I can still remember watching my oldest Son using a sharp knife for carving pumpkins several years ago and realizing that a sharp knife was just not the best tool for the job, nor the safest for his age. I was twinging and worried watching him with that sharp knife in his hands. I think this project really started out more for my sake rather than for my kids! Even though today that same Son is much older and carries a pocket knife almost daily like his father. And I support knife rights organizations like AKTI.org and KnifeRights.org. I still think a saw is just a whole lot safer that a knife for a younger child to use carving a pumpkin. I think it gives better control of your big cuts than you get with a knife. We do use knives for the detail work when we carve our pumpkins, now that my kids are older... but really for most of the cuts everyone still heads straight to these saws.
For this project I used blades for some old hand saws I have. I just needed to make the blades for the saws a little shorter and a bit narrower so they would be more usable. The shorter blade keeps you from hitting the other side of the pumpkin and the narrow blade makes it easier to maneuver while cutting your design in the pumpkin. The saws blades shown in this instructable were made at different times over the past few year and have carved many pumpkins. All of the saws pictured have changeable blades and I do use a couple of the saw handles with the normal length blades throughout the rest year.
In my collection of things I had extra blades for two of the saw handles, so I was able to use my older beat up blades and still keep the good blades I have for cutting wood. The saw pictured with the narrowest blade was already broken to about the right length it is now. Using my bench grinder I cleaned up the end of the blade to remove a sharp point left behind from when it broke. I felt the blade was already narrow enough. That was the first Pumpkin Saw I made. To shorten the full length blades I used my pneumatic angle grinder with a cut off wheel to cut the tip off of the blades. When I cut my blades I did not measure and mark I just kind of eye balled it and made them between 5 and 6 inches long. I then used my bench grinder to narrow the blades by removing materiel from the back of the blades. Be sure to keep a bucket of water handy to dip the blade in as you grind to cool the blade down, the blade will get hot quick and discolor otherwise.
Please be safe and remember to supervise your children when they carve their pumpkins.
Thanks and Enjoy