The title says it all I think... I've been eyeballing the very rough wood pattern I started years ago (reason I got into casting) and was thinking the part I want could be better done in foam. However, the outside perimeter of the pattern has a consistent profile that would be difficult to play around with if I was using say a router. So I'm wondering if I can bend a profile into wire and experiment in that fashion. Anyone does this before..? All the hot wire cutters I've seen cut straight lines only. Thanks in advance
Bent hot-wire foam cutting is possible; I'm sure you can come up with some kind of jig to make your cuts more precise than this handheld overpriced freehand hot wire tool would give: Jeff
http://hotwirefoamcutterinfo.com/_NiChromeData.html I was just looking at this site. I'm glad I could find it again. Kanthal and NiCr are the 2 heating coil wires and this site tells about the differences in them. They are much easier to get now with all the vaping going on. It says you can shape 20 gauge wire to cut contours. I would only be concerned about the shape changing when the current is put to it. It could be ok as long as you don't over heat. 100 foot coils of wire is available on e-bay for about $7 in all different gauges.
Yes. You just need to use thicker resistance wire that can hold its shape, typically 11-16 gage. However, this gauge wire will have a different power supply requirement to achieve the optimum cutting temperature. Not a big deal but it usually doesn't line up very well with your thin wire cutting power supply. The ends of the formed wire are screwed to an insulating board and regular conductors from there to the power supply. The wire needs to be in the vicinity of 600F so the board either needs to take that or use insulating spacers. You can freehand but I usually mount the formed wire and use a fence to hand guide the foam or sometimes rotate the foam on a pin if the profile is to be applied to circular shape. You can also pattern cut. Just mount the foam on a thin piece of Masonite or ply with two sided tape or coarse drywall screws and have the base of your profile wire glide on the edge of the pattern board. I just let the hot wire glide on the pattern board on my thine wire table set up. If you don't dwell, it wont burn wood or wood based board like MDF. The site Jammer posted has useful information. Also have a look around here. http://jacobs-online.biz/wire-xformer_selection.htm Best, Kelly
Well that's excellent news... I think...lol. Now I have no reason not to explore lost foam casting and making a hot wire cutter.... I meant to include this in my first post but this is the kind of profile I was aiming for...:
J, What are the LxW dimensions of that profile? Like most cutting, hot wire cutting is about feed and speed, except the speed part is heat of the wire instead of cutter tip speed. Too slow, the foam burns or glazes. To fast and the cutting wire deflects. When the wire gets thicker you'll be vaporizing more foam per inch of cut and there's typical more drag and effort required for the wire to travel through the foam. That Jacob's site I posted is convenient because it has some rules of thumb, practical approaches to power sources, and they sell small lengths of wire at fairly reasonable prices so you can experiment, If you have a Variac, they're vey useful as you only need AC but you may need to throw 10-15 amps at some of the thicker wires so transformers can get a little spendier........best to regulate down to safe voltages. Best, Kelly
For sake of discussion lets say 2" vertical x 2.5" horizontal... I don't think the real dimensions deviate much from that, if at all. I've started surfing amazon for wire. Figure if I'm going to buy wire, and it's cheap anyway, I may as well buy the stuff to make a little furnace with. Kanthal seems to be the product of choice in the furnace application so I figure I'll go with that product.
I think that size profile will cut fine with a formed wire. I was worried it would be less than an 1" square or much larger. You'll still need to experiment a little with wire gauge but I'd think 14ga-16ga would be about right. IMO, Kanthal is probably no better or worse than the others for hot wire cutting because it's only at 600F or so. A bigger factor is the resistance and how it suits you for power supply. Also, if you look at the bottom of the page there's a chart that shows the free air temp of various wire and gage for a given current...which is useful to know. I use 26ga NiCr on my hot wire table and a dimmer switch ahead of step down (to <=12vac) transformer for power supply. http://jacobs-online.biz/nichrome_wire.htm Best, Kelly
