Hey guys, For project O² I need to bend a 12cm wide strip of 5mm polycarb in two places. The bends are 90 degrees and a radius of approx 3cm. What kind of heat will I need to achieve this effectively? Is there an alternative to a heatgun? Thanks in advance
You can bend polycarb without heat, but at the radius and width you're talking about I'm not sure if it's possible. I've done a lot of heat-gunning lately, but I'd like to see what alternatives there are as well. I would probably make a mold out of wood to bend it around, and clamp the plastic to it. Heat it up evenly - you might want to give the underside a little heat too, since it's so thick. Depending on how much plastic is on the other side of the bend, you can use something flat and press it against the mold, or just slowly push the sheet inwards at a spot that wont burn your fingers.
I was going to make a jig from a block of wood so thats in the works - was just wondering because at the size I need a cigarette lighter is too small to get the job done! Maybe bake it in the oven for a short while then quickly mold and clamp it? Don't want warping/melting though Thanks for your comments
I have an alternative to heatgun but it's probably not worth the trouble for only a couple bends, unless you have use for it on future projects. I use a line bender also called a strip heater, or to be technical, a straight nichrome wire resistance heater. There are many sources online to find info to purchase commercial and hobby units as well as make your own from spare parts around the house. Here is an example of the process in action, It's relatively fast and the lines are very straight, I've done up to 1/4" thick materials with no blistering, cracking or warping. I built my own, capable of bending up to 2ft wide, as shown in the pic. Made from a nichrome wire pulled from a hair dryer, a few nuts and bolts, an mdf base, aluminum u-channel and an automotive battery charger. I just straightened the wire (it was basically a very long spring), doubled it over a few times and twisted it tightly, i use a spring to hold tension so it doesn't sag and arc to the aluminum channel when heated. Keep in mind for anyone considering this that there is a risk of a serious burn/shock hazard when working with an exposed heat element and uninsulated electrical contacts.
OOh - that one scares me! Hmm ideas are helpful though. Maybe heat a metal bar in a fire/oven and then hold the poly over it. Might not hold temp long enough to soften the poly though :S Wait a sec - Toaster! Or the shaft of a soldering iron... Investigation time
Lighter - bad idea, it will scorch the plastic and create no-where near enough heat. Heating metal bar - won't get enough heat onto the acrylic Putting in the oven then bending over mould - acrylic will lose it's 'squareness' and it will become incredibly soft and very very easy to dent and mark - put a clamp on it and it will leave a mark. Strip heater - great option for bending acrylic and other plastics, however they are expensive to buy, dangerous to make and you want a 3cm bend radius which just isn't possible with a strip heater - they give a very sharp bend. In my opinion, your best bet is a hot air gun and a solid MDF mould. Depending on the size you may need a couple of hot air guns. You then get your plastic, clamp the flat surface to the mould and start heating the acrylic along the bend. When it gets hot enough you should just have to bend the acrylic down (gloves are advisable, it is hot ) and hold it against the mould for a few minutes until it cools down.
You can do a radius bend with a strip heater. You need a bar that's the radius of the bend and a jig for the 90 surfaces. The trick is you have to mark the area that's to be bent and move the plastic over the element to heat the whole bend area. -Having said that, I've never bent polycarb. You should shoot an E-mail to Tap plastics about it.
