×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Copying a windshield

Copying a windshield

Copying a windshield

(OP)
Hi, I have a cracked windshield and been wanting to copy it so that I would have a new one.

I tried to mold plexiglass over it with a heat gun... very hard work and always ugly.

I tried to make a ciment mold that would be raised to high temp and then mold the fiberglass with a heat gun on it... very hard work and still ugly.

I'm thinking about making my next windshield with fiberglass (I don't care if it's painted).

In an ideal world I would have one of those machines that heats the fiberglass and then mold it, but I don't. Any ideas ?

BeerBaron

RE: Copying a windshield

I have made medium sized polycarbonate canopies for my quarter scale radio controlled sailplanes using a home made vacuum forming mold.  It would take a lot more  work to make a motorcycle windscreen...but still doable.
Any modeler magazine, Google, etc. will yield a variety of plans.  A trip to a hobby shop to look over the commercially available ones (too small) should give you an idea how to uprate their design.  
If the windscreen is that bad, why not buy a new one.  It will be a whole bunch cheaper than making your own.

Rod

RE: Copying a windshield

(OP)
I know, but the principle of making my own mold will be quite usefull for some other projects I have. Making a windshield is kinda my road test.

BeerBaron

RE: Copying a windshield

(OP)
By the way evelrod, how did you mold polycarbonate, I was told polycarbonate needed a 12 hour drying phase to get rid of the moisture? Is polycarbonate's flashpoint as high as acrylique ?

Thanks
BeerBaron

RE: Copying a windshield

The parts I made were from very thin sheets of Lexan and I did not know there was a problem until just now!  Ignorance is bliss.

Rod

RE: Copying a windshield

Perhaps you could heat a sheet of acrylic in a pizza oven. Know a buddy who works in a pizza place?

RE: Copying a windshield

The trick to molding and forming plastic sheet, whether acrylic or polycarbonate, is close control of the temperature, and patience.  

It takes a loooong time to heat all the way through a sheet of plastic because its thermal conductivity is very poor.  If you want to drape form it, you need to ramp the temperature up to near the softening temperature over a period of hours.  Tens of hours are better.  If you want the plastic to come out without locked in stresses that can cause cracking and optical effects, the temperature should also be ramped down, over tens of hours.  Vacuum assist can make the forming happen faster and at a lower temperature, but you stll need a ramping temperature controller for best results.

Heat guns and pizza ovens are way too crude.

Mike Halloran
Pembroke Pines, FL, USA

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close