acrylic bender?

[Carla Lange]

Can anyone tell me where I can purchase an acrylic bender?
I tried a search on the internet, but really didn't have much luck.
Thanks!

Carla

[Bob Tate]

Sure, look here.

http://www.delviesplastics.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=DP&Category_Code=Strip_heaters

[Joe Pelonio]

This place has a store in the same business park as me, so I let them do my bending, but they do sell the strip.

http://www.tapplastics.com/shop/product.php?pid=169

[Dave Fifield]

Carla,

Depending on the nature of the object you are making, how many you have to make and how accurate/repeatable it needs to be, you may not need to spend a whole lot on specialized heating/bending equipment.

I have had good luck bending acrylic using just a blowtorch and a rounded-off straight edge. Heat up the acrylic along the area you need to bend (the faster you get it (the joint area) up to temp, the better) until the acrylic just begins to become pliable, remove the heat as you bend the piece over the straight edge to the angle you want. Vary the roundover-ness of the straight edge to suit the curve of the bend you want to make. Make sure the straight edge is clean and smooth. Once away from the heat, the acrylic will cool and solidify in a few seconds. Pre-drilled stress relief holes are necessary for sharp angles/corners sometimes.

Dave F.

[Rodne Gold]

Dave , using a heat gun or blow torch on acrylic is bad news , it stresses the acrylic in a major way and any solvents used to clean it or indeed even nearbye will stress crack it , worst of all is the fact that stress cracks can only appear some time after.
A nichrome wire bender is ideal for shap localised bends and a strip heater is ideal for longer more gently radiused bends.
Search for line bender , strip heater etc and you will get many plans for building one at real cheap prices. If you have a laser , a strip/wire bender is a must , the kind of products you can mnake with a little glue and one of these will astound you and make you big bucks. Bending is childs play , a few attempts and your's on your way. KEY to bending is the correct temp , localised heating and heating throughout the thickness of the acrylic.

[Carla Lange]

Thank you all for your suggestions. I think the smaller unit would be too slow for me. I don't think I'll try the blow torch, that's a scary thought with my abilities. I'll check further online and see what I can come up. Thank you again.

Carla

[Dave Fifield]

Hi Rodne,

I respectfully beg to differ. Of course, I agree that if you just go straight at the surface of the acrylic with a big mapp gas blowtorch (one designed for paint stripping and the like) with too much heat, you will indeed set up thermal stress fractures. I'm not advocating this method.

I use a small butane torch, not a big one, I forgot to mention that in my previous posting. I keep the flame very low and heat the acrylic just in the joint area fast. I play the flame over the joint area (both sides of the acrylic) evenly until the acrylic becomes pliable (i.e. the acrylic is heated all the way through). I continue to play heat on the joint area as I start to make the bend and remove it as soon as it'd obvious it doesn't need any more heat (i.e. use just enough heat to get the job done). I really can't see how this is any different to adding heat to the joint area with a nichrome wire heating element - with my method, I too have good control over the temperature of the acrylic all the way through the joint area.

I have never seen any cracking or crazing using my method, ever, and I have pieces that I did years ago that still look like new. I have used acrylic cement on and near my bends too. Too much acrylic cement on any joint (regardless of whether the material was heat bent or not) will result in crazing, of course (I learnt that the hard way many years ago on my first few projects with the stuff ;) ).

Here's a piece I just did for show and tell. It's difficult to photograph clear acrylic. I think I have captured it OK using manual focus. My torch is in the picture too (you see it there? hiding behind the acrylic.... :D ). The piece is just under 1/8" thick and has a completely crystal clear 90 deg bend in it (there are a couple of specks of acrylic swarf that hung around if you look closely, but there's no cracking). Took me about a minute to heat the bend area and a few seconds to make the bend.

http://www.fifield.name/AcrylicBend_s.jpg

I think this clearly (pun intended) makes the point that you really don't have to buy expensive machines to do jobs like this, just like many of the hints and tips do for woodworking methods/jigs that you find elsewhere on the SMC forums.

YMMV, of course.

Cheers,
Dave F.

[Bob Cole]

Sorry to throw salt in an old wound, but like to bring this topic up again.

I purchased a small strip heater (model 03-160) from Delvies to bend name plates and not getting the results that I want.

The acrylic isn't warming up as quickly as I expected and my bends are not as uniform as I think they should. I know this is probably user error, so went looking for more information and found this thread.

Rodne mentions a strip/wire bender is a must. I went searching some more and found the below site that discusses filament and wire benders.

http://www.ashcombe.surrey.sch.uk/curriculum/dt/videos/bendingVid/bending.htm

It shows a couple of models that I have not come across in searching for plastic benders. Anyone know of where someone can find these more commercial grade plastic benders?

[Pete Wood]

Here in England, every school workshop has a line bender. So every child over the age of 11 can bend acrylic with ease.

I always turn on the line bender at least 10 minutes before a class is due in, to allow the element to warm up fully.

I teach the kids to draw a line (using a felt tip pen, so it can be cleaned off later) on the acrylic - at the place where they want the acrylic to bend.

About the only problems I ever encounter, and our line benders are 10+ years old and used daily are, that heating up anything thicker than 3mm you need to turn the acrylic over and heat up the other side. I tell the kids to count to 100, while trying to bend the acrylic. It soon goes like butter, and you are ready to lift the acrylic off the line bender.

We use a very simple MDF jig (just a block clamped to a work bench) to get a nice bend. Or we use a clean steel ruler, placed on the felt tip line, if the kids want a really tight turn - so they can bend the acrylic back on itself by 180 degrees (when they make a photoframe etc).

It's fun.

We get our equipment from CR Clarke & Co, in the UK http://www.crclarke.co.uk/

[Mike Null]

I believe you can get the benders at Johnson Plastics.

[David Epperson]

I've worked acrylic and making a good and attractive bend takes a bit of practice. :D Which is why I've come to prefer polycarbonate (Tuffak to be precise). On stock 1/8" or thinner no heating is required for bends up to about 100° (or 80° degrees included angle).
But I have no idea how Polycarb would react to a laser.

[Bob Cole]

Johnson plastics only has the strip heaters along with Delvies and Tap Plastics.

I will probably just have to create a forming device. The problem I am having is I only have 3-5 seconds of time to bend once I remove from the heat so whatever I do needs to be fast.

The book for the Delvies bender states to let it heat up for 10-15 minutes prior to using. I found it worked a lot better after it was on for an hour. This is a new bender so maybe it will work better after its been used a few times.

I did a couple more and got a little better. I am only bending 1/16 (~1.6mm) acrylic and not sure if this device will really work for thicknesses up to 3/8 (9.5mm) as stated in the book. I guess if you left the acrylic there for a couple hours it would heat up enough along with flipping.

Guess with anything, it will just take practice and patience.

Pete,

I looked at that site and the only device I can find is Triform 180. Is this the device you use in your classes?

[Bruce Boone]

It's very easy to make your own bender for acrylic. Just use a straight heating element, maybe 10 or 12" long, and used in ovens and such. They are available from places like McMaster Carr. Hook up a light dimmer to it, and place a curved metal plate below it to reflect the heat upward. The base can be made from something like 3/4" plywood. There is a gap in the middle, maybe around 1" wide where the heating element and reflector go. The heating element stays somewhere around 3/8" below the plastic. You can control the heat very well with the dimmer switch. Just heat once on either side, and it's set to bend. If you do the reflector right to reflect the heat to a nice line, you get very crisp bends. It works great.

[Bob Cole]

Maybe that is part of the problem with the bender I purchased. The area where the element is about 1 1/4 wide and is not curved but boxed. The entire area gets heat so the acrylic doesn't have a fine bend.

Maybe I will make a V to channel the heat to a smaller area. Maybe bring it down to 1/2 inch.

[Pete Wood]

Pete,

I looked at that site and the only device I can find is Triform 180. Is this the device you use in your classes?

Hi Bob

Here is a picture of our line bender (and it is the same model as that in just about every school/college in the UK). It simply says CR Clarke, and is nowhere near as fancy as that currently sold by this company. It is a fairly heavy beast.....

http://www.technologystudent.com/equip1/striph1.htm

At one school, when our filament broke, and we were awaiting a replacement, I temporarily used a 1KW electric heater (turned on its side). It worked fine (disclaimer - for the benefit of PC members, children were not allowed to use this device).

It doesn't sound, judging by the 3-5 seconds you have before it cools, that it is reaching a high temperature. I have never timed it, but it feels as though you should have around 10+ seconds before it starts to 'set.' You're not working in an igloo are you...?? :)

I must confess though, that we don't usually bend anything thicker than about 6mm.

I do agree that the longer the filament has been on, the better/quicker it performs.

[Brian Robison]

This is a timely discussion for me. I made a heater from a strip according to Tap Plastics. It works good but I need to make sure that the heater doesn't touch the plastic. I'm ATTEMPTING to bend 3/8" thick acrylic, eight foot long and forty inches wide. Wish me luck. I think I'll draw a line, heat, flip after about 1 minute and see how that goes. BTW I cut some on the little 25 watt Mini and it did great! I was very impressed.

[Scott Shepherd]

I think it was in Engraver's Journal about 6-8 months ago, a great article about this exact topic. It showed the heaters, then the benders, it was very well written. Sad thing is that it even said in the article that the things shown are no longer available. I think it was a bender from Hermes, if I recall correctly. Super simple design, but no longer made :(