vac 10 amp rated)
  3. 1 ea AC power cord

Address for Berkley fishing supplies:

 Outdoor Technologies Group
 One Berkley Drive
 Sprit Lake,lA 51360

Figures: (Full page each, save and print out for easy viewing)

Cutting Table Drop Arm Bow Detail Template Holder Detail

Template Holder layout Power Supply Table Layout

My address is:

Delmar Brengman 6054 Emlyn Ct.
San Jose, CA 95123 

My phone number is (408) 629-1325

My Email is