Picture of plexiglass bending

[cdnfthree2]

The pros offered a price of $150 for an 1/8" replacement of my cracked 1/4" CC windsheild. I found this piece of 1/4" so I felt I had nothing to lose but everything to gain by trying it on my own. So in truth, regardless of what you've been told, thick plexi can be bent 90 degrees nearly as sharply as 1/2" in radius. Just thought someone might find this useful.

Tips:
Don't get in a hurry. It takes a while to get the plexi ready.
When it's ready, It won't even give you the least bit of hesitation.

I used a 1/2" round-over bit on the edge of my jig and it helped alot in guiding the bend.

Rather than bend it by hand, pressure it with a block of wood like in the picture. Bending by hand causes the bend to start too far outside the edge of jig resulting in a window that is too wide when finished. Using a pressure block keeps it tight.

Finally, If your windshield is tapered, make these cuts after bending the plexi. Having an odd shaped piece of material may cause bend to helix or bend off axis.

 

[jcsercsa]

Re: Picture of plexiglass bending

very cool post cdnfthree2, I will remember that one !! John

 

[mthieme]

Re: Picture of plexiglass bending

Yes, excellent.
One of my neighbors has a cracked plexiglass windshield on his center console.
I'll pass this tidbit on.

 

[cdnfthree2]

Re: Picture of plexiglass bending

Thanks alot. I'll add that my heat gun only puts out 730-830*F. I kept it close and had no bubbles or discolorations.
It may take several minutes to heat well enough but when it finally does it remains soft and reatains heat across the working area well . Also, you need to hold it in place while cooling.

 

[tashasdaddy]

Re: Picture of plexiglass bending

nice job, i need to replace mine.

 

[cdnfthree2]

Re: Picture of plexiglass bending

Almost finished!!! Got the slope cut in on the sides this morning. It was too dark to finish last night. Waiting on a buddy with a torch to come and clean-melt the edges.

I have a little more advice for practical people. Plastic cutting blades are great for vynil siding but aren't neccessary and IMHO a waste of time and money for plexi. I used a table saw with a wood blade for the basic cuts and my circular saw for the sloped sides. I originally used a plastic cutting blade but it just wanted to bind up and walk the material away from the fence. I lost an 1/8" straightening up the mess the plastic cutting blade made.

 

[Darren Nemeth]

Re: Picture of plexiglass bending

I don't know if this will be of help but here is a site on making windshields.

http://www.glen-l.com/weblettr/webletters-5/wl43-windshield1.html

 

[oops!]

Re: Picture of plexiglass bending

i will allso add.....that to "glue" plexi glass....a liquid called meythil chloride is used....

it is sold any where that plexi glass is sold and its cheap....you will also need a small bottle "like an eye drop bottle".....with a syringe type needle sticking out of it......also readily avaliable at the plexi store......
less is more....a small drop will glue an entire edge as the viscosity is that of water.

thank you very much for the post......
ant the title will make it easy to search in the future.

cheers
oops

 

[Mark42]

Re: Picture of plexiglass bending

Thanks for documenting you work. This is valuable info.

 

[Ned L]

Re: Picture of plexiglass bending

I was going to comment on the differences in properties between Lexan (polycarbonate) & Plexiglas (acrylic), but just saw that it was covered on another thread.

 

[proshadetree]

Re: Picture of plexiglass bending

Anyone know if you can do a compound curve?I have one curved at the bottom and then curve across the width of boat.i assume it would thin out the first curve to make a different angle on it.

 

[Tim Frank]

Re: Picture of plexiglass bending

1) Best way of cutting plastics (and some soft metals) on a circular saw is to use a carbide blade, and mount it backwards.

2) What is, or how do you, "clear melt an edge"?

 

[erikgreen]

Re: Picture of plexiglass bending

It's AKA "flame polishing"... basically you use a high heat source near the edge to bring that little part of the plexi near melting temp, and surface tension pulls it into a smooth, clear edge. Nice, really.

....the more you know.

 

[DaveHawkins]

Re: Picture of plexiglass bending

For those of you that would prefer to use Polycarbonate (Lexan) instead of Plexi...you can cold-bend polycarbonate in a metal break without using a heat source. It's more expensive than plexi, but stronger (kinda like the comparison of poly vs/ epoxy resin ).

 

[Darren Nemeth]

Re: Picture of plexiglass bending

For those of you that would prefer to use Polycarbonate (Lexan) instead of Plexi...you can cold-bend polycarbonate in a metal break without using a heat source. It's more expensive than plexi, but stronger (kinda like the comparison of poly vs/ epoxy resin ).

When bending plexi or Lexan how does one prevent scratching?

 

[oops!]

Re: Picture of plexiglass bending

preventing scratching is really tough darren.......both plexi and lexxan are prone to it.....more so is lexxan......it really scratches easy even tho its tougher stuff.....thats why it has a plastic film over it, that is removed AFTER instlation.

to prevent scratching.....take all the caution in the world....


after you finish ....some scratches can be buffed out with a polishing compound supplied by the plexi glass stores.

 

[Tim Frank]

Re: Picture of plexiglass bending

It's AKA "flame polishing"... basically you use a high heat source near the edge to bring that little part of the plexi near melting temp, and surface tension pulls it into a smooth, clear edge. Nice, really.

....the more you know.

How good do you have to be to get a consistent result on that much edge?
I have polished plastic edges with progressively finer abrasives with good results, but this sounds like an interesting option.
Is a hand-held propane torch enough?

 

[cdnfthree2]

Re: Picture of plexiglass bending

Yes, That's what I used and ot worked fine (Propane). Just keep a steady hand and keep it moving slowly. Your right though, sanding is just fine and look good to. Melting it give it a kind of a mild rounded buillnose.

 

[cdnfthree2]

Re: Picture of plexiglass bending

1) Best way of cutting plastics (and some soft metals) on a circular saw is to use a carbide blade, and mount it backwards.QUOTE]

Tim, I'd agree with you in about 90% of applications when cutting plastics because the reversed blade helps prevent chipping or shattering. But, on thick plexiglass I'd only make sure that my blade is sharp and leave it in normal rotation. The reason I say this is with the blade reversed it slows the cut. When the cut slows, things heat up. When things head up, bad cuts are likely to occur. I used to build
ALOT of plexiglass porches at RV parks and as a result, I've ripped alot of plastics. Again, I'd agree 90% of the time.

 

[Tim Frank]

Re: Picture of plexiglass bending

Re-read your original post and saw that you are talking about 1/4" plexi.
I've never cut plastic that thick.
1/8" and less it works great, and for vinyl siding and aluminum soffit and fascia it is slick.
I did my last 2 houses in vinyl and went to buy a "special" vinyl blade at the siding store.....They wanted $20- for a $10- plywood blade that they had simply marked for "reverse rotation"....
Bit of a scam.